This shader uses triangles from a `WindowVertexBuffer` to render to the full window size.
```cs
public class ScreenShader : SmartShader
{
protected override string FragmentOuter =>
"out vec4 oColor;";
protected override string FragmentInner =>
"oColor = vec4(vUV.x, vUV.y, 0.0, 1.0);";
// These three are sealed
protected override sealed string Varyings =>
"in vec2 vUV;";
protected override sealed string VertexOuter =>
VertexAttribStrings.Get<WindowVertexBuffer>();
protected override sealed string VertexInner => @"
vUV = aUV;
gl_Position = vec4(aPosition, 0.0, 1.0);
";
}
```