[Mesa-dev] [PATCH] mesa: Don't override S3TC internalFormat if data is pre-compressed.

[Kenneth Graunke]

Commit 42723d88d intended to override an S3TC internalFormat to a
generic compressed format when the application requested online
compression of uncompressed data.  Unfortunately, it also broke
pre-compressed textures when libtxc_dxtn isn't installed but the
extensions are forced on.

Both glCompressedTexImage2D() and glTexImage2D() call teximage(), which
calls _mesa_choose_texture_format(), hitting this override code.  If we
have actual S3TC source data, we can't treat it as any other format, and
need to avoid the override.

Since glCompressedTexImage2D() passes in a format of GL_NONE (which is
illegal for glTexImage), we can use that to detect the pre-compressed
case and avoid the overrides.

Fixes a regression since 42723d88d370a7599398cc1c2349aeb951ba1c57.

NOTE: This is a candidate for the 9.0 branch.

Signed-off-by: Kenneth Graunke <kenneth at whitecape.org>
Cc: Ian Romanick <idr at freedesktop.org>
Cc: Jordan Justen <jljusten at gmail.com>
---
 src/mesa/main/teximage.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/mesa/main/teximage.c b/src/mesa/main/teximage.c
index da8fbcd..dff50ca 100644
--- a/src/mesa/main/teximage.c
+++ b/src/mesa/main/teximage.c
@@ -2806,7 +2806,7 @@ _mesa_choose_texture_format(struct gl_context *ctx,
    /* If the application requested compression to an S3TC format but we don't
     * have the DTXn library, force a generic compressed format instead.
     */
-   if (internalFormat != format) {
+   if (internalFormat != format && format != GL_NONE) {
       const GLenum before = internalFormat;
 
       switch (internalFormat) {
-- 
1.7.11.4