Python API: option for render engines to disable image file saving

For some custom rendering engines it's advantageous not to write the image files to disk.
An example would be a network rendering engine which does it's own image writing.

This feature is only supported when bl_use_postprocess is also disabled, since render
engines can't influence the saving behavior of the sequencer or compositor.

Differential Revision: https://developer.blender.org/D11512

2 files changed, 43 insertions, 27 deletions

diff --git a/source/blender/render/RE_engine.h b/source/blender/render/RE_engine.h
index 7352ac7b12e..6b2861bbefd 100644
--- a/source/blender/render/RE_engine.h
+++ b/source/blender/render/RE_engine.h
@@ -65,6 +65,7 @@ extern "C" {
 #define RE_USE_STEREO_VIEWPORT 256
 #define RE_USE_GPU_CONTEXT 512
 #define RE_USE_CUSTOM_FREESTYLE 1024
+#define RE_USE_NO_IMAGE_SAVE 2048
 
 /* RenderEngine.flag */
 #define RE_ENGINE_ANIMATION 1
diff --git a/source/blender/render/intern/pipeline.c b/source/blender/render/intern/pipeline.c
index a39214b609d..20f868ca86f 100644
--- a/source/blender/render/intern/pipeline.c
+++ b/source/blender/render/intern/pipeline.c
@@ -2215,35 +2215,42 @@ static int do_write_image_or_movie(Render *re,
   RenderResult rres;
   double render_time;
   bool ok = true;
+  RenderEngineType *re_type = RE_engines_find(re->r.engine);
 
-  RE_AcquireResultImageViews(re, &rres);
+  /* Only disable file writing if postprocessing is also disabled. */
+  const bool do_write_file = !(re_type->flag & RE_USE_NO_IMAGE_SAVE) ||
+                             (re_type->flag & RE_USE_POSTPROCESS);
 
-  /* write movie or image */
-  if (BKE_imtype_is_movie(scene->r.im_format.imtype)) {
-    RE_WriteRenderViewsMovie(
-        re->reports, &rres, scene, &re->r, mh, re->movie_ctx_arr, totvideos, false);
-  }
-  else {
-    if (name_override) {
-      BLI_strncpy(name, name_override, sizeof(name));
+  if (do_write_file) {
+    RE_AcquireResultImageViews(re, &rres);
+
+    /* write movie or image */
+    if (BKE_imtype_is_movie(scene->r.im_format.imtype)) {
+      RE_WriteRenderViewsMovie(
+          re->reports, &rres, scene, &re->r, mh, re->movie_ctx_arr, totvideos, false);
     }
     else {
-      BKE_image_path_from_imformat(name,
-                                   scene->r.pic,
-                                   BKE_main_blendfile_path(bmain),
-                                   scene->r.cfra,
-                                   &scene->r.im_format,
-                                   (scene->r.scemode & R_EXTENSION) != 0,
-                                   true,
-                                   NULL);
+      if (name_override) {
+        BLI_strncpy(name, name_override, sizeof(name));
+      }
+      else {
+        BKE_image_path_from_imformat(name,
+                                     scene->r.pic,
+                                     BKE_main_blendfile_path(bmain),
+                                     scene->r.cfra,
+                                     &scene->r.im_format,
+                                     (scene->r.scemode & R_EXTENSION) != 0,
+                                     true,
+                                     NULL);
+      }
+
+      /* write images as individual images or stereo */
+      ok = RE_WriteRenderViewsImage(re->reports, &rres, scene, true, name);
     }
 
-    /* write images as individual images or stereo */
-    ok = RE_WriteRenderViewsImage(re->reports, &rres, scene, true, name);
+    RE_ReleaseResultImageViews(re, &rres);
   }
 
-  RE_ReleaseResultImageViews(re, &rres);
-
   render_time = re->i.lastframetime;
   re->i.lastframetime = PIL_check_seconds_timer() - re->i.starttime;
 
@@ -2257,8 +2264,10 @@ static int do_write_image_or_movie(Render *re,
    * Not sure it's actually even used anyway, we could as well pass NULL? */
   render_callback_exec_null(re, G_MAIN, BKE_CB_EVT_RENDER_STATS);
 
-  BLI_timecode_string_from_time_simple(name, sizeof(name), re->i.lastframetime - render_time);
-  printf(" (Saving: %s)\n", name);
+  if (do_write_file) {
+    BLI_timecode_string_from_time_simple(name, sizeof(name), re->i.lastframetime - render_time);
+    printf(" (Saving: %s)\n", name);
+  }
 
   fputc('\n', stdout);
   fflush(stdout);
@@ -2330,9 +2339,15 @@ void RE_RenderAnim(Render *re,
     return;
   }
 
+  RenderEngineType *re_type = RE_engines_find(re->r.engine);
+
+  /* Only disable file writing if postprocessing is also disabled. */
+  const bool do_write_file = !(re_type->flag & RE_USE_NO_IMAGE_SAVE) ||
+                             (re_type->flag & RE_USE_POSTPROCESS);
+
   render_init_depsgraph(re);
 
-  if (is_movie) {
+  if (is_movie && do_write_file) {
     size_t width, height;
     int i;
     bool is_error = false;
@@ -2415,7 +2430,7 @@ void RE_RenderAnim(Render *re,
       nfra += tfra;
 
       /* Touch/NoOverwrite options are only valid for image's */
-      if (is_movie == false) {
+      if (is_movie == false && do_write_file) {
         if (rd.mode & (R_NO_OVERWRITE | R_TOUCH)) {
           BKE_image_path_from_imformat(name,
                                        rd.pic,
@@ -2508,7 +2523,7 @@ void RE_RenderAnim(Render *re,
 
       if (G.is_break == true) {
         /* remove touched file */
-        if (is_movie == false) {
+        if (is_movie == false && do_write_file) {
           if ((rd.mode & R_TOUCH)) {
             if (!is_multiview_name) {
               if ((BLI_file_size(name) == 0)) {
@@ -2548,7 +2563,7 @@ void RE_RenderAnim(Render *re,
   }
 
   /* end movie */
-  if (is_movie) {
+  if (is_movie && do_write_file) {
     re_movie_free_all(re, mh, totvideos);
   }