optimized Mod_BuildBumpVectors slightly

git-svn-id: svn://svn.icculus.org/twilight/trunk/darkplaces@4505 d7cf8633-e32d-0410-b094-e92efae38249

diff --git a/model_shared.c b/model_shared.c
index f2a0ccc7780416dd52864da80a2a6b5f52584459..309b40e1d40b58acf5a447891811e38b45b6464f 100644 (file)
--- a/model_shared.c
+++ b/model_shared.c
@@ -622,26 +622,45 @@ void Mod_ValidateElements(const int *elements, int numtriangles, int numverts, c
 
 void Mod_BuildBumpVectors(const float *v0, const float *v1, const float *v2, const float *tc0, const float *tc1, const float *tc2, float *svector3f, float *tvector3f, float *normal3f)
 {
-       float f, tangentcross[3];
-       normal3f[0] = (v1[1] - v0[1]) * (v2[2] - v0[2]) - (v1[2] - v0[2]) * (v2[1] - v0[1]);
-       normal3f[1] = (v1[2] - v0[2]) * (v2[0] - v0[0]) - (v1[0] - v0[0]) * (v2[2] - v0[2]);
-       normal3f[2] = (v1[0] - v0[0]) * (v2[1] - v0[1]) - (v1[1] - v0[1]) * (v2[0] - v0[0]);
+       float f, tangentcross[3], v10[3], v20[3], tc10[2], tc20[2];
+       // 103 add/sub/negate/multiply (1 cycle), 3 divide (20 cycle), 3 sqrt (22 cycle), 4 compare (3 cycle?), total cycles not counting load/store/exchange roughly 241 cycles
+       // 12 add, 28 subtract, 57 multiply, 3 divide, 3 sqrt, 4 compare, 50% chance of 6 negates
+
+       // 18 multiply, 19 subtract
+       VectorSubtract(v1, v0, v10);
+       VectorSubtract(v2, v0, v20);
+       normal3f[0] = v10[1] * v20[2] - v10[2] * v20[1];
+       normal3f[1] = v10[2] * v20[0] - v10[0] * v20[2];
+       normal3f[2] = v10[0] * v20[1] - v10[1] * v20[0];
+       tc10[1] = tc1[1] - tc0[1];
+       tc20[1] = tc2[1] - tc0[1];
+       svector3f[0] = tc10[1] * v20[0] - tc20[1] * v10[0];
+       svector3f[1] = tc10[1] * v20[1] - tc20[1] * v10[1];
+       svector3f[2] = tc10[1] * v20[2] - tc20[1] * v10[2];
+       tc10[0] = tc1[0] - tc0[0];
+       tc20[0] = tc2[0] - tc0[0];
+       tvector3f[0] = tc10[0] * v20[0] - tc20[0] * v10[0];
+       tvector3f[1] = tc10[0] * v20[1] - tc20[0] * v10[1];
+       tvector3f[2] = tc10[0] * v20[2] - tc20[0] * v10[2];
+       // 1 sqrt, 1 divide, 6 multiply, 2 add, 1 compare
        VectorNormalize(normal3f);
-       tvector3f[0] = ((tc1[0] - tc0[0]) * (v2[0] - v0[0]) - (tc2[0] - tc0[0]) * (v1[0] - v0[0]));
-       tvector3f[1] = ((tc1[0] - tc0[0]) * (v2[1] - v0[1]) - (tc2[0] - tc0[0]) * (v1[1] - v0[1]));
-       tvector3f[2] = ((tc1[0] - tc0[0]) * (v2[2] - v0[2]) - (tc2[0] - tc0[0]) * (v1[2] - v0[2]));
-       f = -DotProduct(tvector3f, normal3f);
-       VectorMA(tvector3f, f, normal3f, tvector3f);
-       VectorNormalize(tvector3f);
-       // note: can't be a CrossProduct as that sometimes flips the texture
-       svector3f[0] = ((tc1[1] - tc0[1]) * (v2[0] - v0[0]) - (tc2[1] - tc0[1]) * (v1[0] - v0[0]));
-       svector3f[1] = ((tc1[1] - tc0[1]) * (v2[1] - v0[1]) - (tc2[1] - tc0[1]) * (v1[1] - v0[1]));
-       svector3f[2] = ((tc1[1] - tc0[1]) * (v2[2] - v0[2]) - (tc2[1] - tc0[1]) * (v1[2] - v0[2]));
-       f = -DotProduct(svector3f, normal3f);
-       VectorMA(svector3f, f, normal3f, svector3f);
+       // 12 multiply, 4 add, 6 subtract
+       f = DotProduct(svector3f, normal3f);
+       svector3f[0] -= f * normal3f[0];
+       svector3f[1] -= f * normal3f[1];
+       svector3f[2] -= f * normal3f[2];
+       f = DotProduct(tvector3f, normal3f);
+       tvector3f[0] -= f * normal3f[0];
+       tvector3f[1] -= f * normal3f[1];
+       tvector3f[2] -= f * normal3f[2];
+       // 2 sqrt, 2 divide, 12 multiply, 4 add, 2 compare
        VectorNormalize(svector3f);
+       VectorNormalize(tvector3f);
+       // if texture is mapped the wrong way (counterclockwise), the tangents
+       // have to be flipped, this is detected by calculating a normal from the
+       // two tangents, and seeing if it is opposite the surface normal
+       // 9 multiply, 2 add, 3 subtract, 1 compare, 50% chance of: 6 negates
        CrossProduct(tvector3f, svector3f, tangentcross);
-       // if texture is mapped the wrong way (counterclockwise), the tangents have to be flipped, this is detected by calculating a normal from the two tangents, and seeing if it is opposite the surface normal
        if (DotProduct(tangentcross, normal3f) < 0)
        {
                VectorNegate(svector3f, svector3f);