mesa: fix ms fallback texture creation

when a ms fallback texture is created, it has to actually be a ms texture
in order to be consistent with driver expectations for a given sampler in
a shader

this adds sample querying to both ends of the fallback creation to ensure
that a sample count is passed to the driver

affects:
KHR-GL46.sample_variables.position.fixed.samples_0

Reviewed-by: Emma Anholt <emma@anholt.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/22492>

2 files changed, 31 insertions, 8 deletions

diff --git a/src/mesa/main/texobj.c b/src/mesa/main/texobj.c
index 1546551d8a4..7f0cfed9bd1 100644
--- a/src/mesa/main/texobj.c
+++ b/src/mesa/main/texobj.c
@@ -1084,12 +1084,27 @@ _mesa_get_fallback_texture(struct gl_context *ctx, gl_texture_index tex, bool is
          /* initialize level[0] texture image */
          texImage = _mesa_get_tex_image(ctx, texObj, faceTarget, 0);
 
-         _mesa_init_teximage_fields(ctx, texImage,
-                                    width,
-                                    (dims > 1) ? height : 1,
-                                    (dims > 2) ? depth : 1,
-                                    0, /* border */
-                                    is_depth ? GL_DEPTH_COMPONENT : GL_RGBA, texFormat);
+         GLenum internalFormat = is_depth ? GL_DEPTH_COMPONENT : GL_RGBA;
+         if (tex == TEXTURE_2D_MULTISAMPLE_INDEX ||
+             tex == TEXTURE_2D_MULTISAMPLE_ARRAY_INDEX) {
+            int samples[16];
+            st_QueryInternalFormat(ctx, 0, internalFormat, GL_SAMPLES, samples);
+            _mesa_init_teximage_fields_ms(ctx, texImage,
+                                          width,
+                                          (dims > 1) ? height : 1,
+                                          (dims > 2) ? depth : 1,
+                                          0, /* border */
+                                          internalFormat, texFormat,
+                                          samples[0],
+                                          GL_TRUE);
+         } else {
+            _mesa_init_teximage_fields(ctx, texImage,
+                                       width,
+                                       (dims > 1) ? height : 1,
+                                       (dims > 2) ? depth : 1,
+                                       0, /* border */
+                                       internalFormat, texFormat);
+         }
          _mesa_update_texture_object_swizzle(ctx, texObj);
          if (ctx->st->can_null_texture && is_depth) {
             texObj->NullTexture = GL_TRUE;
diff --git a/src/mesa/state_tracker/st_cb_texture.c b/src/mesa/state_tracker/st_cb_texture.c
index a21aa1c138c..9cb9293535a 100644
--- a/src/mesa/state_tracker/st_cb_texture.c
+++ b/src/mesa/state_tracker/st_cb_texture.c
@@ -1071,14 +1071,22 @@ guess_and_alloc_texture(struct st_context *st,
                                    width, height, depth,
                                    &ptWidth, &ptHeight, &ptDepth, &ptLayers);
 
+   enum pipe_texture_target target = gl_target_to_pipe(stObj->Target);
+   unsigned nr_samples = 0;
+   if (stObj->TargetIndex == TEXTURE_2D_MULTISAMPLE_INDEX ||
+       stObj->TargetIndex == TEXTURE_2D_MULTISAMPLE_ARRAY_INDEX) {
+      int samples[16];
+      st_QueryInternalFormat(st->ctx, 0, stImage->InternalFormat, GL_SAMPLES, samples);
+      nr_samples = samples[0];
+   }
    stObj->pt = st_texture_create(st,
-                                 gl_target_to_pipe(stObj->Target),
+                                 target,
                                  fmt,
                                  lastLevel,
                                  ptWidth,
                                  ptHeight,
                                  ptDepth,
-                                 ptLayers, 0,
+                                 ptLayers, nr_samples,
                                  bindings,
                                  false);