Implements support for FRONT_AND_BACK culling.

TRAC #11331

Author:    Shannon Woods
Signed-off-by: Andrew Lewycky
Signed-off-by: Daniel Koch

git-svn-id: https://angleproject.googlecode.com/svn/trunk@57 736b8ea6-26fd-11df-bfd4-992fa37f6226

src/include/Context.h

@@ -283,6 +283,8 @@ class Context : public State
 
     Texture *getIncompleteTexture(SamplerType type);
 
+    bool cullSkipsDraw(GLenum primitiveType);
+
     const egl::Config *const mConfig;
 
     Texture2D *mTexture2DZero;

src/libGLESv2/Context.cpp

@@ -1458,9 +1458,12 @@ void Context::drawArrays(GLenum mode, GLint first, GLsizei count)
     applyShaders();
     applyTextures();
 
-    device->BeginScene();
-    device->DrawPrimitive(primitiveType, first, primitiveCount);
-    device->EndScene();
+    if (!cullSkipsDraw(mode))
+    {
+        device->BeginScene();
+        device->DrawPrimitive(primitiveType, first, primitiveCount);
+        device->EndScene();
+    }
 }
 
 void Context::drawElements(GLenum mode, GLsizei count, GLenum type, const void* indices)
@@ -1498,9 +1501,12 @@ void Context::drawElements(GLenum mode, GLsizei count, GLenum type, const void*
     applyShaders();
     applyTextures();
 
-    device->BeginScene();
-    device->DrawIndexedPrimitive(primitiveType, 0, 0, count, startIndex, primitiveCount);
-    device->EndScene();
+    if (!cullSkipsDraw(mode))
+    {
+        device->BeginScene();
+        device->DrawIndexedPrimitive(primitiveType, 0, 0, count, startIndex, primitiveCount);
+        device->EndScene();
+    }
 }
 
 void Context::finish()
@@ -1771,6 +1777,20 @@ Texture *Context::getIncompleteTexture(SamplerType type)
 
     return t;
 }
+
+bool Context::cullSkipsDraw(GLenum primitiveType)
+{
+    if (cullFace && cullMode == GL_FRONT_AND_BACK &&
+        (primitiveType == GL_TRIANGLES || primitiveType == GL_TRIANGLE_FAN || primitiveType == GL_TRIANGLE_STRIP))
+    {
+        return true;
+    }
+    else
+    {
+        return false;
+    }
+}
+
 }
 
 extern "C"

src/libGLESv2/utilities.cpp

@@ -131,7 +131,7 @@ D3DCULL ConvertCullMode(GLenum cullFace, GLenum frontFace)
         cull = (frontFace == GL_CCW ? D3DCULL_CCW : D3DCULL_CW);
         break;
       case GL_FRONT_AND_BACK:
-        UNIMPLEMENTED();   // FIXME
+        cull = D3DCULL_NONE; // culling will be handled during draw
         break;
       default: UNREACHABLE();
     }