Backdrop (component)

The parallax driver of Ashcross. The camera is orthographic, so a quad parked thirty units behind the street tracks the camera exactly and reads as glued to it: every bit of depth in this game is scripted, and this is where.

Modes

mode = "band" — the entity is a full-frame quad locked to the camera, and the district it shows lives inside its material as a procedural pattern. The component writes scroll_x / scroll_y on that material every frame at spanX / worldWidth * parallax * cameraX (and the same in y). Nothing recycles because the pattern never ends.

mode = "anchor" — the entity stands at a fixed district point (anchorX, anchorY) and is drawn at cam + (anchor - cam) * parallax. Lanterns, braziers, shafts and hanging props ride a band this way, so a lamp on the mid band slides past at exactly the rate the wall behind it does.

parallax is the whole vocabulary: 0 is infinitely far (locked to the eye), 1 moves exactly with the street, above 1 is the foreground band that overtakes it.

Transient lights

Set lifetime above zero and the entity swells to peakW x peakH over attack seconds, shrinks away over the rest, drifts up at rise, and despawns itself. The fade is carried by the entity's SCALE, not by its material, because a material is shared by every puff wearing it and they have to be able to die at different moments.

Notes

• The material is taken from the entity's own Model, never resolved by name: a component may not resolve an asset from a computed string, and two entities that share a band should share its scroll. Call :rebind() after swapping the Model's material.
• Culling (cullMargin) collapses the quad to zero scale rather than deactivating the entity. An inactive entity stops running its components, and a component that has stopped running can never decide to come back.
• editorUpdate runs the same driver as update, so the bands line up in edit mode as well as in play — every screenshot of this game is taken from a scene camera either way.

Fields

mode parallax bandZ · band: worldWidth worldHeight spanX spanY phaseX phaseY · anchor: anchorX anchorY bob bobSpeed · transient: lifetime attack peakW peakH rise · both: cullMargin.

Methods

:rebind() — re-read the material from the Model. :setAnchor(x, y) — move a prop to a new district point immediately.