Implement Geometry shaders (#280)

* Implement Geometry shaders

* Add EmitVertex() and EndPrimitive()

* Read output geometry data from header

* Stub Vmad

* Add Iadd_I32

* Stub Mov_S (S2R)

* Stub Isberd

* Change vertex index to gpr39 in Abuf

* Add stub messages for consistency

* Do not print input block when there is no attributes

* Use GL_ARB_enhanced_layouts

* Skip geometry shaders when there's no GL_ARB_enhanced_layouts

* Address feedback

* Address feedback

2 files changed, 59 insertions, 6 deletions

diff --git a/Ryujinx.Graphics/Gal/OpenGL/OGLExtension.cs b/Ryujinx.Graphics/Gal/OpenGL/OGLExtension.cs
new file mode 100644
index 00000000..69fce6d3
--- /dev/null
+++ b/Ryujinx.Graphics/Gal/OpenGL/OGLExtension.cs
@@ -0,0 +1,43 @@
+using OpenTK.Graphics.OpenGL;
+
+namespace Ryujinx.Graphics.Gal.OpenGL
+{
+    static class OGLExtension
+    {
+        private static bool Initialized = false;
+
+        private static bool EnhancedLayouts;
+
+        public static bool HasEnhancedLayouts()
+        {
+            EnsureInitialized();
+
+            return EnhancedLayouts;
+        }
+
+        private static void EnsureInitialized()
+        {
+            if (Initialized)
+            {
+                return;
+            }
+
+            EnhancedLayouts = HasExtension("GL_ARB_enhanced_layouts");
+        }
+
+        private static bool HasExtension(string Name)
+        {
+            int NumExtensions = GL.GetInteger(GetPName.NumExtensions);
+
+            for (int Extension = 0; Extension < NumExtensions; Extension++)
+            {
+                if (GL.GetString(StringNameIndexed.Extensions, Extension) == Name)
+                {
+                    return true;
+                }
+            }
+
+            return false;
+        }
+    }
+}
\ No newline at end of file
diff --git a/Ryujinx.Graphics/Gal/OpenGL/OGLShader.cs b/Ryujinx.Graphics/Gal/OpenGL/OGLShader.cs
index ad717755..fe98aa09 100644
--- a/Ryujinx.Graphics/Gal/OpenGL/OGLShader.cs
+++ b/Ryujinx.Graphics/Gal/OpenGL/OGLShader.cs
@@ -118,20 +118,20 @@ namespace Ryujinx.Graphics.Gal.OpenGL
 
             if (IsDualVp)
             {
-                ShaderDumper.Dump(Memory, Position  + 0x50, Type, "a");
-                ShaderDumper.Dump(Memory, PositionB + 0x50, Type, "b");
+                ShaderDumper.Dump(Memory, Position,  Type, "a");
+                ShaderDumper.Dump(Memory, PositionB, Type, "b");
 
                 Program = Decompiler.Decompile(
                     Memory,
-                    Position  + 0x50,
-                    PositionB + 0x50,
+                    Position,
+                    PositionB,
                     Type);
             }
             else
             {
-                ShaderDumper.Dump(Memory, Position + 0x50, Type);
+                ShaderDumper.Dump(Memory, Position, Type);
 
-                Program = Decompiler.Decompile(Memory, Position + 0x50, Type);
+                Program = Decompiler.Decompile(Memory, Position, Type);
             }
 
             return new ShaderStage(
@@ -198,6 +198,16 @@ namespace Ryujinx.Graphics.Gal.OpenGL
 
         private void Bind(ShaderStage Stage)
         {
+            if (Stage.Type == GalShaderType.Geometry)
+            {
+                //Enhanced layouts are required for Geometry shaders
+                //skip this stage if current driver has no ARB_enhanced_layouts
+                if (!OGLExtension.HasEnhancedLayouts())
+                {
+                    return;
+                }
+            }
+
             switch (Stage.Type)
             {
                 case GalShaderType.Vertex:         Current.Vertex         = Stage; break;