LightSystem

LittleJS Light System Plugin

• Adds 2D dynamic lighting to the scene
• Lights are first-class EngineObjects (the Light class)
• Each Light draws a soft falloff blob of its color into a shared lightmap
• Lights accumulate ADDITIVELY in the lightmap (red + blue = magenta)
• The lightmap is then MULTIPLIED with the scene during composite, so unlit areas go to the ambient color and lit areas show the scene tinted by the accumulated light color
• Draw the world at full brightness — the lightmap does the darkening
• The pass runs after gameRenderPost, so a HUD drawn there with WebGL is darkened too; draw the HUD with useWebGL=false (the main canvas) or from a plugin created after this one
• Any EngineObject may override renderLight() to additively contribute to the lightmap (e.g. lava that lights the floor around it, weapon flashes, glowing crystals)
• Set obj.emissive to 1 to show an object at full brightness in its own colors, lit or not, or between 0 and 1 for partly: it draws its shape into the lightmap through renderEmissive(), which calls render() by default; exact for solid pixels, a partly transparent one is self lit by its alpha too, so it shows darker
• Set lightSystem.shadows for objects to block light: each frame every object draws black into a shadow map through renderShadow(), which calls render() by default; obj.castShadow = false keeps it out (a floor TileLayer, a background), a draw's alpha sets how much light it blocks, and setShadowTransparent lets its color tint the light
• Set light.glow for a soft hazy glow over a light, like a lamp at night; it is added over the lit scene after the lightmap, so it shows in the dark and sits in front of everything there
• A DirectionalLight is a sun: one per scene, it lights everything from one direction, foreground casters throw long shadows and objects with castBackgroundShadow are lit only at their edges facing it
• Must be constructed BEFORE PostProcessPlugin so post-process sees lit pixels