postProcess

Declaration

var postProcess: ((ARView.PostProcessContext) -> Void)?

Mentioned in

• Implementing postprocess effects using Metal compute functions
• Applying core image filters as a postprocess effect
• Using Metal performance shaders to create custom postprocess effects

Discussion

Assign a function or closure to this property to implement postprocessing effects for a RealityKit scene. If this value is non-nil, RealityKit calls the assigned function or closure once every frame before it displays the scene. If you register a postprocess render callback, the callback function needs to encode the modified frame buffer to the context’s targetColorTexture, or nothing renders.

A postprocess callback looks like this:

func myPostProcessCallback(context:ARView.PostProcessContext) {
   // Handle postprocessing here.
}

To register the function so RealityKit begins calling it, assign it to the postProcess property of the view’s renderCallbacks property.

arView.renderCallbacks.postProcess = myPostProcessCallback

To stop RealityKit from calling your function, assign nil:

arView.renderCallbacks.postProcess = nil

If your app turns postprocessing on and off frequently, another option for disabling postprocess effects is to keep your callback registered, but use an MTLBlitCommandEncoder to encode the unmodified frame directly to the output texture whenever postprocess effects aren’t active.

func myPostProcessCallback(context:ARView.PostProcessContext) {
    if (usePostProcessEffects) {
        handlePostProcessing(context: ARView.PostProcessContext)
        return
    }

    // If postprocess effects are disabled, copy sourceColorTexture
    // directly to targetColorTexture.
    let blitEncoder = context.commandBuffer.makeBlitCommandEncoder()
    blitEncoder?.copy(from: context.sourceColorTexture, to: context.targetColorTexture)
    blitEncoder?.endEncoding()
}

See Also

Register callback closures

• prepareWithDevice