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, 3 insertions, 0 deletions

diff --git a/video/out/opengl/ra_gl.c b/video/out/opengl/ra_gl.c
index e4c9c36562..46caca1eea 100644
--- a/video/out/opengl/ra_gl.c
+++ b/video/out/opengl/ra_gl.c
@@ -150,6 +150,9 @@ static int ra_init_gl(struct ra *ra, GL *gl)
             .linear_filter  = gl_fmt->flags & F_TF,
             .renderable     = (gl_fmt->flags & F_CR) &&
                               (gl->mpgl_caps & MPGL_CAP_FB),
+            // TODO: Check whether it's a storable format
+            // https://www.khronos.org/opengl/wiki/Image_Load_Store
+            .storable       = true,
         };
 
         int csize = gl_component_size(gl_fmt->type) * 8;