pointGlow

pointGlow produces linear RGB radiance for a bounded point sprite with a white core and a colored halo. The module supports GLSL and WGSL and does not depend on Deck or a postprocess pass.

import {pointGlow} from '@luma.gl/shadertools';

const model = new Model(device, {modules: [pointGlow], /* application shaders and geometry */});
model.shaderInputs.setProps({pointGlow: {coreRadius: 0.12, haloIntensity: 0.6, falloff: 5}});

Call pointGlow_getColor(coordinates, tint) from the fragment shader with coordinates spanning [-1, 1] across the sprite and a linear RGB tint. The returned vec3 contains radiance, not a premultiplied RGBA surface color. Multiply it by application opacity before additive blending. The caller owns geometry, projection, depth testing, picking, and tone mapping.

Property	Default	Meaning
coreRadius	0.12	White core radius relative to the outer sprite radius, clamped to 0–1
coreIntensity	1	Nonnegative white-core radiance; values above 1 are allowed
haloIntensity	0.6	Nonnegative colored-halo radiance; values above 1 are allowed
falloff	5	Exponential radial falloff, clamped to at least 0.01; larger values tighten the halo

Partial updates retain previous values. A zero core radius removes the core, and zero intensity removes its component. The halo approaches zero at radius 1 and contributes nothing outside it. Derivatives soften the core and sprite boundary; call the function outside divergent fragment branches. Very small sprites can lose their core detail; no temporal or energy-preserving subpixel accumulation is performed.

Use additive color blending (one, one) after scaling radiance by opacity, and disable depth writes for the halo. Destination alpha can be preserved independently. This is suitable for an opaque scene or an HDR light buffer; adding RGB to a transparent premultiplied canvas without also defining its alpha composition is not supported by this recipe. Standard normalized color targets clamp overlapping brightness. HDR targets preserve it for a later tone-mapping pass.

See Riverfront lights for a Deck example with feature picking.