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@typegpu/radiance-cascades

A helper library for computing 2D radiance cascades with TypeGPU.

import { createRadianceCascades } from '@typegpu/radiance-cascades';

const runner = createRadianceCascades({
  root,
  size: { width, height },
  sdfResolution: { width: sdfWidth, height: sdfHeight },
  sdf: (uv) => {
    'use gpu';
    return sampleSdf(uv);
  },
  color: (uv) => {
    'use gpu';
    return sampleColor(uv);
  },
});

runner.run();

run() batches all cascade passes and the final radiance-field build into one command buffer. Pass your own encoder to batch it with surrounding work:

const encoder = root.device.createCommandEncoder();
runner.run(encoder);
root.device.queue.submit([encoder.finish()]);

Scene contract

The default marcher expects sdf(uv) to return a signed distance in short-axis-normalized UV units:

  • positive outside geometry
  • negative inside geometry
  • zero on the blocking or emitting surface

color(uv) should return linear radiance/emission. If the source texture is sRGB-like, linearize it before returning from color.

Quality and memory options

const runner = createRadianceCascades({
  root,
  size: { width, height },
  sdfResolution,
  sdf,
  color,

  // Direction density in the base cascade. 2 matches the classic default.
  baseStoredRayDim: 2,

  // hardware keeps the single filtered upper sample. bilinear-fix forks toward
  // the four upper probes before merging.
  mergeMode: 'bilinear-fix',

  // Two active 2D ping-pong cascade textures are used by default. Enable this
  // only when you need to inspect every cascade layer after a run.
  keepCascadeLayers: false,

  erodeBiasPx: 1,
  epsPx: 0.25,
  minStepPx: 0.125,
  maxRaySteps: 64,
  stepSafety: 1,
  intervalOverlapPx: 0,
});

Available merge modes are:

  • 'hardware'
  • 'bilinear-fix'

intervalOverlapPx may also be set to 'upperProbeSpacing' to use each layer's upper-probe spacing as the overlap amount.

If you provide an output texture view, runner.output is that view. When the runner owns or can prove it has a sampled texture, runner.outputTexture is also available for creating sampled views.