Images: refactor how failed image load attempts are remembered

Previously, `ImageTile->ok` and `ImageUser->ok` were used to indicate
whether an image failed to load. There were three possible values
which (probably) had the following meanings:
* `0`: There was an error while loading the image. Don't try to load again.
* `1`: Default value. Try to load the image.
* `2`: The image was loaded successfully.

This image-wide flag did not make sense unfortunately, because loading
may work for some frames of an image sequence but not for others.
Remember than an image data block can also contain a movie.

The purpose of the `->ok` flag was to serve as an optimization to avoid
trying to load a file over and over again when there is an error (e.g. the
file does not exist or is invalid). To get the optimization back, the patch
is changing `MovieCache` so that it can also cache failed load attempts.
As a consequence, `ibuf` is allowed to be `NULL` in a few more places.
I added the appropriate null checks.

This also solves issues when image sequences are used with the
Image Texture node in Geometry nodes (also see D12827).

Differential Revision: https://developer.blender.org/D12957

3 files changed, 1 insertions, 9 deletions

diff --git a/source/blender/editors/render/render_internal.c b/source/blender/editors/render/render_internal.c
index 2ff47edabf4..49e7ebf6340 100644
--- a/source/blender/editors/render/render_internal.c
+++ b/source/blender/editors/render/render_internal.c
@@ -976,7 +976,6 @@ static int screen_render_invoke(bContext *C, wmOperator *op, const wmEvent *even
   rj->anim = is_animation;
   rj->write_still = is_write_still && !is_animation;
   rj->iuser.scene = scene;
-  rj->iuser.ok = 1;
   rj->reports = op->reports;
   rj->orig_layer = 0;
   rj->last_layer = 0;
diff --git a/source/blender/editors/render/render_opengl.c b/source/blender/editors/render/render_opengl.c
index 4c539bdea90..1e1a95f2965 100644
--- a/source/blender/editors/render/render_opengl.c
+++ b/source/blender/editors/render/render_opengl.c
@@ -836,7 +836,6 @@ static bool screen_opengl_render_init(bContext *C, wmOperator *op)
   BKE_image_backup_render(oglrender->scene, oglrender->ima, true);
 
   oglrender->iuser.scene = scene;
-  oglrender->iuser.ok = 1;
 
   /* create render result */
   RE_InitState(oglrender->re, NULL, &scene->r, &scene->view_layers, NULL, sizex, sizey, NULL);
diff --git a/source/blender/editors/render/render_preview.c b/source/blender/editors/render/render_preview.c
index 6f49b03f07f..4bf250b9d4f 100644
--- a/source/blender/editors/render/render_preview.c
+++ b/source/blender/editors/render/render_preview.c
@@ -1476,14 +1476,8 @@ static void icon_preview_startjob(void *customdata, short *stop, short *do_updat
         return;
       }
 
-      ImageTile *tile = BKE_image_get_tile(ima, 0);
-      /* tile->ok is zero when Image cannot load */
-      if (tile->ok == 0) {
-        return;
-      }
-
       /* setup dummy image user */
-      iuser.ok = iuser.framenr = 1;
+      iuser.framenr = 1;
       iuser.scene = sp->scene;
 
       /* elubie: this needs to be changed: here image is always loaded if not