H5 雪碧图 移动的机器猫
精灵图（英语：Sprite），又被称为雪碧图或拼合图。在计算机图形学中，当一张二维图像 集成进场景中，成为整个显示图像的一部分时，这张图就称为精灵图。
本文中用的就是这张，来自爱给网。
效果
操作
键盘上下左右控制移动
document.addEventListener("keydown", (ev) => {
let x = 0,
y = 0;
if (ev.code === "ArrowUp") y = -1;
if (ev.code === "ArrowDown") y = 1;
if (ev.code === "ArrowLeft") x = -1;
if (ev.code === "ArrowRight") x = 1;
if (x || y) move(x, y);
});
动画
通过判断不同状态来展示不同动画
function sprite() {
/** @type {{x:number,y:number}[]} */
let anim = anims[currSprite];
let animIndex = 0;
let render = () => {
let curr = anim[animIndex];
let currX = Math.round(curr.x * 25); // 25 指单个小图的宽度
let currY = Math.round(curr.y * 38); // 38 指单个小图的高度
backgroundPosition = `background-position: ${currX}px ${currY}px;`;
doraemon.setAttribute("style", `${transform}${backgroundPosition}`);
animIndex++;
if (anim.length === animIndex) animIndex = 0;
};
render();
return setInterval(render, 200); // 200 是指每帧渲染间隔0.2s
}
源码
没有进行精简，属于粗略的代码
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8" />
<meta http-equiv="X-UA-Compatible" content="IE=edge" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<style>
.doraemon {
width: 25px;
height: 38px;
position: relative;
background-image: url("./assets/doraemon.png");
}
.doraemon .name {
position: absolute;
top: -14px;
left: 50%;
transform: translateX(-50%);
font-size: 12px;
text-align: center;
white-space: nowrap;
}
</style>
</head>
<body>
<div class="doraemon">
<div class="name">哆啦A梦</div>
</div>
<script>
// 写一下 doraemon 移动
// 操作元素
let doraemon = document.querySelector(".doraemon");
// 当前位置
let pos = { x: 0, y: 0 };
// 移动速度
let speed = 2;
// 当前动画
let currSprite = "idle";
// 默认
let idleSprite = [{ x: 2, y: 0 }];
// 向下
let downSprite = [
{ x: 1, y: 0 },
{ x: 2, y: 0 },
{ x: 3, y: 0 },
];
// 向上
let upSprite = [
{ x: 1, y: 1 },
{ x: 2, y: 1 },
{ x: 3, y: 1 },
];
// 向左
let leftSprite = [
{ x: 1, y: 3 },
{ x: 2, y: 3 },
{ x: 3, y: 3 },
];
// 向右
let rightSprite = [
{ x: 1, y: 2 },
{ x: 2, y: 2 },
{ x: 3, y: 2 },
];
// 动画集
let anims = {
idle: idleSprite,
down: downSprite,
up: upSprite,
left: leftSprite,
right: rightSprite,
};
// 当前操作的位置
let backgroundPosition = "";
// 当前的位移
let transform = "";
// 初始动画
let spriteInterval = sprite();
// 延迟默认
let idleTimeout = 0;
document.addEventListener("keydown", (ev) => {
let x = 0,
y = 0;
if (ev.code === "ArrowUp") y = -1;
if (ev.code === "ArrowDown") y = 1;
if (ev.code === "ArrowLeft") x = -1;
if (ev.code === "ArrowRight") x = 1;
if (x || y) move(x, y);
});
function sprite() {
/** @type {{x:number,y:number}[]} */
let anim = anims[currSprite];
let animIndex = 0;
let render = () => {
let curr = anim[animIndex];
let currX = Math.round(curr.x * 25);
let currY = Math.round(curr.y * 38);
backgroundPosition = `background-position: ${currX}px ${currY}px;`;
doraemon.setAttribute("style", `${transform}${backgroundPosition}`);
animIndex++;
if (anim.length === animIndex) animIndex = 0;
};
render();
return setInterval(render, 200);
}
/**
* 元素移动
* @param {number} x
* @param {number} y
*/
function move(x, y) {
clearTimeout(idleTimeout);
idleTimeout = setTimeout(() => {
clearInterval(spriteInterval);
currSprite = "idle";
spriteInterval = sprite();
}, 500);
x *= speed;
y *= speed;
pos.x += x;
pos.y += y;
if (x > 0 && currSprite != "right") {
clearInterval(spriteInterval);
currSprite = "right";
spriteInterval = sprite();
}
if (y > 0 && currSprite != "down") {
clearInterval(spriteInterval);
currSprite = "down";
spriteInterval = sprite();
}
if (x < 0 && currSprite != "left") {
clearInterval(spriteInterval);
currSprite = "left";
spriteInterval = sprite();
}
if (y < 0 && currSprite != "up") {
clearInterval(spriteInterval);
currSprite = "up";
spriteInterval = sprite();
}
transform = `transform: translate(${pos.x}px,${pos.y}px);`;
doraemon.setAttribute("style", `${transform}${backgroundPosition}`);
}
</script>
</body>
</html>
