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Orthographic UI Surface ​

orthographic-ui-surface is a small retained presentation surface for standalone Space UI examples and simple apps. It owns a LayoutRoot, a BuildContext, viewport-scaled world units, and a HUD-like renderer presentation target.

Use it when an example needs normal Space widgets, text, rectangles, and layout without importing the full product HUD shell.

Do not use it for product HUD panels, command hints, focus/movable/resizable registries, activity slots, world cameras, or Canvas rendering.

API ​

fennel
(local OrthographicUiSurface (require :orthographic-ui-surface))
(local surface (OrthographicUiSurface.create {:viewport viewport}))
(local entity (surface:build builder))
(surface:update-viewport viewport)
(surface:update)
(surface:presentation-target)
(surface:drop)

builder receives the surface BuildContext and should return a retained widget/entity with :layout, optional :update, and optional :drop.

Coordinates ​

The surface uses a lower-left origin and non-inverted Y projection:

fennel
(glm.ortho 0 world-width 0 world-height -100.0 100.0)

Higher world Y renders higher on screen. Text remains upright.

Example ​

examples/snake uses this surface for its board, title, status, and controls while remaining a standalone example app.