From 9bc466a4439e9a95655b9036072c2d7237286111 Mon Sep 17 00:00:00 2001
From: Jules Blok <jules.blok@gmail.com>
Date: Thu, 8 Sep 2016 01:34:18 +0200
Subject: [PATCH] PixelShaderGen: Add support for dithering.

---
 Source/Core/VideoCommon/PixelShaderGen.cpp | 7 +++++++
 Source/Core/VideoCommon/PixelShaderGen.h   | 3 ++-
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/Source/Core/VideoCommon/PixelShaderGen.cpp b/Source/Core/VideoCommon/PixelShaderGen.cpp
index 45ac231544..a0ef76546d 100644
--- a/Source/Core/VideoCommon/PixelShaderGen.cpp
+++ b/Source/Core/VideoCommon/PixelShaderGen.cpp
@@ -170,6 +170,7 @@ PixelShaderUid GetPixelShaderUid(DSTALPHA_MODE dstAlphaMode)
   uid_data->bounding_box = g_ActiveConfig.backend_info.bSupportsBBox &&
                            g_ActiveConfig.bBBoxEnable && BoundingBox::active;
   uid_data->rgba6_format = bpmem.zcontrol.pixel_format == PEControl::RGBA6_Z24;
+  uid_data->dither = bpmem.blendmode.dither;
 
   u32 numStages = uid_data->genMode_numtevstages + 1;
 
@@ -779,6 +780,12 @@ ShaderCode GeneratePixelShaderCode(APIType ApiType, const pixel_shader_uid_data*
       out.Write("\tdepth = float(zCoord) / 16777216.0;\n");
   }
 
+  if (uid_data->dither && uid_data->rgba6_format)
+  {
+    out.Write("\tint2 dither = int2(rawpos.xy) & 1;\n");
+    out.Write("\tprev.rgb = (prev.rgb - (prev.rgb >> 6)) + abs(dither.y * 3 - dither.x * 2);\n");
+  }
+
   if (uid_data->dstAlphaMode == DSTALPHA_ALPHA_PASS)
   {
     out.SetConstantsUsed(C_ALPHA, C_ALPHA);
diff --git a/Source/Core/VideoCommon/PixelShaderGen.h b/Source/Core/VideoCommon/PixelShaderGen.h
index 86806cf877..d141fd57f8 100644
--- a/Source/Core/VideoCommon/PixelShaderGen.h
+++ b/Source/Core/VideoCommon/PixelShaderGen.h
@@ -54,7 +54,8 @@ struct pixel_shader_uid_data
   u32 ssaa : 1;
   u32 numColorChans : 2;
   u32 rgba6_format : 1;
-  u32 pad : 13;
+  u32 dither : 1;
+  u32 pad : 12;
 
   u32 texMtxInfo_n_projection : 8;  // 8x1 bit
   u32 tevindref_bi0 : 3;