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2D lights and shadows

· 2 min read
Dragos
Balaur

A 2D scene draws unlit until something lights it. Add one light2d and everything already drawn is multiplied by a light map — sprites, polygons, tile maps — with nothing else having to know.

What landed​

  • light2d. Point or directional, with color, radius, intensity and shadows. A point light fades quadratically to exactly nothing at radius, so its edge has no seam. The camera's ambient is what the unlit parts fall to: black is a cave, a dim blue is dusk.

  • occluder2d. Left empty, the outline follows the node's collider2d, or its circle, capsule, rect or sprite — the thing a player sees casts the shadow, authored once. A directional light's shadows are parallel because its rays are.

    Three occluders under one directional light, each casting a parallel strip

  • Bloom. post = ["bloom"] on the camera; an intensity past 1 is what it picks up. ssao, ssr and dof are the 3D three.

  • In the editor. A Lights chip draws every light's reach and every occluder's resolved outline, and the Polygon tool traces an occluder in Points mode.

    The editor with an occluder selected: the Points chip, an Occluder section, light gizmos over the lit scene

[nodes.light2d]
kind = "point"
color = "#ffd28a"
radius = 8.0
intensity = 1.6
shadows = true

Lights never touch the simulation: a lit game and a headless one tick identically. A scene with no light2d draws exactly as it did before, with no extra pass; a frame draws at most 64 lights. Rendering has the rest.