From bd6d22973381b43369670300a707e86084c040e0 Mon Sep 17 00:00:00 2001
From: Jules Blok <jules.blok@gmail.com>
Date: Tue, 16 Dec 2014 17:28:35 +0100
Subject: [PATCH] GeometryShader: Disable the geometry shader stage if it is a
 pass-through shader.

---
 Source/Core/VideoBackends/D3D/GeometryShaderCache.cpp | 11 ++++++++++-
 Source/Core/VideoBackends/D3D/GeometryShaderCache.h   |  1 +
 Source/Core/VideoBackends/OGL/ProgramShaderCache.cpp  |  3 ++-
 Source/Core/VideoCommon/GeometryShaderGen.cpp         |  6 ++++++
 Source/Core/VideoCommon/GeometryShaderGen.h           |  1 +
 5 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/Source/Core/VideoBackends/D3D/GeometryShaderCache.cpp b/Source/Core/VideoBackends/D3D/GeometryShaderCache.cpp
index bed0ff95b7..7088cd70f5 100644
--- a/Source/Core/VideoBackends/D3D/GeometryShaderCache.cpp
+++ b/Source/Core/VideoBackends/D3D/GeometryShaderCache.cpp
@@ -28,6 +28,7 @@ GeometryShaderCache::GSCache GeometryShaderCache::GeometryShaders;
 const GeometryShaderCache::GSCacheEntry* GeometryShaderCache::last_entry;
 GeometryShaderUid GeometryShaderCache::last_uid;
 UidChecker<GeometryShaderUid,ShaderCode> GeometryShaderCache::geometry_uid_checker;
+const GeometryShaderCache::GSCacheEntry GeometryShaderCache::pass_entry;
 
 ID3D11GeometryShader* ClearGeometryShader = nullptr;
 ID3D11GeometryShader* CopyGeometryShader = nullptr;
@@ -203,12 +204,20 @@ bool GeometryShaderCache::SetShader(u32 primitive_type)
 		if (uid == last_uid)
 		{
 			GFX_DEBUGGER_PAUSE_AT(NEXT_PIXEL_SHADER_CHANGE,true);
-			return (last_entry->shader != nullptr);
+			return true;
 		}
 	}
 
 	last_uid = uid;
 
+	// Check if the shader is a pass-through shader
+	if (IsPassthroughGeometryShader(uid))
+	{
+		// Return the default pass-through shader
+		last_entry = &pass_entry;
+		return true;
+	}
+
 	// Check if the shader is already in the cache
 	GSCache::iterator iter;
 	iter = GeometryShaders.find(uid);
diff --git a/Source/Core/VideoBackends/D3D/GeometryShaderCache.h b/Source/Core/VideoBackends/D3D/GeometryShaderCache.h
index fe4aea4a36..d88b88f4ae 100644
--- a/Source/Core/VideoBackends/D3D/GeometryShaderCache.h
+++ b/Source/Core/VideoBackends/D3D/GeometryShaderCache.h
@@ -43,6 +43,7 @@ private:
 	static GSCache GeometryShaders;
 	static const GSCacheEntry* last_entry;
 	static GeometryShaderUid last_uid;
+	static const GSCacheEntry pass_entry;
 
 	static UidChecker<GeometryShaderUid, ShaderCode> geometry_uid_checker;
 };
diff --git a/Source/Core/VideoBackends/OGL/ProgramShaderCache.cpp b/Source/Core/VideoBackends/OGL/ProgramShaderCache.cpp
index d2ec0d049b..8f90aff28a 100644
--- a/Source/Core/VideoBackends/OGL/ProgramShaderCache.cpp
+++ b/Source/Core/VideoBackends/OGL/ProgramShaderCache.cpp
@@ -211,7 +211,8 @@ SHADER* ProgramShaderCache::SetShader(DSTALPHA_MODE dstAlphaMode, u32 components
 	ShaderCode gcode;
 	GenerateVertexShaderCode(vcode, components, API_OPENGL);
 	GeneratePixelShaderCode(pcode, dstAlphaMode, API_OPENGL, components);
-	GenerateGeometryShaderCode(gcode, primitive_type, API_OPENGL);
+	if (!IsPassthroughGeometryShader(uid.guid))
+		GenerateGeometryShaderCode(gcode, primitive_type, API_OPENGL);
 
 	if (g_ActiveConfig.bEnableShaderDebugging)
 	{
diff --git a/Source/Core/VideoCommon/GeometryShaderGen.cpp b/Source/Core/VideoCommon/GeometryShaderGen.cpp
index bf40056a8d..3d478a6a4d 100644
--- a/Source/Core/VideoCommon/GeometryShaderGen.cpp
+++ b/Source/Core/VideoCommon/GeometryShaderGen.cpp
@@ -281,3 +281,9 @@ void GenerateGeometryShaderCode(ShaderCode& object, u32 primitive_type, API_TYPE
 {
 	GenerateGeometryShader<ShaderCode>(object, primitive_type, ApiType);
 }
+
+bool IsPassthroughGeometryShader(GeometryShaderUid& object)
+{
+	geometry_shader_uid_data* uid_data = object.GetUidData<geometry_shader_uid_data>();
+	return uid_data->primitive_type == PRIMITIVE_TRIANGLES && !uid_data->stereo;
+}
diff --git a/Source/Core/VideoCommon/GeometryShaderGen.h b/Source/Core/VideoCommon/GeometryShaderGen.h
index 93e222b25e..0f66f7a4f9 100644
--- a/Source/Core/VideoCommon/GeometryShaderGen.h
+++ b/Source/Core/VideoCommon/GeometryShaderGen.h
@@ -25,3 +25,4 @@ typedef ShaderUid<geometry_shader_uid_data> GeometryShaderUid;
 
 void GenerateGeometryShaderCode(ShaderCode& object, u32 primitive_type, API_TYPE ApiType);
 void GetGeometryShaderUid(GeometryShaderUid& object, u32 primitive_type, API_TYPE ApiType);
+bool IsPassthroughGeometryShader(GeometryShaderUid& object);