God Rays [bugged]

Notes:	-

        public override void Draw(GameTime gameTime, SpriteBatch spriteBatch)
        {
            base.Draw(gameTime, spriteBatch);

	    //Set the rendertarget to draw the Blinn-Phong shaded scene to
            GraphicsDevice.SetRenderTarget(renderTarget);
            GraphicsDevice.Clear(ClearOptions.Target | ClearOptions.DepthBuffer, Color.Black, 1.0f, 0);

            Material material = new Material();
            material.DiffuseColor = Color.Red;
            material.AmbientColor = Color.Red;
            material.AmbientIntensity = 0.2f;
            material.SpecularColor = Color.White;
            material.SpecularIntensity = 2.0f;
            material.SpecularPower = 25.0f;

	    //Draw all the models
            foreach (ModelData m in models)
            {
                ModelMesh mesh = m.Model.Meshes[0];
                Effect e = mesh.Effects[0];

                e.CurrentTechnique = e.Techniques[m.Technique];
                material.SetEffectParameters(e);
                this.camera.SetEffectParameters(e);
                e.Parameters["World"].SetValue(world * m.Transform);
                e.Parameters["WorldInverseTransposed"].SetValue(Matrix.Transpose(Matrix.Invert(world * m.Transform)));
                e.Parameters["CameraEye"].SetValue(new Vector4(this.camera.Eye, 0));
                // TODO: LightSource Color + Intensity
                e.Parameters["LightSources"].SetValue(lightPositions);

                mesh.Draw();
            }

	    //Restore the rendertarget to the backbuffer and clear it.
            GraphicsDevice.SetRenderTarget(null);
            GraphicsDevice.Clear(Color.Black);

	    //Pass the standard variable to the spriteBatch vertex shader.
	    //The vertex shader isn't used (for as far as I can tell at least) but because the standard
	    //vertex shader for spriteBatch is compiled in 2_0 and the God Ray shader in 3_0 I had to implement it
	    //manually in order to compile it in 3_0.
            Matrix projection = Matrix.CreateOrthographicOffCenter(0,
            GraphicsDevice.Viewport.Width, GraphicsDevice.Viewport.Height, 0, 0, 1);
            Matrix halfPixelOffset = Matrix.CreateTranslation(-0.5f, -0.5f, 0);
            postProcessing.Parameters["MatrixTransform"].SetValue(halfPixelOffset * projection);

	    //Setup all the required data for the shader
            postProcessing.CurrentTechnique = postProcessing.Techniques["Technique1"];
            Vector3 lightPosition = Vector3.Transform(lightPositions[0], world * camera.ViewMatrix * camera.ProjectionMatrix);
            postProcessing.Parameters["lightPosition"].SetValue(new Vector2(lightPosition.X, lightPosition.Y));
            postProcessing.Parameters["exposure"].SetValue(0.5f);
            postProcessing.Parameters["decay"].SetValue(0.5f);
            postProcessing.Parameters["weight"].SetValue(0.5f);
            postProcessing.Parameters["density"].SetValue(0.5f);

	    //Draw the renderTarget to the screen at the size of the viewport so it fits the screen
            spriteBatch.Begin(SpriteSortMode.Deferred, BlendState.Additive, SamplerState.PointWrap, DepthStencilState.Default, RasterizerState.CullNone, postProcessing);
            spriteBatch.Draw(renderTarget, new Rectangle(spriteBatch.GraphicsDevice.Viewport.X, spriteBatch.GraphicsDevice.Viewport.Y, spriteBatch.GraphicsDevice.Viewport.Width, spriteBatch.GraphicsDevice.Viewport.Height), Color.White);
            spriteBatch.End();

	    //Restore some of the changes spriteBatch.Begin() made to the graphics device so the 3D render won't break
            GraphicsDevice.BlendState = BlendState.Opaque;
            GraphicsDevice.DepthStencilState = DepthStencilState.Default;
            GraphicsDevice.SamplerStates[0] = SamplerState.LinearWrap;
        }