This patch fixed two major problems when we do the color convesion with
GLES2.
1. lack of necessary formats in FBO pool.
GLES2 has three different possible texture formats, GL_RGBA,
GL_BGRA and GL_ALPHA. Previous implementation only has one bucket
for all the three formats which may reuse a incorrect texture format
when do the cache lookup. After this fix, we can enable fbo safely
when running with GLES2.
2. Refine the format matching method in
glamor_get_tex_format_type_from_pictformat.
If both revertion and swap_rb are needed, for example use GL_RGBA
to represent PICT_b8g8r8a8. Then the downloading and uploading should
be handled differently.
The picture's format is PICT_b8g8r8a8,
Then the expecting color layout is as below (little endian):
0 1 2 3 : address
a r g b
Now the in GLES2 the supported color format is GL_RGBA, type is
GL_UNSIGNED_TYPE, then we need to shuffle the fragment
color as :
frag_color = sample(texture).argb;
before we use glReadPixel to get it back.
For the uploading process, the shuffle is a revert shuffle.
We still use GL_RGBA, GL_UNSIGNED_BYTE to upload the color
to a texture, then let's see
0 1 2 3 : address
a r g b : correct colors
R G B A : GL_RGBA with GL_UNSIGNED_BYTE
Now we need to shuffle again, the mapping rule is
r = G, g = B, b = A, a = R. Then the uploading shuffle is as
below:
frag_color = sample(texture).gbar;
After this commit, gles2 version can pass render check with all
the formats except those 1555/2101010.
Signed-off-by: Zhigang Gong <zhigang.gong@linux.intel.com>
3add375065