From c4e165067d4578b5e26123ea5d7b6c37be56e32d Mon Sep 17 00:00:00 2001
From: Gregory Hainaut <gregory.hainaut@gmail.com>
Date: Sat, 18 Jul 2015 14:37:08 +0200
Subject: [PATCH] glsl: use signed integer when working with substraction...

It mostly fixes rendering of GoW with ultra blending

Color is still a bit wrong but rounding is likely incorrect
---
 plugins/GSdx/res/glsl/tfx_fs.glsl | 7 +++++--
 plugins/GSdx/res/glsl_source.h    | 7 +++++--
 2 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/plugins/GSdx/res/glsl/tfx_fs.glsl b/plugins/GSdx/res/glsl/tfx_fs.glsl
index 4d2770403f..2c4a510fcf 100644
--- a/plugins/GSdx/res/glsl/tfx_fs.glsl
+++ b/plugins/GSdx/res/glsl/tfx_fs.glsl
@@ -462,15 +462,18 @@ void ps_blend(inout vec4 Color, float As)
 	Color.rgb = clamp(Color.rgb, vec3(0.0f), vec3(255.0f));
 #endif
 
+	// FIXME rouding of negative float?
+	// compiler uses trunc but it might need floor
+
     // Warning: normally blending equation is mult(A, B) = A * B >> 7. GPU have the full accuracy
     // GS: Color = 1, Alpha = 255 => output 1
     // GPU: Color = 1/255, Alpha = 255/255 * 255/128 => output 1.9921875
 #if PS_DFMT == FMT_16
 	// In 16 bits format, only 5 bits of colors are used. It impacts shadows computation of Castlevania
 
-	Color.rgb = vec3(uvec3(Color.rgb) & uvec3(0xF8));
+	Color.rgb = vec3(ivec3(Color.rgb) & ivec3(0xF8));
 #elif PS_COLCLIP == 3
-	Color.rgb = vec3(uvec3(Color.rgb) & uvec3(0xFF));
+	Color.rgb = vec3(ivec3(Color.rgb) & ivec3(0xFF));
 #endif
 
 #endif
diff --git a/plugins/GSdx/res/glsl_source.h b/plugins/GSdx/res/glsl_source.h
index 0cbe96af57..dc67ca2bb5 100644
--- a/plugins/GSdx/res/glsl_source.h
+++ b/plugins/GSdx/res/glsl_source.h
@@ -1325,15 +1325,18 @@ static const char* tfx_fs_all_glsl =
 	"	Color.rgb = clamp(Color.rgb, vec3(0.0f), vec3(255.0f));\n"
 	"#endif\n"
 	"\n"
+	"	// FIXME rouding of negative float?\n"
+	"	// compiler uses trunc but it might need floor\n"
+	"\n"
 	"    // Warning: normally blending equation is mult(A, B) = A * B >> 7. GPU have the full accuracy\n"
 	"    // GS: Color = 1, Alpha = 255 => output 1\n"
 	"    // GPU: Color = 1/255, Alpha = 255/255 * 255/128 => output 1.9921875\n"
 	"#if PS_DFMT == FMT_16\n"
 	"	// In 16 bits format, only 5 bits of colors are used. It impacts shadows computation of Castlevania\n"
 	"\n"
-	"	Color.rgb = vec3(uvec3(Color.rgb) & uvec3(0xF8));\n"
+	"	Color.rgb = vec3(ivec3(Color.rgb) & ivec3(0xF8));\n"
 	"#elif PS_COLCLIP == 3\n"
-	"	Color.rgb = vec3(uvec3(Color.rgb) & uvec3(0xFF));\n"
+	"	Color.rgb = vec3(ivec3(Color.rgb) & ivec3(0xFF));\n"
 	"#endif\n"
 	"\n"
 	"#endif\n"