static void
face_to_sphere (guVector *out, int face, float a, float b)
{
guVector sphere;
guVector eye = { 0, 0, -1 };
switch (face)
{
case 0: /* left */
sphere.x = -1.0;
sphere.y = -b;
sphere.z = -a;
break;
case 1: /* front */
sphere.x = -a;
sphere.y = -b;
sphere.z = 1.0;
break;
case 2: /* right */
sphere.x = 1.0;
sphere.y = -b;
sphere.z = a;
break;
case 3: /* back */
sphere.x = a;
sphere.y = -b;
sphere.z = -1;
break;
case 4: /* top */
sphere.x = -a;
sphere.y = 1.0;
sphere.z = b;
break;
case 5: /* bottom */
sphere.x = -a;
sphere.y = -1.0;
sphere.z = -b;
break;
}
/* We just need to add the "sphere" & eye vectors, then normalize. */
guVecNormalize (&sphere);
guVecAdd (&sphere, &eye, out);
if (out->x == 0 && out->y == 0 && out->z == 0)
out->z += 0.0001;
guVecNormalize (out);
}
void guVecHalfAngle(Vector *a,Vector *b,Vector *half)
{
Vector tmp1,tmp2,tmp3;
tmp1.x = -a->x;
tmp1.y = -a->y;
tmp1.z = -a->z;
tmp2.x = -b->x;
tmp2.y = -b->y;
tmp2.z = -b->z;
guVecNormalize(&tmp1);
guVecNormalize(&tmp2);
guVecAdd(&tmp1,&tmp2,&tmp3);
if(guVecDotProduct(&tmp3,&tmp3)>0.0f) guVecNormalize(&tmp3);
*half = tmp3;
}
