video/out/gpu: Add a `storable` flag to ra_format

While `ra` supports the concept of a texture as a storage
destination, it does not support the concept of a texture format
being usable for a storage texture. This can lead to us attempting
to create a texture from an incompatible format, with undefined
results.

So, let's introduce an explicit format flag for storage and use
it. In `ra_pl` we can simply reflect the `storable` flag. For
GL and D3D, we'll need to write some new code to do the compatibility
checks. I'm not going to do it here because it's not a regression;
we were already implicitly assuming all formats were storable.

Fixes #6657

1 files changed, 1 insertions, 0 deletions

diff --git a/video/out/gpu/ra.h b/video/out/gpu/ra.h
index f35489e25d..58bf55357b 100644
--- a/video/out/gpu/ra.h
+++ b/video/out/gpu/ra.h
@@ -107,6 +107,7 @@ struct ra_format {
                             // only applies to 2-component textures
     bool linear_filter;     // linear filtering available from shader
     bool renderable;        // can be used for render targets
+    bool storable;          // can be used for storage images
     bool dummy_format;      // is not a real ra_format but a fake one (e.g. FBO).
                             // dummy formats cannot be used to create textures