From 4e1d2f0cb20e3fce2a4eb0e4c5a4ecc823c18b52 Mon Sep 17 00:00:00 2001
From: Tony Wasserka <neobrainx@gmail.com>
Date: Sun, 21 Jul 2013 20:56:01 +0200
Subject: [PATCH] softgpu: Implement logic ops.

---
 GPU/Software/Rasterizer.cpp | 70 +++++++++++++++++++++++++++++++++++++
 1 file changed, 70 insertions(+)

diff --git a/GPU/Software/Rasterizer.cpp b/GPU/Software/Rasterizer.cpp
index 7c069609f4..664965a254 100644
--- a/GPU/Software/Rasterizer.cpp
+++ b/GPU/Software/Rasterizer.cpp
@@ -647,6 +647,76 @@ void DrawTriangle(const VertexData& v0, const VertexData& v1, const VertexData&
 
 				u32 new_color = Vec4<int>(prim_color_rgb.r(), prim_color_rgb.g(), prim_color_rgb.b(), prim_color_a).ToRGBA();
 				u32 old_color = GetPixelColor(p.x, p.y);
+
+				// TODO: Is alpha blending still performed if logic ops are enabled?
+				if (gstate.isLogicOpEnabled()) {
+					switch (gstate.getLogicOp()) {
+					case GE_LOGIC_CLEAR:
+						new_color = 0;
+						break;
+
+					case GE_LOGIC_AND:
+						new_color = new_color & old_color;
+						break;
+
+					case GE_LOGIC_AND_REVERSE:
+						new_color = new_color & ~old_color;
+						break;
+
+					case GE_LOGIC_COPY:
+						//new_color = new_color;
+						break;
+
+					case GE_LOGIC_AND_INVERTED:
+						new_color = ~new_color & old_color;
+						break;
+
+					case GE_LOGIC_NOOP:
+						new_color = old_color;
+						break;
+
+					case GE_LOGIC_XOR:
+						new_color = new_color ^ old_color;
+						break;
+
+					case GE_LOGIC_OR:
+						new_color = new_color | old_color;
+						break;
+
+					case GE_LOGIC_NOR:
+						new_color = ~(new_color | old_color);
+						break;
+
+					case GE_LOGIC_EQUIV:
+						new_color = ~(new_color ^ old_color);
+						break;
+
+					case GE_LOGIC_INVERTED:
+						new_color = ~old_color;
+						break;
+
+					case GE_LOGIC_OR_REVERSE:
+						new_color = new_color | ~old_color;
+						break;
+
+					case GE_LOGIC_COPY_INVERTED:
+						new_color = ~new_color;
+						break;
+
+					case GE_LOGIC_OR_INVERTED:
+						new_color = ~new_color | old_color;
+						break;
+
+					case GE_LOGIC_NAND:
+						new_color = ~(new_color & old_color);
+						break;
+
+					case GE_LOGIC_SET:
+						new_color = 0xFFFFFFFF;
+						break;
+					}
+				}
+
 				new_color = (new_color & ~gstate.getColorMask()) | (old_color & gstate.getColorMask());
 
 				SetPixelColor(p.x, p.y, new_color);