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