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Fix T46521: Python: bvh.ray_cast doesn't find a plane facing in the other direction under certain circumstances 

The issue was caused by wrong sign check. It originally came from more optimized
Cycles code where because of other reasons it wasn't visible yet. But in fact it
should be solved there as well.
This commit is contained in:
Sergey Sharybin 2015-10-22 20:29:52 +05:00
parent 9a6a3f5346
commit 0d54aa9c02
Notes: blender-bot 2023-02-14 08:31:10 +01:00 
Referenced by issue #46521, Python: bvh.ray_cast doesn't find a plane facing in the other direction under certain circumstances
1 changed files with 9 additions and 10 deletions
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19
source/blender/blenlib/intern/math_geom.c
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@ -1373,16 +1373,14 @@ bool isect_ray_tri_watertight_v3(
const float cy = c_ky - sy * c_kz;
/* Calculate scaled barycentric coordinates. */
float u = cx * by - cy * bx;
int sign_mask = (float_as_int(u) & (int)0x80000000);
float v = ax * cy - ay * cx;
float w, det;
const float u = cx * by - cy * bx;
const float v = ax * cy - ay * cx;
const float w = bx * ay - by * ax;
float det;
if (sign_mask != (float_as_int(v) & (int)0x80000000)) {
return false;
}
w = bx * ay - by * ax;
if (sign_mask != (float_as_int(w) & (int)0x80000000)) {
if ((u < 0.0f || v < 0.0f || w < 0.0f) &&
(u > 0.0f || v > 0.0f || w > 0.0f))
{
return false;
}
@ -1395,8 +1393,9 @@ bool isect_ray_tri_watertight_v3(
/* Calculate scaled z-coordinates of vertices and use them to calculate
* the hit distance.
*/
const int sign_det = (float_as_int(det) & (int)0x80000000);
const float t = (u * a_kz + v * b_kz + w * c_kz) * sz;
const float sign_t = xor_fl(t, sign_mask);
const float sign_t = xor_fl(t, sign_det);
if ((sign_t < 0.0f)
/* differ from Cycles, don't read r_lambda's original value
* otherwise we won't match any of the other intersect functions here...