From 5f247a6e16638220f352b9c23038e91f5f70c4e2 Mon Sep 17 00:00:00 2001
From: Gregory Hainaut <gregory.hainaut@gmail.com>
Date: Fri, 17 Jul 2015 20:05:31 +0200
Subject: [PATCH] glsl: rewrite tfx function to ease future update

No need to put lots of ifdef, compiler will optimize everything
It increases a bit the readability
---
 plugins/GSdx/res/glsl/tfx_fs.glsl | 34 +++++++++++++++----------------
 plugins/GSdx/res/glsl_source.h    | 34 +++++++++++++++----------------
 2 files changed, 34 insertions(+), 34 deletions(-)

diff --git a/plugins/GSdx/res/glsl/tfx_fs.glsl b/plugins/GSdx/res/glsl/tfx_fs.glsl
index 0567d52c92..24cd3cd324 100644
--- a/plugins/GSdx/res/glsl/tfx_fs.glsl
+++ b/plugins/GSdx/res/glsl/tfx_fs.glsl
@@ -277,30 +277,30 @@ vec4 sample_color(vec2 st, float q)
 	return t;
 }
 
-// FIXME Precompute the factor 255/128 in VS
 vec4 tfx(vec4 t, vec4 c)
 {
-	vec4 c_out = c;
+	vec4 c_out;
+	// Note: It will be possible to precompute the factor 255/128 in the VS/GS
+	// However, I didn't see real speedup and it might make the code more difficult
+	// to support proper rounding
+	vec4 FxT = c * t * 255.0f / 128.0f;
+
 #if (PS_TFX == 0)
-	if(PS_TCC != 0)
-		c_out = c * t * 255.0f / 128.0f;
-	else
-		c_out.rgb = c.rgb * t.rgb * 255.0f / 128.0f;
+	c_out = FxT;
 #elif (PS_TFX == 1)
-	if(PS_TCC != 0)
-		c_out = t;
-	else
-		c_out.rgb = t.rgb;
+	c_out = t;
 #elif (PS_TFX == 2)
-	c_out.rgb = c.rgb * t.rgb * 255.0f / 128.0f + c.a;
-
-	if(PS_TCC != 0)
-		c_out.a += t.a;
+	c_out.rgb = FxT.rgb + c.a;
+	c_out.a = t.a + c.a;
 #elif (PS_TFX == 3)
-	c_out.rgb = c.rgb * t.rgb * 255.0f / 128.0f + c.a;
+	c_out.rgb = FxT.rgb + c.a;
+	c_out.a = t.a;
+#else
+	c_out = c;
+#endif
 
-	if(PS_TCC != 0)
-		c_out.a = t.a;
+#if (PS_TCC == 0)
+    c_out.a = c.a;
 #endif
 
 	return c_out;
diff --git a/plugins/GSdx/res/glsl_source.h b/plugins/GSdx/res/glsl_source.h
index 8df29ac112..49c0e6234a 100644
--- a/plugins/GSdx/res/glsl_source.h
+++ b/plugins/GSdx/res/glsl_source.h
@@ -1138,30 +1138,30 @@ static const char* tfx_fs_all_glsl =
 	"	return t;\n"
 	"}\n"
 	"\n"
-	"// FIXME Precompute the factor 255/128 in VS\n"
 	"vec4 tfx(vec4 t, vec4 c)\n"
 	"{\n"
-	"	vec4 c_out = c;\n"
+	"	vec4 c_out;\n"
+	"	// Note: It will be possible to precompute the factor 255/128 in the VS/GS\n"
+	"	// However, I didn't see real speedup and it might make the code more difficult\n"
+	"	// to support proper rounding\n"
+	"	vec4 FxT = c * t * 255.0f / 128.0f;\n"
+	"\n"
 	"#if (PS_TFX == 0)\n"
-	"	if(PS_TCC != 0)\n"
-	"		c_out = c * t * 255.0f / 128.0f;\n"
-	"	else\n"
-	"		c_out.rgb = c.rgb * t.rgb * 255.0f / 128.0f;\n"
+	"	c_out = FxT;\n"
 	"#elif (PS_TFX == 1)\n"
-	"	if(PS_TCC != 0)\n"
-	"		c_out = t;\n"
-	"	else\n"
-	"		c_out.rgb = t.rgb;\n"
+	"	c_out = t;\n"
 	"#elif (PS_TFX == 2)\n"
-	"	c_out.rgb = c.rgb * t.rgb * 255.0f / 128.0f + c.a;\n"
-	"\n"
-	"	if(PS_TCC != 0)\n"
-	"		c_out.a += t.a;\n"
+	"	c_out.rgb = FxT.rgb + c.a;\n"
+	"	c_out.a = t.a + c.a;\n"
 	"#elif (PS_TFX == 3)\n"
-	"	c_out.rgb = c.rgb * t.rgb * 255.0f / 128.0f + c.a;\n"
+	"	c_out.rgb = FxT.rgb + c.a;\n"
+	"	c_out.a = t.a;\n"
+	"#else\n"
+	"	c_out = c;\n"
+	"#endif\n"
 	"\n"
-	"	if(PS_TCC != 0)\n"
-	"		c_out.a = t.a;\n"
+	"#if (PS_TCC == 0)\n"
+	"    c_out.a = c.a;\n"
 	"#endif\n"
 	"\n"
 	"	return c_out;\n"