Fix #34783: smoke simulation crash when changing frame while preview rendering.

Added a mutex lock for smoke data access. The render was already working with a
copy of the volume data, so it's just a short lock to copy things and should not
block the UI much.

1 files changed, 22 insertions, 3 deletions

diff --git a/source/blender/render/intern/source/voxeldata.c b/source/blender/render/intern/source/voxeldata.c
index 9990ad7e900..1c76a228566 100644
--- a/source/blender/render/intern/source/voxeldata.c
+++ b/source/blender/render/intern/source/voxeldata.c
@@ -42,6 +42,7 @@
 
 #include "BLI_math.h"
 #include "BLI_blenlib.h"
+#include "BLI_threads.h"
 #include "BLI_voxel.h"
 #include "BLI_utildefines.h"
 
@@ -239,6 +240,13 @@ static void init_frame_smoke(VoxelData *vd, float cfra)
 		SmokeDomainSettings *sds = smd->domain;
 		
 		if (sds && sds->fluid) {
+			BLI_rw_mutex_lock(sds->fluid_mutex, THREAD_LOCK_READ);
+
+			if (!sds->fluid) {
+				BLI_rw_mutex_unlock(sds->fluid_mutex);
+				return;
+			}
+
 			if (cfra < sds->point_cache[0]->startframe)
 				;  /* don't show smoke before simulation starts, this could be made an option in the future */
 			else if (vd->smoked_type == TEX_VD_SMOKEHEAT) {
@@ -246,7 +254,10 @@ static void init_frame_smoke(VoxelData *vd, float cfra)
 				size_t i;
 				float *heat;
 
-				if (!smoke_has_heat(sds->fluid)) return;
+				if (!smoke_has_heat(sds->fluid)) {
+					BLI_rw_mutex_unlock(sds->fluid_mutex);
+					return;
+				}
 
 				copy_v3_v3_int(vd->resol, sds->res);
 				totRes = vd_resol_size(vd);
@@ -283,12 +294,18 @@ static void init_frame_smoke(VoxelData *vd, float cfra)
 				float *flame;
 
 				if (sds->flags & MOD_SMOKE_HIGHRES) {
-					if (!smoke_turbulence_has_fuel(sds->wt)) return;
+					if (!smoke_turbulence_has_fuel(sds->wt)) {
+						BLI_rw_mutex_unlock(sds->fluid_mutex);
+						return;
+					}
 					smoke_turbulence_get_res(sds->wt, vd->resol);
 					flame = smoke_turbulence_get_flame(sds->wt);
 				}
 				else {
-					if (!smoke_has_fuel(sds->fluid)) return;
+					if (!smoke_has_fuel(sds->fluid)) {
+						BLI_rw_mutex_unlock(sds->fluid_mutex);
+						return;
+					}
 					copy_v3_v3_int(vd->resol, sds->res);
 					flame = smoke_get_flame(sds->fluid);
 				}
@@ -333,6 +350,8 @@ static void init_frame_smoke(VoxelData *vd, float cfra)
 					}
 				}
 			}  /* end of fluid condition */
+
+			BLI_rw_mutex_unlock(sds->fluid_mutex);
 		}
 	}