32 lines
1.5 KiB
C
32 lines
1.5 KiB
C
#include "StgSharpC.h"
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#include "ssgc_internal.h"
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SSCAPI void SSCDECL normalize(__m128* source, __m128* target)
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{
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// 计算source的长度的平方
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__m128 a_length_sq = _mm_mul_ps(*source, *source); // 向量点乘自身
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a_length_sq = _mm_add_ps(a_length_sq, _mm_shuffle_ps(a_length_sq, a_length_sq, _MM_SHUFFLE(2, 3, 0, 1)));
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a_length_sq = _mm_add_ss(a_length_sq, _mm_shuffle_ps(a_length_sq, a_length_sq, _MM_SHUFFLE(0, 0, 3, 2)));
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// 归一化向量source
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__m128 a_inv_length = _mm_rsqrt_ps(a_length_sq); // 计算source长度的倒数平方根
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*source = _mm_mul_ps(*source, a_inv_length); // 用source乘以其长度的倒数平方根得到单位向量
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// 计算target与source的点积
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__m128 dot_product = _mm_mul_ps(*target, *source);
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dot_product = _mm_add_ps(dot_product, _mm_shuffle_ps(dot_product, dot_product, _MM_SHUFFLE(2, 3, 0, 1)));
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dot_product = _mm_add_ss(dot_product, _mm_shuffle_ps(dot_product, dot_product, _MM_SHUFFLE(0, 0, 3, 2)));
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// 从target中减去source的方向分量，使其垂直于source
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__m128 b_orthogonal = _mm_sub_ps(*target, _mm_mul_ps(*source, dot_product));
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// 归一化向量b_orthogonal
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__m128 b_length_sq = _mm_mul_ps(b_orthogonal, b_orthogonal);
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b_length_sq = _mm_add_ps(b_length_sq, _mm_shuffle_ps(b_length_sq, b_length_sq, _MM_SHUFFLE(2, 3, 0, 1)));
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b_length_sq = _mm_add_ss(b_length_sq, _mm_shuffle_ps(b_length_sq, b_length_sq, _MM_SHUFFLE(0, 0, 3, 2)));
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__m128 b_inv_length = _mm_rsqrt_ps(b_length_sq);
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*target = _mm_mul_ps(b_orthogonal, b_inv_length);
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}
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