import { Fn } from '../tsl/TSLBase.js';
import { screenUV } from '../display/ScreenNode.js';
import { viewportDepthTexture } from '../display/ViewportDepthTextureNode.js';
import { linearDepth } from '../display/ViewportDepthNode.js';
/** @module ViewportUtils **/
/**
* A special version of a screen uv function that involves a depth comparison
* when computing the final uvs. The function mitigates visual errors when
* using viewport texture nodes for refraction purposes. Without this function
* objects in front of a refractive surface might appear on the refractive surface
* which is incorrect.
*
* @method
* @param {Node<vec2>?} uv - Optional uv coordinates. By default `screenUV` is used.
* @return {Node<vec2>} The update uv coordinates.
*/
export const viewportSafeUV = /*@__PURE__*/ Fn( ( [ uv = null ] ) => {
const depth = linearDepth();
const depthDiff = linearDepth( viewportDepthTexture( uv ) ).sub( depth );
const finalUV = depthDiff.lessThan( 0 ).select( screenUV, uv );
return finalUV;
} );