Fix T63359: no render preview when save buffers is on

2 files changed, 11 insertions, 3 deletions

diff --git a/source/blender/render/intern/source/external_engine.c b/source/blender/render/intern/source/external_engine.c
index 83d857211d0..0292a807131 100644
--- a/source/blender/render/intern/source/external_engine.c
+++ b/source/blender/render/intern/source/external_engine.c
@@ -288,6 +288,7 @@ void RE_engine_end_result(
     if (re->result->do_exr_tile) {
       if (!cancel && merge_results) {
         render_result_exr_file_merge(re->result, result, re->viewname);
+        render_result_merge(re->result, result);
       }
     }
     else if (!(re->test_break(re->tbh) && (re->r.scemode & R_BUTS_PREVIEW))) {
diff --git a/source/blender/render/intern/source/render_result.c b/source/blender/render/intern/source/render_result.c
index 8a95cc6397f..cf9bfe99474 100644
--- a/source/blender/render/intern/source/render_result.c
+++ b/source/blender/render/intern/source/render_result.c
@@ -240,7 +240,10 @@ static RenderPass *render_layer_add_pass(RenderResult *rr,
                           false);
     }
   }
-  else {
+
+  /* Always allocate combined for display, in case of save buffers
+   * other passes are not allocated and only saved to the EXR file. */
+  if (rl->exrhandle == NULL || STREQ(rpass->name, RE_PASSNAME_COMBINED)) {
     float *rect;
     int x;
 
@@ -853,10 +856,14 @@ void render_result_merge(RenderResult *rr, RenderResult *rrpart)
   for (rl = rr->layers.first; rl; rl = rl->next) {
     rlp = RE_GetRenderLayer(rrpart, rl->name);
     if (rlp) {
-      /* passes are allocated in sync */
+      /* Passes are allocated in sync. */
       for (rpass = rl->passes.first, rpassp = rlp->passes.first; rpass && rpassp;
            rpass = rpass->next) {
-        /* renderresult have all passes, renderpart only the active view's passes */
+        /* For save buffers, skip any passes that are only saved to disk. */
+        if (rpass->rect == NULL || rpassp->rect == NULL) {
+          continue;
+        }
+        /* Renderresult have all passes, renderpart only the active view's passes. */
         if (strcmp(rpassp->fullname, rpass->fullname) != 0) {
           continue;
         }