Made an attempt for fixing an instability issue regarding animation

rendering.

RE_BlenderFrame() and RE_BlenderAnim() are Blender's internal
top-level rendering API functions for a single frame and a series of
frames, respectively.  These functions rely on global variables to
keep render pipeline states.  Freestyle's stroke rendering was also
using RE_BlenderFrame to render a temporary scene of stroke meshes.
These nested calls of the top-level rendering API functions were
causing broken render pipeline states and eventually led to a crash.

This commit is intended to fix the issue, by introducing an rendering
API function RE_RenderFreestyleStrokes specifically used for stroke
rendering in Freestyle.  The new function does not do anything with
regard to the global variables in the rendering API implementation.

3 files changed, 12 insertions, 1 deletions

diff --git a/source/blender/freestyle/intern/blender_interface/BlenderStrokeRenderer.cpp b/source/blender/freestyle/intern/blender_interface/BlenderStrokeRenderer.cpp
index 30577287b72..f6798384f0a 100644
--- a/source/blender/freestyle/intern/blender_interface/BlenderStrokeRenderer.cpp
+++ b/source/blender/freestyle/intern/blender_interface/BlenderStrokeRenderer.cpp
@@ -341,6 +341,6 @@ Render* BlenderStrokeRenderer::RenderScene( Render *re ) {
 	
 	Render *freestyle_render = RE_NewRender(freestyle_scene->id.name, RE_SLOT_DEFAULT);
 
-	RE_BlenderFrame( freestyle_render, freestyle_scene, NULL, 1);
+	RE_RenderFreestyleStrokes(freestyle_render, freestyle_scene);
 	return freestyle_render;
 }
diff --git a/source/blender/render/extern/include/RE_pipeline.h b/source/blender/render/extern/include/RE_pipeline.h
index f9c4e9690a1..0218f7458cb 100644
--- a/source/blender/render/extern/include/RE_pipeline.h
+++ b/source/blender/render/extern/include/RE_pipeline.h
@@ -216,6 +216,7 @@ void RE_TileProcessor(struct Render *re, int firsttile, int threaded);
 /* only RE_NewRender() needed, main Blender render calls */
 void RE_BlenderFrame(struct Render *re, struct Scene *scene, struct SceneRenderLayer *srl, int frame);
 void RE_BlenderAnim(struct Render *re, struct Scene *scene, int sfra, int efra, int tfra, struct ReportList *reports);
+void RE_RenderFreestyleStrokes(struct Render *re, struct Scene *scene);
 
 void RE_ReadRenderResult(struct Scene *scene, struct Scene *scenode);
 void RE_WriteRenderResult(RenderResult *rr, char *filename, int compress);
diff --git a/source/blender/render/intern/source/pipeline.c b/source/blender/render/intern/source/pipeline.c
index a5b3b1dd18c..6e63e023793 100644
--- a/source/blender/render/intern/source/pipeline.c
+++ b/source/blender/render/intern/source/pipeline.c
@@ -2839,6 +2839,16 @@ void RE_BlenderFrame(Render *re, Scene *scene, SceneRenderLayer *srl, int frame)
 	RenderGlobal.renderingslot= RenderGlobal.viewslot;
 }
 
+void RE_RenderFreestyleStrokes(Render *re, Scene *scene)
+{
+	re->result_ok= 0;
+	scene->r.cfra= 1;
+	if(render_initialize_from_scene(re, scene, NULL, 0, 0)) {
+		do_render_all_options(re);
+	}
+	re->result_ok= 1;
+}
+
 static int do_write_image_or_movie(Render *re, Scene *scene, bMovieHandle *mh, ReportList *reports)
 {
 	char name[FILE_MAX];