Reviewed-by: Ilia Mirkin <imir...@alum.mit.edu>
Awesome! Now I can go remove this set of hacks from freedreno. And
this fixes the same issue in nouveau. Thanks for doing it the real way
:)
On Tue, Apr 28, 2015 at 6:16 PM, Brian Paul <bri...@vmware.com> wrote:
> If the user requested a GL_RGB texture but the driver actually allocated
> an RGBA texture, the alpha values in the texture may not be defined.
>
> If we later bind the texture as a color target and try to blend into
> it with GL_DST_ALPHA or GL_ONE_MINUS_DST_ALPHA we may blend with
> undefined alpha values when, in fact, the dest alpha value should be one.
> So replace GL_DST_ALPHA/GL_ONE_MINUS_DST_ALPHA with GL_ONE/GL_ZERO.
>
> Fixes the piglit fbo-blending-formats test for some GL_RGB formats
> with the VMware driver. Also tested with llvmpipe.
> ---
> src/mesa/state_tracker/st_atom_blend.c | 38
> +++++++++++++++++++++++++---------
> 1 file changed, 28 insertions(+), 10 deletions(-)
>
> diff --git a/src/mesa/state_tracker/st_atom_blend.c
> b/src/mesa/state_tracker/st_atom_blend.c
> index 6bb4077..30bff7a 100644
> --- a/src/mesa/state_tracker/st_atom_blend.c
> +++ b/src/mesa/state_tracker/st_atom_blend.c
> @@ -44,10 +44,21 @@
> /**
> * Convert GLenum blend tokens to pipe tokens.
> * Both blend factors and blend funcs are accepted.
> + * \param destBaseFormat the base format of the render target, such as
> + * GL_RGBA, GL_RGB, GL_RED, GL_ALPHA, etc.
> */
> static GLuint
> -translate_blend(GLenum blend)
> +translate_blend(GLenum blend, GLenum destBaseFormat)
> {
> + /* If we don't have destination alpha and the blend factor is either
> + * GL_DST_ALPHA or GL_ONE_MINUS_DST_ALPHA then we use
> + * PIPE_BLENDFACTOR_ONE or _ZERO instead.
> + */
> + const bool haveDstA = (destBaseFormat == GL_RGBA ||
> + destBaseFormat == GL_ALPHA ||
> + destBaseFormat == GL_INTENSITY ||
> + destBaseFormat == GL_LUMINANCE_ALPHA);
> +
> switch (blend) {
> /* blend functions */
> case GL_FUNC_ADD:
> @@ -69,7 +80,7 @@ translate_blend(GLenum blend)
> case GL_SRC_ALPHA:
> return PIPE_BLENDFACTOR_SRC_ALPHA;
> case GL_DST_ALPHA:
> - return PIPE_BLENDFACTOR_DST_ALPHA;
> + return haveDstA ? PIPE_BLENDFACTOR_DST_ALPHA : PIPE_BLENDFACTOR_ONE;
> case GL_DST_COLOR:
> return PIPE_BLENDFACTOR_DST_COLOR;
> case GL_SRC_ALPHA_SATURATE:
> @@ -91,7 +102,7 @@ translate_blend(GLenum blend)
> case GL_ONE_MINUS_DST_COLOR:
> return PIPE_BLENDFACTOR_INV_DST_COLOR;
> case GL_ONE_MINUS_DST_ALPHA:
> - return PIPE_BLENDFACTOR_INV_DST_ALPHA;
> + return haveDstA ? PIPE_BLENDFACTOR_INV_DST_ALPHA :
> PIPE_BLENDFACTOR_ZERO;
> case GL_ONE_MINUS_CONSTANT_COLOR:
> return PIPE_BLENDFACTOR_INV_CONST_COLOR;
> case GL_ONE_MINUS_CONSTANT_ALPHA:
> @@ -208,14 +219,21 @@ update_blend( struct st_context *st )
> else if (ctx->Color.BlendEnabled) {
> /* blending enabled */
> for (i = 0, j = 0; i < num_state; i++) {
> + const struct gl_renderbuffer *rb;
> + GLenum baseFormat;
>
> blend->rt[i].blend_enable = (ctx->Color.BlendEnabled >> i) & 0x1;
>
> if (ctx->Extensions.ARB_draw_buffers_blend)
> j = i;
>
> + /* _NEW_BUFFERS */
> + /* Get the base format of the render target */
> + rb = ctx->DrawBuffer->_ColorDrawBuffers[j];
> + baseFormat = rb ? rb->_BaseFormat : GL_RGBA;
> +
> blend->rt[i].rgb_func =
> - translate_blend(ctx->Color.Blend[j].EquationRGB);
> + translate_blend(ctx->Color.Blend[j].EquationRGB, baseFormat);
>
> if (ctx->Color.Blend[i].EquationRGB == GL_MIN ||
> ctx->Color.Blend[i].EquationRGB == GL_MAX) {
> @@ -225,13 +243,13 @@ update_blend( struct st_context *st )
> }
> else {
> blend->rt[i].rgb_src_factor =
> - translate_blend(ctx->Color.Blend[j].SrcRGB);
> + translate_blend(ctx->Color.Blend[j].SrcRGB, baseFormat);
> blend->rt[i].rgb_dst_factor =
> - translate_blend(ctx->Color.Blend[j].DstRGB);
> + translate_blend(ctx->Color.Blend[j].DstRGB, baseFormat);
> }
>
> blend->rt[i].alpha_func =
> - translate_blend(ctx->Color.Blend[j].EquationA);
> + translate_blend(ctx->Color.Blend[j].EquationA, baseFormat);
>
> if (ctx->Color.Blend[i].EquationA == GL_MIN ||
> ctx->Color.Blend[i].EquationA == GL_MAX) {
> @@ -241,9 +259,9 @@ update_blend( struct st_context *st )
> }
> else {
> blend->rt[i].alpha_src_factor =
> - translate_blend(ctx->Color.Blend[j].SrcA);
> + translate_blend(ctx->Color.Blend[j].SrcA, baseFormat);
> blend->rt[i].alpha_dst_factor =
> - translate_blend(ctx->Color.Blend[j].DstA);
> + translate_blend(ctx->Color.Blend[j].DstA, baseFormat);
> }
> }
> }
> @@ -285,7 +303,7 @@ update_blend( struct st_context *st )
> const struct st_tracked_state st_update_blend = {
> "st_update_blend", /* name */
> { /* dirty */
> - (_NEW_COLOR | _NEW_MULTISAMPLE), /* XXX _NEW_BLEND someday? */ /*
> mesa */
> + (_NEW_BUFFERS | _NEW_COLOR | _NEW_MULTISAMPLE), /* mesa */
> 0, /* st */
> },
> update_blend, /* update */
> --
> 1.9.1
>
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> mesa-dev mailing list
> mesa-dev@lists.freedesktop.org
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