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JavaScript

import Node, { addNodeClass } from '../core/Node.js';
import { nodeImmutable, nodeProxy } from '../shadernode/ShaderNode.js';
import { cameraNear, cameraFar } from '../accessors/CameraNode.js';
import { positionView } from '../accessors/PositionNode.js';
import { viewportDepthTexture } from './ViewportDepthTextureNode.js';
class ViewportDepthNode extends Node {
constructor( scope, textureNode = null ) {
super( 'float' );
this.scope = scope;
this.textureNode = textureNode;
this.isViewportDepthNode = true;
}
setup( /*builder*/ ) {
const { scope } = this;
let node = null;
if ( scope === ViewportDepthNode.DEPTH ) {
node = viewZToOrthographicDepth( positionView.z, cameraNear, cameraFar );
} else if ( scope === ViewportDepthNode.DEPTH_TEXTURE ) {
const texture = this.textureNode || viewportDepthTexture();
const viewZ = perspectiveDepthToViewZ( texture, cameraNear, cameraFar );
node = viewZToOrthographicDepth( viewZ, cameraNear, cameraFar );
}
return node;
}
}
// NOTE: viewZ, the z-coordinate in camera space, is negative for points in front of the camera
// -near maps to 0; -far maps to 1
export const viewZToOrthographicDepth = ( viewZ, near, far ) => viewZ.add( near ).div( near.sub( far ) );
// maps orthographic depth in [ 0, 1 ] to viewZ
export const orthographicDepthToViewZ = ( depth, near, far ) => near.sub( far ).mul( depth ).sub( near );
// NOTE: https://twitter.com/gonnavis/status/1377183786949959682
// -near maps to 0; -far maps to 1
export const viewZToPerspectiveDepth = ( viewZ, near, far ) => near.add( viewZ ).mul( far ).div( near.sub( far ).mul( viewZ ) );
// maps perspective depth in [ 0, 1 ] to viewZ
export const perspectiveDepthToViewZ = ( depth, near, far ) => near.mul( far ).div( far.sub( near ).mul( depth ).sub( far ) );
ViewportDepthNode.DEPTH = 'depth';
ViewportDepthNode.DEPTH_TEXTURE = 'depthTexture';
export default ViewportDepthNode;
export const depth = nodeImmutable( ViewportDepthNode, ViewportDepthNode.DEPTH );
export const depthTexture = nodeProxy( ViewportDepthNode, ViewportDepthNode.DEPTH_TEXTURE );
addNodeClass( 'ViewportDepthNode', ViewportDepthNode );