javascript - 一段时间后取消 requestAnimationFrame 循环

Question

我想在超时后取消动画。这是我的代码

function animate(){
        id = requestAnimationFrame(animate);
        console.log(id);
        c.clearRect(0,0, window.innerWidth, window.innerHeight);
        for(let i = 0; i < circleArray.length; i++){
            circleArray[i].scatter();
        }
        setTimeout(function(){
            id = requestAnimationFrame(animate);
            cancelAnimationFrame(id);
            update();
        },5000)
    }
    
    function update(){
        requestAnimationFrame(update);
        c.clearRect(0,0, window.innerWidth, window.innerHeight);
        for(let i = 0; i < circleArray.length; i++){
            circleArray[i].update();
        }
    }

在这里，我想停止 animate 函数的递归并启动更新函数。但动画不会停止，更新功能在给定时间后同时运行。

Answer 1

只需使用一个变量来引用当前的渲染函数并在计时器事件上更改该变量。

例子

var currentFrameRender = animate;  // set current render
requestAnimationFrame(currentFrameRender); // request first frame
setTimeout(() => currentFrameRender = update ,5000); // switch render in 5s
setTimeout(() => currentFrameRender = undefined ,10000); // stop animation in 10s

function animate(){
    c.clearRect(0, 0, c.canvas.width, c.canvas.height);
    for(let i = 0; i < circles.length; i++){
        circleArray[i].scatter();
    }

    // request frame only if currentFrameRender is defined
    currentFrameRender && requestAnimationFrame(currentFrameRender);
}

function update(){
    c.clearRect(0, 0, c.canvas.width, c.canvas.height);
    for(let i = 0; i < circles.length; i++){
        circleArray[i].update();
    }

    // request frame only if currentFrameRender is defined
    currentFrameRender && requestAnimationFrame(currentFrameRender);
}