Fix T75096: Crash when using liquid simulation as dynamic paint brush

Reviewers: sergey

Differential Revision: https://developer.blender.org/D7853

1 files changed, 4 insertions, 3 deletions

diff --git a/source/blender/blenkernel/intern/dynamicpaint.c b/source/blender/blenkernel/intern/dynamicpaint.c
index a704e199007..79f0aacc3f8 100644
--- a/source/blender/blenkernel/intern/dynamicpaint.c
+++ b/source/blender/blenkernel/intern/dynamicpaint.c
@@ -2701,15 +2701,16 @@ static void dynamic_paint_find_island_border(const DynamicPaintCreateUVSurfaceDa
       }
     }
 
+    const int final_tri_index = tempPoints[final_index].tri_index;
     /* If found pixel still lies on wrong face ( mesh has smaller than pixel sized faces) */
-    if (tempPoints[final_index].tri_index != target_tri) {
+    if (final_tri_index != target_tri && final_tri_index != -1) {
       /* Check if it's close enough to likely touch the intended triangle. Any triangle
        * becomes thinner than a pixel at its vertices, so robustness requires some margin. */
       const float final_pt[2] = {((final_index % w) + 0.5f) / w, ((final_index / w) + 0.5f) / h};
       const float threshold = square_f(0.7f) / (w * h);
 
-      if (dist_squared_to_looptri_uv_edges(
-              mlooptri, mloopuv, tempPoints[final_index].tri_index, final_pt) > threshold) {
+      if (dist_squared_to_looptri_uv_edges(mlooptri, mloopuv, final_tri_index, final_pt) >
+          threshold) {
         continue;
       }
     }