From 531b3941ff612f9cc8dcb4b1d7de6cbec3ff1c08 Mon Sep 17 00:00:00 2001
From: Jules Blok <jules.blok@gmail.com>
Date: Fri, 19 Dec 2014 14:09:16 +0100
Subject: [PATCH] GeometryShaderGen: Re-emit the first vertex when wireframe
 mode is enabled.

---
 Source/Core/VideoCommon/GeometryShaderGen.cpp | 40 ++++++++++++++-----
 1 file changed, 29 insertions(+), 11 deletions(-)

diff --git a/Source/Core/VideoCommon/GeometryShaderGen.cpp b/Source/Core/VideoCommon/GeometryShaderGen.cpp
index eaba7652d6..a85e36b9bc 100644
--- a/Source/Core/VideoCommon/GeometryShaderGen.cpp
+++ b/Source/Core/VideoCommon/GeometryShaderGen.cpp
@@ -26,7 +26,8 @@ static const char* primitives_d3d[] =
 	"triangle"
 };
 
-template<class T> static inline void EmitVertex(T& out, const char* vertex, API_TYPE ApiType);
+template<class T> static inline void EmitVertex(T& out, const char* vertex, API_TYPE ApiType, bool first_vertex = false);
+template<class T> static inline void EndPrimitive(T& out, API_TYPE ApiType);
 
 template<class T>
 static inline void GenerateGeometryShader(T& out, u32 primitive_type, API_TYPE ApiType)
@@ -45,10 +46,13 @@ static inline void GenerateGeometryShader(T& out, u32 primitive_type, API_TYPE A
 
 	uid_data->primitive_type = primitive_type;
 	const unsigned int vertex_in = primitive_type + 1;
-	const unsigned int vertex_out = primitive_type == PRIMITIVE_TRIANGLES ? 3 : 4;
+	unsigned int vertex_out = primitive_type == PRIMITIVE_TRIANGLES ? 3 : 4;
+
+	uid_data->wireframe = g_ActiveConfig.bWireFrame;
+	if (g_ActiveConfig.bWireFrame)
+		vertex_out++;
 
 	uid_data->stereo = g_ActiveConfig.iStereoMode > 0;
-	uid_data->wireframe = g_ActiveConfig.bWireFrame;
 	if (ApiType == API_OPENGL)
 	{
 		// Insert layout parameters
@@ -178,6 +182,9 @@ static inline void GenerateGeometryShader(T& out, u32 primitive_type, API_TYPE A
 			out.Write("\tfor (int eye = 0; eye < 2; ++eye) {\n");
 	}
 
+	if (g_ActiveConfig.bWireFrame)
+		out.Write("\tVS_OUTPUT first;\n");
+
 	out.Write("\tfor (int i = 0; i < %d; ++i) {\n", vertex_in);
 
 	if (ApiType == API_OPENGL)
@@ -221,7 +228,7 @@ static inline void GenerateGeometryShader(T& out, u32 primitive_type, API_TYPE A
 		}
 		out.Write("\t}\n");
 
-		EmitVertex<T>(out, "l", ApiType);
+		EmitVertex<T>(out, "l", ApiType, true);
 		EmitVertex<T>(out, "r", ApiType);
 	}
 	else if (primitive_type == PRIMITIVE_POINTS)
@@ -249,22 +256,19 @@ static inline void GenerateGeometryShader(T& out, u32 primitive_type, API_TYPE A
 		}
 		out.Write("\t}\n");
 
-		EmitVertex<T>(out, "ll", ApiType);
+		EmitVertex<T>(out, "ll", ApiType, true);
 		EmitVertex<T>(out, "lr", ApiType);
 		EmitVertex<T>(out, "ul", ApiType);
 		EmitVertex<T>(out, "ur", ApiType);
 	}
 	else
 	{
-		EmitVertex<T>(out, "f", ApiType);
+		EmitVertex<T>(out, "f", ApiType, true);
 	}
 
 	out.Write("\t}\n");
 
-	if (ApiType == API_OPENGL)
-		out.Write("\tEndPrimitive();\n");
-	else
-		out.Write("\toutput.RestartStrip();\n");
+	EndPrimitive<T>(out, ApiType);
 
 	if (g_ActiveConfig.iStereoMode > 0 && !g_ActiveConfig.backend_info.bSupportsGSInstancing)
 		out.Write("\t}\n");
@@ -279,8 +283,11 @@ static inline void GenerateGeometryShader(T& out, u32 primitive_type, API_TYPE A
 }
 
 template<class T>
-static inline void EmitVertex(T& out, const char* vertex, API_TYPE ApiType)
+static inline void EmitVertex(T& out, const char* vertex, API_TYPE ApiType, bool first_vertex)
 {
+	if (g_ActiveConfig.bWireFrame && first_vertex)
+		out.Write("\tif (i == 0) first = %s;\n", vertex);
+
 	if (ApiType == API_OPENGL)
 		out.Write("\tgl_Position = %s.pos;\n", vertex);
 
@@ -291,6 +298,17 @@ static inline void EmitVertex(T& out, const char* vertex, API_TYPE ApiType)
 	else
 		out.Write("\toutput.Append(ps);\n");
 }
+template<class T>
+static inline void EndPrimitive(T& out, API_TYPE ApiType)
+{
+	if (g_ActiveConfig.bWireFrame)
+		EmitVertex<T>(out, "first", ApiType);
+
+	if (ApiType == API_OPENGL)
+		out.Write("\tEndPrimitive();\n");
+	else
+		out.Write("\toutput.RestartStrip();\n");
+}
 
 void GetGeometryShaderUid(GeometryShaderUid& object, u32 primitive_type, API_TYPE ApiType)
 {