520 lines
13 KiB
JavaScript
520 lines
13 KiB
JavaScript
import {
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Line3,
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Mesh,
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Plane,
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Vector3
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} from 'three';
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import { ConvexGeometry } from '../geometries/ConvexGeometry.js';
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/**
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* @fileoverview This class can be used to subdivide a convex Geometry object into pieces.
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*
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* Usage:
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*
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* Use the function prepareBreakableObject to prepare a Mesh object to be broken.
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*
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* Then, call the various functions to subdivide the object (subdivideByImpact, cutByPlane)
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*
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* Sub-objects that are product of subdivision don't need prepareBreakableObject to be called on them.
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*
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* Requisites for the object:
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*
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* - Mesh object must have a buffer geometry and a material
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*
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* - Vertex normals must be planar (not smoothed)
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*
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* - The geometry must be convex (this is not checked in the library). You can create convex
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* geometries with ConvexGeometry. The BoxGeometry, SphereGeometry and other convex primitives
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* can also be used.
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*
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* Note: This lib adds member variables to object's userData member (see prepareBreakableObject function)
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* Use with caution and read the code when using with other libs.
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*
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* @param {double} minSizeForBreak Min size a debris can have to break.
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* @param {double} smallDelta Max distance to consider that a point belongs to a plane.
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*
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*/
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const _v1 = new Vector3();
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class ConvexObjectBreaker {
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constructor( minSizeForBreak = 1.4, smallDelta = 0.0001 ) {
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this.minSizeForBreak = minSizeForBreak;
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this.smallDelta = smallDelta;
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this.tempLine1 = new Line3();
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this.tempPlane1 = new Plane();
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this.tempPlane2 = new Plane();
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this.tempPlane_Cut = new Plane();
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this.tempCM1 = new Vector3();
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this.tempCM2 = new Vector3();
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this.tempVector3 = new Vector3();
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this.tempVector3_2 = new Vector3();
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this.tempVector3_3 = new Vector3();
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this.tempVector3_P0 = new Vector3();
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this.tempVector3_P1 = new Vector3();
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this.tempVector3_P2 = new Vector3();
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this.tempVector3_N0 = new Vector3();
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this.tempVector3_N1 = new Vector3();
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this.tempVector3_AB = new Vector3();
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this.tempVector3_CB = new Vector3();
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this.tempResultObjects = { object1: null, object2: null };
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this.segments = [];
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const n = 30 * 30;
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for ( let i = 0; i < n; i ++ ) this.segments[ i ] = false;
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}
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prepareBreakableObject( object, mass, velocity, angularVelocity, breakable ) {
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// object is a Object3d (normally a Mesh), must have a buffer geometry, and it must be convex.
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// Its material property is propagated to its children (sub-pieces)
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// mass must be > 0
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const userData = object.userData;
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userData.mass = mass;
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userData.velocity = velocity.clone();
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userData.angularVelocity = angularVelocity.clone();
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userData.breakable = breakable;
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}
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/*
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* @param {int} maxRadialIterations Iterations for radial cuts.
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* @param {int} maxRandomIterations Max random iterations for not-radial cuts
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*
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* Returns the array of pieces
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*/
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subdivideByImpact( object, pointOfImpact, normal, maxRadialIterations, maxRandomIterations ) {
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const debris = [];
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const tempPlane1 = this.tempPlane1;
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const tempPlane2 = this.tempPlane2;
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this.tempVector3.addVectors( pointOfImpact, normal );
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tempPlane1.setFromCoplanarPoints( pointOfImpact, object.position, this.tempVector3 );
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const maxTotalIterations = maxRandomIterations + maxRadialIterations;
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const scope = this;
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function subdivideRadial( subObject, startAngle, endAngle, numIterations ) {
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if ( Math.random() < numIterations * 0.05 || numIterations > maxTotalIterations ) {
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debris.push( subObject );
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return;
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}
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let angle = Math.PI;
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if ( numIterations === 0 ) {
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tempPlane2.normal.copy( tempPlane1.normal );
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tempPlane2.constant = tempPlane1.constant;
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} else {
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if ( numIterations <= maxRadialIterations ) {
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angle = ( endAngle - startAngle ) * ( 0.2 + 0.6 * Math.random() ) + startAngle;
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// Rotate tempPlane2 at impact point around normal axis and the angle
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scope.tempVector3_2.copy( object.position ).sub( pointOfImpact ).applyAxisAngle( normal, angle ).add( pointOfImpact );
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tempPlane2.setFromCoplanarPoints( pointOfImpact, scope.tempVector3, scope.tempVector3_2 );
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} else {
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angle = ( ( 0.5 * ( numIterations & 1 ) ) + 0.2 * ( 2 - Math.random() ) ) * Math.PI;
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// Rotate tempPlane2 at object position around normal axis and the angle
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scope.tempVector3_2.copy( pointOfImpact ).sub( subObject.position ).applyAxisAngle( normal, angle ).add( subObject.position );
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scope.tempVector3_3.copy( normal ).add( subObject.position );
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tempPlane2.setFromCoplanarPoints( subObject.position, scope.tempVector3_3, scope.tempVector3_2 );
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}
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}
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// Perform the cut
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scope.cutByPlane( subObject, tempPlane2, scope.tempResultObjects );
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const obj1 = scope.tempResultObjects.object1;
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const obj2 = scope.tempResultObjects.object2;
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if ( obj1 ) {
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subdivideRadial( obj1, startAngle, angle, numIterations + 1 );
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}
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if ( obj2 ) {
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subdivideRadial( obj2, angle, endAngle, numIterations + 1 );
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}
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}
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subdivideRadial( object, 0, 2 * Math.PI, 0 );
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return debris;
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}
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cutByPlane( object, plane, output ) {
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// Returns breakable objects in output.object1 and output.object2 members, the resulting 2 pieces of the cut.
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// object2 can be null if the plane doesn't cut the object.
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// object1 can be null only in case of internal error
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// Returned value is number of pieces, 0 for error.
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const geometry = object.geometry;
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const coords = geometry.attributes.position.array;
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const normals = geometry.attributes.normal.array;
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const numPoints = coords.length / 3;
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let numFaces = numPoints / 3;
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let indices = geometry.getIndex();
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if ( indices ) {
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indices = indices.array;
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numFaces = indices.length / 3;
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}
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function getVertexIndex( faceIdx, vert ) {
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// vert = 0, 1 or 2.
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const idx = faceIdx * 3 + vert;
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return indices ? indices[ idx ] : idx;
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}
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const points1 = [];
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const points2 = [];
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const delta = this.smallDelta;
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// Reset segments mark
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const numPointPairs = numPoints * numPoints;
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for ( let i = 0; i < numPointPairs; i ++ ) this.segments[ i ] = false;
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const p0 = this.tempVector3_P0;
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const p1 = this.tempVector3_P1;
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const n0 = this.tempVector3_N0;
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const n1 = this.tempVector3_N1;
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// Iterate through the faces to mark edges shared by coplanar faces
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for ( let i = 0; i < numFaces - 1; i ++ ) {
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const a1 = getVertexIndex( i, 0 );
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const b1 = getVertexIndex( i, 1 );
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const c1 = getVertexIndex( i, 2 );
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// Assuming all 3 vertices have the same normal
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n0.set( normals[ a1 ], normals[ a1 ] + 1, normals[ a1 ] + 2 );
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for ( let j = i + 1; j < numFaces; j ++ ) {
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const a2 = getVertexIndex( j, 0 );
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const b2 = getVertexIndex( j, 1 );
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const c2 = getVertexIndex( j, 2 );
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// Assuming all 3 vertices have the same normal
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n1.set( normals[ a2 ], normals[ a2 ] + 1, normals[ a2 ] + 2 );
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const coplanar = 1 - n0.dot( n1 ) < delta;
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if ( coplanar ) {
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if ( a1 === a2 || a1 === b2 || a1 === c2 ) {
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if ( b1 === a2 || b1 === b2 || b1 === c2 ) {
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this.segments[ a1 * numPoints + b1 ] = true;
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this.segments[ b1 * numPoints + a1 ] = true;
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} else {
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this.segments[ c1 * numPoints + a1 ] = true;
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this.segments[ a1 * numPoints + c1 ] = true;
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}
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} else if ( b1 === a2 || b1 === b2 || b1 === c2 ) {
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this.segments[ c1 * numPoints + b1 ] = true;
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this.segments[ b1 * numPoints + c1 ] = true;
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}
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}
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}
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}
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// Transform the plane to object local space
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const localPlane = this.tempPlane_Cut;
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object.updateMatrix();
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ConvexObjectBreaker.transformPlaneToLocalSpace( plane, object.matrix, localPlane );
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// Iterate through the faces adding points to both pieces
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for ( let i = 0; i < numFaces; i ++ ) {
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const va = getVertexIndex( i, 0 );
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const vb = getVertexIndex( i, 1 );
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const vc = getVertexIndex( i, 2 );
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for ( let segment = 0; segment < 3; segment ++ ) {
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const i0 = segment === 0 ? va : ( segment === 1 ? vb : vc );
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const i1 = segment === 0 ? vb : ( segment === 1 ? vc : va );
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const segmentState = this.segments[ i0 * numPoints + i1 ];
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if ( segmentState ) continue; // The segment already has been processed in another face
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// Mark segment as processed (also inverted segment)
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this.segments[ i0 * numPoints + i1 ] = true;
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this.segments[ i1 * numPoints + i0 ] = true;
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p0.set( coords[ 3 * i0 ], coords[ 3 * i0 + 1 ], coords[ 3 * i0 + 2 ] );
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p1.set( coords[ 3 * i1 ], coords[ 3 * i1 + 1 ], coords[ 3 * i1 + 2 ] );
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// mark: 1 for negative side, 2 for positive side, 3 for coplanar point
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let mark0 = 0;
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let d = localPlane.distanceToPoint( p0 );
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if ( d > delta ) {
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mark0 = 2;
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points2.push( p0.clone() );
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} else if ( d < - delta ) {
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mark0 = 1;
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points1.push( p0.clone() );
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} else {
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mark0 = 3;
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points1.push( p0.clone() );
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points2.push( p0.clone() );
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}
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// mark: 1 for negative side, 2 for positive side, 3 for coplanar point
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let mark1 = 0;
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d = localPlane.distanceToPoint( p1 );
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if ( d > delta ) {
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mark1 = 2;
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points2.push( p1.clone() );
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} else if ( d < - delta ) {
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mark1 = 1;
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points1.push( p1.clone() );
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} else {
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mark1 = 3;
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points1.push( p1.clone() );
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points2.push( p1.clone() );
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}
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if ( ( mark0 === 1 && mark1 === 2 ) || ( mark0 === 2 && mark1 === 1 ) ) {
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// Intersection of segment with the plane
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this.tempLine1.start.copy( p0 );
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this.tempLine1.end.copy( p1 );
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let intersection = new Vector3();
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intersection = localPlane.intersectLine( this.tempLine1, intersection );
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if ( intersection === null ) {
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// Shouldn't happen
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console.error( 'Internal error: segment does not intersect plane.' );
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output.segmentedObject1 = null;
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output.segmentedObject2 = null;
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return 0;
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}
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points1.push( intersection );
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points2.push( intersection.clone() );
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}
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}
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}
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// Calculate debris mass (very fast and imprecise):
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const newMass = object.userData.mass * 0.5;
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// Calculate debris Center of Mass (again fast and imprecise)
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this.tempCM1.set( 0, 0, 0 );
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let radius1 = 0;
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const numPoints1 = points1.length;
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if ( numPoints1 > 0 ) {
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for ( let i = 0; i < numPoints1; i ++ ) this.tempCM1.add( points1[ i ] );
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this.tempCM1.divideScalar( numPoints1 );
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for ( let i = 0; i < numPoints1; i ++ ) {
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const p = points1[ i ];
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p.sub( this.tempCM1 );
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radius1 = Math.max( radius1, p.x, p.y, p.z );
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}
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this.tempCM1.add( object.position );
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}
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this.tempCM2.set( 0, 0, 0 );
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let radius2 = 0;
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const numPoints2 = points2.length;
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if ( numPoints2 > 0 ) {
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for ( let i = 0; i < numPoints2; i ++ ) this.tempCM2.add( points2[ i ] );
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this.tempCM2.divideScalar( numPoints2 );
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for ( let i = 0; i < numPoints2; i ++ ) {
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const p = points2[ i ];
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p.sub( this.tempCM2 );
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radius2 = Math.max( radius2, p.x, p.y, p.z );
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}
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this.tempCM2.add( object.position );
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}
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let object1 = null;
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let object2 = null;
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let numObjects = 0;
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if ( numPoints1 > 4 ) {
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object1 = new Mesh( new ConvexGeometry( points1 ), object.material );
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object1.position.copy( this.tempCM1 );
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object1.quaternion.copy( object.quaternion );
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this.prepareBreakableObject( object1, newMass, object.userData.velocity, object.userData.angularVelocity, 2 * radius1 > this.minSizeForBreak );
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numObjects ++;
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}
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if ( numPoints2 > 4 ) {
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object2 = new Mesh( new ConvexGeometry( points2 ), object.material );
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object2.position.copy( this.tempCM2 );
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object2.quaternion.copy( object.quaternion );
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this.prepareBreakableObject( object2, newMass, object.userData.velocity, object.userData.angularVelocity, 2 * radius2 > this.minSizeForBreak );
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numObjects ++;
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}
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output.object1 = object1;
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output.object2 = object2;
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return numObjects;
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}
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static transformFreeVector( v, m ) {
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// input:
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// vector interpreted as a free vector
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// THREE.Matrix4 orthogonal matrix (matrix without scale)
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const x = v.x, y = v.y, z = v.z;
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const e = m.elements;
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v.x = e[ 0 ] * x + e[ 4 ] * y + e[ 8 ] * z;
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v.y = e[ 1 ] * x + e[ 5 ] * y + e[ 9 ] * z;
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v.z = e[ 2 ] * x + e[ 6 ] * y + e[ 10 ] * z;
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return v;
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}
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static transformFreeVectorInverse( v, m ) {
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// input:
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// vector interpreted as a free vector
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// THREE.Matrix4 orthogonal matrix (matrix without scale)
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const x = v.x, y = v.y, z = v.z;
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const e = m.elements;
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v.x = e[ 0 ] * x + e[ 1 ] * y + e[ 2 ] * z;
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v.y = e[ 4 ] * x + e[ 5 ] * y + e[ 6 ] * z;
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v.z = e[ 8 ] * x + e[ 9 ] * y + e[ 10 ] * z;
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return v;
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}
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static transformTiedVectorInverse( v, m ) {
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// input:
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// vector interpreted as a tied (ordinary) vector
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// THREE.Matrix4 orthogonal matrix (matrix without scale)
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const x = v.x, y = v.y, z = v.z;
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const e = m.elements;
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v.x = e[ 0 ] * x + e[ 1 ] * y + e[ 2 ] * z - e[ 12 ];
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v.y = e[ 4 ] * x + e[ 5 ] * y + e[ 6 ] * z - e[ 13 ];
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v.z = e[ 8 ] * x + e[ 9 ] * y + e[ 10 ] * z - e[ 14 ];
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return v;
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}
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static transformPlaneToLocalSpace( plane, m, resultPlane ) {
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resultPlane.normal.copy( plane.normal );
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resultPlane.constant = plane.constant;
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const referencePoint = ConvexObjectBreaker.transformTiedVectorInverse( plane.coplanarPoint( _v1 ), m );
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ConvexObjectBreaker.transformFreeVectorInverse( resultPlane.normal, m );
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// recalculate constant (like in setFromNormalAndCoplanarPoint)
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resultPlane.constant = - referencePoint.dot( resultPlane.normal );
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}
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}
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export { ConvexObjectBreaker };
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