window.requestAnimFrame = (function() {

return window.requestAnimationFrame || window.webkitRequestAnimationFrame || window.mozRequestAnimationFrame || window.oRequestAnimationFrame || window.msRequestAnimationFrame ||

function( /* function FrameRequestCallback */ callback, /* DOMElement Element */ element) {

return window.setTimeout(callback, 1000 / 60);

};

})();

function calLength2(x1, y1, x2, y2) {

return Math.pow(x1 - x2, 2) + Math.pow(y1 - y2, 2);

}

function randomColor() {

var col = [0, 1, 2];

col[0] = Math.random() * 100 + 155;

col[0] = col[0].toFixed();

col[1] = Math.random() * 100 + 155;

col[1] = col[1].toFixed();

col[2] = Math.random() * 100 + 155;

col[2] = col[2].toFixed();

var num = Math.floor(Math.random() * 3);

col[num] = 0;

return "rgba(" + col[0] + "," + col[1] + "," + col[2] + ",";

}

function lerpAngle(a, b, t) {

var d = b - a;

if (d > Math.PI) d = d - 2 * Math.PI;

if (d < -Math.PI) d = d + 2 * Math.PI;

return a + d * t;

}

function inOboundary(arrX, arrY, l, r, t, b) { //在l r t b范圍內(nèi)的檢測(cè)

return arrX > l && arrX < r && arrY > t && arrY < b;

}

function rgbColor(r, g, b) {

r = Math.round(r * 256);

g = Math.round(g * 256);

b = Math.round(b * 256);

return "rgba(" + r + "," + g + "," + b + ",1)";

}

function rgbNum(r, g, b) {

r = Math.round(r * 256);

g = Math.round(g * 256);

b = Math.round(b * 256);

return "rgba(" + r + "," + g + "," + b;

}

function rnd(m) {

var n = m || 1;

return Math.random() * n;

}

function rateRandom(m, n) {

var sum = 0;

for (var i = 1; i < (n - m); i++) {

sum += i;

}

var ran = Math.random() * sum;

for (var i = 1; i < (n - m); i++) {

ran -= i;

if (ran < 0) {

return i - 1 + m;

}

}

}

function distance(x1, y1, x2, y2, l) {

var x = Math.abs(x1 - x2);

var y = Math.abs(y1 - y2);

if (x < l && y < l) {

return true;

}

return false;

}

function AABBbox(object1, w1, h1, object2, w2, h2, overlap) {

A1 = object1.x + overlap;

B1 = object1.x + w1 - overlap;

C1 = object1.y + overlap;

D1 = object1.y + h1 - overlap;

A2 = object2.x + overlap;

B2 = object2.x + w2 - overlap;

C2 = object2.y + overlap;

D2 = object2.y + h2 - overlap;

if (A1 > B2 || B1 < A2 || C1 > D2 || D1 < C2) return false;

else return true;

}

function dis2(x, y, x0, y0) {

var dx = x - x0;

var dy = y - y0;

return dx * dx + dy * dy;

}

function rndi2(m, n) {

var a = Math.random() * (n - m) + m;

return Math.floor(a);

}