Screen-Space Ambient Occlusion

Darken tight creases and nearby surface contacts using the current scene depth buffer. createSSAOShaderPassPipeline evaluates screen-space ambient visibility, smooths it with a depth-aware bilateral blur, and composites the result into scene color.

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At a Glance

Property	Value
Export	createSSAOShaderPassPipeline
Backend	WebGPU
Render passes	Four: evaluate, horizontal blur, vertical blur, and composite
Required binding	depthTexture
Optional binding	normalTexture when normalSource: 'normal-texture'
History	None

Usage

import {ShaderPassRenderer} from '@luma.gl/engine';
import {createSSAOShaderPassPipeline} from '@luma.gl/effects';

const renderer = new ShaderPassRenderer(device, {
  shaderPasses: [
    createSSAOShaderPassPipeline({
      normalSource: 'normal-texture',
      resolutionScale: 0.5
    })
  ]
});

renderer.renderToScreen({
  sourceTexture: gBuffer.colorTexture,
  bindings: gBuffer.getShaderPassBindings(),
  uniforms: {
    ssaoEvaluate: {
      nearPlane: 0.1,
      farPlane: 200,
      radius: 7,
      bias: 0.03,
      intensity: 1.35
    }
  }
});

Parameters

Parameter	Default	Description
normalSource	'reconstruct-from-depth'	Reconstruct normals from depth or consume an explicit normalTexture.
resolutionScale	1	Relative resolution of all three occlusion intermediates.
nearPlane	0.1	Camera near plane used to linearize hardware depth.
farPlane	200	Camera far plane used to linearize hardware depth.
radius	7	Screen-space sampling radius around the current pixel.
bias	0.03	Depth tolerance that reduces self-occlusion.
intensity	1.35	Strength of the accumulated occlusion estimate.

Performance and Composition

The evaluation stage visits 12 nearby depth samples; two subsequent Depth-Aware Blur passes preserve foreground/background boundaries. resolutionScale: 0.5 reduces intermediate pixel count to approximately one quarter. SSAO does not maintain temporal history and composites onto the complete source color.

Choose GTAO when horizon integration, temporal stabilization, or ambient-only composition is required.

Related Effects

• GTAO adds horizon-based visibility, temporal history, and ambient-only composition.
• Depth-Aware Blur explains the bilateral denoising stages.
• Outlines can consume the same depth and normal attachments.