From 3c611980431eeb78c37ebc6fc33e76d99e5e97c6 Mon Sep 17 00:00:00 2001
From: Sergey Lipskiy <gonetz@ngs.ru>
Date: Fri, 10 Nov 2017 23:53:27 +0700
Subject: [PATCH] Hardcode blend mode, which is impossible to emulate with
 shaders.

Fixed Tony Hawk's Pro Skater 2 Shadow Glitch #1337
---
 .../GLSL/glsl_CombinerProgramUniformFactory.cpp       |  6 ++++++
 src/GraphicsDrawer.cpp                                | 11 +++++++++++
 2 files changed, 17 insertions(+)

diff --git a/src/Graphics/OpenGLContext/GLSL/glsl_CombinerProgramUniformFactory.cpp b/src/Graphics/OpenGLContext/GLSL/glsl_CombinerProgramUniformFactory.cpp
index b1710152..6e5a8740 100644
--- a/src/Graphics/OpenGLContext/GLSL/glsl_CombinerProgramUniformFactory.cpp
+++ b/src/Graphics/OpenGLContext/GLSL/glsl_CombinerProgramUniformFactory.cpp
@@ -306,6 +306,12 @@ public:
 
 	void update(bool _force) override
 	{
+		if ((gDP.otherMode.l & 0xFFFF0000) == 0x01500000) {
+			uForceBlendCycle1.set(0, _force);
+			uForceBlendCycle2.set(0, _force);
+			return;
+		}
+
 		uBlendMux1.set(gDP.otherMode.c1_m1a,
 			gDP.otherMode.c1_m1b,
 			gDP.otherMode.c1_m2a,
diff --git a/src/GraphicsDrawer.cpp b/src/GraphicsDrawer.cpp
index c48ecc59..1a1cb53e 100644
--- a/src/GraphicsDrawer.cpp
+++ b/src/GraphicsDrawer.cpp
@@ -441,6 +441,17 @@ void GraphicsDrawer::_setBlendMode() const
 		return;
 	}
 
+	if ((gDP.otherMode.l & 0xFFFF0000) == 0x01500000) {
+		// clr_in * a_in + clr_mem * (1-a)
+		// clr_in * a_fog + clr_mem * (1-a)
+		// impossible to emulate
+		if (gDP.otherMode.forceBlender != 0 && gDP.otherMode.cycleType < G_CYC_COPY) {
+			gfxContext.enable(enable::BLEND, true);
+			gfxContext.setBlending(blend::SRC_ALPHA, blend::ONE_MINUS_SRC_ALPHA);
+			return;
+		}
+	}
+
 	if (gDP.otherMode.forceBlender != 0 && gDP.otherMode.cycleType < G_CYC_COPY) {
 		BlendParam srcFactor = blend::ONE;
 		BlendParam dstFactor = blend::ZERO;