From 4659184cc1a9c883064bd93c1a3b3992f4275aed Mon Sep 17 00:00:00 2001
From: Gregory Hainaut <gregory.hainaut@gmail.com>
Date: Sat, 27 Sep 2014 19:39:17 +0200
Subject: [PATCH] gsdx-ogl: add support of clip_control (depth only)

* replace the [-1;1] depth range of openGL with the DX range [0;1].
---
 plugins/GSdx/GSDeviceOGL.cpp    | 19 +++++++++++++++++++
 plugins/GSdx/GSShaderOGL.cpp    |  5 ++---
 plugins/GSdx/GSTextureFXOGL.cpp | 11 -----------
 plugins/GSdx/res/glsl_source.h  |  5 ++++-
 plugins/GSdx/res/tfx.glsl       |  5 ++++-
 5 files changed, 29 insertions(+), 16 deletions(-)

diff --git a/plugins/GSdx/GSDeviceOGL.cpp b/plugins/GSdx/GSDeviceOGL.cpp
index d90aa7a82a..2b8fa0fc43 100644
--- a/plugins/GSdx/GSDeviceOGL.cpp
+++ b/plugins/GSdx/GSDeviceOGL.cpp
@@ -307,6 +307,25 @@ bool GSDeviceOGL::Create(GSWnd* wnd)
 //	m_date.bs->SetMask(false, false, false, false);
 //#endif
 
+	// ****************************************************************
+	// Use DX coordinate convention
+	// ****************************************************************
+
+
+	// VS gl_position.z => [-1,-1]
+	// FS depth => [0, 1]
+	// because of -1 we loose lot of precision for small GS value
+	// This extension allow FS depth to range from -1 to 1. So
+	// gl_position.z could range from [0, 1]
+#ifndef ENABLE_GLES
+	if (GLLoader::found_GL_ARB_clip_control) {
+		// Change depth convention
+		gl_ClipControl(GL_LOWER_LEFT, GL_ZERO_TO_ONE);
+	} else if (GLLoader::found_GL_NV_depth_buffer_float) {
+		gl_DepthRangedNV(-1.0f, 1.0f);
+	}
+#endif
+
 	// ****************************************************************
 	// HW renderer shader
 	// ****************************************************************
diff --git a/plugins/GSdx/GSShaderOGL.cpp b/plugins/GSdx/GSShaderOGL.cpp
index dbe106e885..ec5a76e9fb 100644
--- a/plugins/GSdx/GSShaderOGL.cpp
+++ b/plugins/GSdx/GSShaderOGL.cpp
@@ -403,9 +403,8 @@ std::string GSShaderOGL::GenGlslHeader(const std::string& entry, GLenum type, co
 		header += "#define ENABLE_BINDLESS_TEX\n";
 	}
 
-	if (GLLoader::found_GL_NV_depth_buffer_float) {
-		// Specific nvidia extension that seem to help for z fighting
-		header += "#define NV_DEPTH\n";
+	if (GLLoader::found_GL_NV_depth_buffer_float || GLLoader::found_GL_ARB_clip_control) {
+		header += "#define ZERO_TO_ONE_DEPTH\n";
 	}
 
 #else
diff --git a/plugins/GSdx/GSTextureFXOGL.cpp b/plugins/GSdx/GSTextureFXOGL.cpp
index 09b1ae98d3..98589c8aa7 100644
--- a/plugins/GSdx/GSTextureFXOGL.cpp
+++ b/plugins/GSdx/GSTextureFXOGL.cpp
@@ -59,17 +59,6 @@ void GSDeviceOGL::CreateTextureFX()
 
 	// Help to debug FS in apitrace
 	m_apitrace = CompilePS(PSSelector());
-
-	// VS gl_position.z => [-1,-1]
-	// FS depth => [0, 1]
-	// because of -1 we loose lot of precision for small GS value
-	// This extension allow FS depth to range from -1 to 1. So
-	// gl_position.z could range from [0, 1]
-#ifndef ENABLE_GLES
-	if (GLLoader::found_GL_NV_depth_buffer_float) {
-		gl_DepthRangedNV(-1.0f, 1.0f);
-	}
-#endif
 }
 
 GSDepthStencilOGL* GSDeviceOGL::CreateDepthStencil(OMDepthStencilSelector dssel)
diff --git a/plugins/GSdx/res/glsl_source.h b/plugins/GSdx/res/glsl_source.h
index d68b6c8637..c85b7429d2 100644
--- a/plugins/GSdx/res/glsl_source.h
+++ b/plugins/GSdx/res/glsl_source.h
@@ -664,8 +664,11 @@ static const char* tfx_glsl =
 	"    vec2 TextureScale;\n"
 	"};\n"
 	"\n"
+	"#ifdef ZERO_TO_ONE_DEPTH\n"
 	"const float exp_min32 = exp2(-32.0f);\n"
+	"#else\n"
 	"const float exp_min31 = exp2(-31.0f);\n"
+	"#endif\n"
 	"\n"
 	"#ifdef SUBROUTINE_GL40\n"
 	"// Function pointer type\n"
@@ -740,7 +743,7 @@ static const char* tfx_glsl =
 	"    p.xy = vec2(i_p) - vec2(0.05f, 0.05f);\n"
 	"    p.xy = p.xy * VertexScale - VertexOffset;\n"
 	"    p.w = 1.0f;\n"
-	"#ifdef NV_DEPTH\n"
+	"#ifdef ZERO_TO_ONE_DEPTH\n"
 	"    if(VS_LOGZ == 1) {\n"
 	"        p.z = log2(float(1u+z)) / 32.0f;\n"
 	"    } else {\n"
diff --git a/plugins/GSdx/res/tfx.glsl b/plugins/GSdx/res/tfx.glsl
index 35cc49fc45..dbbd64b014 100644
--- a/plugins/GSdx/res/tfx.glsl
+++ b/plugins/GSdx/res/tfx.glsl
@@ -105,8 +105,11 @@ layout(std140, binding = 20) uniform cb20
     vec2 TextureScale;
 };
 
+#ifdef ZERO_TO_ONE_DEPTH
 const float exp_min32 = exp2(-32.0f);
+#else
 const float exp_min31 = exp2(-31.0f);
+#endif
 
 #ifdef SUBROUTINE_GL40
 // Function pointer type
@@ -181,7 +184,7 @@ void vs_main()
     p.xy = vec2(i_p) - vec2(0.05f, 0.05f);
     p.xy = p.xy * VertexScale - VertexOffset;
     p.w = 1.0f;
-#ifdef NV_DEPTH
+#ifdef ZERO_TO_ONE_DEPTH
     if(VS_LOGZ == 1) {
         p.z = log2(float(1u+z)) / 32.0f;
     } else {