mesa/main: add support for EXT_texture_storage

It's sometimes really, really useful if GL_BGRA8 can be used as a
sized internal format, and the combination of EXT_texture_storage
and EXT_texture_format_BGRA8888 allows this (only when using
texture-storage, which is good enough in some cases). Until now,
we've only implemented ARB_texture_storage, and not the EXT
version.

So let's implement the EXT version as well, so we get the benefit
of the interaction here. This pulls in a lot of other similar
interactions as well, which also seems useful.

...because the ARB version is created from the EXT version, let's move
the EXT function definitions to the EXT extension. These should probably
have been suffixed with ARB in the ARB-version, but things seems to have
just ended up kinda confused. Oh well.

Reviewed-by: Daniel Stone <daniels@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/27222>

2 files changed, 51 insertions, 0 deletions

diff --git a/src/mesa/main/extensions_table.h b/src/mesa/main/extensions_table.h
index 417ffe2a905..add6c849fbe 100644
--- a/src/mesa/main/extensions_table.h
+++ b/src/mesa/main/extensions_table.h
@@ -341,6 +341,7 @@ EXT(EXT_texture_sRGB_decode                 , EXT_texture_sRGB_decode
 EXT(EXT_texture_shadow_lod                  , EXT_texture_shadow_lod                 , GLL, GLC,  x ,  30, 2018)
 EXT(EXT_texture_shared_exponent             , EXT_texture_shared_exponent            , GLL, GLC,  x ,  x , 2004)
 EXT(EXT_texture_snorm                       , EXT_texture_snorm                      , GLL, GLC,  x ,  x , 2009)
+EXT(EXT_texture_storage                     , dummy_true                             , GLL, GLC,  x , ES2, 2009)
 EXT(EXT_texture_swizzle                     , EXT_texture_swizzle                    , GLL, GLC,  x ,  x , 2008)
 EXT(EXT_texture_type_2_10_10_10_REV         , EXT_texture_type_2_10_10_10_REV        ,  x ,  x ,  x , ES2, 2008)
 EXT(EXT_texture_view                        , OES_texture_view                       ,  x ,  x ,  x ,  31, 2014)
diff --git a/src/mesa/main/texstorage.c b/src/mesa/main/texstorage.c
index b1f8de70c41..636fcbf97e7 100644
--- a/src/mesa/main/texstorage.c
+++ b/src/mesa/main/texstorage.c
@@ -221,6 +221,56 @@ GLboolean
 _mesa_is_legal_tex_storage_format(const struct gl_context *ctx,
                                   GLenum internalformat)
 {
+   if (!_mesa_is_desktop_gl(ctx)) {
+      assert(_mesa_has_EXT_texture_storage(ctx));
+
+      /* EXT_texture_storage allows us to use some sized internal formats
+       * for TexStorage* that aren't otherwise allowed in OpenGL ES.
+       **/
+      switch (internalformat) {
+      case GL_ALPHA8:
+      case GL_LUMINANCE8:
+      case GL_LUMINANCE8_ALPHA8:
+         return true;
+
+      case GL_RGBA32F:
+      case GL_RGB32F:
+      case GL_ALPHA32F_EXT:
+      case GL_LUMINANCE32F_EXT:
+      case GL_LUMINANCE_ALPHA32F_EXT:
+         return _mesa_has_OES_texture_float(ctx);
+
+      case GL_RGBA16F:
+      case GL_RGB16F:
+      case GL_ALPHA16F_EXT:
+      case GL_LUMINANCE16F_EXT:
+      case GL_LUMINANCE_ALPHA16F_EXT:
+         return _mesa_has_OES_texture_half_float(ctx);
+
+      case GL_RGB10_A2:
+      case GL_RGB10:
+         return _mesa_has_EXT_texture_type_2_10_10_10_REV(ctx);
+
+      case GL_BGRA8_EXT:
+         assert(_mesa_has_EXT_texture_format_BGRA8888(ctx));
+         return true;
+
+      case GL_R8:
+      case GL_RG8:
+         return _mesa_has_EXT_texture_rg(ctx);
+
+      case GL_R32F_EXT:
+      case GL_RG32F_EXT:
+         return _mesa_has_EXT_texture_rg(ctx) &&
+                _mesa_has_OES_texture_float(ctx);
+
+      case GL_R16F_EXT:
+      case GL_RG16F_EXT:
+         return _mesa_has_EXT_texture_rg(ctx) &&
+                _mesa_has_OES_texture_half_float(ctx);
+      }
+   }
+
    /* check internal format - note that only sized formats are allowed */
    switch (internalformat) {
    case GL_ALPHA: