Fix T39711: cycles particle motion blur affected by viewport draw method.

2 files changed, 25 insertions, 0 deletions

diff --git a/source/blender/render/extern/include/RE_engine.h b/source/blender/render/extern/include/RE_engine.h
index 2c6492b5c5a..c76cf3406a1 100644
--- a/source/blender/render/extern/include/RE_engine.h
+++ b/source/blender/render/extern/include/RE_engine.h
@@ -147,6 +147,8 @@ int RE_engine_render(struct Render *re, int do_all);
 
 bool RE_engine_is_external(struct Render *re);
 
+void RE_engine_frame_set(struct RenderEngine *engine, int frame, float subframe);
+
 /* Engine Types */
 
 void RE_engines_init(void);
diff --git a/source/blender/render/intern/source/external_engine.c b/source/blender/render/intern/source/external_engine.c
index e8751210540..6ba2c57a6fc 100644
--- a/source/blender/render/intern/source/external_engine.c
+++ b/source/blender/render/intern/source/external_engine.c
@@ -481,6 +481,29 @@ bool RE_bake_engine(
 	return true;
 }
 
+void RE_engine_frame_set(RenderEngine *engine, int frame, float subframe)
+{
+	Render *re = engine->re;
+	Scene *scene = re->scene;
+	double cfra = (double)frame + (double)subframe;
+
+	CLAMP(cfra, MINAFRAME, MAXFRAME);
+	BKE_scene_frame_set(scene, cfra);
+
+#ifdef WITH_PYTHON
+	BPy_BEGIN_ALLOW_THREADS;
+#endif
+
+	/* It's possible that here we're including layers which were never visible before. */
+	BKE_scene_update_for_newframe_ex(re->eval_ctx, re->main, scene, (1 << 20) - 1, true);
+
+#ifdef WITH_PYTHON
+	BPy_END_ALLOW_THREADS;
+#endif
+
+	BKE_scene_camera_switch_update(scene);
+}
+
 /* Render */
 
 static bool render_layer_exclude_animated(Scene *scene, SceneRenderLayer *srl)