File: src/collision/Pairs.js
/**
* The `Matter.Pairs` module contains methods for creating and manipulating collision pair sets.
*
* @class Pairs
*/
var Pairs = {};
module.exports = Pairs;
var Pair = require('./Pair');
var Common = require('../core/Common');
(function() {
/**
* Creates a new pairs structure.
* @method create
* @param {object} options
* @return {pairs} A new pairs structure
*/
Pairs.create = function(options) {
return Common.extend({
table: {},
list: [],
collisionStart: [],
collisionActive: [],
collisionEnd: []
}, options);
};
/**
* Updates pairs given a list of collisions.
* @method update
* @param {object} pairs
* @param {collision[]} collisions
* @param {number} timestamp
*/
Pairs.update = function(pairs, collisions, timestamp) {
var pairsList = pairs.list,
pairsListLength = pairsList.length,
pairsTable = pairs.table,
collisionsLength = collisions.length,
collisionStart = pairs.collisionStart,
collisionEnd = pairs.collisionEnd,
collisionActive = pairs.collisionActive,
collision,
pairIndex,
pair,
i;
// clear collision state arrays, but maintain old reference
collisionStart.length = 0;
collisionEnd.length = 0;
collisionActive.length = 0;
for (i = 0; i < pairsListLength; i++) {
pairsList[i].confirmedActive = false;
}
for (i = 0; i < collisionsLength; i++) {
collision = collisions[i];
pair = collision.pair;
if (pair) {
// pair already exists (but may or may not be active)
if (pair.isActive) {
// pair exists and is active
collisionActive.push(pair);
} else {
// pair exists but was inactive, so a collision has just started again
collisionStart.push(pair);
}
// update the pair
Pair.update(pair, collision, timestamp);
pair.confirmedActive = true;
} else {
// pair did not exist, create a new pair
pair = Pair.create(collision, timestamp);
pairsTable[pair.id] = pair;
// push the new pair
collisionStart.push(pair);
pairsList.push(pair);
}
}
// find pairs that are no longer active
var removePairIndex = [];
pairsListLength = pairsList.length;
for (i = 0; i < pairsListLength; i++) {
pair = pairsList[i];
if (!pair.confirmedActive) {
Pair.setActive(pair, false, timestamp);
collisionEnd.push(pair);
if (!pair.collision.bodyA.isSleeping && !pair.collision.bodyB.isSleeping) {
removePairIndex.push(i);
}
}
}
// remove inactive pairs
for (i = 0; i < removePairIndex.length; i++) {
pairIndex = removePairIndex[i] - i;
pair = pairsList[pairIndex];
pairsList.splice(pairIndex, 1);
delete pairsTable[pair.id];
}
};
/**
* Clears the given pairs structure.
* @method clear
* @param {pairs} pairs
* @return {pairs} pairs
*/
Pairs.clear = function(pairs) {
pairs.table = {};
pairs.list.length = 0;
pairs.collisionStart.length = 0;
pairs.collisionActive.length = 0;
pairs.collisionEnd.length = 0;
return pairs;
};
})();