Fix T53971: single layer render showing the wrong render layer in image editor.

Original patch Cheryl Chen, extra fixes by Brecht.

Differential Revision: https://developer.blender.org/D3098

3 files changed, 37 insertions, 11 deletions

diff --git a/source/blender/editors/render/render_internal.c b/source/blender/editors/render/render_internal.c
index 58b4c0fe222..c27570aabc5 100644
--- a/source/blender/editors/render/render_internal.c
+++ b/source/blender/editors/render/render_internal.c
@@ -521,10 +521,8 @@ static void render_image_update_pass_and_layer(RenderJob *rj, RenderResult *rr,
 			int layer = BLI_findstringindex(&main_rr->layers,
 			                                (char *)rr->renlay->name,
 			                                offsetof(RenderLayer, name));
-			if (layer != rj->last_layer) {
-				sima->iuser.layer = layer;
-				rj->last_layer = layer;
-			}
+			sima->iuser.layer = layer;
+			rj->last_layer = layer;
 		}
 
 		iuser->pass = sima->iuser.pass;
@@ -621,7 +619,21 @@ static void render_image_restore_layer(RenderJob *rj)
 				if (sa == rj->sa) {
 					if (sa->spacetype == SPACE_IMAGE) {
 						SpaceImage *sima = sa->spacedata.first;
-						sima->iuser.layer = rj->orig_layer;
+
+						if (RE_HasSingleLayer(rj->re)) {
+							/* For single layer renders keep the active layer
+							 * visible, or show the compositing result. */
+							RenderResult *rr = RE_AcquireResultRead(rj->re);
+							if(RE_HasCombinedLayer(rr)) {
+								sima->iuser.layer = 0;
+							}
+							RE_ReleaseResult(rj->re);
+						}
+						else {
+							/* For multiple layer render, set back the layer
+							 * that was set at the start of rendering. */
+							sima->iuser.layer = rj->orig_layer;
+						}
 					}
 					return;
 				}
diff --git a/source/blender/render/extern/include/RE_pipeline.h b/source/blender/render/extern/include/RE_pipeline.h
index bb056675887..de71b8d1023 100644
--- a/source/blender/render/extern/include/RE_pipeline.h
+++ b/source/blender/render/extern/include/RE_pipeline.h
@@ -236,6 +236,8 @@ void RE_render_result_rect_from_ibuf(
 struct RenderLayer *RE_GetRenderLayer(struct RenderResult *rr, const char *name);
 float *RE_RenderLayerGetPass(volatile struct RenderLayer *rl, const char *name, const char *viewname);
 
+bool RE_HasSingleLayer(struct Render *re);
+
 /* add passes for grease pencil */
 struct RenderPass *RE_create_gp_pass(struct RenderResult *rr, const char *layername, const char *viewname);
 
diff --git a/source/blender/render/intern/source/pipeline.c b/source/blender/render/intern/source/pipeline.c
index 7cab5f43aca..e17a503cd4e 100644
--- a/source/blender/render/intern/source/pipeline.c
+++ b/source/blender/render/intern/source/pipeline.c
@@ -257,6 +257,11 @@ RenderLayer *RE_GetRenderLayer(RenderResult *rr, const char *name)
 	}
 }
 
+bool RE_HasSingleLayer(Render *re)
+{
+	return (re->r.scemode & R_SINGLE_LAYER);
+}
+
 RenderResult *RE_MultilayerConvert(void *exrhandle, const char *colorspace, bool predivide, int rectx, int recty)
 {
 	return render_result_new_from_exr(exrhandle, colorspace, predivide, rectx, recty);
@@ -264,12 +269,19 @@ RenderResult *RE_MultilayerConvert(void *exrhandle, const char *colorspace, bool
 
 RenderLayer *render_get_active_layer(Render *re, RenderResult *rr)
 {
-	RenderLayer *rl = BLI_findlink(&rr->layers, re->r.actlay);
-	
-	if (rl)
-		return rl;
-	else 
-		return rr->layers.first;
+	SceneRenderLayer *srl = BLI_findlink(&re->r.layers, re->r.actlay);
+
+	if (srl) {
+		RenderLayer *rl = BLI_findstring(&rr->layers,
+		                                 srl->name,
+		                                 offsetof(RenderLayer, name));
+
+		if (rl) {
+			return rl;
+		}
+	}
+
+	return rr->layers.first;
 }
 
 static int render_scene_needs_vector(Render *re)