Interface EffectRenderPass

Which §70 effect to apply. COPY_EFFECT is the blit.

Required, and the only value — this is the discriminant.

Optional destination-pixel rectangle (R-6 follow-up). Omitted or undefined covers the whole destination — today's default, so a graph that never names a rectangle stays transcript-identical. See EffectDestinationRect.

The surface to sample: a RenderTarget's colorTexture.

Typed as RenderTargetTexture rather than as a RenderTarget because it is a texture the pass reads, and because that is the type R-4 made assignable to every material slot — so the same expression feeds an effect pass and a textured quad, and the day a target grows several colour attachments the source names which one.

Where to draw, or absent/null for the backend's default drawing buffer. The last pass of a chain usually has none — that is the pass that puts the post-processed frame on screen.