Fix T66340: Missing particles in Grid and Volume distribution.

This solution only alleviates the problem.

1 files changed, 28 insertions, 12 deletions

diff --git a/source/blender/blenkernel/intern/particle_distribute.c b/source/blender/blenkernel/intern/particle_distribute.c
index 070c3c7a566..96030b7361d 100644
--- a/source/blender/blenkernel/intern/particle_distribute.c
+++ b/source/blender/blenkernel/intern/particle_distribute.c
@@ -232,6 +232,9 @@ static void distribute_grid(Mesh *mesh, ParticleSystem *psys)
 
           /* lets intersect the faces */
           for (i = 0; i < totface; i++, mface++) {
+            ParticleData *pa1 = NULL, *pa2 = NULL;
+            bool isect1 = false, isect2 = false;
+
             copy_v3_v3(v1, mvert[mface->v1].co);
             copy_v3_v3(v2, mvert[mface->v2].co);
             copy_v3_v3(v3, mvert[mface->v3].co);
@@ -239,24 +242,37 @@ static void distribute_grid(Mesh *mesh, ParticleSystem *psys)
             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;
-              }
-              else { /* store number of intersections */
-                (pa + (int)(lambda * size[a]) * a0mul)->hair_index++;
-              }
+              pa1 = (pa + (int)(lambda * size[a]) * a0mul);
+              isect1 = true;
             }
 
             if (mface->v4 && (!intersects_tri || from == PART_FROM_VOLUME)) {
               copy_v3_v3(v4, mvert[mface->v4].co);
 
               if (isect_ray_tri_watertight_v3(co1, &isect_precalc, v1, v3, v4, &lambda, NULL)) {
-                if (from == PART_FROM_FACE) {
-                  (pa + (int)(lambda * size[a]) * a0mul)->flag &= ~PARS_UNEXIST;
-                }
-                else {
-                  (pa + (int)(lambda * size[a]) * a0mul)->hair_index++;
-                }
+                pa2 = (pa + (int)(lambda * size[a]) * a0mul);
+                isect2 = true;
+              }
+            }
+
+            if (pa1 == pa2) {
+              isect1 |= isect2;
+            }
+            else if (isect2) {
+              if (from == PART_FROM_FACE) {
+                pa2->flag &= ~PARS_UNEXIST;
+              }
+              else { /* store number of intersections */
+                pa2->hair_index++;
+              }
+            }
+
+            if (isect1) {
+              if (from == PART_FROM_FACE) {
+                pa1->flag &= ~PARS_UNEXIST;
+              }
+              else { /* store number of intersections */
+                pa1->hair_index++;
               }
             }
           }