只需多做一点,您就可以做到使用键盘控制你的精灵。这里我建议您使用这个名为keyboard
的自定义函数,它监听并捕获键盘事件。
function keyboard(value) {
let key = {};
key.value = value;
key.isDown = false;
key.isUp = true;
key.press = undefined;
key.release = undefined;
//The `downHandler`
key.downHandler = event => {
if (event.key === key.value) {
if (key.isUp && key.press) key.press();
key.isDown = true;
key.isUp = false;
event.preventDefault();
}
};
//The `upHandler`
key.upHandler = event => {
if (event.key === key.value) {
if (key.isDown && key.release) key.release();
key.isDown = false;
key.isUp = true;
event.preventDefault();
}
};
//Attach event listeners
const downListener = key.downHandler.bind(key);
const upListener = key.upHandler.bind(key);
window.addEventListener(
"keydown", downListener, false
);
window.addEventListener(
"keyup", upListener, false
);
// Detach event listeners
key.unsubscribe = () => {
window.removeEventListener("keydown", downListener);
window.removeEventListener("keyup", upListener);
};
return key;
}
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keyboard
用起来很方便,就像下面这样:
let keyObject = keyboard(keyValue);
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它只有一个参数,它的值就是你想监听的按键名称。所有按键列表,点击查看
可以为keyboard对象定义press
和release
方法,就像下面这样:
keyObject.press = () => {
//key object pressed
};
keyObject.release = () => {
//key object released
};
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keyboard对象也有isDown
和isUp
属性,值为布尔值。你可以通过他们检查每个按键的状态。
不要忘记使用unsubscribe
方法删除事件监听器:
keyObject.unsubscribe();
1
你可以在examples
目录下找到keyboardMovement.html
,来查看我们是如何使用keyboard
函数的,那里我们通过方向键移动精灵。
;
这个案例代码如下:
function setup() {
//Create the `cat` sprite
cat = new Sprite(resources["images/cat.png"].texture);
cat.y = 96;
cat.vx = 0;
cat.vy = 0;
app.stage.addChild(cat);
//Capture the keyboard arrow keys
let left = keyboard("ArrowLeft"),
up = keyboard("ArrowUp"),
right = keyboard("ArrowRight"),
down = keyboard("ArrowDown");
//Left arrow key `press` method
left.press = () => {
//Change the cat's velocity when the key is pressed
cat.vx = -5;
cat.vy = 0;
};
//Left arrow key `release` method
left.release = () => {
//If the left arrow has been released, and the right arrow isn't down,
//and the cat isn't moving vertically:
//Stop the cat
if (!right.isDown && cat.vy === 0) {
cat.vx = 0;
}
};
//Up
up.press = () => {
cat.vy = -5;
cat.vx = 0;
};
up.release = () => {
if (!down.isDown && cat.vx === 0) {
cat.vy = 0;
}
};
//Right
right.press = () => {
cat.vx = 5;
cat.vy = 0;
};
right.release = () => {
if (!left.isDown && cat.vy === 0) {
cat.vx = 0;
}
};
//Down
down.press = () => {
cat.vy = 5;
cat.vx = 0;
};
down.release = () => {
if (!up.isDown && cat.vx === 0) {
cat.vy = 0;
}
};
//Set the game state
state = play;
//Start the game loop
app.ticker.add(delta => gameLoop(delta));
}
function gameLoop(delta){
//Update the current game state:
state(delta);
}
function play(delta) {
//Use the cat's velocity to make it move
cat.x += cat.vx;
cat.y += cat.vy
}
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