graphics: preserve logical alpha when blending reordered targets (PPSA02721)

Co-authored-by: EmK530 <admin@emk530.net>
This commit is contained in:
nmzik
2026-09-29 19:48:07 +04:00
parent 6799ecbc5b
commit 73615c31ff
10 changed files with 280 additions and 20 deletions
@@ -452,6 +452,11 @@ void EmitSetAttribute(ValueEmitContext& ctx, const IR::Inst& inst) {
if (exp.kind == IR::ExportTargetKind::Null || exp.en == 0u) {
return;
}
// Skip dormant color exports after their valid mask; MRT1 is reserved for logical alpha.
if (state.program.stage == ShaderType::Pixel && exp.kind == IR::ExportTargetKind::Mrt &&
exp.index != 0 && state.input_info.pixel->alpha_blend_source_remap) {
return;
}
EmitIfCondition(state, exec, [&]() {
const auto data = ctx.Arg(inst, 0);
if (exp.kind == IR::ExportTargetKind::Primitive) {
@@ -492,6 +497,18 @@ void EmitSetAttribute(ValueEmitContext& ctx, const IR::Inst& inst) {
const bool uint_output = MrtOutputMode(state, exp) == 7u;
const auto vector_type = uint_output ? TypeU32Vector(state, 4) : TypeF32Vector(state, 4);
auto value = ExportVector(ctx, data, exp, uint_output);
if (state.program.stage == ShaderType::Pixel && exp.kind == IR::ExportTargetKind::Mrt &&
exp.index == 0 && !uint_output && state.input_info.pixel->alpha_blend_source_remap) {
// Broadcast logical alpha before swizzling the primary output.
const auto blend_output =
OutputVariableForExport(state, {.kind = IR::ExportTargetKind::Mrt, .index = 1});
if (blend_output != 0) {
const auto alpha = state.builder.AllocateId();
state.builder.AddFunction(spv::OpVectorShuffle, vector_type, alpha, value, value,
3u, 3u, 3u, 3u);
state.builder.AddFunction(spv::OpStore, blend_output, alpha);
}
}
if (state.program.stage == ShaderType::Pixel && exp.kind == IR::ExportTargetKind::Mrt &&
exp.index < state.input_info.pixel->target_export_mapping.size()) {
const auto mapping = state.input_info.pixel->target_export_mapping[exp.index];
@@ -326,6 +326,8 @@ void CollectBuiltinInputs(const Program& program, ShaderInfo& info) {
}
void CollectOutputs(const Program& program, ShaderStageInputInfo input_info, ShaderInfo& info) {
const bool alpha_remap = program.stage == ShaderType::Pixel && input_info.pixel != nullptr &&
input_info.pixel->alpha_blend_source_remap;
for (const auto* block: program.blocks) {
for (const auto& inst: *block) {
if (inst.GetOpcode() != ValueOpcode::SetAttribute) {
@@ -385,8 +387,14 @@ void CollectOutputs(const Program& program, ShaderStageInputInfo input_info, Sha
export_info.index, fmt::format("out_param_{}", export_info.index));
break;
case ExportTargetKind::Mrt:
if (alpha_remap && export_info.index != 0) {
break;
}
AddOutput(info, StageOutputKind::Mrt, export_info.index, export_info.index,
fmt::format("out_mrt_{}", export_info.index));
if (alpha_remap) {
AddOutput(info, StageOutputKind::Mrt, 1, 1, "out_mrt_1");
}
break;
default: break;
}