From 59253a79d823a4cfd1d65466c0a165d6d4c43a92 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Jos=C3=A9=20Fonseca?= Date: Sun, 2 May 2010 21:36:12 +0100 Subject: [PATCH] llvmpipe: Fix alpha blending for formats without alpha channel. Don't use the dst alpha channel from the swizzled tile when it does not exist in the true format. --- src/gallium/drivers/llvmpipe/lp_state_fs.c | 53 +++++++++++++++++++++- 1 file changed, 51 insertions(+), 2 deletions(-) diff --git a/src/gallium/drivers/llvmpipe/lp_state_fs.c b/src/gallium/drivers/llvmpipe/lp_state_fs.c index 513e62e39e5..5f861d6ca4d 100644 --- a/src/gallium/drivers/llvmpipe/lp_state_fs.c +++ b/src/gallium/drivers/llvmpipe/lp_state_fs.c @@ -1061,6 +1061,34 @@ llvmpipe_set_constant_buffer(struct pipe_context *pipe, } +/** + * Return the blend factor equivalent to a destination alpha of one. + */ +static INLINE unsigned +force_dst_alpha_one(unsigned factor, boolean alpha) +{ + switch(factor) { + case PIPE_BLENDFACTOR_DST_ALPHA: + return PIPE_BLENDFACTOR_ONE; + case PIPE_BLENDFACTOR_INV_DST_ALPHA: + return PIPE_BLENDFACTOR_ZERO; + case PIPE_BLENDFACTOR_SRC_ALPHA_SATURATE: + return PIPE_BLENDFACTOR_ZERO; + } + + if (alpha) { + switch(factor) { + case PIPE_BLENDFACTOR_DST_COLOR: + return PIPE_BLENDFACTOR_ONE; + case PIPE_BLENDFACTOR_INV_DST_COLOR: + return PIPE_BLENDFACTOR_ZERO; + } + } + + return factor; +} + + /** * We need to generate several variants of the fragment pipeline to match * all the combinations of the contributing state atoms. @@ -1102,6 +1130,7 @@ make_variant_key(struct llvmpipe_context *lp, key->nr_cbufs = lp->framebuffer.nr_cbufs; for (i = 0; i < lp->framebuffer.nr_cbufs; i++) { + struct pipe_rt_blend_state *blend_rt = &key->blend.rt[i]; const struct util_format_description *format_desc; unsigned chan; @@ -1109,7 +1138,7 @@ make_variant_key(struct llvmpipe_context *lp, assert(format_desc->colorspace == UTIL_FORMAT_COLORSPACE_RGB || format_desc->colorspace == UTIL_FORMAT_COLORSPACE_SRGB); - key->blend.rt[i].colormask = lp->blend->rt[i].colormask; + blend_rt->colormask = lp->blend->rt[i].colormask; /* mask out color channels not present in the color buffer. * Should be simple to incorporate per-cbuf writemasks: @@ -1118,7 +1147,27 @@ make_variant_key(struct llvmpipe_context *lp, enum util_format_swizzle swizzle = format_desc->swizzle[chan]; if(swizzle > UTIL_FORMAT_SWIZZLE_W) - key->blend.rt[i].colormask &= ~(1 << chan); + blend_rt->colormask &= ~(1 << chan); + } + + /* + * Our swizzled render tiles always have an alpha channel, but the linear + * render target format often does not, so force here the dst alpha to be + * one. + * + * This is not a mere optimization. Wrong results will be produced if the + * dst alpha is used, the dst format does not have alpha, and the previous + * rendering was not flushed from the swizzled to linear buffer. For + * example, NonPowTwo DCT. + * + * TODO: This should be generalized to all channels for better + * performance, but only alpha causes correctness issues. + */ + if (format_desc->swizzle[3] > UTIL_FORMAT_SWIZZLE_W) { + blend_rt->rgb_src_factor = force_dst_alpha_one(blend_rt->rgb_src_factor, FALSE); + blend_rt->rgb_dst_factor = force_dst_alpha_one(blend_rt->rgb_dst_factor, FALSE); + blend_rt->alpha_src_factor = force_dst_alpha_one(blend_rt->alpha_src_factor, TRUE); + blend_rt->alpha_dst_factor = force_dst_alpha_one(blend_rt->alpha_dst_factor, TRUE); } }