UPBGE: Remove 2d filter vertex transformation.

Removing the vertex tranformation avoid doing extra call
to setup identity projection and modelview matrices.

doc/python_api/rst/bge_types/bge.types.KX_2DFilter.rst

@@ -9,6 +9,17 @@ base class --- :class:`BL_Shader`
 
    2D filter shader object. Can be alterated with :class:`BL_Shader`'s functions.
 
+   .. warning::
+
+      The vertex shader must not apply modelview and projection transformation. It should be similar to:
+
+      .. code-block:: glsl
+
+         void main()
+         {
+             gl_Position = gl_Vertex;
+         }
+
    .. method:: setTexture(index, bindCode, samplerName)
 
       Set specified texture bind code :data:`bindCode` in specified slot :data:`index`. Any call to :data:`setTexture`

source/gameengine/Rasterizer/RAS_2DFilter.cpp

@@ -337,17 +337,7 @@ void RAS_2DFilter::DrawOverlayPlane(RAS_IRasterizer *rasty, RAS_ICanvas *canvas)
 
 	rasty->SetLines(false);
 
-	rasty->PushMatrix();
-	rasty->LoadIdentity();
-	rasty->SetMatrixMode(RAS_IRasterizer::RAS_PROJECTION);
-	rasty->PushMatrix();
-	rasty->LoadIdentity();
-
 	rasty->DrawOverlayPlane();
 
-	rasty->PopMatrix();
-	rasty->SetMatrixMode(RAS_IRasterizer::RAS_MODELVIEW);
-	rasty->PopMatrix();
-
 	rasty->Enable(RAS_IRasterizer::RAS_DEPTH_TEST);
 }

source/gameengine/Rasterizer/RAS_OpenGLFilters/RAS_VertexShader2DFilter.h

@@ -31,7 +31,7 @@ static const char *VertexShader = STRINGIFY(
 
 void main(void)
 {
-	gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;
+	gl_Position = gl_Vertex;
 	gl_TexCoord[0] = gl_MultiTexCoord0;
 }
 );