[Bf-blender-cvs] [17c00d222f9] blender-v2.79a-release: Fix T52732: Particle system volume grid particles out of volume

[Sergey Sharybin]

Commit: 17c00d222f9eb0b9ff006619bfdec7fa9b193335
Author: Sergey Sharybin
Date:   Thu Sep 14 19:43:00 2017 +0500
Branches: blender-v2.79a-release
https://developer.blender.org/rB17c00d222f9eb0b9ff006619bfdec7fa9b193335

Fix T52732: Particle system volume grid particles out of volume

Use more watertight and robust intersection test.

It uses now ray to triangle intersection, but it's all fine because segment was
covering the whole bounding box anyway.

===================================================================

M	source/blender/blenkernel/intern/particle_distribute.c

===================================================================

diff --git a/source/blender/blenkernel/intern/particle_distribute.c b/source/blender/blenkernel/intern/particle_distribute.c
index ac9c60e8999..bcef6c2ace0 100644
--- a/source/blender/blenkernel/intern/particle_distribute.c
+++ b/source/blender/blenkernel/intern/particle_distribute.c
@@ -39,6 +39,7 @@
 #include "BLI_jitter.h"
 #include "BLI_kdtree.h"
 #include "BLI_math.h"
+#include "BLI_math_geom.h"
 #include "BLI_rand.h"
 #include "BLI_sort.h"
 #include "BLI_task.h"
@@ -213,14 +214,22 @@ static void distribute_grid(DerivedMesh *dm, ParticleSystem *psys)
 					copy_v3_v3(co2, co1);
 					co2[a] += delta[a] + 0.001f*d;
 					co1[a] -= 0.001f*d;
-					
+
+					struct IsectRayPrecalc isect_precalc;
+					float ray_direction[3];
+					sub_v3_v3v3(ray_direction, co2, co1);
+					isect_ray_tri_watertight_v3_precalc(&isect_precalc, ray_direction);
+
 					/* lets intersect the faces */
 					for (i=0; i<totface; i++,mface++) {
 						copy_v3_v3(v1, mvert[mface->v1].co);
 						copy_v3_v3(v2, mvert[mface->v2].co);
 						copy_v3_v3(v3, mvert[mface->v3].co);
 
-						bool intersects_tri = isect_axial_line_segment_tri_v3(a, co1, co2, v2, v3, v1, &lambda);
+						bool intersects_tri = isect_ray_tri_watertight_v3(co1,
+						                                                  &isect_precalc,
+						                                                  v1, v2, v3,
+						                                                  &lambda, NULL);
 						if (intersects_tri) {
 							if (from==PART_FROM_FACE)
 								(pa+(int)(lambda*size[a])*a0mul)->flag &= ~PARS_UNEXIST;
@@ -231,7 +240,10 @@ static void distribute_grid(DerivedMesh *dm, ParticleSystem *psys)
 						if (mface->v4 && (!intersects_tri || from==PART_FROM_VOLUME)) {
 							copy_v3_v3(v4, mvert[mface->v4].co);
 
-							if (isect_axial_line_segment_tri_v3(a, co1, co2, v4, v1, v3, &lambda)) {
+							if (isect_ray_tri_watertight_v3(co1,
+							                                &isect_precalc,
+							                                v1, v2, v3,
+							                                &lambda, NULL)) {
 								if (from==PART_FROM_FACE)
 									(pa+(int)(lambda*size[a])*a0mul)->flag &= ~PARS_UNEXIST;
 								else