From b1ed7e80fb689da5a4679e5c178f91391e55a6ff Mon Sep 17 00:00:00 2001
From: Jules Blok <jules.blok@gmail.com>
Date: Thu, 4 Aug 2016 14:09:35 +0200
Subject: [PATCH] VertexShaderGen: Clip z using user-defined clipping planes.

---
 Source/Core/VideoBackends/OGL/Render.cpp    | 1 +
 Source/Core/VideoCommon/ShaderGenCommon.h   | 4 ++++
 Source/Core/VideoCommon/VertexShaderGen.cpp | 5 +++++
 3 files changed, 10 insertions(+)

diff --git a/Source/Core/VideoBackends/OGL/Render.cpp b/Source/Core/VideoBackends/OGL/Render.cpp
index 26f1c8cc21..13a34ce2e1 100644
--- a/Source/Core/VideoBackends/OGL/Render.cpp
+++ b/Source/Core/VideoBackends/OGL/Render.cpp
@@ -724,6 +724,7 @@ Renderer::Renderer()
   glClearDepthf(1.0f);
   glEnable(GL_DEPTH_TEST);
   glDepthFunc(GL_LEQUAL);
+  glEnable(GL_CLIP_DISTANCE0);
 
   glPixelStorei(GL_UNPACK_ALIGNMENT, 4);  // 4-byte pixel alignment
 
diff --git a/Source/Core/VideoCommon/ShaderGenCommon.h b/Source/Core/VideoCommon/ShaderGenCommon.h
index e7d0667861..434099e85e 100644
--- a/Source/Core/VideoCommon/ShaderGenCommon.h
+++ b/Source/Core/VideoCommon/ShaderGenCommon.h
@@ -196,6 +196,8 @@ inline void GenerateVSOutputMembers(T& object, APIType api_type, u32 texgens,
     DefineOutputMember(object, api_type, qualifier, "float3", "WorldPos", -1, "TEXCOORD",
                        texgens + 2);
   }
+
+  DefineOutputMember(object, api_type, qualifier, "float", "clipDist", -1, "SV_ClipDistance");
 }
 
 template <class T>
@@ -216,6 +218,8 @@ inline void AssignVSOutputMembers(T& object, const char* a, const char* b, u32 t
     object.Write("\t%s.Normal = %s.Normal;\n", a, b);
     object.Write("\t%s.WorldPos = %s.WorldPos;\n", a, b);
   }
+
+  object.Write("\t%s.clipDist = %s.clipDist;\n", a, b);
 }
 
 // We use the flag "centroid" to fix some MSAA rendering bugs. With MSAA, the
diff --git a/Source/Core/VideoCommon/VertexShaderGen.cpp b/Source/Core/VideoCommon/VertexShaderGen.cpp
index 0863e9f17f..abb79d90fc 100644
--- a/Source/Core/VideoCommon/VertexShaderGen.cpp
+++ b/Source/Core/VideoCommon/VertexShaderGen.cpp
@@ -399,6 +399,10 @@ ShaderCode GenerateVertexShaderCode(APIType api_type, const vertex_shader_uid_da
       out.Write("o.colors_1 = color1;\n");
   }
 
+  // Since we're adjusting z for the depth range before the perspective divide, we have to do our
+  // own clipping.
+  out.Write("o.clipDist = o.pos.z + o.pos.w;\n");
+
   // We have to handle the depth range in the vertex shader, because some games will use a depth range beyond
   // the normal depth range of 0..1.
   out.Write("o.pos.z = o.pos.w * " I_PIXELCENTERCORRECTION".w + o.pos.z * " I_PIXELCENTERCORRECTION".z;\n");
@@ -457,6 +461,7 @@ ShaderCode GenerateVertexShaderCode(APIType api_type, const vertex_shader_uid_da
       out.Write("colors_1 = o.colors_1;\n");
     }
 
+    out.Write("gl_ClipDistance[0] = o.clipDist;\n");
     out.Write("gl_Position = o.pos;\n");
   }
   else  // D3D