129 lines
3.4 KiB
C++
129 lines
3.4 KiB
C++
// Copyright 2016 Dolphin Emulator Project
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// Licensed under GPLv2+
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// Refer to the license.txt file included.
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#include "VideoCommon/RenderState.h"
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// If the framebuffer format has no alpha channel, it is assumed to
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// ONE on blending. As the backends may emulate this framebuffer
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// configuration with an alpha channel, we just drop all references
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// to the destination alpha channel.
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static BlendMode::BlendFactor RemoveDstAlphaUsage(BlendMode::BlendFactor factor)
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{
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switch (factor)
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{
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case BlendMode::DSTALPHA:
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return BlendMode::ONE;
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case BlendMode::INVDSTALPHA:
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return BlendMode::ZERO;
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default:
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return factor;
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}
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}
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// We separate the blending parameter for rgb and alpha. For blending
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// the alpha component, CLR and ALPHA are indentical. So just always
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// use ALPHA as this makes it easier for the backends to use the second
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// alpha value of dual source blending.
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static BlendMode::BlendFactor RemoveSrcColorUsage(BlendMode::BlendFactor factor)
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{
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switch (factor)
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{
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case BlendMode::SRCCLR:
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return BlendMode::SRCALPHA;
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case BlendMode::INVSRCCLR:
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return BlendMode::INVSRCALPHA;
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default:
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return factor;
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}
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}
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// Same as RemoveSrcColorUsage, but because of the overlapping enum,
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// this must be written as another function.
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static BlendMode::BlendFactor RemoveDstColorUsage(BlendMode::BlendFactor factor)
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{
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switch (factor)
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{
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case BlendMode::DSTCLR:
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return BlendMode::DSTALPHA;
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case BlendMode::INVDSTCLR:
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return BlendMode::INVDSTALPHA;
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default:
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return factor;
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}
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}
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void BlendingState::Generate(const BPMemory& bp)
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{
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// Start with everything disabled.
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hex = 0;
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bool target_has_alpha = bp.zcontrol.pixel_format == PEControl::RGBA6_Z24;
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bool alpha_test_may_success = bp.alpha_test.TestResult() != AlphaTest::FAIL;
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colorupdate = bp.blendmode.colorupdate && alpha_test_may_success;
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alphaupdate = bp.blendmode.alphaupdate && target_has_alpha && alpha_test_may_success;
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dstalpha = bp.dstalpha.enable && alphaupdate;
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usedualsrc = true;
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// The subtract bit has the highest priority
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if (bp.blendmode.subtract)
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{
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blendenable = true;
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subtractAlpha = subtract = true;
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srcfactoralpha = srcfactor = BlendMode::ONE;
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dstfactoralpha = dstfactor = BlendMode::ONE;
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if (dstalpha)
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{
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subtractAlpha = false;
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srcfactoralpha = BlendMode::ONE;
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dstfactoralpha = BlendMode::ZERO;
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}
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}
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// The blendenable bit has the middle priority
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else if (bp.blendmode.blendenable)
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{
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blendenable = true;
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srcfactor = bp.blendmode.srcfactor;
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dstfactor = bp.blendmode.dstfactor;
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if (!target_has_alpha)
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{
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// uses ONE instead of DSTALPHA
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srcfactor = RemoveDstAlphaUsage(srcfactor);
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dstfactor = RemoveDstAlphaUsage(dstfactor);
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}
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// replaces SRCCLR with SRCALPHA
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srcfactoralpha = RemoveSrcColorUsage(srcfactor);
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dstfactoralpha = RemoveDstColorUsage(dstfactor);
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if (dstalpha)
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{
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srcfactoralpha = BlendMode::ONE;
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dstfactoralpha = BlendMode::ZERO;
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}
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}
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// The logicop bit has the lowest priority
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else if (bp.blendmode.logicopenable)
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{
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if (bp.blendmode.logicmode == BlendMode::NOOP)
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{
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// Fast path for Kirby's Return to Dreamland, they use it with dstAlpha.
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colorupdate = false;
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alphaupdate = alphaupdate && dstalpha;
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}
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else
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{
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logicopenable = true;
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logicmode = bp.blendmode.logicmode;
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if (dstalpha)
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{
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// TODO: Not supported by backends.
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}
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}
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}
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}
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