public void BeginDraw(Image image, RenderMode mode)
{
//begin draw and we need set the render target before we draw anything
Mode = mode;
//reset device and set render target
mDevice.Reset();
mDevice.SetRenderTarget(image);
//set blend and raster state and input layout
mDevice.SetBlendState(mBlendState);
mDevice.SetInputLayout(mInputLayout);
mDevice.SetRasterizerState(mRasterizerState);
//set vertex shader, pixel shader
switch (Mode)
{
case RenderMode.Fill:
mDevice.SetPixelShader(mFillBezierPixelShader);
mDevice.SetVertexShader(mFillBezierVertexShader);
break;
case RenderMode.Draw:
mDevice.SetPixelShader(mDrawBezierPixelShader);
mDevice.SetVertexShader(mDrawBezierVertexShader);
break;
default: throw new Exception("Mode Not Supported.");
}
//set primitive type
mDevice.SetPrimitiveType(GpuPrimitiveType.TriangleList);
//set view port
mDevice.SetViewPort(new Rectangle <float>(0, 0, image.Size.Width, image.Size.Height));
//set the project matrix, need set null when we end draw
mProjection = Matrix4x4.CreateOrthographicOffCenter(
0, image.Size.Width,
0, image.Size.Height, 0, 1);
//set the canvas size
mCanvasSize = image.Size;
}