[Mesa-dev] [PATCH] mesa: Improve handling of GL_BGRA format in es3 format_and_type checks

[Eduardo Lima Mitev]

We recently added support for GL_BGRA internal format when validating
combination of format+type+internal_format in Tex(Sub)ImageXD calls
(to fix https://bugs.freedesktop.org/show_bug.cgi?id=92265).

However, the current implementation handles it as a special case when
obtaining the effective internal format, treating GL_BGRA as if its
base format is GL_RGBA execpt for the case of validation.

This causes Mesa to accept a combination like:
internalFormat = GL_BGRA_EXT, format = GL_RGBA, type = GL_UNSIGNED_BYTE as
valid arguments to TexImage2D, when it is actually an invalid combination
per EXT_texture_format_BGRA8888
<https://www.khronos.org/registry/gles/extensions/EXT/EXT_texture_format_BGRA8888.txt>

This patch makes _mesa_base_tex_format() return GL_BGRA_EXT as base format of
GL_BGRA_EXT internal format, which is consistent with the extension
spec. As a result, the code for handling GL_BGRA during validation gets
simplified.
---
 src/mesa/main/glformats.c | 21 +++++++--------------
 1 file changed, 7 insertions(+), 14 deletions(-)

diff --git a/src/mesa/main/glformats.c b/src/mesa/main/glformats.c
index faa6382..e0192fe 100644
--- a/src/mesa/main/glformats.c
+++ b/src/mesa/main/glformats.c
@@ -2148,6 +2148,9 @@ _mesa_es_error_check_format_and_type(GLenum format, GLenum type,
  *
  * \return the corresponding \u base internal format (GL_ALPHA, GL_LUMINANCE,
  * GL_LUMANCE_ALPHA, GL_INTENSITY, GL_RGB, or GL_RGBA), or -1 if invalid enum.
+ * When profile is GLES, it will also return GL_BGRA as base format of
+ * GL_BGRA internal format, as specified by extension
+ * EXT_texture_format_BGRA8888.
  *
  * This is the format which is used during texture application (i.e. the
  * texture format and env mode determine the arithmetic used.
@@ -2215,7 +2218,7 @@ _mesa_base_tex_format(const struct gl_context *ctx, GLint internalFormat)
    if (_mesa_is_gles(ctx)) {
       switch (internalFormat) {
       case GL_BGRA:
-         return GL_RGBA;
+         return GL_BGRA_EXT;
       default:
          ; /* fallthrough */
       }
@@ -2799,18 +2802,8 @@ _mesa_es3_error_check_format_and_type(const struct gl_context *ctx,
          return GL_INVALID_OPERATION;
 
       GLenum baseInternalFormat;
-      if (internalFormat == GL_BGRA_EXT) {
-         /* Unfortunately, _mesa_base_tex_format returns a base format of
-          * GL_RGBA for GL_BGRA_EXT.  This makes perfect sense if you're
-          * asking the question, "what channels does this format have?"
-          * However, if we're trying to determine if two internal formats
-          * match in the ES3 sense, we actually want GL_BGRA.
-          */
-         baseInternalFormat = GL_BGRA_EXT;
-      } else {
-         baseInternalFormat =
-            _mesa_base_tex_format(ctx, effectiveInternalFormat);
-      }
+      baseInternalFormat =
+         _mesa_base_tex_format(ctx, effectiveInternalFormat);
 
       if (internalFormat != baseInternalFormat)
          return GL_INVALID_OPERATION;
@@ -2820,7 +2813,7 @@ _mesa_es3_error_check_format_and_type(const struct gl_context *ctx,
 
    switch (format) {
    case GL_BGRA_EXT:
-      if (type != GL_UNSIGNED_BYTE || internalFormat != GL_BGRA)
+      if (type != GL_UNSIGNED_BYTE || internalFormat != format)
          return GL_INVALID_OPERATION;
       break;
 
-- 
2.5.3