VideoCommon: Assembly blending state in a shared state object.

1 files changed, 119 insertions, 0 deletions

diff --git a/Source/Core/VideoCommon/RenderState.cpp b/Source/Core/VideoCommon/RenderState.cpp
new file mode 100644
index 0000000000..2750d43695
--- /dev/null
+++ b/Source/Core/VideoCommon/RenderState.cpp
@@ -0,0 +1,119 @@
+// Copyright 2016 Dolphin Emulator Project
+// Licensed under GPLv2+
+// Refer to the license.txt file included.
+
+#include "VideoCommon/RenderState.h"
+
+// If the framebuffer format has no alpha channel, it is assumed to
+// ONE on blending. As the backends may emulate this framebuffer
+// configuration with an alpha channel, we just drop all references
+// to the destination alpha channel.
+static BlendMode::BlendFactor RemoveDstAlphaUsage(BlendMode::BlendFactor factor)
+{
+  switch (factor)
+  {
+  case BlendMode::DSTALPHA:
+    return BlendMode::ONE;
+  case BlendMode::INVDSTALPHA:
+    return BlendMode::ZERO;
+  default:
+    return factor;
+  }
+}
+
+// We separate the blending parameter for rgb and alpha. For blending
+// the alpha component, CLR and ALPHA are indentical. So just always
+// use ALPHA as this makes it easier for the backends to use the second
+// alpha value of dual source blending.
+static BlendMode::BlendFactor RemoveSrcColorUsage(BlendMode::BlendFactor factor)
+{
+  switch (factor)
+  {
+  case BlendMode::SRCCLR:
+    return BlendMode::SRCALPHA;
+  case BlendMode::INVSRCCLR:
+    return BlendMode::INVSRCALPHA;
+  default:
+    return factor;
+  }
+}
+
+// Same as RemoveSrcColorUsage, but because of the overlapping enum,
+// this must be written as another function.
+static BlendMode::BlendFactor RemoveDstColorUsage(BlendMode::BlendFactor factor)
+{
+  switch (factor)
+  {
+  case BlendMode::DSTCLR:
+    return BlendMode::DSTALPHA;
+  case BlendMode::INVDSTCLR:
+    return BlendMode::INVDSTALPHA;
+  default:
+    return factor;
+  }
+}
+
+void BlendingState::Generate(const BPMemory& bp)
+{
+  // Start with everything disabled.
+  hex = 0;
+
+  bool target_has_alpha = bp.zcontrol.pixel_format == PEControl::RGBA6_Z24;
+  bool alpha_test_may_success = bp.alpha_test.TestResult() != AlphaTest::FAIL;
+
+  dither = bp.blendmode.dither;
+  colorupdate = bp.blendmode.colorupdate && alpha_test_may_success;
+  alphaupdate = bp.blendmode.alphaupdate && target_has_alpha && alpha_test_may_success;
+  dstalpha = bp.dstalpha.enable && alphaupdate;
+
+  // The subtract bit has the highest priority
+  if (bp.blendmode.subtract)
+  {
+    blendenable = true;
+    subtractAlpha = subtract = true;
+    srcfactoralpha = srcfactor = BlendMode::ONE;
+    dstfactoralpha = dstfactor = BlendMode::ONE;
+
+    if (dstalpha)
+    {
+      subtractAlpha = false;
+      srcfactoralpha = BlendMode::ONE;
+      dstfactoralpha = BlendMode::ZERO;
+    }
+  }
+
+  // The blendenable bit has the middle priority
+  else if (bp.blendmode.blendenable)
+  {
+    blendenable = true;
+    srcfactor = bp.blendmode.srcfactor;
+    dstfactor = bp.blendmode.dstfactor;
+    if (!target_has_alpha)
+    {
+      // uses ONE instead of DSTALPHA
+      srcfactor = RemoveDstAlphaUsage(srcfactor);
+      dstfactor = RemoveDstAlphaUsage(dstfactor);
+    }
+    // replaces SRCCLR with SRCALPHA
+    srcfactoralpha = RemoveSrcColorUsage(srcfactor);
+    dstfactoralpha = RemoveDstColorUsage(dstfactor);
+
+    if (dstalpha)
+    {
+      srcfactoralpha = BlendMode::ONE;
+      dstfactoralpha = BlendMode::ZERO;
+    }
+  }
+
+  // The logicop bit has the lowest priority
+  else if (bp.blendmode.logicopenable)
+  {
+    logicopenable = true;
+    logicmode = bp.blendmode.logicmode;
+
+    if (dstalpha)
+    {
+      // TODO: Not supported by backends.
+    }
+  }
+}