OpenGL rebuild project start!

2023-04-29 03:06:32 +08:00
parent 7dba067146
commit 4dd3f4f6d1
263 changed files with 51374 additions and 1522 deletions
@@ -0,0 +1,90 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace StgSharp.Math
+{ 
+    public static unsafe partial class Calc
+    {
+        /// <summary>
+        /// calculate the value of x^y
+        /// </summary>
+        /// <param name="x"></param>
+        /// <param name="y"></param>
+        /// <returns>Returns the value of x^y</returns>
+        public static unsafe float Pow(float x, float y)
+        {
+            /* 
+             * x^y = E ^ ( log( x ) * y )
+             * Now define z = | log(x) * y | = m * n  
+             * and m is an integer, and 0.5 < |n| < 1
+             * then E ^ z = ( E ^ n ) ^ m
+             * 
+             * 
+             * As a float number can be expressed in (1+e)*(2^f)
+             * n = (1+e)/2
+             * m = 2 ^ (f + 1)
+             * 
+             */
+            float z, t;
+            if (x == 1 || y == 0)
+            {
+                return 1;
+            }
+            if (x==1&&y==0)
+            {
+                return 1.0f / 0;
+            }
+            z = Calc.Log(x) * y;
+
+            bool sign = false;
+            if (z < 0)
+            {
+                sign = true;
+                z = -z;
+            }
+
+            if (z<0.5f)
+            {
+                t = 1.0f + z * (
+                    1.0f + z * (
+                    0.5f + z * (
+                    0.1666666667f + z * (
+                    0.0416666666667f + z *
+                    8.333333333e-3f))));
+            }
+            else
+            {
+                uint zBit = *(uint*)&z;
+                uint zBitAbs = zBit & 0b_0111_1111_1111_1111_1111_1111_1111_1111;
+                uint uintm = (zBitAbs >> 23);
+                int m = (*(int*)&uintm) - 126;
+
+
+                uint nBit = (zBitAbs & 0b_0000_0000_0111_1111_1111_1111_1111_1111)
+                    + 0b_0011_1111_0000_0000_0000_0000_0000_0000;
+                float n = *(float*)&nBit - 1;
+
+                t = 2.718281828f + n * (
+                    2.718281828f + n * (
+                    1.359140914f + n * (
+                    0.4530469714f + n * (
+                    0.1132617429f + n *
+                    0.02265234857f))));
+
+                for (int i = 0; i < m; i++)
+                {
+                    t = t * t;
+                }
+
+                
+            }
+            if (sign)
+            {
+                t = 1 / t;
+            }
+
+            return t;
+        }
+    }
+}