使用JavaScript在画布上平滑设置关键帧动画
我对编程非常陌生,我正在尝试创建一些代码,允许我通过按箭头键在画布上移动一个正方形。我能让正方形移动,但它的运动不是很平稳。我让它一次以10像素的增量移动,所以我理解为什么它感觉有点不稳定,因为10帧差的每个位置之间没有任何动画,但是以较小的增量移动会使它太慢。到目前为止,我所做的工作如下:使用JavaScript在画布上平滑设置关键帧动画,javascript,animation,canvas,keydown,smooth,Javascript,Animation,Canvas,Keydown,Smooth,我对编程非常陌生,我正在尝试创建一些代码,允许我通过按箭头键在画布上移动一个正方形。我能让正方形移动,但它的运动不是很平稳。我让它一次以10像素的增量移动,所以我理解为什么它感觉有点不稳定,因为10帧差的每个位置之间没有任何动画,但是以较小的增量移动会使它太慢。到目前为止,我所做的工作如下: window.onload = function init() { var canvas = document.getElementById("canvas"); var ctx = can
window.onload = function init() {
var canvas = document.getElementById("canvas");
var ctx = canvas.getContext("2d");
setInterval(gameLoop,50);
window.addEventListener('keydown',whatKey,true);
}
avatarX = 400
avatarY = 300
function gameLoop() {
var canvas = document.getElementById("canvas");
var ctx = canvas.getContext("2d");
canvas.width = 800
canvas.height = 600
ctx.fillRect(avatarX,avatarY,50,50);
}
function whatKey(e) {
switch(e.keyCode) {
case 37:
avatarX = avatarX - 10;
break;
case 39:
avatarX = avatarX + 10;
break;
case 40:
avatarY = avatarY + 10;
break;
case 38:
avatarY = avatarY - 10;
break;
}
}
每次我向右按箭头键时,我都希望正方形能以恒定的速率平稳地向那个方向移动。提前感谢您的帮助 添加了一些内容,第一个是
requestAnimationFrame
然后我添加了一个keyup
和keydown
事件处理程序,它们将跟踪使用数组当前正在推送的键。如果当前正在推送的数组中的键为true,则为false。此方法还允许您同时按住多个键
然后我添加了速度变量,这些变量根据被按下的内容增加或减少,以及一个maxSpeed
变量,这样你的速度就不会超过某个特定的速度。可以删除maxSpeed
变量,也可以删除递增和递减velX
和velY
变量,您只需取消我留下的行的注释。它似乎在10点走得太快了,这就是为什么我增加了渐进加速
(function () {
var requestAnimationFrame = window.requestAnimationFrame || window.mozRequestAnimationFrame || window.webkitRequestAnimationFrame || window.msRequestAnimationFrame;
window.requestAnimationFrame = requestAnimationFrame;
})();
window.onload = function init() {
var canvas = document.getElementById("canvas");
var ctx = canvas.getContext("2d");
gameLoop();
}
window.addEventListener("keydown", function (e) {
keys[e.keyCode] = true;
});
window.addEventListener("keyup", function (e) {
keys[e.keyCode] = false;
});
var avatarX = 400,
avatarY = 300,
velX = 0,
velY = 0,
keys = [],
maxSpeed = 10;
function gameLoop() {
whatKey();
var canvas = document.getElementById("canvas");
var ctx = canvas.getContext("2d");
canvas.width = 800;
canvas.height = 600;
avatarX += velX;
avatarY += velY;
ctx.fillRect(avatarX, avatarY, 50, 50);
requestAnimationFrame(gameLoop);
}
function whatKey() {
if (keys[37]) {
//velX = -10;
if (velX > -maxSpeed) {
velX -= 0.5;
}
}
if (keys[39]) {
//velX = 10;
if (velX < maxSpeed) {
velX += 0.5;
}
}
if (keys[40]) {
//velY = 10;
if (velY < maxSpeed) {
velY += 0.5;
}
}
if (keys[38]) {
//velY = -10;
if (velY > -maxSpeed) {
velY -= 0.5;
}
}
}
上面的内容看起来有些急促,因为画面是用上下箭头滚动的,因为画布有点苦,所以使用全屏链接来完全测试运动
(function () {
var requestAnimationFrame = window.requestAnimationFrame || window.mozRequestAnimationFrame || window.webkitRequestAnimationFrame || window.msRequestAnimationFrame;
window.requestAnimationFrame = requestAnimationFrame;
})();
window.onload = function init() {
var canvas = document.getElementById("canvas");
var ctx = canvas.getContext("2d");
gameLoop();
}
window.addEventListener("keydown", function (e) {
keys[e.keyCode] = true;
});
window.addEventListener("keyup", function (e) {
keys[e.keyCode] = false;
});
var avatarX = 400,
avatarY = 300,
velX = 0,
velY = 0,
keys = [],
maxSpeed = 10;
function gameLoop() {
whatKey();
var canvas = document.getElementById("canvas");
var ctx = canvas.getContext("2d");
canvas.width = 800;
canvas.height = 600;
avatarX += velX;
avatarY += velY;
ctx.fillRect(avatarX, avatarY, 50, 50);
requestAnimationFrame(gameLoop);
}
function whatKey() {
if (keys[37]) {
//velX = -10;
if (velX > -maxSpeed) {
velX -= 0.5;
}
}
if (keys[39]) {
//velX = 10;
if (velX < maxSpeed) {
velX += 0.5;
}
}
if (keys[40]) {
//velY = 10;
if (velY < maxSpeed) {
velY += 0.5;
}
}
if (keys[38]) {
//velY = -10;
if (velY > -maxSpeed) {
velY -= 0.5;
}
}
}
(函数(){
var requestAnimationFrame=window.requestAnimationFrame | | window.mozRequestAnimationFrame | | window.webkitRequestAnimationFrame | | window.msRequestAnimationFrame;
window.requestAnimationFrame=requestAnimationFrame;
})();
window.onload=函数init(){
var canvas=document.getElementById(“canvas”);
var ctx=canvas.getContext(“2d”);
gameLoop();
}
window.addEventListener(“向下键”,函数(e){
键[e.keyCode]=真;
});
window.addEventListener(“键控”,函数(e){
密钥[e.keyCode]=假;
});
变量rx=400,
阿凡达=300,
velX=0,
Vy=0,
键=[],
最大速度=10;
函数gameLoop(){
whatKey();
var canvas=document.getElementById(“canvas”);
var ctx=canvas.getContext(“2d”);
画布宽度=800;
帆布高度=600;
avatarX+=velX;
化身+=虚拟的;
ctx.fillRect(化身,化身,50,50);
requestAnimationFrame(gameLoop);
}
函数whatKey(){
如果(键[37]){
//velX=-10;
如果(velX>-maxSpeed){
velX-=0.5;
}
}
如果(键[39]){
//velX=10;
如果(velX-maxSpeed){
Vly-=0.5;
}
}
}
@leetylor哈哈,我也这么想,花了一秒钟的时间才弄清楚到底发生了什么,因为画布比框架大一点,请检查此全屏链接,非常感谢!这真的很有帮助。