using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Runtime.InteropServices;

namespace StgSharp.Graphics
{  
    public  partial class gl
    {
        
        /// <summary>
        /// bind a named texture to a texturing target.
        /// </summary>
        /// <param name="target">
        /// <para>Specifies the target to which the texture is bound. </para> 
        /// <para> Must be either GL_TEXTURE_1D, GL_TEXTURE_2D, GL_TEXTURE_3D, or GL_TEXTURE_CUBE_MAP.</para> 
        /// </param>
        /// <param name="texture">
        /// Specifies the name of a texture. 
        /// </param>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glBindTexture", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void BindTexture(uint target, uint texture);


        /// <summary>
        /// specify pixel arithmetic.
        /// </summary>
        /// <param name="sfactor">
        /// <para>Specifies how the red, green, blue, and alpha source blending factors are computed.</para> 
        /// <para>The following symbolic constants are accepted:</para> 
        /// <para>GL_ZERO, GL_ONE, GL_SRC_COLOR, GL_ONE_MINUS_SRC_COLOR, GL_DST_COLOR, GL_ONE_MINUS_DST_COLOR, GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA,</para> 
        /// <para>GL_DST_ALPHA, GL_ONE_MINUS_DST_ALPHA, GL_CONSTANT_COLOR,GL_ONE_MINUS_CONSTANT_COLOR, GL_CONSTANT_ALPHA, GL_ONE_MINUS_CONSTANT_ALPHA, and GL_SRC_ALPHA_SATURATE.</para> 
        /// <para> The initial value is GL_ONE. </para> 
        /// </param>
        /// <param name="dfactor">
        /// <para>Specifies how the red, green, blue, and alpha destination blending factors are computed.</para> 
        /// <para> The following symbolic constants are accepted: GL_ZERO, GL_ONE, GL_SRC_COLOR, GL_ONE_MINUS_SRC_COLOR,</para> 
        /// <para>GL_DST_COLOR, GL_ONE_MINUS_DST_COLOR, GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA, GL_DST_ALPHA, GL_ONE_MINUS_DST_ALPHA.</para> 
        /// <para>GL_CONSTANT_COLOR, GL_ONE_MINUS_CONSTANT_COLOR, GL_CONSTANT_ALPHA, and GL_ONE_MINUS_CONSTANT_ALPHA.</para> 
        /// <para>The initial value is GL_ZERO. </para> 
        /// </param>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glBlendFunc", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void BlendFunc(uint sfactor, uint dfactor);

        /// <summary>
        /// clear buffers to preset values.
        /// </summary>
        /// <param name="mask">
        /// <para> Bitwise OR of masks that indicate the buffers to be cleared.</para> 
        /// <para>The four masks are GL_COLOR_BUFFER_BIT, GL_DEPTH_BUFFER_BIT, GL_ACCUM_BUFFER_BIT,and GL_STENCIL_BUFFER_BIT.</para>  
        /// </param>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glClear", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void Clear(uint mask);

        /// <summary>
        /// specify clear values for the color buffers.
        /// </summary>
        /// <param name="red">
        /// Specify the red value used when the color buffers are cleared. The initial value is 0. 
        /// </param>
        /// <param name="green">
        /// Specify the green value used when the color buffers are cleared. The initial value is 0. 
        /// </param>
        /// <param name="blue">
        /// Specify the  blue value used when the color buffers are cleared. The initial value is 0. 
        /// </param>
        /// <param name="alpha">
        /// Specify the  alpha value used when the color buffers are cleared. The initial value is 0. 
        /// </param>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glClearColor", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void ClearColor(float red, float green, float blue, float alpha);

        /// <summary>
        /// specify the clear value for the depth buffer.
        /// </summary>
        /// <param name="depth">
        /// Specifies the depth value used when the depth buffer is cleared. The initial value is 1.
        /// </param>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glClearDepth", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void ClearDepth(double depth);

        /// <summary>
        /// specify the clear value for the stencil buffer.
        /// </summary>
        /// <param name="s">
        /// Specifies the index used when the stencil buffer is cleared. The initial value is 0. 
        /// </param>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glClearStencil", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void ClearStencil(int s);       

        /// <summary>
        ///  enable and disable writing of frame buffer color components.
        /// </summary>
        /// <param name="red">
        /// <para>Specify whether red can or cannot be written into the frame buffer. The initial value is  GL_TRUE, </para> 
        /// <para> indicating that the color component can be written. </para> 
        /// </param>
        /// <param name="green">
        /// <para> Specify whether green can or cannot be written into the frame buffer. The initial value is  GL_TRUE, </para> 
        /// <para>indicating that the color component can be written. </para> 
        /// </param>
        /// <param name="blue">
        /// <para>Specify whether blue can or cannot be written into the frame buffer. The initial value is  GL_TRUE, </para> 
        /// <para>indicating that the color component can be written. </para> 
        /// </param>
        /// <param name="alpha">
        /// <para>Specify whether alpha can or cannot be written into the frame buffer. The initial value is  GL_TRUE, </para> 
        /// <para>indicating that the color component can be written. </para> 
        /// </param>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glColorMask", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void ColorMask(bool red, bool green, bool blue, bool alpha);

        /// <summary>
        /// copy pixels into a 1D texture image.
        /// </summary>
        /// <param name="target">
        /// Specifies the target texture. Must be GL_TEXTURE_1D. 
        /// </param>
        /// <param name="level">
        /// <para> Specifies the level-of-detail number. Level 0 is the base image level.</para> 
        /// <para> Level n is the nth mipmap reduction image. </para> 
        /// </param>
        /// <param name="internalFormat">
        /// <para>Specifies the internal format of the texture.</para> 
        /// <para>Must be one of the following symbolic constants: </para> 
        /// <para>GL_ALPHA, GL_ALPHA4, GL_ALPHA8, GL_ALPHA12, GL_ALPHA16, GL_COMPRESSED_ALPHA, GL_COMPRESSED_LUMINANCE, GL_COMPRESSED_LUMINANCE_ALPHA, GL_COMPRESSED_INTENSITY,</para>  
        /// <para> GL_COMPRESSED_RGB, GL_COMPRESSED_RGBA, GL_DEPTH_COMPONENT, GL_DEPTH_COMPONENT16,GL_DEPTH_COMPONENT24, GL_DEPTH_COMPONENT32, GL_LUMINANCE, GL_LUMINANCE4, GL_LUMINANCE8,</para> 
        /// <para>GL_LUMINANCE12, GL_LUMINANCE16, GL_LUMINANCE_ALPHA, GL_LUMINANCE4_ALPHA4, GL_LUMINANCE6_ALPHA2,GL_LUMINANCE8_ALPHA8, GL_LUMINANCE12_ALPHA4, GL_LUMINANCE12_ALPHA12, GL_LUMINANCE16_ALPHA16, </para> 
        /// <para>GL_INTENSITY, GL_INTENSITY4, GL_INTENSITY8, GL_INTENSITY12, GL_INTENSITY16, GL_RGB, GL_R3_G3_B2,GL_RGB4, GL_RGB5, GL_RGB8, GL_RGB10, GL_RGB12, GL_RGB16, GL_RGBA, GL_RGBA2, GL_RGBA4, GL_RGB5_A1, </para> 
        /// <para> GL_RGBA8, GL_RGB10_A2, GL_RGBA12, GL_RGBA16, GL_SLUMINANCE, GL_SLUMINANCE8, GL_SLUMINANCE_ALPHA, GL_SLUMINANCE8_ALPHA8, GL_SRGB, GL_SRGB8, GL_SRGB_ALPHA, or GL_SRGB8_ALPHA8. </para> 
        /// </param>
        /// <param name="x">
        /// Specify the window coordinates of the left corner of the row of pixels to be copied. 
        /// </param>
        /// <param name="y">
        /// Specify the window coordinates of the left corner of the row of pixels to be copied. 
        /// </param>
        /// <param name="width">
        /// <para> Specifies the width of the texture image. Must be 0 or 2^n+2(border) for some integer n. </para> 
        /// <para>The height of the texture image is 1. </para> 
        /// </param>
        /// <param name="border">
        /// Specifies the width of the border. Must be either 0 or 1. 
        /// </param>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glCopyTexImage1D", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void CopyTexImage1D(uint target, int level, uint internalFormat, int x, int y, int width, int border);

        /// <summary>
        /// copy pixels into a 2D texture image.
        /// </summary>
        /// <param name="target">
        /// <para>Specifies the target texture. </para> 
        /// <para>Must be GL_TEXTURE_2D, GL_TEXTURE_CUBE_MAP_POSITIVE_X, GL_TEXTURE_CUBE_MAP_NEGATIVE_X,</para> 
        /// <para>GL_TEXTURE_CUBE_MAP_POSITIVE_Y, GL_TEXTURE_CUBE_MAP_NEGATIVE_Y, GL_TEXTURE_CUBE_MAP_POSITIVE_Z, or GL_TEXTURE_CUBE_MAP_NEGATIVE_Z. </para> 
        /// </param>
        /// <param name="level">
        /// <para>Specifies the level-of-detail number. Level 0 is the base image level.</para> 
        /// <para>Level n is the nth mipmap reduction image. </para> 
        /// </param>
        /// <param name="internalFormat">
        /// <para>Specifies the internal format of the texture. </para> 
        /// <para>Must be one of the following symbolic constants: </para> 
        /// <para> GL_ALPHA, GL_ALPHA4, GL_ALPHA8, GL_ALPHA12, GL_ALPHA16, GL_COMPRESSED_ALPHA,GL_COMPRESSED_LUMINANCE, GL_COMPRESSED_LUMINANCE_ALPHA, GL_COMPRESSED_INTENSITY, </para> 
        /// <para>GL_COMPRESSED_RGB, GL_COMPRESSED_RGBA, GL_DEPTH_COMPONENT, GL_DEPTH_COMPONENT16,GL_DEPTH_COMPONENT24, GL_DEPTH_COMPONENT32, GL_LUMINANCE, GL_LUMINANCE4, GL_LUMINANCE8, </para> 
        /// <para>GL_LUMINANCE12, GL_LUMINANCE16, GL_LUMINANCE_ALPHA, GL_LUMINANCE4_ALPHA4, GL_LUMINANCE6_ALPHA2,GL_LUMINANCE8_ALPHA8, GL_LUMINANCE12_ALPHA4, GL_LUMINANCE12_ALPHA12, GL_LUMINANCE16_ALPHA16,</para> 
        /// <para>GL_INTENSITY, GL_INTENSITY4, GL_INTENSITY8, GL_INTENSITY12, GL_INTENSITY16, GL_RGB, GL_R3_G3_B2,GL_RGB4, GL_RGB5, GL_RGB8, GL_RGB10, GL_RGB12, GL_RGB16, GL_RGBA, GL_RGBA2, GL_RGBA4, GL_RGB5_A1,</para>  
        /// <para> GL_RGBA8, GL_RGB10_A2, GL_RGBA12, GL_RGBA16, GL_SLUMINANCE, GL_SLUMINANCE8, GL_SLUMINANCE_ALPHA,GL_SLUMINANCE8_ALPHA8, GL_SRGB, GL_SRGB8, GL_SRGB_ALPHA, or GL_SRGB8_ALPHA8. </para> 
        /// </param>
        /// <param name="x">
        /// Specify the window coordinates of the lower left corner of the rectangular region of pixels to be copied.
        /// </param>
        /// <param name="y">
        /// Specify the window coordinates of the lower left corner of the rectangular region of pixels to be copied.
        /// </param>
        /// <param name="width">
        /// Specifies the width of the texture image. Must be 0 or 2^n+2(border) for some integer n. 
        /// </param>
        /// <param name="height">
        /// Specifies the height of the texture image. Must be 0 or 2^m+2(border) for some integer m. 
        /// </param>
        /// <param name="border">
        /// Specifies the width of the border. Must be either 0 or 1. 
        /// </param>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glCopyTexImage2D", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void CopyTexImage2D(uint target, int level, uint internalFormat, int x, int y, int width, int height, int border);

        /// <summary>
        /// copy a one-dimensional texture subimage.
        /// </summary>
        /// <param name="target">
        /// Specifies the target texture. Must be GL_TEXTURE_1D. 
        /// </param>
        /// <param name="level">
        /// <para>Specifies the level-of-detail number. Level 0 is the base image level.</para> 
        /// <para>Level n is the nth mipmap reduction image. </para> 
        /// </param>
        /// <param name="xoffset">
        /// Specifies the texel offset within the texture array. 
        /// </param>
        /// <param name="x">
        /// Specify the window coordinates of the left corner of the row of pixels to be copied. 
        /// </param>
        /// <param name="y">
        /// Specify the window coordinates of the left corner of the row of pixels to be copied. 
        /// </param>
        /// <param name="width">
        /// Specifies the width of the texture subimage. 
        /// </param>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glCopyTexSubImage1D", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void CopyTexSubImage1D(uint target, int level, int xoffset, int x, int y, int width);

        /// <summary>
        /// copy a two-dimensional texture subimage.
        /// </summary>
        /// <param name="target">
        /// <para>Specifies the target texture. </para> 
        /// <para>Must be GL_TEXTURE_2D, GL_TEXTURE_CUBE_MAP_POSITIVE_X, GL_TEXTURE_CUBE_MAP_NEGATIVE_X,</para> 
        /// <para>GL_TEXTURE_CUBE_MAP_POSITIVE_Y, GL_TEXTURE_CUBE_MAP_NEGATIVE_Y, GL_TEXTURE_CUBE_MAP_POSITIVE_Z,or GL_TEXTURE_CUBE_MAP_NEGATIVE_Z. </para> 
        /// </param>
        /// <param name="level">
        /// <para>Specifies the level-of-detail number. Level 0 is the base image level.</para> 
        /// <para>Level n is the nth mipmap reduction image. </para> 
        /// </param>
        /// <param name="xoffset">
        /// Specifies a texel offset in the x direction within the texture array. 
        /// </param>
        /// <param name="yoffset">
        /// Specifies a texel offset in the y direction within the texture array. 
        /// </param>
        /// <param name="x">
        /// Specify the window coordinates of the lower left corner of the rectangular region of pixels to be copied.
        /// </param>
        /// <param name="y">
        /// Specify the window coordinates of the lower left corner of the rectangular region of pixels to be copied.
        /// </param>
        /// <param name="width">
        /// Specifies the width of the texture subimage. 
        /// </param>
        /// <param name="height">
        /// Specifies the height of the texture subimage. 
        /// </param>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glCopyTexSubImage2D", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void CopyTexSubImage2D(uint target, int level, int xoffset, int yoffset, int x, int y, int width, int height);

        /// <summary>
        /// specify whether front- or back-facing facets can be culled.
        /// </summary>
        /// <param name="mode">
        /// <para>Specifies whether front- or back-facing facets are candidates for culling. </para> 
        /// <para>Symbolic constants GL_FRONT, GL_BACK, and GL_FRONT_AND_BACK are accepted. </para> 
        /// <para>The initial value is GL_BACK. </para>
        /// </param>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glCullFace", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void CullFace(uint mode);

        /// <summary>
        /// delete named textures.
        /// </summary>
        /// <param name="n">
        /// Specifies the number of textures to be deleted.
        /// </param>
        /// <param name="textures">
        /// Specifies an array of textures to be deleted. 
        /// </param>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glDeleteTextures", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void DeleteTextures(int n, uint[] textures);

        /// <summary>
        /// specify the value used for depth buffer comparisons.
        /// </summary>
        /// <param name="func">
        /// <para>Specifies the depth comparison function. </para> 
        /// <para>Symbolic constants GL_NEVER, GL_LESS, GL_EQUAL, GL_LEQUAL, GL_GREATER, GL_NOTEQUAL, GL_GEQUAL, </para> 
        /// <para>and GL_ALWAYS are accepted. The initial value is GL_LESS. </para> 
        /// </param>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glDepthFunc", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void DepthFunc(uint func);

        /// <summary>
        /// enable or disable writing into the depth buffer.
        /// </summary>
        /// <param name="flag">
        /// <para>Specifies whether the depth buffer is enabled for writing. </para> 
        /// <para>If flag is GL_FALSE, depth buffer writing is disabled. Otherwise, it is enabled.</para> 
        /// <para>Initially, depth buffer writing is enabled. </para> 
        /// </param>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glDepthMask", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void DepthMask(bool flag);

        /// <summary>
        /// specify mapping of depth values from normalized device coordinates to window coordinates.
        /// </summary>
        /// <param name="zNear">
        /// Specifies the mapping of the near clipping plane to window coordinates. The initial value is 0. 
        /// </param>
        /// <param name="zFar">
        /// Specifies the mapping of the far clipping plane to window coordinates. The initial value is 1.
        /// </param>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glDepthRange", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void DepthRange(double zNear, double zFar);

        /// <summary>
        /// disable server-side GL capabilities.
        /// </summary>
        /// <param name="cap">
        /// Specifies a symbolic constant indicating a GL capability.
        /// </param>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glDisable", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void Disable(uint cap);

        /// <summary>
        /// render primitives from array data.
        /// </summary>
        /// <param name="mode">
        /// <para>Specifies what kind of primitives to render. </para> 
        /// <para>Symbolic constants GL_POINTS, GL_LINE_STRIP, GL_LINE_LOOP, GL_LINES, GL_TRIANGLE_STRIP,</para> 
        /// <para>GL_TRIANGLE_FAN, GL_TRIANGLES, GL_QUAD_STRIP, GL_QUADS, and GL_POLYGON are accepted</para> 
        /// </param>
        /// <param name="first">
        /// Specifies the starting index in the enabled arrays. 
        /// </param>
        /// <param name="count">
        /// Specifies the number of indices to be rendered. 
        /// </param>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glDrawArrays", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void DrawArrays(uint mode, int first, int count);

        /// <summary>
        /// specify which color buffers are to be drawn into.
        /// </summary>
        /// <param name="mode">
        /// <para>Specifies up to four color buffers to be drawn into.</para> 
        /// <para>Symbolic constants GL_NONE, GL_FRONT_LEFT, GL_FRONT_RIGHT, GL_BACK_LEFT, GL_BACK_RIGHT, GL_FRONT, GL_BACK, GL_LEFT, GL_RIGHT, GL_FRONT_AND_BACK,</para>  
        /// <para>and GL_AUXi, where i is between 0 and the value of GL_AUX_BUFFERS minus 1, are accepted.</para> 
        /// </param>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glDrawBuffer", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void DrawBuffer(uint mode);

        /// <summary>
        /// render primitives from array data.
        /// </summary>
        /// <param name="mode">
        /// <para>Specifies what kind of primitives to render. </para> 
        /// <para>Symbolic constants GL_POINTS, GL_LINE_STRIP, GL_LINE_LOOP, GL_LINES,GL_TRIANGLE_STRIP, GL_TRIANGLE_FAN, GL_TRIANGLES, GL_QUAD_STRIP, GL_QUADS, and GL_POLYGON are accepted. </para> 
        /// </param>
        /// <param name="count">
        /// Specifies the number of elements to be rendered.
        /// </param>
        /// <param name="type">
        /// <para>Specifies the type of the values in indices.</para> 
        /// <para>Must be one of GL_UNSIGNED_BYTE, GL_UNSIGNED_SHORT, or GL_UNSIGNED_INT. </para> 
        /// </param>
        /// <param name="indices">
        /// <para>Specifies a pointer to the location where the indices are stored. </para> 
        /// <para>please using the function glaux.ArrayToPointer to get array pointer.</para> 
        /// </param>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glDrawElements", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void DrawElements(uint mode, int count, uint type,  IntPtr indices);

        /// <summary>
        /// enable server-side GL capabilities
        /// </summary>
        /// <param name="cap">
        /// Specifies a symbolic constant indicating a GL capability. 
        /// </param>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glEnable", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void Enable(uint cap);

        /// <summary>
        /// block until all GL execution is complete.
        /// </summary>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glFinish", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void Finish();

        /// <summary>
        /// force execution of GL commands in finite time
        /// </summary>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glFlush", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void Flush();

        /// <summary>
        /// define front- and back-facing polygons.
        /// </summary>
        /// <param name="mode">
        /// <para>Specifies the orientation of front-facing polygons. GL_CW and GL_CCW are accepted.</para> 
        /// <para>The initial value is GL_CCW.</para> 
        /// </param>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glFrontFace", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void FrontFace(uint mode);

        /// <summary>
        /// generate texture names.
        /// </summary>
        /// <param name="n">
        /// Specifies the number of texture names to be generated. 
        /// </param>
        /// <param name="textures">
        /// Specifies an array in which the generated texture names are stored. 
        /// </param>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glGenTextures", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void GenTextures(int n, uint[] textures);

        /// <summary>
        /// return the value or values of a selected parameter
        /// </summary>
        /// <param name="pname">
        /// <para>Specifies the parameter value to be returned. </para> 
        /// <para>The symbolic constants in the list below are accepted. </para> 
        /// </param>
        /// <param name="Params">
        /// Returns the value or values of the specified parameter.
        /// </param>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glGetBooleanv", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void GetBoolean(uint pname, bool[] Params);

        /// <summary>
        /// return the value or values of a selected parameter.
        /// </summary>
        /// <param name="pname">
        /// Specifies the parameter value to be returned. The symbolic constants in the list below are accepted. 
        /// </param>
        /// <param name="Params">
        /// Returns the value or values of the specified parameter. 
        /// </param>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glGetDoublev", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void GetDouble(uint pname, double[] Params);

        /// <summary>
        /// return error information.
        /// </summary>
        /// <returns>
        /// returns the value of the error flag.
        /// </returns>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glGetError", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern uint GetError();

        /// <summary>
        /// return the value or values of a selected parameter.
        /// </summary>
        /// <param name="pname">
        /// Specifies the parameter value to be returned. The symbolic constants in the list below are accepted. 
        /// </param>
        /// <param name="Params">
        /// Returns the value or values of the specified parameter. 
        /// </param>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glGetFloatv", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void GetFloat(uint pname, float[] Params);

        /// <summary>
        /// return the value or values of a selected parameter.
        /// </summary>
        /// <param name="pname">
        /// Specifies the parameter value to be returned. The symbolic constants in the list below are accepted. 
        /// </param>
        /// <param name="Params">
        /// Returns the value or values of the specified parameter. 
        /// </param>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glGetIntegerv", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void GetInteger(uint pname, int[] Params);

        /// <summary>
        /// return the address of the specified pointer.
        /// </summary>
        /// <param name="pname">
        /// <para>Specifies the array or buffer pointer to be returned.</para> 
        /// <para>Symbolic constants GL_COLOR_ARRAY_POINTER, GL_EDGE_FLAG_ARRAY_POINTER, GL_FOG_COORD_ARRAY_POINTER, </para> 
        /// <para>GL_FEEDBACK_BUFFER_POINTER, GL_INDEX_ARRAY_POINTER, GL_NORMAL_ARRAY_POINTER, </para> 
        /// <para>GL_SECONDARY_COLOR_ARRAY_POINTER, GL_SELECTION_BUFFER_POINTER, GL_TEXTURE_COORD_ARRAY_POINTER,or GL_VERTEX_ARRAY_POINTER are accepted. </para> 
        /// </param>
        /// <param name="Params">
        /// Returns the pointer value specified by pname. 
        /// </param>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glGetPointerv", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void GetPointer(uint pname, IntPtr[] Params);

        /// <summary>
        /// return a string describing the current GL connection.
        /// </summary>
        /// <param name="name">
        /// <para>Specifies a symbolic constant, one of GL_VENDOR, GL_RENDERER, GL_VERSION, GL_SHADING_LANGUAGE_VERSION,or GL_EXTENSIONS. </para>
        /// </param>
        /// <returns></returns>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glGetString", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern IntPtr GetString(uint name);


        /// <summary>
        /// return a texture image
        /// </summary>
        /// <param name="target">
        /// <para>Specifies which texture is to be obtained.</para> 
        /// <para>GL_TEXTURE_1D, GL_TEXTURE_2D, GL_TEXTURE_3D, GL_TEXTURE_CUBE_MAP_POSITIVE_X, </para> 
        /// <para>GL_TEXTURE_CUBE_MAP_NEGATIVE_X, GL_TEXTURE_CUBE_MAP_POSITIVE_Y, GL_TEXTURE_CUBE_MAP_NEGATIVE_Y, </para> 
        /// <para>GL_TEXTURE_CUBE_MAP_POSITIVE_Z, and GL_TEXTURE_CUBE_MAP_NEGATIVE_Z are accepted. </para> 
        /// </param>
        /// <param name="level">
        /// <para>Specifies the level-of-detail number of the desired image. Level 0 is the base image level. </para> 
        /// <para>Level n is the nth mipmap reduction image.</para> 
        /// </param>
        /// <param name="format">
        /// <para>Specifies a pixel format for the returned data. </para> 
        /// <para>The supported formats are GL_RED, GL_GREEN, GL_BLUE, GL_ALPHA, GL_RGB, GL_BGR, GL_RGBA, GL_BGRA,</para> 
        /// <para>GL_LUMINANCE, and GL_LUMINANCE_ALPHA. </para> 
        /// </param>
        /// <param name="type">
        /// <para>Specifies a pixel type for the returned data. </para> 
        /// <para>The supported types are GL_UNSIGNED_BYTE, GL_BYTE, GL_UNSIGNED_SHORT, GL_SHORT, GL_UNSIGNED_INT, </para> 
        /// <para>GL_INT, GL_FLOAT, GL_UNSIGNED_BYTE_3_3_2, GL_UNSIGNED_BYTE_2_3_3_REV, GL_UNSIGNED_SHORT_5_6_5,</para> 
        /// <para>GL_UNSIGNED_SHORT_5_6_5_REV, GL_UNSIGNED_SHORT_4_4_4_4, GL_UNSIGNED_SHORT_4_4_4_4_REV,</para> 
        /// <para>GL_UNSIGNED_SHORT_5_5_5_1, GL_UNSIGNED_SHORT_1_5_5_5_REV, GL_UNSIGNED_INT_8_8_8_8, </para> 
        /// <para>GL_UNSIGNED_INT_8_8_8_8_REV, GL_UNSIGNED_INT_10_10_10_2, and GL_UNSIGNED_INT_2_10_10_10_REV. </para> 
        /// </param>
        /// <param name="pixels">
        /// <para> Returns the texture image. Should be a pointer to an array of the type specified by type.</para> 
        /// <para> You can use the function glaux.ArrayToPointer to get the array pointer.</para> 
        /// </param>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glGetTexImage", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void GetTexImage(uint target, int level, uint format, uint type, IntPtr pixels);

        /// <summary>
        /// Returns the texture image. Should be a pointer to an array of the type specified by type.
        /// </summary>
        /// <param name="target">
        /// <para>Specifies the symbolic name of the target texture, either GL_TEXTURE_1D, GL_TEXTURE_2D,</para> 
        /// <para>GL_TEXTURE_3D, GL_PROXY_TEXTURE_1D, GL_PROXY_TEXTURE_2D, GL_PROXY_TEXTURE_3D, </para> 
        /// <para>GL_TEXTURE_CUBE_MAP_POSITIVE_X, GL_TEXTURE_CUBE_MAP_NEGATIVE_X, GL_TEXTURE_CUBE_MAP_POSITIVE_Y,</para> 
        /// <para>GL_TEXTURE_CUBE_MAP_NEGATIVE_Y, GL_TEXTURE_CUBE_MAP_POSITIVE_Z, GL_TEXTURE_CUBE_MAP_NEGATIVE_Z, or GL_PROXY_TEXTURE_CUBE_MAP. </para> 
        /// </param>
        /// <param name="level">
        /// <para>Specifies the level-of-detail number of the desired image.</para> 
        /// <para>Level 0 is the base image level. Level n is the nth mipmap reduction image. </para> 
        /// </param>
        /// <param name="pname">
        /// <para>Specifies the symbolic name of a texture parameter.</para> 
        /// <para>GL_TEXTURE_WIDTH, GL_TEXTURE_HEIGHT, GL_TEXTURE_DEPTH, GL_TEXTURE_INTERNAL_FORMAT,</para> 
        /// <para>GL_TEXTURE_BORDER, GL_TEXTURE_RED_SIZE, GL_TEXTURE_GREEN_SIZE, GL_TEXTURE_BLUE_SIZE, </para> 
        /// <para>GL_TEXTURE_ALPHA_SIZE, GL_TEXTURE_LUMINANCE_SIZE, GL_TEXTURE_INTENSITY_SIZE, GL_TEXTURE_DEPTH_SIZE,</para> 
        /// <para>GL_TEXTURE_COMPRESSED, and GL_TEXTURE_COMPRESSED_IMAGE_SIZE are accepted. </para> 
        /// </param>
        /// <param name="Params">
        /// Returns the requested data. 
        /// </param>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glGetTexLevelParameterfv", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void GetTexLevelParameter(uint target, int level, uint pname, float[] Params);

        /// <summary>
        /// Returns the texture image. Should be a pointer to an array of the type specified by type.
        /// </summary>
        /// <param name="target">
        /// <para>Specifies the symbolic name of the target texture, either GL_TEXTURE_1D, GL_TEXTURE_2D,</para> 
        /// <para>GL_TEXTURE_3D, GL_PROXY_TEXTURE_1D, GL_PROXY_TEXTURE_2D, GL_PROXY_TEXTURE_3D, </para> 
        /// <para>GL_TEXTURE_CUBE_MAP_POSITIVE_X, GL_TEXTURE_CUBE_MAP_NEGATIVE_X, GL_TEXTURE_CUBE_MAP_POSITIVE_Y,</para> 
        /// <para>GL_TEXTURE_CUBE_MAP_NEGATIVE_Y, GL_TEXTURE_CUBE_MAP_POSITIVE_Z, GL_TEXTURE_CUBE_MAP_NEGATIVE_Z,or GL_PROXY_TEXTURE_CUBE_MAP. </para> 
        /// </param>
        /// <param name="level">
        /// <para>Specifies the level-of-detail number of the desired image.</para> 
        /// <para>Level 0 is the base image level. Level n is the nth mipmap reduction image. </para> 
        /// </param>
        /// <param name="pname">
        /// <para>Specifies the symbolic name of a texture parameter.</para> 
        /// <para>GL_TEXTURE_WIDTH, GL_TEXTURE_HEIGHT, GL_TEXTURE_DEPTH, GL_TEXTURE_INTERNAL_FORMAT,</para> 
        /// <para>GL_TEXTURE_BORDER, GL_TEXTURE_RED_SIZE, GL_TEXTURE_GREEN_SIZE, GL_TEXTURE_BLUE_SIZE</para> , 
        /// <para> GL_TEXTURE_ALPHA_SIZE, GL_TEXTURE_LUMINANCE_SIZE, GL_TEXTURE_INTENSITY_SIZE, GL_TEXTURE_DEPTH_SIZE,</para> 
        /// <para> GL_TEXTURE_COMPRESSED, and GL_TEXTURE_COMPRESSED_IMAGE_SIZE are accepted. </para> 
        /// </param>
        /// <param name="Params">
        /// Returns the requested data. 
        /// </param>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glGetTexLevelParameteriv", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void GetTexLevelParameter(uint target, int level, uint pname, int[] Params);

        /// <summary>
        /// return texture parameter values.
        /// </summary>
        /// <param name="target">
        /// <para>Specifies the symbolic name of the target texture. </para> 
        /// <para>GL_TEXTURE_1D, GL_TEXTURE_2D, GL_TEXTURE_3D, and GL_TEXTURE_CUBE_MAP are accepted. </para> 
        /// </param>
        /// <param name="pname">
        /// <para>Specifies the symbolic name of a texture parameter. </para> 
        /// <para>GL_TEXTURE_MAG_FILTER, GL_TEXTURE_MIN_FILTER, GL_TEXTURE_MIN_LOD, GL_TEXTURE_MAX_LOD,</para> 
        /// <para>GL_TEXTURE_BASE_LEVEL, GL_TEXTURE_MAX_LEVEL, GL_TEXTURE_WRAP_S, GL_TEXTURE_WRAP_T, </para> 
        /// <para>GL_TEXTURE_WRAP_R, GL_TEXTURE_BORDER_COLOR, GL_TEXTURE_PRIORITY, GL_TEXTURE_RESIDENT, </para> 
        /// <para>GL_TEXTURE_COMPARE_MODE, GL_TEXTURE_COMPARE_FUNC, GL_DEPTH_TEXTURE_MODE,and GL_GENERATE_MIPMAP are accepted. </para> 
        /// </param>
        /// <param name="Params">
        /// Returns the texture parameters.
        /// </param>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glGetTexParameterfv", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void GetTexParameter(uint target, uint pname, float[] Params);

        /// <summary>
        /// return texture parameter values.
        /// </summary>
        /// <param name="target">
        /// <para>Specifies the symbolic name of the target texture. </para> 
        /// <para>GL_TEXTURE_1D, GL_TEXTURE_2D, GL_TEXTURE_3D, and GL_TEXTURE_CUBE_MAP are accepted.</para>  
        /// </param>
        /// <param name="pname">
        /// <para>Specifies the symbolic name of a texture parameter. </para> 
        /// <para>GL_TEXTURE_MAG_FILTER, GL_TEXTURE_MIN_FILTER, GL_TEXTURE_MIN_LOD, GL_TEXTURE_MAX_LOD,</para> 
        /// <para>GL_TEXTURE_BASE_LEVEL, GL_TEXTURE_MAX_LEVEL, GL_TEXTURE_WRAP_S, GL_TEXTURE_WRAP_T, </para> 
        /// <para>GL_TEXTURE_WRAP_R, GL_TEXTURE_BORDER_COLOR, GL_TEXTURE_PRIORITY, GL_TEXTURE_RESIDENT, </para> 
        /// <para>GL_TEXTURE_COMPARE_MODE, GL_TEXTURE_COMPARE_FUNC, GL_DEPTH_TEXTURE_MODE,and GL_GENERATE_MIPMAP are accepted. </para> 
        /// </param>
        /// <param name="Params">
        /// Returns the texture parameters.
        /// </param>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glGetTexParameteriv", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void GetTexParameter(uint target, uint pname, int[] Params);

        /// <summary>
        /// specify implementation-specific hints.
        /// </summary>
        /// <param name="target">
        /// <para>Specifies a symbolic constant indicating the behavior to be controlled. </para> 
        /// <para>GL_FOG_HINT, GL_GENERATE_MIPMAP_HINT, GL_LINE_SMOOTH_HINT, GL_PERSPECTIVE_CORRECTION_HINT, </para> 
        /// <para>GL_POINT_SMOOTH_HINT, GL_POLYGON_SMOOTH_HINT, GL_TEXTURE_COMPRESSION_HINT,and GL_FRAGMENT_SHADER_DERIVATIVE_HINT are accepted. </para> 
        /// </param>
        /// <param name="mode">
        /// <para>Specifies a symbolic constant indicating the desired behavior.</para> 
        /// <para>GL_FASTEST, GL_NICEST, and GL_DONT_CARE are accepted. </para> 
        /// </param>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glHint", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void Hint(uint target, uint mode);

        /// <summary>
        /// test whether a capability is enabled
        /// </summary>
        /// <param name="cap">
        /// Specifies a symbolic constant indicating a GL capability. 
        /// </param>
        /// <returns>
        /// returns GL_TRUE if cap is an enabled capability and returns GL_FALSE otherwise.
        /// </returns>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glIsEnabled", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern bool IsEnabled(uint cap);

        /// <summary>
        /// determine if a name corresponds to a texture
        /// </summary>
        /// <param name="texture">
        /// Specifies a value that may be the name of a texture.
        /// </param>
        /// <returns>
        /// returns GL_TRUE if texture is currently the name of a texture.
        /// </returns>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glIsTexture", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern bool IsTexture(uint texture);

   

        /// <summary>
        /// specify the width of rasterized lines.
        /// </summary>
        /// <param name="width">
        /// Specifies the width of rasterized lines. The initial value is 1. 
        /// </param>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glLineWidth", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void LineWidth(float width);

        /// <summary>
        /// specify a logical pixel operation for color index rendering.
        /// </summary>
        /// <param name="opcode">
        /// <para>Specifies a symbolic constant that selects a logical operation. </para> 
        /// <para>The following symbols are accepted: GL_CLEAR, GL_SET, GL_COPY, GL_COPY_INVERTED, GL_NOOP, GL_INVERT,</para> 
        /// <para>GL_AND, GL_NAND, GL_OR, GL_NOR, GL_XOR, GL_EQUIV, GL_AND_REVERSE, GL_AND_INVERTED, GL_OR_REVERSE, </para> 
        /// <para>and GL_OR_INVERTED. The initial value is GL_COPY. </para> 
        /// </param>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glLogicOp", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void LogicOp(uint opcode);

      
        /// <summary>
        /// set pixel storage modes.
        /// </summary>
        /// <param name="pname">
        /// <para>Specifies the symbolic name of the parameter to be set.</para> 
        /// <para>Six values affect the packing of pixel data into memory: GL_PACK_SWAP_BYTES, GL_PACK_LSB_FIRST,</para>
        /// <para>GL_PACK_ROW_LENGTH, GL_PACK_IMAGE_HEIGHT, GL_PACK_SKIP_PIXELS, GL_PACK_SKIP_ROWS, GL_PACK_SKIP_IMAGES,</para>
        /// <para>and GL_PACK_ALIGNMENT. Six more affect the unpacking of pixel data from memory: GL_UNPACK_SWAP_BYTES,</para>
        /// <para>GL_UNPACK_LSB_FIRST, GL_UNPACK_ROW_LENGTH, GL_UNPACK_IMAGE_HEIGHT, GL_UNPACK_SKIP_PIXELS,GL_UNPACK_SKIP_ROWS, GL_UNPACK_SKIP_IMAGES, and GL_UNPACK_ALIGNMENT. </para>
        /// </param>
        /// <param name="param">
        /// Specifies the value that pname is set to. 
        /// </param>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glPixelStoref", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void PixelStore(uint pname, float param);

        /// <summary>
        /// set pixel storage modes.
        /// </summary>
        /// <param name="pname">
        /// <para>Specifies the symbolic name of the parameter to be set. </para>
        /// <para>Six values affect the packing of pixel data into memory: GL_PACK_SWAP_BYTES, GL_PACK_LSB_FIRST,</para>
        /// <para>GL_PACK_ROW_LENGTH, GL_PACK_IMAGE_HEIGHT, GL_PACK_SKIP_PIXELS, GL_PACK_SKIP_ROWS, GL_PACK_SKIP_IMAGES,</para>
        /// <para>and GL_PACK_ALIGNMENT. Six more affect the unpacking of pixel data from memory: GL_UNPACK_SWAP_BYTES,</para>
        /// <para>GL_UNPACK_LSB_FIRST, GL_UNPACK_ROW_LENGTH, GL_UNPACK_IMAGE_HEIGHT, GL_UNPACK_SKIP_PIXELS,</para>
        /// <para>GL_UNPACK_SKIP_ROWS, GL_UNPACK_SKIP_IMAGES, and GL_UNPACK_ALIGNMENT. </para>
        /// </param>
        /// <param name="param">
        /// Specifies the value that pname is set to. 
        /// </param>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glPixelStorei", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void PixelStore(uint pname, int param);

        /// <summary>
        /// specify the diameter of rasterized points.
        /// </summary>
        /// <param name="size">
        /// Specifies the diameter of rasterized points. The initial value is 1. 
        /// </param>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glPointSize", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void PointSize(float size);

        /// <summary>
        /// select a polygon rasterization mode.
        /// </summary>
        /// <param name="face">
        /// <para>Specifies the polygons that mode applies to.</para>
        /// <para>Must be GL_FRONT for front-facing polygons, GL_BACK for back-facing polygons,or GL_FRONT_AND_BACK for front- and back-facing polygons. </para>
        /// </param>
        /// <param name="mode">
        /// <para>Specifies how polygons will be rasterized. Accepted values are GL_POINT, GL_LINE, and GL_FILL. </para>
        /// <para>The initial value is GL_FILL for both front- and back-facing polygons. </para>
        /// </param>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glPolygonMode", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void PolygonMode(uint face, uint mode);

        /// <summary>
        /// set the scale and units used to calculate depth values.
        /// </summary>
        /// <param name="factor">
        /// <para>Specifies a scale factor that is used to create a variable depth offset for each polygon. </para>
        /// <para>The initial value is 0.</para>
        /// </param>
        /// <param name="units">
        /// <para>Is multiplied by an implementation-specific value to create a constant depth offset. </para>
        /// <para>The initial value is 0. </para>
        /// </param>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glPolygonOffset", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void PolygonOffset(float factor, float units);

        /// <summary>
        /// select a color buffer source for pixels.
        /// </summary>
        /// <param name="mode">
        /// <para>Specifies a color buffer. </para>
        /// <para>Accepted values are GL_FRONT_LEFT, GL_FRONT_RIGHT, GL_BACK_LEFT, GL_BACK_RIGHT, GL_FRONT,GL_BACK, GL_LEFT, GL_RIGHT, and GL_AUXi, where i is between 0 and the value of GL_AUX_BUFFERS minus 1. </para>
        /// </param>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glReadBuffer", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void ReadBuffer(uint mode);

        /// <summary>
        /// read a block of pixels from the frame buffer.
        /// </summary>
        /// <param name="x">
        /// <para>Specify the window coordinates of the first pixel that is read from the frame buffer. </para>
        /// <para>This location is the lower left corner of a rectangular block of pixels. </para>
        /// </param>
        /// <param name="y">
        /// <para>Specify the window coordinates of the first pixel that is read from the frame buffer.</para>
        /// <para>This location is the lower left corner of a rectangular block of pixels. </para>
        /// </param>
        /// <param name="width">
        /// Specify the dimensions of the pixel rectangle. width and height of one correspond to a single pixel. 
        /// </param>
        /// <param name="height">
        /// Specify the dimensions of the pixel rectangle. width and height of one correspond to a single pixel. 
        /// </param>
        /// <param name="format">
        /// <para>Specifies the format of the pixel data. </para>
        /// <para>The following symbolic values are accepted: GL_COLOR_INDEX, GL_STENCIL_INDEX, GL_DEPTH_COMPONENT, </para>
        /// <para>GL_RED, GL_GREEN, GL_BLUE, GL_ALPHA, GL_RGB, GL_BGR, GL_RGBA, GL_BGRA, GL_LUMINANCE, and GL_LUMINANCE_ALPHA. </para>
        /// </param>
        /// <param name="type">
        /// <para>Specifies the data type of the pixel data. </para>
        /// <para>Must be one of GL_UNSIGNED_BYTE, GL_BYTE, GL_BITMAP, GL_UNSIGNED_SHORT, GL_SHORT, GL_UNSIGNED_INT, </para>
        /// <para>GL_INT, GL_FLOAT, GL_UNSIGNED_BYTE_3_3_2, GL_UNSIGNED_BYTE_2_3_3_REV, GL_UNSIGNED_SHORT_5_6_5, </para>        
        /// <para>GL_UNSIGNED_SHORT_5_6_5_REV, GL_UNSIGNED_SHORT_4_4_4_4, GL_UNSIGNED_SHORT_4_4_4_4_REV,</para>
        /// <para>GL_UNSIGNED_SHORT_5_5_5_1, GL_UNSIGNED_SHORT_1_5_5_5_REV, GL_UNSIGNED_INT_8_8_8_8, </para>
        /// <para>GL_UNSIGNED_INT_8_8_8_8_REV, GL_UNSIGNED_INT_10_10_10_2, or GL_UNSIGNED_INT_2_10_10_10_REV. </para>
        /// </param>
        /// <param name="pixels">
        /// <para>Returns the pixel data. </para>
        /// <para>You can use the function glaux.ArrayToPointer to get the array pointer.</para>
        /// </param>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glReadPixels", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void ReadPixels(int x, int y, int width, int height, uint format, uint type, IntPtr pixels);

        /// <summary>
        /// define the scissor box.
        /// </summary>
        /// <param name="x">
        /// Specify the lower left corner of the scissor box. Initially (0, 0). 
        /// </param>
        /// <param name="y">
        /// Specify the lower left corner of the scissor box. Initially (0, 0). 
        /// </param>
        /// <param name="width">
        /// <para>Specify the width of the scissor box. </para>
        /// <para>When a GL context is first attached to a window, width and height are set to the dimensions of that window. </para>
        /// </param>
        /// <param name="height">
        /// Specify the height of the scissor box. When a GL context is first attached to a window, width and height are set to the dimensions of that window. 
        /// </param>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glScissor", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void Scissor(int x, int y, int width, int height);

        /// <summary>
        /// set front and back function and reference value for stencil testing.
        /// </summary>
        /// <param name="func">
        /// <para>Specifies the test function. </para>
        /// <para>Eight symbolic constants are valid: GL_NEVER, GL_LESS, GL_LEQUAL, GL_GREATER, GL_GEQUAL, </para>
        /// <para>GL_EQUAL, GL_NOTEQUAL, and GL_ALWAYS. The initial value is GL_ALWAYS. </para>
        /// </param>
        /// <param name="Ref">
        /// <para>Specifies the reference value for the stencil test. </para>
        /// <para>ref is clamped to the range [0,2n−1], where n is the number of bitplanes in the stencil buffer. </para>
        /// <para>The initial value is 0. </para>
        /// </param>
        /// <param name="mask">
        /// <para>Specifies a mask that is ANDed with both the reference value and the stored stencil value when the test is done.</para> 
        /// <para>The initial value is all 1's.</para>
        /// </param>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glStencilFunc", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void StencilFunc(uint func, int Ref, uint mask);

        /// <summary>
        /// control the front and back writing of individual bits in the stencil planes.
        /// </summary>
        /// <param name="mask">
        /// <para>Specifies a bit mask to enable and disable writing of individual bits in the stencil planes. </para>
        /// <para>Initially, the mask is all 1's.</para>
        /// </param>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glStencilMask", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void StencilMask(uint mask);

        /// <summary>
        /// set front and back stencil test actions.
        /// </summary>
        /// <param name="fail">
        /// <para>Specifies the action to take when the stencil test fails. </para>
        /// <para>Eight symbolic constants are accepted:</para>
        /// <para>GL_KEEP, GL_ZERO, GL_REPLACE, GL_INCR, GL_INCR_WRAP, GL_DECR, GL_DECR_WRAP, and GL_INVERT.</para>
        /// <para>The initial value is GL_KEEP. </para>
        /// </param>
        /// <param name="zfail">
        /// <para>Specifies the stencil action when the stencil test passes, but the depth test fails. </para>
        /// <para>dpfail accepts the same symbolic constants as sfail. The initial value is GL_KEEP. </para>
        /// </param>
        /// <param name="zpass">
        /// <para>Specifies the stencil action when both the stencil test and the depth test pass, </para>
        /// <para>or when the stencil test passes and either there is no depth buffer or depth testing is not enabled. </para>
        /// <para>dppass accepts the same symbolic constants as sfail. The initial value is GL_KEEP. </para>
        /// </param>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glStencilOp", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void StencilOp(uint fail, uint zfail, uint zpass);


        /// <summary>
        /// specify a one-dimensional texture image.
        /// </summary>
        /// <param name="target">
        /// Specifies the target texture. Must be GL_TEXTURE_1D or GL_PROXY_TEXTURE_1D. 
        /// </param>
        /// <param name="level">
        /// <para>Specifies the level-of-detail number. Level 0 is the base image level. </para>
        /// <para>Level n is the nth mipmap reduction image</para>
        /// </param>
        /// <param name="internalformat">
        /// <para> Specifies the number of color components in the texture. </para>
        /// <para>Must be 1, 2, 3, or 4, or one of the following symbolic constants: GL_ALPHA, GL_ALPHA4, GL_ALPHA8,</para>
        /// <para>GL_ALPHA12, GL_ALPHA16, GL_COMPRESSED_ALPHA, GL_COMPRESSED_LUMINANCE, GL_COMPRESSED_LUMINANCE_ALPHA,</para>
        /// <para>GL_COMPRESSED_INTENSITY, GL_COMPRESSED_RGB, GL_COMPRESSED_RGBA, GL_DEPTH_COMPONENT, GL_DEPTH_COMPONENT16,</para> 
        /// <para>GL_DEPTH_COMPONENT24, GL_DEPTH_COMPONENT32, GL_LUMINANCE, GL_LUMINANCE4, GL_LUMINANCE8, GL_LUMINANCE12,</para>
        /// <para>GL_LUMINANCE16, GL_LUMINANCE_ALPHA, GL_LUMINANCE4_ALPHA4, GL_LUMINANCE6_ALPHA2, GL_LUMINANCE8_ALPHA8, </para>
        /// <para> GL_LUMINANCE12_ALPHA4, GL_LUMINANCE12_ALPHA12, GL_LUMINANCE16_ALPHA16, GL_INTENSITY, GL_INTENSITY4, </para>
        /// <para>GL_INTENSITY8, GL_INTENSITY12, GL_INTENSITY16, GL_R3_G3_B2, GL_RGB, GL_RGB4, GL_RGB5, GL_RGB8, GL_RGB10,</para>
        /// <para>GL_RGB12, GL_RGB16, GL_RGBA, GL_RGBA2, GL_RGBA4, GL_RGB5_A1, GL_RGBA8, GL_RGB10_A2, GL_RGBA12, GL_RGBA16,</para>
        /// <para>GL_SLUMINANCE, GL_SLUMINANCE8, GL_SLUMINANCE_ALPHA, GL_SLUMINANCE8_ALPHA8, GL_SRGB, GL_SRGB8, GL_SRGB_ALPHA, or GL_SRGB8_ALPHA8.</para>
        /// </param>
        /// <param name="width">
        /// <para>Specifies the width of the texture image including the border if any. </para>
        /// <para>If the GL version does not support non-power-of-two sizes, this value must be 2^n+2(border) for some integer n.</para>
        /// <para>All implementations support texture images that are at least 64 texels wide. </para>
        /// <para>The height of the 1D texture image is 1. </para>
        /// </param>
        /// <param name="border">
        /// Specifies the width of the border. Must be either 0 or 1. 
        /// </param>
        /// <param name="format">
        /// <para>Specifies the format of the pixel data. </para>
        /// <para>The following symbolic values are accepted: </para>
        /// <para>GL_COLOR_INDEX, GL_RED, GL_GREEN, GL_BLUE, GL_ALPHA, GL_RGB, GL_BGR, GL_RGBA, GL_BGRA, GL_LUMINANCE, and GL_LUMINANCE_ALPHA.</para>
        /// </param>
        /// <param name="type">
        /// <para>Specifies the data type of the pixel data. </para>
        /// <para>The following symbolic values are accepted: GL_UNSIGNED_BYTE, GL_BYTE, GL_BITMAP, GL_UNSIGNED_SHORT,</para>
        /// <para>GL_SHORT, GL_UNSIGNED_INT, GL_INT, GL_FLOAT, GL_UNSIGNED_BYTE_3_3_2, GL_UNSIGNED_BYTE_2_3_3_REV,</para>
        /// <para>GL_UNSIGNED_SHORT_5_6_5, GL_UNSIGNED_SHORT_5_6_5_REV, GL_UNSIGNED_SHORT_4_4_4_4,</para>
        /// <para>GL_UNSIGNED_SHORT_4_4_4_4_REV, GL_UNSIGNED_SHORT_5_5_5_1, GL_UNSIGNED_SHORT_1_5_5_5_REV, </para>
        /// <para>GL_UNSIGNED_INT_8_8_8_8, GL_UNSIGNED_INT_8_8_8_8_REV, GL_UNSIGNED_INT_10_10_10_2,and GL_UNSIGNED_INT_2_10_10_10_REV. </para>
        /// </param>
        /// <param name="pixels">
        /// <para>Specifies a pointer to the image data in memory. </para>
        /// <para>You can use the function glaux.ArrayToPointer to get the array pointer.</para>
        /// </param>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glTexImage1D", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void TexImage1D(uint target, int level, int internalformat, int width, int border, uint format, uint type,IntPtr pixels);

        /// <summary>
        /// specify a two-dimensional texture image.
        /// </summary>
        /// <param name="target">
        /// <para>Specifies the target texture. </para>
        /// <para>Must be GL_TEXTURE_2D, GL_PROXY_TEXTURE_2D, GL_TEXTURE_CUBE_MAP_POSITIVE_X,</para> 
        /// <para>GL_TEXTURE_CUBE_MAP_NEGATIVE_X, GL_TEXTURE_CUBE_MAP_POSITIVE_Y, GL_TEXTURE_CUBE_MAP_NEGATIVE_Y, </para>
        /// <para>GL_TEXTURE_CUBE_MAP_POSITIVE_Z, GL_TEXTURE_CUBE_MAP_NEGATIVE_Z, or GL_PROXY_TEXTURE_CUBE_MAP. </para>      
        /// </param>
        /// <param name="level">
        /// <para>Specifies the level-of-detail number. Level 0 is the base image level. </para>
        /// <para>Level n is the nth mipmap reduction image. </para>
        /// </param>
        /// <param name="internalformat">
        /// <para>Specifies the number of color components in the texture. </para>
        /// <para>Must be 1, 2, 3, or 4, or one of the following symbolic constants: GL_ALPHA, GL_ALPHA4, GL_ALPHA8,</para>
        /// <para>GL_ALPHA12, GL_ALPHA16, GL_COMPRESSED_ALPHA, GL_COMPRESSED_LUMINANCE, GL_COMPRESSED_LUMINANCE_ALPHA,</para>
        /// <para>GL_COMPRESSED_INTENSITY, GL_COMPRESSED_RGB, GL_COMPRESSED_RGBA, GL_DEPTH_COMPONENT, GL_DEPTH_COMPONENT16,</para>
        /// <para>GL_DEPTH_COMPONENT24, GL_DEPTH_COMPONENT32, GL_LUMINANCE, GL_LUMINANCE4, GL_LUMINANCE8, GL_LUMINANCE12,</para>
        /// <para>GL_LUMINANCE16, GL_LUMINANCE_ALPHA, GL_LUMINANCE4_ALPHA4, GL_LUMINANCE6_ALPHA2, GL_LUMINANCE8_ALPHA8,</para>
        /// <para>GL_LUMINANCE12_ALPHA4, GL_LUMINANCE12_ALPHA12, GL_LUMINANCE16_ALPHA16, GL_INTENSITY, GL_INTENSITY4, </para>
        /// <para>GL_INTENSITY8, GL_INTENSITY12, GL_INTENSITY16, GL_R3_G3_B2, GL_RGB, GL_RGB4, GL_RGB5, GL_RGB8, GL_RGB10,</para>
        /// <para>GL_RGB12, GL_RGB16, GL_RGBA, GL_RGBA2, GL_RGBA4, GL_RGB5_A1, GL_RGBA8, GL_RGB10_A2, GL_RGBA12, GL_RGBA16,</para>
        /// <para>GL_SLUMINANCE, GL_SLUMINANCE8, GL_SLUMINANCE_ALPHA, GL_SLUMINANCE8_ALPHA8, GL_SRGB, GL_SRGB8, GL_SRGB_ALPHA, or GL_SRGB8_ALPHA8. </para>
        /// </param>
        /// <param name="width">
        /// <para>Specifies the width of the texture image including the border if any.</para>
        /// <para>If the GL version does not support non-power-of-two sizes, this value must be 2^n+2(border) for some integer n.</para>
        /// <para>All implementations support texture images that are at least 64 texels wide. </para>
        /// </param>
        /// <param name="height">
        /// <para>Specifies the height of the texture image including the border if any. </para>
        /// <para>If the GL version does not support non-power-of-two sizes, this value must be 2^m+2(border) for some integer m.</para>
        /// <para>All implementations support texture images that are at least 64 texels high. </para>
        /// </param>
        /// <param name="border">
        /// Specifies the width of the border. Must be either 0 or 1. 
        /// </param>
        /// <param name="format">
        /// <para>Specifies the format of the pixel data. </para>
        /// <para>The following symbolic values are accepted: GL_COLOR_INDEX, GL_RED, GL_GREEN, GL_BLUE, GL_ALPHA, </para>
        /// <para>GL_RGB, GL_BGR, GL_RGBA, GL_BGRA, GL_LUMINANCE, and GL_LUMINANCE_ALPHA. </para>
        /// </param>
        /// <param name="type">
        /// <para>Specifies the data type of the pixel data.</para>
        /// <para>The following symbolic values are accepted: GL_UNSIGNED_BYTE, GL_BYTE, GL_BITMAP, GL_UNSIGNED_SHORT, </para>
        /// <para>GL_SHORT, GL_UNSIGNED_INT, GL_INT, GL_FLOAT, GL_UNSIGNED_BYTE_3_3_2, GL_UNSIGNED_BYTE_2_3_3_REV,</para> 
        /// <para>GL_UNSIGNED_SHORT_5_6_5, GL_UNSIGNED_SHORT_5_6_5_REV, GL_UNSIGNED_SHORT_4_4_4_4, </para>
        /// <para>GL_UNSIGNED_SHORT_4_4_4_4_REV, GL_UNSIGNED_SHORT_5_5_5_1, GL_UNSIGNED_SHORT_1_5_5_5_REV, </para>
        /// <para>GL_UNSIGNED_INT_8_8_8_8, GL_UNSIGNED_INT_8_8_8_8_REV, GL_UNSIGNED_INT_10_10_10_2,and GL_UNSIGNED_INT_2_10_10_10_REV.</para> 
        /// </param>
        /// <param name="pixels">
        /// <para>Specifies a pointer to the image data in memory. </para>
        /// <para>You can use the function glaux.ArrayToPointer to get the array pointer.</para>
        /// </param>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glTexImage2D", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void TexImage2D(uint target, int level, int internalformat, int width, int height, int border, uint format, uint type, IntPtr pixels);

        /// <summary>
        /// set texture parameters.
        /// </summary>
        /// <param name="target">
        /// Specifies the target texture, which must be either GL_TEXTURE_1D, GL_TEXTURE_2D, GL_TEXTURE_3D,or GL_TEXTURE_CUBE_MAP. 
        /// </param>
        /// <param name="pname">
        /// <para>Specifies the symbolic name of a single-valued texture parameter. </para>
        /// <para>pname can be one of the following: GL_TEXTURE_MIN_FILTER, GL_TEXTURE_MAG_FILTER, GL_TEXTURE_MIN_LOD,</para>
        /// <para>GL_TEXTURE_MAX_LOD, GL_TEXTURE_BASE_LEVEL, GL_TEXTURE_MAX_LEVEL, GL_TEXTURE_WRAP_S, GL_TEXTURE_WRAP_T, </para>
        /// <para>GL_TEXTURE_WRAP_R, GL_TEXTURE_PRIORITY, GL_TEXTURE_COMPARE_MODE, GL_TEXTURE_COMPARE_FUNC,GL_DEPTH_TEXTURE_MODE, or GL_GENERATE_MIPMAP.</para> 
        /// </param>
        /// <param name="param">
        /// Specifies the value of pname. 
        /// </param>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glTexParameterf", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void TexParameter(uint target, uint pname, float param);

        /// <summary>
        /// set texture parameters
        /// </summary>
        /// <param name="target">
        /// Specifies the target texture, which must be either GL_TEXTURE_1D, GL_TEXTURE_2D or GL_TEXTURE_3D. 
        /// </param>
        /// <param name="pname">
        /// <para>Specifies the symbolic name of a texture parameter.</para>
        /// <para>pname can be one of the following: GL_TEXTURE_MIN_FILTER, GL_TEXTURE_MAG_FILTER, GL_TEXTURE_MIN_LOD, </para>
        /// <para> GL_TEXTURE_MAX_LOD, GL_TEXTURE_BASE_LEVEL, GL_TEXTURE_MAX_LEVEL, GL_TEXTURE_WRAP_S, GL_TEXTURE_WRAP_T,</para>
        /// <para>GL_TEXTURE_WRAP_R, GL_TEXTURE_BORDER_COLOR, GL_TEXTURE_PRIORITY, GL_TEXTURE_COMPARE_MODE, </para>
        /// <para>GL_TEXTURE_COMPARE_FUNC, GL_DEPTH_TEXTURE_MODE, or GL_GENERATE_MIPMAP. </para>
        /// </param>
        /// <param name="Params">
        /// Specifies an array where the value or values of pname are stored.
        /// </param>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glTexParameterfv", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void TexParameter(uint target, uint pname, float[] Params);

        /// <summary>
        /// set texture parameters.
        /// </summary>
        /// <param name="target">
        /// <para>Specifies the target texture, which must be either GL_TEXTURE_1D, GL_TEXTURE_2D, GL_TEXTURE_3D,or GL_TEXTURE_CUBE_MAP. </para>
        /// </param>
        /// <param name="pname">
        /// <para>Specifies the symbolic name of a single-valued texture parameter. </para>
        /// <para>pname can be one of the following: GL_TEXTURE_MIN_FILTER, GL_TEXTURE_MAG_FILTER, GL_TEXTURE_MIN_LOD,</para>
        /// <para>GL_TEXTURE_MAX_LOD, GL_TEXTURE_BASE_LEVEL, GL_TEXTURE_MAX_LEVEL, GL_TEXTURE_WRAP_S, GL_TEXTURE_WRAP_T, </para>
        /// <para>GL_TEXTURE_WRAP_R, GL_TEXTURE_PRIORITY, GL_TEXTURE_COMPARE_MODE, GL_TEXTURE_COMPARE_FUNC,GL_DEPTH_TEXTURE_MODE, or GL_GENERATE_MIPMAP. </para>
        /// </param>
        /// <param name="param">
        /// Specifies the value of pname. 
        /// </param>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glTexParameteri", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void TexParameter(uint target, uint pname, int param);

        /// <summary>
        /// set texture parameters
        /// </summary>
        /// <param name="target">
        /// Specifies the target texture, which must be either GL_TEXTURE_1D, GL_TEXTURE_2D or GL_TEXTURE_3D. 
        /// </param>
        /// <param name="pname">
        /// <para>Specifies the symbolic name of a texture parameter.</para>
        /// <para>pname can be one of the following: GL_TEXTURE_MIN_FILTER, GL_TEXTURE_MAG_FILTER, GL_TEXTURE_MIN_LOD, </para>
        /// <para> GL_TEXTURE_MAX_LOD, GL_TEXTURE_BASE_LEVEL, GL_TEXTURE_MAX_LEVEL, GL_TEXTURE_WRAP_S, GL_TEXTURE_WRAP_T,</para>
        /// <para> GL_TEXTURE_WRAP_R, GL_TEXTURE_BORDER_COLOR, GL_TEXTURE_PRIORITY, GL_TEXTURE_COMPARE_MODE, </para>
        /// <para>GL_TEXTURE_COMPARE_FUNC, GL_DEPTH_TEXTURE_MODE, or GL_GENERATE_MIPMAP. </para>
        /// </param>
        /// <param name="Params">
        /// Specifies an array where the value or values of pname are stored.
        /// </param>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glTexParameteriv", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void TexParameter(uint target, uint pname, int[] Params);

        /// <summary>
        /// specify a one-dimensional texture subimage.
        /// </summary>
        /// <param name="target">
        /// Specifies the target texture. Must be GL_TEXTURE_1D. 
        /// </param>
        /// <param name="level">
        /// <para>Specifies the level-of-detail number. Level 0 is the base image level. </para>
        /// <para>Level n is the nth mipmap reduction image.</para>
        /// </param>
        /// <param name="xoffset">
        /// Specifies a texel offset in the x direction within the texture array. 
        /// </param>
        /// <param name="width">
        /// Specifies the width of the texture subimage. 
        /// </param>
        /// <param name="format">
        /// <para>Specifies the format of the pixel data.</para>
        /// <para>The following symbolic values are accepted: </para>
        /// <para>GL_COLOR_INDEX, GL_RED, GL_GREEN, GL_BLUE, GL_ALPHA, GL_RGB, GL_BGR, GL_RGBA, GL_BGRA, GL_LUMINANCE, and GL_LUMINANCE_ALPHA. </para>
        /// </param>
        /// <param name="type">
        /// <para>Specifies the data type of the pixel data.</para>
        /// <para>The following symbolic values are accepted: GL_UNSIGNED_BYTE, GL_BYTE, GL_BITMAP, GL_UNSIGNED_SHORT,</para>
        /// <para>GL_SHORT, GL_UNSIGNED_INT, GL_INT, GL_FLOAT, GL_UNSIGNED_BYTE_3_3_2, GL_UNSIGNED_BYTE_2_3_3_REV,</para>
        /// <para>GL_UNSIGNED_SHORT_5_6_5, GL_UNSIGNED_SHORT_5_6_5_REV, GL_UNSIGNED_SHORT_4_4_4_4,</para>
        /// <para>GL_UNSIGNED_SHORT_4_4_4_4_REV, GL_UNSIGNED_SHORT_5_5_5_1, GL_UNSIGNED_SHORT_1_5_5_5_REV, </para>
        /// <para>GL_UNSIGNED_INT_8_8_8_8, GL_UNSIGNED_INT_8_8_8_8_REV, GL_UNSIGNED_INT_10_10_10_2,and GL_UNSIGNED_INT_2_10_10_10_REV</para>
        /// </param>
        /// <param name="pixels">
        /// <para>Specifies a pointer to the image data in memory.</para>
        /// <para>You can use the function glaux.ArrayToPointer to get the array pointer.</para>
        /// </param>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glTexSubImage1D", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void TexSubImage1D(uint target, int level, int xoffset, int width, uint format, uint type,IntPtr pixels);

        /// <summary>
        /// specify a two-dimensional texture subimage.
        /// </summary>
        /// <param name="target">
        /// <para>Specifies the target texture. </para>
        /// <para>Must be GL_TEXTURE_2D, GL_TEXTURE_CUBE_MAP_POSITIVE_X, GL_TEXTURE_CUBE_MAP_NEGATIVE_X,</para>
        ///<para> GL_TEXTURE_CUBE_MAP_POSITIVE_Y, GL_TEXTURE_CUBE_MAP_NEGATIVE_Y, GL_TEXTURE_CUBE_MAP_POSITIVE_Z,or GL_TEXTURE_CUBE_MAP_NEGATIVE_Z. </para>
        /// </param>
        /// <param name="level">
        /// <para>Specifies the level-of-detail number. Level 0 is the base image level.</para>
        /// <para>Level n is the nth mipmap reduction image. </para>
        /// </param>
        /// <param name="xoffset">
        /// Specifies a texel offset in the x direction within the texture array. 
        /// </param>
        /// <param name="yoffset">
        /// Specifies a texel offset in the y direction within the texture array.
        /// </param>
        /// <param name="width">
        /// Specifies the width of the texture subimage. 
        /// </param>
        /// <param name="height">
        /// Specifies the height of the texture subimage. 
        /// </param>
        /// <param name="format">
        /// <para>Specifies the format of the pixel data. </para>
        /// <para>The following symbolic values are accepted:</para>
        /// <para>GL_COLOR_INDEX, GL_RED, GL_GREEN, GL_BLUE, GL_ALPHA, GL_RGB, GL_BGR, GL_RGBA, GL_BGRA, GL_LUMINANCE,and GL_LUMINANCE_ALPHA. </para>
        /// </param>
        /// <param name="type">
        /// <para>Specifies the data type of the pixel data. </para>
        /// <para>The following symbolic values are accepted: GL_UNSIGNED_BYTE, GL_BYTE, GL_BITMAP, GL_UNSIGNED_SHORT,</para>
        /// <para>GL_SHORT, GL_UNSIGNED_INT, GL_INT, GL_FLOAT, GL_UNSIGNED_BYTE_3_3_2, GL_UNSIGNED_BYTE_2_3_3_REV,</para>
        /// <para> GL_UNSIGNED_SHORT_5_6_5, GL_UNSIGNED_SHORT_5_6_5_REV, GL_UNSIGNED_SHORT_4_4_4_4, </para>
        /// <para>GL_UNSIGNED_SHORT_4_4_4_4_REV, GL_UNSIGNED_SHORT_5_5_5_1, GL_UNSIGNED_SHORT_1_5_5_5_REV, </para>
        /// <para>GL_UNSIGNED_INT_8_8_8_8, GL_UNSIGNED_INT_8_8_8_8_REV, GL_UNSIGNED_INT_10_10_10_2,and GL_UNSIGNED_INT_2_10_10_10_REV.</para>
        /// </param>
        /// <param name="pixels">
        /// <para>Specifies a pointer to the image data in memory. </para>
        /// <para>You can use the function glaux.ArrayToPointer to get the array pointer.</para>
        /// </param>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glTexSubImage2D", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void TexSubImage2D(uint target, int level, int xoffset, int yoffset, int width, int height, uint format, uint type,IntPtr pixels);

        /// <summary>
        /// set the viewport.
        /// </summary>
        /// <param name="x">
        /// Specify the lower left corner of the viewport rectangle, in pixels. The initial value is (0,0). 
        /// </param>
        /// <param name="y">
        /// Specify the lower left corner of the viewport rectangle, in pixels. The initial value is (0,0).
        /// </param>
        /// <param name="width">
        /// <para>Specify the width and height of the viewport.</para>
        /// <para>When a GL context is first attached to a window, width and height are set to the dimensions of that window. </para>
        /// </param>
        /// <param name="height">
        /// <para>Specify the width and height of the viewport. </para>
        /// <para>When a GL context is first attached to a window, width and height are set to the dimensions of that window. </para>
        /// </param>
        [DllImport("opengl32.dll", ExactSpelling = false, EntryPoint = "glViewport", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        public static extern void Viewport(int x, int y, int width, int height);

    }

}