Fix T78028: crash with grease pencil and save buffers

Perform grease pencil rendering delayed in this case, as there are no render
buffers available for compositing. This keeps memory usage lower, but does
involve multiple depsgraph evaluation. This seems in line with the intent of
the save buffers feature, to use minimal memory.

1 files changed, 4 insertions, 5 deletions

diff --git a/source/blender/draw/intern/draw_manager.c b/source/blender/draw/intern/draw_manager.c
index f995582149a..a3c8a4a669f 100644
--- a/source/blender/draw/intern/draw_manager.c
+++ b/source/blender/draw/intern/draw_manager.c
@@ -1735,11 +1735,10 @@ static void DRW_render_gpencil_to_image(RenderEngine *engine,
 
 void DRW_render_gpencil(struct RenderEngine *engine, struct Depsgraph *depsgraph)
 {
-  /* Early out if there are no grease pencil objects, especially important
-   * to avoid failing in in background renders without OpenGL context. */
-  if (!DRW_render_check_grease_pencil(depsgraph)) {
-    return;
-  }
+  /* This function should only be called if there are are grease pencil objects,
+   * especially important to avoid failing in in background renders without OpenGL
+   * context. */
+  BLI_assert(DRW_render_check_grease_pencil(depsgraph));
 
   Scene *scene = DEG_get_evaluated_scene(depsgraph);
   ViewLayer *view_layer = DEG_get_evaluated_view_layer(depsgraph);