+void Mod_ValidateElements(const int *elements, int numtriangles, int numverts, const char *filename, int fileline)
+{
+ int i;
+ for (i = 0;i < numtriangles * 3;i++)
+ if ((unsigned int)elements[i] >= (unsigned int)numverts)
+ Con_Printf("Mod_ValidateElements: out of bounds element detected at %s:%d\n", filename, fileline);
+}
+
+/*
+a note on the cost of executing this function:
+per triangle: 188 (83 42 13 45 4 1)
+assignments: 83 (20 3 3 3 1 4 4 1 3 4 3 4 30)
+adds: 42 (2 2 2 2 3 2 2 27)
+subtracts: 13 (3 3 3 1 3)
+multiplies: 45 (6 3 6 6 3 3 6 6 6)
+rsqrts: 4 (1 1 1 1)
+compares: 1 (1)
+per vertex: 39 (12 6 18 3)
+assignments: 12 (4 4 4)
+adds: 6 (2 2 2)
+multiplies: 18 (6 6 6)
+rsqrts: 3 (1 1 1)
+*/
+
+void Mod_BuildTextureVectorsAndNormals(int numverts, int numtriangles, const float *vertex, const float *texcoord, const int *elements, float *svectors, float *tvectors, float *normals)
+{
+ int i, tnum, voffset;
+ float vert[3][4], vec[3][4], sdir[3], tdir[3], normal[3], f, *v;
+ const int *e;
+ // clear the vectors
+ memset(svectors, 0, numverts * sizeof(float[4]));
+ memset(tvectors, 0, numverts * sizeof(float[4]));
+ memset(normals, 0, numverts * sizeof(float[4]));
+ // process each vertex of each triangle and accumulate the results
+ for (tnum = 0, e = elements;tnum < numtriangles;tnum++, e += 3)
+ {
+ // calculate texture matrix for triangle
+ // 20 assignments
+ voffset = e[0] * 4;
+ vert[0][0] = vertex[voffset+0];
+ vert[0][1] = vertex[voffset+1];
+ vert[0][2] = vertex[voffset+2];
+ vert[0][3] = texcoord[voffset];
+ voffset = e[1] * 4;
+ vert[1][0] = vertex[voffset+0];
+ vert[1][1] = vertex[voffset+1];
+ vert[1][2] = vertex[voffset+2];
+ vert[1][3] = texcoord[voffset];
+ voffset = e[2] * 4;
+ vert[2][0] = vertex[voffset+0];
+ vert[2][1] = vertex[voffset+1];
+ vert[2][2] = vertex[voffset+2];
+ vert[2][3] = texcoord[voffset];
+ // 3 assignments, 3 subtracts
+ VectorSubtract(vert[1], vert[0], vec[0]);
+ // 3 assignments, 3 subtracts
+ VectorSubtract(vert[2], vert[0], vec[1]);
+ // 3 assignments, 3 subtracts, 6 multiplies
+ CrossProduct(vec[0], vec[1], normal);
+ // 1 assignment, 2 adds, 3 multiplies, 1 compare
+ if (DotProduct(normal, normal) >= 0.001)
+ {
+ // 4 assignments, 1 rsqrt, 2 adds, 6 multiplies
+ VectorNormalize(normal);
+ sdir[0] = (vert[1][3] - vert[0][3]) * (vert[2][0] - vert[0][0]) - (vert[2][3] - vert[0][3]) * (vert[1][0] - vert[0][0]);
+ sdir[1] = (vert[1][3] - vert[0][3]) * (vert[2][1] - vert[0][1]) - (vert[2][3] - vert[0][3]) * (vert[1][1] - vert[0][1]);
+ sdir[2] = (vert[1][3] - vert[0][3]) * (vert[2][2] - vert[0][2]) - (vert[2][3] - vert[0][3]) * (vert[1][2] - vert[0][2]);
+ // 4 assignments, 1 rsqrt, 2 adds, 6 multiplies
+ VectorNormalize(sdir);
+ // 1 assignments, 1 negates, 2 adds, 3 multiplies
+ f = -DotProduct(sdir, normal);
+ // 3 assignments, 3 adds, 3 multiplies
+ VectorMA(sdir, f, normal, sdir);
+ // 4 assignments, 1 rsqrt, 2 adds, 6 multiplies
+ VectorNormalize(sdir);
+ // 3 assignments, 3 subtracts, 6 multiplies
+ CrossProduct(sdir, normal, tdir);
+ // this is probably not necessary
+ // 4 assignments, 1 rsqrt, 2 adds, 6 multiplies
+ VectorNormalize(tdir);
+ // accumulate matrix onto verts used by triangle
+ // 30 assignments, 27 adds
+ for (i = 0;i < 3;i++)
+ {
+ voffset = e[i] * 4;
+ svectors[voffset ] += sdir[0];
+ svectors[voffset + 1] += sdir[1];
+ svectors[voffset + 2] += sdir[2];
+ tvectors[voffset ] += tdir[0];
+ tvectors[voffset + 1] += tdir[1];
+ tvectors[voffset + 2] += tdir[2];
+ normals[voffset ] += normal[0];
+ normals[voffset + 1] += normal[1];
+ normals[voffset + 2] += normal[2];
+ }
+ }
+ }
+ // now we could divide the vectors by the number of averaged values on
+ // each vertex... but instead normalize them
+ for (i = 0, v = svectors;i < numverts;i++, v += 4)
+ // 4 assignments, 1 rsqrt, 2 adds, 6 multiplies
+ VectorNormalize(v);
+ for (i = 0, v = tvectors;i < numverts;i++, v += 4)
+ // 4 assignments, 1 rsqrt, 2 adds, 6 multiplies
+ VectorNormalize(v);
+ for (i = 0, v = normals;i < numverts;i++, v += 4)
+ // 4 assignments, 1 rsqrt, 2 adds, 6 multiplies
+ VectorNormalize(v);
+}
+