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[GPU] Fix min/max blend operations to properly apply factors

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Applies factors before the MIN/MAX operation - in FSI/ROV via runtime
blending, in FBO/RTV by pre-multiplying shader output when dstFactor is
ONE only, as we don't have access to dest to provide full support as we
do in the FSI/ROV paths.
This commit is contained in:
Herman S.
2025-12-16 23:54:09 +09:00
parent 966d8f0925
commit 067641668f
6 changed files with 716 additions and 164 deletions
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54
src/xenia/gpu/vulkan/vulkan_pipeline_cache.cc
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@@ -344,6 +344,38 @@ VulkanPipelineCache::GetCurrentPixelShaderModification(
} else {
modification.pixel.depth_stencil_mode = DepthStencilMode::kNoModifiers;
}
// Check if MIN/MAX blend is used with non-trivial source factors.
// Vulkan/D3D12 fixed-function blend ignores factors for MIN/MAX, but
// Xbox 360 applies them. If the destination factor is ONE (or ZERO), we can
// pre-multiply the shader output by the source factor to emulate this.
// Only RT0 is supported for now.
modification.pixel.rt0_blend_rgb_factor_for_premult =
xenos::BlendFactor::kOne;
modification.pixel.rt0_blend_a_factor_for_premult =
xenos::BlendFactor::kOne;
if (shader.writes_color_target(0)) {
auto blend_control = regs.Get<reg::RB_BLENDCONTROL>(
reg::RB_BLENDCONTROL::rt_register_indices[0]);
// Pre-multiply by kSrcAlpha for MIN/MAX blend ops when dstFactor is ONE.
if ((blend_control.color_comb_fcn == xenos::BlendOp::kMin ||
blend_control.color_comb_fcn == xenos::BlendOp::kMax) &&
blend_control.color_srcblend == xenos::BlendFactor::kSrcAlpha &&
blend_control.color_destblend == xenos::BlendFactor::kOne) {
modification.pixel.rt0_blend_rgb_factor_for_premult =
xenos::BlendFactor::kSrcAlpha;
}
if ((blend_control.alpha_comb_fcn == xenos::BlendOp::kMin ||
blend_control.alpha_comb_fcn == xenos::BlendOp::kMax) &&
blend_control.alpha_srcblend == xenos::BlendFactor::kSrcAlpha &&
blend_control.alpha_destblend == xenos::BlendFactor::kOne) {
modification.pixel.rt0_blend_a_factor_for_premult =
xenos::BlendFactor::kSrcAlpha;
}
}
}
return modification;
@@ -2383,6 +2415,16 @@ bool VulkanPipelineCache::EnsurePipelineCreated(
VK_BLEND_OP_ADD,
VK_BLEND_OP_ADD,
VK_BLEND_OP_ADD};
// Check if the shader pre-multiplies by blend factors for MIN/MAX.
SpirvShaderTranslator::Modification pixel_shader_modification(
description.pixel_shader_modification);
bool rt0_rgb_premult =
pixel_shader_modification.pixel.rt0_blend_rgb_factor_for_premult !=
xenos::BlendFactor::kOne;
bool rt0_a_premult =
pixel_shader_modification.pixel.rt0_blend_a_factor_for_premult !=
xenos::BlendFactor::kOne;
uint32_t color_rts_remaining = color_rts_used;
uint32_t color_rt_index;
while (xe::bit_scan_forward(color_rts_remaining, &color_rt_index)) {
@@ -2410,6 +2452,18 @@ bool VulkanPipelineCache::EnsurePipelineCreated(
kBlendFactorMap[uint32_t(color_rt.dst_alpha_blend_factor)];
color_blend_attachment.alphaBlendOp =
kBlendOpMap[uint32_t(color_rt.alpha_blend_op)];
// If the shader pre-multiplies by the source blend factor for RT0
// MIN/MAX, set the pipeline source factor to ONE since it's already
// applied in the shader.
if (color_rt_index == 0) {
if (rt0_rgb_premult) {
color_blend_attachment.srcColorBlendFactor = VK_BLEND_FACTOR_ONE;
}
if (rt0_a_premult) {
color_blend_attachment.srcAlphaBlendFactor = VK_BLEND_FACTOR_ONE;
}
}
}
color_blend_attachment.colorWriteMask =
VkColorComponentFlags(color_rt.color_write_mask);