/**
* Same as #interp_v3_v3v3_slerp buy uses fallback values
* for opposite vectors.
*/
void interp_v3_v3v3_slerp_safe(float target[3], const float a[3], const float b[3], const float t)
{
if (UNLIKELY(!interp_v3_v3v3_slerp(target, a, b, t))) {
/* axis are aligned so any otho vector is acceptable */
float ab_ortho[3];
ortho_v3_v3(ab_ortho, a);
normalize_v3(ab_ortho);
if (t < 0.5f) {
if (UNLIKELY(!interp_v3_v3v3_slerp(target, a, ab_ortho, t * 2.0f))) {
BLI_assert(0);
copy_v3_v3(target, a);
}
}
else {
if (UNLIKELY(!interp_v3_v3v3_slerp(target, ab_ortho, b, (t - 0.5f) * 2.0f))) {
BLI_assert(0);
copy_v3_v3(target, b);
}
}
}
}
/**
* Specialized slerp that uses a sphere defined by each points normal.
*/
static void interp_slerp_co_no_v3(
const float co_a[3], const float no_a[3],
const float co_b[3], const float no_b[3],
const float no_dir[3], /* caller already knows, avoid normalize */
float fac,
float r_co[3])
{
/* center of the sphere defined by both normals */
float center[3];
BLI_assert(len_squared_v3v3(no_a, no_b) != 0);
/* calculate sphere 'center' */
{
/* use point on plane to */
float plane_a[4], plane_b[4], plane_c[4];
float no_mid[3], no_ortho[3];
/* pass this as an arg instead */
#if 0
float no_dir[3];
#endif
float v_a_no_ortho[3], v_b_no_ortho[3];
add_v3_v3v3(no_mid, no_a, no_b);
normalize_v3(no_mid);
#if 0
sub_v3_v3v3(no_dir, co_a, co_b);
normalize_v3(no_dir);
#endif
/* axis of slerp */
cross_v3_v3v3(no_ortho, no_mid, no_dir);
normalize_v3(no_ortho);
/* create planes */
cross_v3_v3v3(v_a_no_ortho, no_ortho, no_a);
cross_v3_v3v3(v_b_no_ortho, no_ortho, no_b);
project_v3_plane(v_a_no_ortho, no_ortho, v_a_no_ortho);
project_v3_plane(v_b_no_ortho, no_ortho, v_b_no_ortho);
plane_from_point_normal_v3(plane_a, co_a, v_a_no_ortho);
plane_from_point_normal_v3(plane_b, co_b, v_b_no_ortho);
plane_from_point_normal_v3(plane_c, co_b, no_ortho);
/* find the sphere center from 3 planes */
if (isect_plane_plane_plane_v3(plane_a, plane_b, plane_c, center)) {
/* pass */
}
else {
mid_v3_v3v3(center, co_a, co_b);
}
}
/* calculate the final output 'r_co' */
{
float ofs_a[3], ofs_b[3], ofs_slerp[3];
float dist_a, dist_b;
sub_v3_v3v3(ofs_a, co_a, center);
sub_v3_v3v3(ofs_b, co_b, center);
dist_a = normalize_v3(ofs_a);
dist_b = normalize_v3(ofs_b);
if (interp_v3_v3v3_slerp(ofs_slerp, ofs_a, ofs_b, fac)) {
madd_v3_v3v3fl(r_co, center, ofs_slerp, interpf(dist_b, dist_a, fac));
}
else {
interp_v3_v3v3(r_co, co_a, co_b, fac);
}
}
}
