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