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avoid nan tangents which happen with cubes that have generated UVs

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Campbell Barton 2010-02-03 19:16:18 +00:00
parent 6bdfa43431
commit f590151725
1 changed files with 25 additions and 20 deletions
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45
source/blender/blenlib/intern/math_geom.c
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@ -1848,28 +1848,33 @@ float *find_vertex_tangent(VertexTangent *vtang, float *uv)
void tangent_from_uv(float *uv1, float *uv2, float *uv3, float *co1, float *co2, float *co3, float *n, float *tang)
{
float tangv[3], ct[3], e1[3], e2[3], s1, t1, s2, t2, det;
float s1= uv2[0] - uv1[0];
float s2= uv3[0] - uv1[0];
float t1= uv2[1] - uv1[1];
float t2= uv3[1] - uv1[1];
s1= uv2[0] - uv1[0];
s2= uv3[0] - uv1[0];
t1= uv2[1] - uv1[1];
t2= uv3[1] - uv1[1];
det= 1.0f / (s1 * t2 - s2 * t1);
if(s1 && s2 && t1 && t2) { /* otherwise 'tang' becomes nan */
float tangv[3], ct[3], e1[3], e2[3], det;
det= 1.0f / (s1 * t2 - s2 * t1);
/* normals in render are inversed... */
sub_v3_v3v3(e1, co1, co2);
sub_v3_v3v3(e2, co1, co3);
tang[0] = (t2*e1[0] - t1*e2[0])*det;
tang[1] = (t2*e1[1] - t1*e2[1])*det;
tang[2] = (t2*e1[2] - t1*e2[2])*det;
tangv[0] = (s1*e2[0] - s2*e1[0])*det;
tangv[1] = (s1*e2[1] - s2*e1[1])*det;
tangv[2] = (s1*e2[2] - s2*e1[2])*det;
cross_v3_v3v3(ct, tang, tangv);
/* normals in render are inversed... */
sub_v3_v3v3(e1, co1, co2);
sub_v3_v3v3(e2, co1, co3);
tang[0] = (t2*e1[0] - t1*e2[0])*det;
tang[1] = (t2*e1[1] - t1*e2[1])*det;
tang[2] = (t2*e1[2] - t1*e2[2])*det;
tangv[0] = (s1*e2[0] - s2*e1[0])*det;
tangv[1] = (s1*e2[1] - s2*e1[1])*det;
tangv[2] = (s1*e2[2] - s2*e1[2])*det;
cross_v3_v3v3(ct, tang, tangv);
/* check flip */
if ((ct[0]*n[0] + ct[1]*n[1] + ct[2]*n[2]) < 0.0f)
negate_v3(tang);
/* check flip */
if ((ct[0]*n[0] + ct[1]*n[1] + ct[2]*n[2]) < 0.0f)
negate_v3(tang);
}
else {
tang[0]= tang[1]= tang[0]= 0.0;
}
}
/********************************************************/