cannon
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A lightweight 3D physics engine written in JavaScript.
236 lines (209 loc) • 6.19 kB
JavaScript
module.exports = Box;
var Shape = require('./Shape');
var Vec3 = require('../math/Vec3');
var ConvexPolyhedron = require('./ConvexPolyhedron');
/**
* A 3d box shape.
* @class Box
* @constructor
* @param {Vec3} halfExtents
* @author schteppe
* @extends Shape
*/
function Box(halfExtents){
Shape.call(this);
this.type = Shape.types.BOX;
/**
* @property halfExtents
* @type {Vec3}
*/
this.halfExtents = halfExtents;
/**
* Used by the contact generator to make contacts with other convex polyhedra for example
* @property convexPolyhedronRepresentation
* @type {ConvexPolyhedron}
*/
this.convexPolyhedronRepresentation = null;
this.updateConvexPolyhedronRepresentation();
this.updateBoundingSphereRadius();
}
Box.prototype = new Shape();
Box.prototype.constructor = Box;
/**
* Updates the local convex polyhedron representation used for some collisions.
* @method updateConvexPolyhedronRepresentation
*/
Box.prototype.updateConvexPolyhedronRepresentation = function(){
var sx = this.halfExtents.x;
var sy = this.halfExtents.y;
var sz = this.halfExtents.z;
var V = Vec3;
var vertices = [
new V(-sx,-sy,-sz),
new V( sx,-sy,-sz),
new V( sx, sy,-sz),
new V(-sx, sy,-sz),
new V(-sx,-sy, sz),
new V( sx,-sy, sz),
new V( sx, sy, sz),
new V(-sx, sy, sz)
];
var indices = [
[3,2,1,0], // -z
[4,5,6,7], // +z
[5,4,0,1], // -y
[2,3,7,6], // +y
[0,4,7,3], // -x
[1,2,6,5], // +x
];
var axes = [
new V(0, 0, 1),
new V(0, 1, 0),
new V(1, 0, 0)
];
var h = new ConvexPolyhedron(vertices, indices);
this.convexPolyhedronRepresentation = h;
h.material = this.material;
};
/**
* @method calculateLocalInertia
* @param {Number} mass
* @param {Vec3} target
* @return {Vec3}
*/
Box.prototype.calculateLocalInertia = function(mass,target){
target = target || new Vec3();
Box.calculateInertia(this.halfExtents, mass, target);
return target;
};
Box.calculateInertia = function(halfExtents,mass,target){
var e = halfExtents;
target.x = 1.0 / 12.0 * mass * ( 2*e.y*2*e.y + 2*e.z*2*e.z );
target.y = 1.0 / 12.0 * mass * ( 2*e.x*2*e.x + 2*e.z*2*e.z );
target.z = 1.0 / 12.0 * mass * ( 2*e.y*2*e.y + 2*e.x*2*e.x );
};
/**
* Get the box 6 side normals
* @method getSideNormals
* @param {array} sixTargetVectors An array of 6 vectors, to store the resulting side normals in.
* @param {Quaternion} quat Orientation to apply to the normal vectors. If not provided, the vectors will be in respect to the local frame.
* @return {array}
*/
Box.prototype.getSideNormals = function(sixTargetVectors,quat){
var sides = sixTargetVectors;
var ex = this.halfExtents;
sides[0].set( ex.x, 0, 0);
sides[1].set( 0, ex.y, 0);
sides[2].set( 0, 0, ex.z);
sides[3].set( -ex.x, 0, 0);
sides[4].set( 0, -ex.y, 0);
sides[5].set( 0, 0, -ex.z);
if(quat!==undefined){
for(var i=0; i!==sides.length; i++){
quat.vmult(sides[i],sides[i]);
}
}
return sides;
};
Box.prototype.volume = function(){
return 8.0 * this.halfExtents.x * this.halfExtents.y * this.halfExtents.z;
};
Box.prototype.updateBoundingSphereRadius = function(){
this.boundingSphereRadius = this.halfExtents.norm();
};
var worldCornerTempPos = new Vec3();
var worldCornerTempNeg = new Vec3();
Box.prototype.forEachWorldCorner = function(pos,quat,callback){
var e = this.halfExtents;
var corners = [[ e.x, e.y, e.z],
[ -e.x, e.y, e.z],
[ -e.x, -e.y, e.z],
[ -e.x, -e.y, -e.z],
[ e.x, -e.y, -e.z],
[ e.x, e.y, -e.z],
[ -e.x, e.y, -e.z],
[ e.x, -e.y, e.z]];
for(var i=0; i<corners.length; i++){
worldCornerTempPos.set(corners[i][0],corners[i][1],corners[i][2]);
quat.vmult(worldCornerTempPos,worldCornerTempPos);
pos.vadd(worldCornerTempPos,worldCornerTempPos);
callback(worldCornerTempPos.x,
worldCornerTempPos.y,
worldCornerTempPos.z);
}
};
var worldCornersTemp = [
new Vec3(),
new Vec3(),
new Vec3(),
new Vec3(),
new Vec3(),
new Vec3(),
new Vec3(),
new Vec3()
];
Box.prototype.calculateWorldAABB = function(pos,quat,min,max){
var e = this.halfExtents;
worldCornersTemp[0].set(e.x, e.y, e.z);
worldCornersTemp[1].set(-e.x, e.y, e.z);
worldCornersTemp[2].set(-e.x, -e.y, e.z);
worldCornersTemp[3].set(-e.x, -e.y, -e.z);
worldCornersTemp[4].set(e.x, -e.y, -e.z);
worldCornersTemp[5].set(e.x, e.y, -e.z);
worldCornersTemp[6].set(-e.x, e.y, -e.z);
worldCornersTemp[7].set(e.x, -e.y, e.z);
var wc = worldCornersTemp[0];
quat.vmult(wc, wc);
pos.vadd(wc, wc);
max.copy(wc);
min.copy(wc);
for(var i=1; i<8; i++){
var wc = worldCornersTemp[i];
quat.vmult(wc, wc);
pos.vadd(wc, wc);
var x = wc.x;
var y = wc.y;
var z = wc.z;
if(x > max.x){
max.x = x;
}
if(y > max.y){
max.y = y;
}
if(z > max.z){
max.z = z;
}
if(x < min.x){
min.x = x;
}
if(y < min.y){
min.y = y;
}
if(z < min.z){
min.z = z;
}
}
// Get each axis max
// min.set(Infinity,Infinity,Infinity);
// max.set(-Infinity,-Infinity,-Infinity);
// this.forEachWorldCorner(pos,quat,function(x,y,z){
// if(x > max.x){
// max.x = x;
// }
// if(y > max.y){
// max.y = y;
// }
// if(z > max.z){
// max.z = z;
// }
// if(x < min.x){
// min.x = x;
// }
// if(y < min.y){
// min.y = y;
// }
// if(z < min.z){
// min.z = z;
// }
// });
};