Fix T52653: Render output of linked scenes conflicts with other scenes with the same name

The issue was caused by render result identifier only consist of scene name,
which could indeed cause conflicts.

On the one hand, there are quite some areas in Blender where we need identifier
to be unique to properly address things. Usually this is required for sub-data
of IDs, like bones. On another hand, it's not that hard to support this
particular case and avoid possible frustration.

The idea is, we add library name to render identifier for linked scenes. We use
library name and not pointer so we preserve render results through undo stack.

Reviewers: campbellbarton, mont29, brecht

Reviewed By: mont29

Differential Revision: https://developer.blender.org/D2836

2 files changed, 38 insertions, 5 deletions

diff --git a/source/blender/render/extern/include/RE_pipeline.h b/source/blender/render/extern/include/RE_pipeline.h
index 0d2e29ba4c8..cf9298bdb9e 100644
--- a/source/blender/render/extern/include/RE_pipeline.h
+++ b/source/blender/render/extern/include/RE_pipeline.h
@@ -194,6 +194,10 @@ typedef struct RenderStats {
 struct Render *RE_NewRender(const char *name);
 struct Render *RE_GetRender(const char *name);
 
+struct Scene;
+struct Render *RE_NewSceneRender(const struct Scene *scene);
+struct Render *RE_GetSceneRender(const struct Scene *scene);
+
 /* assign default dummy callbacks */
 void RE_InitRenderCB(struct Render *re);
 
diff --git a/source/blender/render/intern/source/pipeline.c b/source/blender/render/intern/source/pipeline.c
index e078365e1ed..a0ebe241569 100644
--- a/source/blender/render/intern/source/pipeline.c
+++ b/source/blender/render/intern/source/pipeline.c
@@ -307,7 +307,6 @@ Render *RE_GetRender(const char *name)
 	return re;
 }
 
-
 /* if you want to know exactly what has been done */
 RenderResult *RE_AcquireResultRead(Render *re)
 {
@@ -514,6 +513,36 @@ Render *RE_NewRender(const char *name)
 	return re;
 }
 
+/* MAX_ID_NAME + sizeof(Library->name) + space + null-terminator. */
+#define MAX_SCENE_RENDER_NAME (MAX_ID_NAME + 1024 + 2)
+
+static void scene_render_name_get(const Scene *scene,
+                                  const size_t max_size,
+                                  char *render_name)
+{
+	if (ID_IS_LINKED_DATABLOCK(scene)) {
+		BLI_snprintf(render_name, max_size, "%s %s",
+		             scene->id.lib->id.name, scene->id.name);
+	}
+	else {
+		BLI_snprintf(render_name, max_size, "%s", scene->id.name);
+	}
+}
+
+Render *RE_GetSceneRender(const Scene *scene)
+{
+	char render_name[MAX_SCENE_RENDER_NAME];
+	scene_render_name_get(scene, sizeof(render_name), render_name);
+	return RE_GetRender(render_name);
+}
+
+Render *RE_NewSceneRender(const Scene *scene)
+{
+	char render_name[MAX_SCENE_RENDER_NAME];
+	scene_render_name_get(scene, sizeof(render_name), render_name);
+	return RE_NewRender(render_name);
+}
+
 /* called for new renders and when finishing rendering so
  * we always have valid callbacks on a render */
 void RE_InitRenderCB(Render *re)
@@ -1913,7 +1942,7 @@ static void do_render_fields_blur_3d(Render *re)
  */
 static void render_scene(Render *re, Scene *sce, int cfra)
 {
-	Render *resc = RE_NewRender(sce->id.name);
+	Render *resc = RE_NewSceneRender(sce);
 	int winx = re->winx, winy = re->winy;
 	
 	sce->r.cfra = cfra;
@@ -2348,7 +2377,7 @@ static void do_merge_fullsample(Render *re, bNodeTree *ntree)
 		tag_scenes_for_render(re);
 		for (sce = re->main->scene.first; sce; sce = sce->id.next) {
 			if (sce->id.tag & LIB_TAG_DOIT) {
-				re1 = RE_GetRender(sce->id.name);
+				re1 = RE_GetSceneRender(sce);
 
 				if (re1 && (re1->r.scemode & R_FULL_SAMPLE)) {
 					if (sample) {
@@ -3858,9 +3887,9 @@ bool RE_ReadRenderResult(Scene *scene, Scene *scenode)
 		scene = scenode;
 	
 	/* get render: it can be called from UI with draw callbacks */
-	re = RE_GetRender(scene->id.name);
+	re = RE_GetSceneRender(scene);
 	if (re == NULL)
-		re = RE_NewRender(scene->id.name);
+		re = RE_NewSceneRender(scene);
 	RE_InitState(re, NULL, &scene->r, NULL, winx, winy, &disprect);
 	re->scene = scene;
 	re->scene_color_manage = BKE_scene_check_color_management_enabled(scene);