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if(typeof require !== "undefined") { var jaws = require("./core.js"); }
/**
* @fileOverview Collision Detection
*
* Collision detection helpers.
*
* @example
* // collision helper exampels:
* collideOneWithOne(player, boss) // -> false
* collideOneWithMany(player, bullets) // -> [bullet1, bullet1]
* collideManyWithMany(bullets, enemies) // -> [ [bullet1, enemy1], [bullet2, enemy2] ]
* collide(player, boss) // -> false
* collide(player,
* bullets,
* function(player, bullet) {}) // Callback: arguments[0] -> player
* // arguments[1] -> bullets[i]
*
*/
var jaws = (function(jaws) {
/**
* Collides two objects by reading x, y and either method rect() or property radius.
* @public
* @param {object} object1 An object with a 'radius' or 'rect' property
* @param {object} object2 An object with a 'radius' or 'rect' property
* @returns {boolean} If the two objects are colliding or not
*/
jaws.collideOneWithOne = function(object1, object2) {
if (object1.radius && object2.radius && object1 !== object2 && jaws.collideCircles(object1, object2))
return true;
if (object1.rect && object2.rect && object1 !== object2 && jaws.collideRects(object1.rect(), object2.rect()))
return true;
return false;
};
/**
* Compares an object against a list, returning those from list that collide with object, and
* calling 'callback' per collision (if set) with object and item from list.
* (Note: Will never collide objects with themselves.)
* @public
* @param {object} object An object with a 'radius' or 'rect' property
* @param {array|object} list A collection of objects with a 'length' property
* @param {function} callback The function to be called per collison detected
* @returns {array} A collection of items colliding with object from list
* @example
* collideOneWithMany(player, bullets) // -> [bullet1, bullet1]
* collideOneWithMany(player, bullets, function(player, bullet) {
* //player and bullet (bullets[i])
* });
*/
jaws.collideOneWithMany = function(object, list, callback) {
var a = [];
if (callback) {
for (var i = 0; i < list.length; i++) {
if (jaws.collideOneWithOne(object, list[i])) {
callback(object, list[i]);
a.push(list[i])
}
}
return a;
}
else {
return list.filter(function(item) {
return jaws.collideOneWithOne(object, item);
});
}
};
/**
* Compares two lists, returning those items from each that collide with each other, and
* calling 'callback' per collision (if set) with item from list1 and item from list2.
* (Note: Will never collide objects with themselves.)
* @public
* @param {array|object} list1 A collection of objects with a 'forEach' property
* @param {array|object} list2 A collection of objects with a 'forEach' property
* @param {function} callback The function to be called per collison detected
* @returns {array} A collection of items colliding with list1 from list2
* @example
* jaws.collideManyWithMany(bullets, enemies) // --> [[bullet, enemy], [bullet, enemy]]
*/
jaws.collideManyWithMany = function(list1, list2, callback) {
var a = [];
if (list1 === list2) {
combinations(list1, 2).forEach(function(pair) {
if (jaws.collideOneWithOne(pair[0], pair[1])) {
if (callback) {
callback(pair[0], pair[1]);
}
else {
a.push([pair[0], pair[1]]);
}
}
});
}
else {
list1.forEach(function(item1) {
list2.forEach(function(item2) {
if (jaws.collideOneWithOne(item1, item2)) {
if (callback) {
callback(item1, item2);
}
else {
a.push([item1, item2]);
}
}
});
});
}
return a;
};
/**
* Returns if two circle-objects collide with each other
* @public
* @param {object} object1 An object with a 'radius' property
* @param {object} object2 An object with a 'radius' property
* @returns {boolean} If two circle-objects collide or not
*/
jaws.collideCircles = function(object1, object2) {
return (jaws.distanceBetween(object1, object2) < object1.radius + object2.radius);
};
/**
* Returns if two Rects collide with each other or not
* @public
* @param {object} rect1 An object with 'x', 'y', 'right' and 'bottom' properties
* @param {object} rect2 An object with 'x', 'y', 'right' and 'bottom' properties
* @returns {boolean} If two Rects collide with each other or not
*/
jaws.collideRects = function(rect1, rect2) {
return ((rect1.x >= rect2.x && rect1.x <= rect2.right) || (rect2.x >= rect1.x && rect2.x <= rect1.right)) &&
((rect1.y >= rect2.y && rect1.y <= rect2.bottom) || (rect2.y >= rect1.y && rect2.y <= rect1.bottom));
};
/**
* Returns the distance between two objects
* @public
* @param {object} object1 An object with 'x' and 'y' properties
* @param {object} object2 An object with 'x' and 'y' properties
* @returns {number} The distance between two objects
*/
jaws.distanceBetween = function(object1, object2) {
return Math.sqrt(Math.pow(object1.x - object2.x, 2) + Math.pow(object1.y - object2.y, 2));
};
/**
* Creates combinations of items from a list of a specific size
* @private
* @param {array|object} list An object with a 'length' property
* @param {number} n The size of the array to return
* @returns {Array} An array of items having a specific size number of its own entries
*/
function combinations(list, n) {
var f = function(i) {
if (list.isSpriteList !== undefined) {
return list.at(i);
} else { // s is an Array
return list[i];
}
};
var r = [];
var m = new Array(n);
for (var i = 0; i < n; i++)
m[i] = i;
for (var i = n - 1, sn = list.length; 0 <= i; sn = list.length) {
r.push(m.map(f));
while (0 <= i && m[i] === sn - 1) {
i--;
sn--;
}
if (0 <= i) {
m[i] += 1;
for (var j = i + 1; j < n; j++)
m[j] = m[j - 1] + 1;
i = n - 1;
}
}
return r;
}
/**
* If an object has items or not
* @private
* @param {array|object} array An object with a 'length' property
* @returns {boolean} If the object has items (length > 0)
*/
function hasItems(array) {
return (array && array.length > 0);
}
/**
* Compares two objects or lists, returning if they collide, and
* calling 'callback' per collision (if set) between objects or lists.
* @param {array|object} x An object with either 'rect' or 'forEach' property
* @param {array|object} x2 An object with either 'rect' or 'forEach' property
* @param {function} callback
* @returns {boolean}
* @examples
* jaws.collide(player, enemy, function(player, enemy) { ... } )
* jaws.collide(player, enemies, function(player, enemy) { ... } )
* jaws.collide(bullets, enemies, function(bullet, enemy) { ... } )
*/
jaws.collide = function(x, x2, callback) {
if ((x.rect || x.radius) && x2.forEach)
return (jaws.collideOneWithMany(x, x2, callback).length > 0);
if (x.forEach && x2.forEach)
return (jaws.collideManyWithMany(x, x2, callback).length > 0);
if (x.forEach && (x2.rect || x2.radius))
return (jaws.collideOneWithMany(x2, x, callback).length > 0);
if ((x.rect && x2.rect) || (x.radius && x2.radius)) {
var result = jaws.collideOneWithOne(x, x2);
if (callback && result)
callback(x, x2);
else
return result;
}
};
return jaws;
})(jaws || {});
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