            encoder.label = "shadow buffer"
            encoder.setRenderPipelineState(renderPipelineState)
            encoder.setDepthStencilState(shadowDepthStencilState)
            encoder.setCullMode(.front)
            encoder.setDepthBias(0.01, slopeScale: 1.0, clamp: 0.01)

            renderer.renderCommandEncoderStack.append(encoder)
        }
    }

    func end(_ renderer: Renderer) {
        var renderer = renderer
