Layers and the stack

A ZoneQ project is built from layers. Each enabled layer produces an image, and Stage composites those layer results into the final picture.

Inside a layer, cards form a stack. A shader or operator card can read the result from the cards below it, transform that image, and pass a new result upward. This incoming same-frame image is Previous Pass.

Two levels of compositing

1. Inside a layer: cards process the current layer result in stack order.
2. Across layers: layer opacity and blend mode combine each completed layer into Stage.

Changing layer opacity affects Stage compositing; it does not necessarily stop the layer’s graph. An opacity-zero layer can still generate a field or Shared Texture for another layer.

Previous Pass is not feedback

Previous Pass is the image entering the current card during the current frame. It is useful for ordinary effects such as blur, color adjustment, or compositing.

Previous Frame is retained history from the card’s output at an earlier transport step. It is what makes feedback possible. See Feedback for the distinction and the Clear behavior.

Reusing a layer

Library add actions import whole layers because a layer is the stable unit that carries its stack, graph, bindings, controls, and dependencies together. Read Add reusable layers before extracting part of an example.