Fix memory leak in point density

The issue was happening when having unconnected point density which
will cache data but will not free it because there's no actual call
to the actual sampling.

Now the idea is to make sure cache is zeroed on file load and undo
and then caching via RNA will free the data if any exists. This could
leave us with a single copy of cache in the node if it's not used,
but it's quite small amount of memory and it's not leaking.

source/blender/blenloader/intern/readfile.c

@@ -3025,6 +3025,10 @@ static void direct_link_nodetree(FileData *fd, bNodeTree *ntree)
 					NodeShaderScript *nss = (NodeShaderScript *) node->storage;
 					nss->bytecode = newdataadr(fd, nss->bytecode);
 				}
+				else if (node->type==SH_NODE_TEX_POINTDENSITY) {
+					NodeShaderTexPointDensity *npd = (NodeShaderTexPointDensity *) node->storage;
+					memset(&npd->pd, 0, sizeof(npd->pd));
+				}
 			}
 			else if (ntree->type==NTREE_COMPOSIT) {
 				if (ELEM(node->type, CMP_NODE_TIME, CMP_NODE_CURVE_VEC, CMP_NODE_CURVE_RGB, CMP_NODE_HUECORRECT))

source/blender/makesrna/intern/rna_nodetree.c

@@ -3045,8 +3045,11 @@ void rna_ShaderNodePointDensity_density_cache(bNode *self,
 		return;
 	}
 
+	/* Make sure there's no cached data. */
+	BKE_texture_pointdensity_free_data(pd);
+	RE_point_density_free(pd);
+
 	/* Create PointDensity structure from node for sampling. */
-	memset(pd, 0, sizeof(*pd));
 	BKE_texture_pointdensity_init_data(pd);
 	pd->object = (Object *)self->id;
 	pd->radius = shader_point_density->radius;
@@ -3098,6 +3101,7 @@ void rna_ShaderNodePointDensity_density_calc(bNode *self,
 
 	/* We're done, time to clean up. */
 	BKE_texture_pointdensity_free_data(pd);
+	memset(pd, 0, sizeof(*pd));
 }
 
 void rna_ShaderNodePointDensity_density_minmax(bNode *self,

source/blender/nodes/shader/nodes/node_shader_tex_pointdensity.c

@@ -27,6 +27,10 @@
 
 #include "../node_shader_util.h"
 
+#include "BKE_texture.h"
+
+#include "RE_render_ext.h"
+
 /* **************** OUTPUT ******************** */
 
 static bNodeSocketTemplate sh_node_tex_pointdensity_in[] = {
@@ -52,6 +56,26 @@ static void node_shader_init_tex_pointdensity(bNodeTree *UNUSED(ntree),
 	node->storage = point_density;
 }
 
+static void node_shader_free_tex_pointdensity(bNode *node)
+{
+	NodeShaderTexPointDensity *point_density = node->storage;
+	PointDensity *pd = &point_density->pd;
+	RE_point_density_free(pd);
+	BKE_texture_pointdensity_free_data(pd);
+	memset(pd, 0, sizeof(*pd));
+	MEM_freeN(point_density);
+}
+
+static void node_shader_copy_tex_pointdensity(bNodeTree * UNUSED(dest_ntree),
+                                              bNode *dest_node,
+                                              bNode *src_node)
+{
+	dest_node->storage = MEM_dupallocN(src_node->storage);
+	NodeShaderTexPointDensity *point_density = dest_node->storage;
+	PointDensity *pd = &point_density->pd;
+	memset(pd, 0, sizeof(*pd));
+}
+
 /* node type definition */
 void register_node_type_sh_tex_pointdensity(void)
 {
@@ -69,8 +93,8 @@ void register_node_type_sh_tex_pointdensity(void)
 	node_type_init(&ntype, node_shader_init_tex_pointdensity);
 	node_type_storage(&ntype,
 	                  "NodeShaderTexPointDensity",
-	                  node_free_standard_storage,
-	                  node_copy_standard_storage);
+	                  node_shader_free_tex_pointdensity,
+	                  node_shader_copy_tex_pointdensity);
 
 	nodeRegisterType(&ntype);
 }

source/blender/render/extern/include/RE_render_ext.h

@@ -86,5 +86,7 @@ void RE_point_density_sample(
         const bool use_render_params,
         float *values);
 
+void RE_point_density_free(struct PointDensity *pd);
+
 #endif /* __RE_RENDER_EXT_H__ */
 

source/blender/render/intern/source/pointdensity.c

@@ -832,3 +832,8 @@ void RE_point_density_sample(
 	free_pointdensity(pd);
 	BLI_mutex_unlock(&sample_mutex);
 }
+
+void RE_point_density_free(struct PointDensity *pd)
+{
+	free_pointdensity(pd);
+}