void UpdateRenderTarget(FrameworkElement fe)
{
// We need to consider a special case for rendering Opacity masks: in this case the alpha blending is enabled on device already. If we render now without changes,
// the Visual will not be visible in target texture. In this case we switch back to normal rendering mode and restore blending mode after the Visual is rendered.
var wasBlendingEnabled = GraphicsDevice.IsAlphaChannelBlendingEnabled;
if (wasBlendingEnabled)
{
// Opposite steps as done inside FrameworkElement.RenderOpacityBrush
GraphicsDevice.DisableAlphaChannelBlending();
GraphicsDevice.EnableAlphaTest();
}
RectangleF bounds = new RectangleF(0, 0, _vertsBounds.Size.Width, _vertsBounds.Size.Height);
fe.RenderToTexture(_visualTexture, new RenderContext(Matrix.Identity, Opacity, bounds, 1.0f));
if (wasBlendingEnabled)
{
// Redo steps as done inside FrameworkElement.RenderOpacityBrush
GraphicsDevice.EnableAlphaChannelBlending();
GraphicsDevice.DisableAlphaTest();
}
}
