Accueil / npm / three@0.186.1 / examples / jsm / tsl / utils / Raymarching.js
Raymarching.js
import { varying, vec4, modelWorldMatrixInverse, cameraPosition, positionGeometry, float, Fn, Loop, max, min, vec2, vec3 } from 'three/tsl';
/**
* @module Raymarching
* @three_import import { RaymarchingBox } from 'three/addons/tsl/utils/Raymarching.js';
*/
const hitBox = /*@__PURE__*/ Fn( ( { orig, dir } ) => {
const box_min = vec3( - 0.5 );
const box_max = vec3( 0.5 );
const inv_dir = dir.reciprocal();
const tmin_tmp = box_min.sub( orig ).mul( inv_dir );
const tmax_tmp = box_max.sub( orig ).mul( inv_dir );
const tmin = min( tmin_tmp, tmax_tmp );
const tmax = max( tmin_tmp, tmax_tmp );
const t0 = max( tmin.x, max( tmin.y, tmin.z ) );
const t1 = min( tmax.x, min( tmax.y, tmax.z ) );
return vec2( t0, t1 );
} );
/**
* TSL function for performing raymarching in a box-area using the specified number of steps
* and a callback function.
*
* ```js
* RaymarchingBox( count, ( { positionRay } ) => {
*
* } );
* ```
*
* @tsl
* @function
* @param {number|Node} steps - The number of steps for raymarching.
* @param {Function|FunctionNode} callback - The callback function to execute at each step.
*/
export const RaymarchingBox = ( steps, callback ) => {
const vOrigin = varying( vec3( modelWorldMatrixInverse.mul( vec4( cameraPosition, 1.0 ) ) ) );
const vDirection = varying( positionGeometry.sub( vOrigin ) );
const rayDir = vDirection.normalize();
const bounds = vec2( hitBox( { orig: vOrigin, dir: rayDir } ) ).toVar();
bounds.x.greaterThan( bounds.y ).discard();
bounds.assign( vec2( max( bounds.x, 0.0 ), bounds.y ) );
const inc = vec3( rayDir.abs().reciprocal() ).toVar();
const stepSize = float( min( inc.x, min( inc.y, inc.z ) ) ).toVar();
stepSize.divAssign( float( steps ) );
const positionRay = vec3( vOrigin.add( bounds.x.mul( rayDir ) ) ).toVar();
Loop( { type: 'float', start: bounds.x, end: bounds.y, update: stepSize }, () => {
callback( { positionRay, stepSize } );
positionRay.addAssign( rayDir.mul( stepSize ) );
} );
};