[英]Easing function object goes too fast
我最近遇到了这个包含一些缓动功能的网站: http : //gizma.com/easing/
并且已经尝试在其中实现quadratic easing in/out
进入我的脚本,但我的精灵似乎超级迅速地从屏幕上移开。 我不确定我的逻辑出错了,需要帮助理解我的错误。
我的缓动功能如下所示:
//t = time, b = startvalue, c = change in value
function ease(t, b, c, duration) {
t /= duration/2; //duration is in milliseconds
if (t < 1) return c/2*t*t + b;
t--;
return -c/2 * (t*(t-2) - 1) + b;
};
我动画动画的代码是从一个mousedown
监听器中触发的:
function animate(e){
clearTimeout(timer);
var duration = 2000; //2 seconds
var startX = camera.x;
var startY = camera.y;
var targetX = e.offsetX - element.width/2 + camera.x; //world space
var targetY = e.offsetY - element.height/2 + camera.y; //world space
var vectorX = targetX - startX / duration;
var vectorY = targetY - startY / duration;
var startTime = Date.now();
function update(){
var t = Date.now() - startTime; //time elapsed so far
var cX = vectorX * t; //change in X
var cY = vectorY * t; //change in Y
var amountX = ease(t,startX,cX,duration); // see function above
var amountY = ease(t,startY,cY,duration);
var difX = startX - amountX; //get the difference
var difY = startY - amountY;
camera.x += difX;
camera.y += difY;
if (t >= duration){
clearTimeout(timer);
} else {
timer = setTimeout(update,0);
}
}
update();
}
是什么导致动画如此迅速而且到目前为止?
编辑:添加,一个小提琴包括它帮助: http : //jsfiddle.net/a86m33nj/
https://jsfiddle.net/pcconsolidated/xesnom2t/
你的问题只是简单地使它复杂化。 二次缓和函数只是想知道起始坐标,移动距离,相对于开始时间的当前时间以及总持续时间。 二次方的输出也是新坐标,而不是对象移动的距离,因此只需将坐标替换为四舍五入到最接近数字的函数中的值。
var element = document.getElementById('background'); var output = document.getElementById('output'); var camera=document.getElementById("camera"); var timer; var targetX=0; var targetY=0; document.addEventListener('click', animate,true); var duration = 2000; //2 seconds var startX = 0; var startY = 0; var startTime =0; function animate(e){ targetX = e.clientX ; targetY = e.clientY ; clearTimeout(timer); startX = parseInt(camera.style.left.split("p")[0]); startY = parseInt(camera.style.top.split("p")[0]); startTime = Date.now(); updateLoc(); } function updateLoc(){ var t = (Date.now() - startTime); var cX = targetX-startX; //change in X var cY = targetY-startY; //change in Y var amountX = ease(t,startX,cX,duration); var amountY = ease(t,startY,cY,duration); newX=Math.floor(amountX); newY=Math.floor(amountY); camera.style.left = Math.floor(newX)+"px"; camera.style.top = Math.floor(newY)+"px"; output.innerHTML+=newX+","+newY+"___"; if (Date.now() - startTime >= duration){ clearTimeout(timer); } else { timer = setTimeout(updateLoc,0); } } //t = time, b = startvalue, c = change in value function ease(t, b, c,duration) { t /= duration/2; if (t < 1) return c/2*t*t + b; t--; return -c/2 * (t*(t-2) - 1) + b; }; </script>
<canvas id="background" width="500" height="500"> </canvas><br/> <div id="output"></div><div id="camera" style="background-color:green;top:250px;left:150px;position:absolute;height:30px;width:30px;"></div> <script type="text/javascript">
这是相当粗鲁的,我的抵消是错误的,但在晚餐后病态继续修补,看看我是否可以得到它。 这是我的代码希望它适合你。
好吧,在玩了你的代码之后我就开始了。 现在,只要您点击,相机就会跟随:
function animate(e){
clearTimeout(timer);
var duration = 2000; //2 seconds
var startX = camera.x;
var startY = camera.y;
var targetX = e.offsetX - element.width/2 + camera.x;
var targetY = e.offsetY - element.height/2 + camera.y;
var startTime = Date.now();
//t = time, b = startvalue, c = change in value
function ease(t, b, c,duration) {
t /= duration/2;
if (t < 1) return c/2*t*t + b;
t--;
return -c/2 * (t*(t-2) - 1) + b;
};
function update(){
var t = (Date.now() - startTime);
var cX = -targetX; //change in X
var cY = -targetY; //change in Y
camera.x = ease(t,startX,cX,duration);
camera.y = ease(t,startY,cY,duration);
if (Date.now() - startTime > duration){
clearTimeout(timer);
} else {
timer = setTimeout(update,10);
}
}
update();
}
我希望它有所帮助。 干杯!
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