如何减慢动画？ [英] How to slow down the animation?

问题描述

我有动画矩形 jsFiddle演示

如何减慢动画速度并使其更稳定？

How to slow down the animation and make it more stable?

我尝试使用循环延迟，但延迟循环和requestAnimationFrame之间存在冲突

I try to use loop delay but there is conflict between the delay loop and requestAnimationFrame

我不想更改参数 window.setTimeout（f，1e3 / 60）;

因为有更多的代码块需要良好的偏好。

becose there is more block of code which require good preferences.

非常感谢。

循环延迟：

loop delay :

for (i = 0; i < 10; i++) {
        (function (i) {
            window.setTimeout(function () {}, i * 2000);
        }(i));
    }

我的代码：

My code :

var canvas = document.getElementById('c');
var ctx = canvas.getContext('2d');
var my_gradient = ctx.createLinearGradient(0, 0, 0, 300);

    window.requestAnimationFrame = function() {
    return window.requestAnimationFrame ||
      window.webkitRequestAnimationFrame ||
      window.mozRequestAnimationFrame ||
      window.msRequestAnimationFrame ||
      window.oRequestAnimationFrame ||
      function(f) {
        window.setTimeout(f,1e3/60);
      }
  }();


  window.cancelAnimationFrame = function() {
    return window.cancelAnimationFrame ||
      window.webkitCancelAnimationFrame ||
      window.mozCancelAnimationFrame ||
      window.msCancelAnimationFrame ||
      window.oCancelAnimationFrame ||
      function(f) {
        window.setTimeout(f,1e3/60);
      }
  }();  
var randompos = {};
RandomPosition();

function DrawBackround() {
    ctx.globalAlpha = 1;
    ctx.clearRect(0, 0, 200, 200);
    my_gradient.addColorStop(0, '#002EB8');
    my_gradient.addColorStop(1, '#4D6DCD');
    ctx.fillStyle = my_gradient;
    ctx.fillRect(0, 0, 200, 200);
}

function get_random_color() {
    var letters = '0123456789ABCDEF'.split('');
    var color = '#';
    for (var i = 0; i < 6; i++) {
        color += letters[Math.round(Math.random() * 15)];
    }
    return color;
}

function RandomPosition() {
    DrawBackround();
    ctx.globalAlpha = 0.5;
    var dt = 10;
    for (i = 0; i < 3; i++) {
        n = Math.floor(Math.random() * 8) + 1;
        switch (n) {
            case 1:
                randompos.x = 0;
                randompos.y = dt; //12
                break;
            case 2:
                randompos.x = dt;
                randompos.y = dt; //1
                break;
            case 3:
                randompos.x = dt;
                randompos.y = 0; //3
                break;
            case 4:
                randompos.x = dt;
                randompos.y = -dt; //4
                break;
            case 5:
                randompos.x = 0;
                randompos.y = -dt; //6
                break;
            case 6:
                randompos.x = -dt;
                randompos.y = -dt;
                break;
            case 7:
                randompos.x = -dt;
                randompos.y = 0;
                break;
            case 8:
                randompos.x = -dt;
                randompos.y = dt;
                break;
            default:
        }
        ctx.fillStyle = get_random_color();
        ctx.fillRect(randompos.x + 50, randompos.y + 50, 100, 100);
    }
    window.requestAnimationFrame(RandomPosition);

    for (i = 0; i < 10; i++) {
        (function (i) {
            window.setTimeout(function () {}, i * 2000);
        }(i));
    }
}

推荐答案

一个减慢你的特定功能的选项是让它只运行每一个X帧，

One option to slow down your particular function would be to make it run only every X frames,

将RandomPosition（）编辑成这样的东西使它每10帧运行一次：

Editing your RandomPosition() to something like this makes it run once every 10 frames:

var counter=0;
function RandomPosition() {
    if(++counter % 10){
        window.requestAnimationFrame(RandomPosition);
        return false;
    }

http://jsfiddle.net/jaibuu/kHvaX/1/

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