mesa: call ctx->Driver.ChooseTextureFormat() only when necessary.

When defining mipmap level 'L' and level L-1 exists and the new level's
internalFormat matches level L-1's internalFormat, then use the same hw
format.  Otherwise, do the regular ctx->Driver.ChooseTextureFormat() call.

This avoids a problem where we end up choosing different hw formats for
different mipmap levels depending on how the levels are defined (glTexImage
vs. glCopyTexImage vs. glGenerateMipmap, etc).

The root problem is the ChooseTextureFormat() implementation in some
drivers uses the user's glTexImage format/type parameters in the choosing
heuristic.  Later mipmap levels might be generated with different calls
(ex: glCopyTexImage()) so we don't always have format/type info and the
driver may choose a different format.

For more background info see the July 2010 mesa-dev thread "Bug in
_mesa_meta_GenerateMipmap"

1 files changed, 8 insertions, 0 deletions

diff --git a/src/mesa/main/teximage.h b/src/mesa/main/teximage.h
index d82cc985211..0dcacab3cd0 100644
--- a/src/mesa/main/teximage.h
+++ b/src/mesa/main/teximage.h
@@ -73,6 +73,14 @@ _mesa_init_teximage_fields(GLcontext *ctx, GLenum target,
 
 
 extern void
+_mesa_choose_texture_format(GLcontext *ctx,
+                            struct gl_texture_object *texObj,
+                            struct gl_texture_image *texImage,
+                            GLenum target, GLint level,
+                            GLenum internalFormat, GLenum format, GLenum type);
+
+
+extern void
 _mesa_clear_texture_image(GLcontext *ctx, struct gl_texture_image *texImage);