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framebuffer: Support the GL_RED texture workaround when querying bits

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When a component-alpha texture is made using a GL3 context a GL_RED
texture is actually used and a swizzle is set up to hide it. However
if a framebuffer is then bound to that texture then when the bits are
queried this workaround will leak out of the API. To fix this it now
detects the situation and reports the number of red bits as the number
of alpha bits.

Reviewed-by: Robert Bragg <robert@linux.intel.com>

(cherry picked from commit 425cfb2675912a2cbcaaaeed7c2196d563948222)
This commit is contained in:
Neil Roberts 2012-12-13 15:55:05 +00:00 committed by Robert Bragg
parent 520ccba49d
commit 988486ac7d
1 changed files with 10 additions and 0 deletions
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10
cogl/driver/gl/cogl-framebuffer-gl.c
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@ -948,6 +948,16 @@ _cogl_framebuffer_init_bits (CoglFramebuffer *framebuffer)
GE( ctx, glGetIntegerv (GL_STENCIL_BITS, &framebuffer->bits.stencil) );
}
/* If we don't have alpha textures then the alpha bits are actually
* stored in the red component */
if ((ctx->private_feature_flags &
COGL_PRIVATE_FEATURE_ALPHA_TEXTURES) == 0 &&
framebuffer->type == COGL_FRAMEBUFFER_TYPE_OFFSCREEN &&
framebuffer->format == COGL_PIXEL_FORMAT_A_8)
{
framebuffer->bits.alpha = framebuffer->bits.red;
framebuffer->bits.red = 0;
}
COGL_NOTE (OFFSCREEN,
"RGBA/D/S Bits for framebuffer[%p, %s]: %d, %d, %d, %d, %d, %d",