Fix/Workaround T44662: Freestyle gives no visual output when the Save Buffers option is enabled

For now we solve this for non-multiview renders by merging exr file back into
full render result prior to rendering freestyle strokes. Multiview case is
still to be supported tho.

1 files changed, 34 insertions, 1 deletions

diff --git a/source/blender/render/intern/source/pipeline.c b/source/blender/render/intern/source/pipeline.c
index af6ea2bc81f..cac4970cd11 100644
--- a/source/blender/render/intern/source/pipeline.c
+++ b/source/blender/render/intern/source/pipeline.c
@@ -121,6 +121,17 @@
  *
  */
 
+/* Freestyle needs the whole frame to be merged into memory prior to
+ * doing stroke rendering. This conflicts a bit with multiview save
+ * buffers behavior which does a merge of exr files after all the
+ * views are rendered.
+ *
+ * For until a proper solution is implemented we'll just merge single
+ * view image prior to freestyle stroke rendering, which is how this
+ * worked prior to multiview. Multiview+freestyle+save buffers are
+ * considered unsupported for the time being.
+ */
+#define FREESTYLR_SAVEBUFFERS_WORKAROUND
 
 /* ********* globals ******** */
 
@@ -1426,6 +1437,9 @@ void RE_TileProcessor(Render *re)
 
 static void do_render_3d(Render *re)
 {
+#ifdef FREESTYLR_SAVEBUFFERS_WORKAROUND
+	const bool do_early_result_merge = (re->r.scemode & R_MULTIVIEW) == 0;
+#endif
 	RenderView *rv;
 	int cfra_backup;
 
@@ -1473,7 +1487,13 @@ static void do_render_3d(Render *re)
 			re->draw_lock(re->dlh, 0);
 	
 		threaded_tile_processor(re);
-	
+
+#ifdef FREESTYLR_SAVEBUFFERS_WORKAROUND
+		if (do_early_result_merge) {
+			main_render_result_end(re);
+		}
+#endif
+
 #ifdef WITH_FREESTYLE
 		/* Freestyle */
 		if (re->r.mode & R_EDGE_FRS)
@@ -1490,7 +1510,13 @@ static void do_render_3d(Render *re)
 		RE_Database_Free(re);
 	}
 
+#ifdef FREESTYLR_SAVEBUFFERS_WORKAROUND
+	if (!do_early_result_merge) {
+		main_render_result_end(re);
+	}
+#else
 	main_render_result_end(re);
+#endif
 
 	re->scene->r.cfra = cfra_backup;
 	re->scene->r.subframe = 0.f;
@@ -2929,6 +2955,13 @@ bool RE_is_rendering_allowed(Scene *scene, Object *camera_override, ReportList *
 			BKE_report(reports, RPT_ERROR, "Fields not supported in Freestyle");
 			return false;
 		}
+
+#  ifdef FREESTYLR_SAVEBUFFERS_WORKAROUND
+		if ((scene->r.scemode & R_MULTIVIEW) != 0 && (scene->r.scemode & R_EXR_TILE_FILE) != 0) {
+			BKE_report(reports, RPT_ERROR, "Multiview combined with Save Buffers not supported in Freestyle");
+			return false;
+		}
+#  endif
 	}
 #endif