代码： 全选
// Setup requestAnimationFrame
requestAnimationFrame = window.requestAnimationFrame || window.mozRequestAnimationFrame ||
window.webkitRequestAnimationFrame || window.msRequestAnimationFrame;
// Create the canvas
var canvas = document.createElement("canvas");
var ctx = canvas.getContext("2d");
canvas.width = 1250;
canvas.height = 580;
document.body.appendChild(canvas);
// Background image
var bgReady = false;
var bgImage = new Image();
bgImage.onload = function () {
bgReady = true;
};
bgImage.src = "img/background.png";
// Hero image
var heroReady = false;
var heroImage = new Image();
heroImage.onload = function () {
heroReady = true;
};
heroImage.src = "img/hero.png";
// Monster image
var monsterReady = false;
var monsterImage = new Image();
monsterImage.onload = function () {
monsterReady = true;
};
//var hostReady = false;
//var hostImage = new Image()
//hostImage.onload =function (){
// hostReady =true;
//};
monsterImage.src = "img/monster.png";
//hostImage.src = "img/host.png
// Game objects
var hero = {
speed: 512 // movement in pixels per second
};
var monster = {
speed: 256};
//var host = {
// speed: 1
var monstersCaught = 0;
// Handle keyboard controls
var keysDown = {};
addEventListener("keydown", function (e) {
keysDown[e.keyCode] = true;
}, false);
addEventListener("keyup", function (e) {
delete keysDown[e.keyCode];
}, false);
// Reset the game when the player catches a monster
var reset = function () {
// hero.x = canvas.width / 2;
// hero.y = canvas.height / 2;
// Throw the monster somewhere on the screen randomly
monster.x = 550 + (Math.random() * (canvas.width - 64));
monster.y = 50 + (Math.random() * (canvas.height - 64));
};
// Update game objects
var update = function (modifier) {
// host.x -=hoster.speed * modifier;
monster.x -=monster.speed * modifier;
if (monster.x < 0){
alert ("Game is over!")};
// monster.y += monster.speed * modifier;
if (38 in keysDown) { // Player holding up
hero.y -= hero.speed * modifier;
}
if (40 in keysDown) { // Player holding down
hero.y += hero.speed * modifier;
}
if (37 in keysDown) { // Player holding left
hero.x -= hero.speed * modifier;
}
if (39 in keysDown) { // Player holding right
hero.x += hero.speed * modifier;
}
// Are they touching?
if (
hero.x <= (monster.x + 32)
&& monster.x <= (hero.x + 32)
&& hero.y <= (monster.y + 32)
&& monster.y <= (hero.y + 32)
) {
++monstersCaught;
reset();
}
};
// Draw everything
var render = function () {
if (bgReady) {
ctx.drawImage(bgImage, 0, 0);
}
if (heroReady) {
ctx.drawImage(heroImage, hero.x, hero.y);
}
if (monsterReady) {
ctx.drawImage(monsterImage, monster.x, monster.y);
// if (hostReady) {
// ctx.drawImage(hostImage, host.x, host.y)
}
// Score
ctx.fillStyle = "rgb(250, 250, 250)";
ctx.font = "24px Helvetica";
ctx.textAlign = "left";
ctx.textBaseline = "top";
ctx.fillText("Goblins caught: " + monstersCaught, 32, 32);
};
// The main game loop
var main = function () {
var now = Date.now();
var delta = now - then;
update(delta / 1000);
render();
then = now;
requestAnimationFrame(main);
};
// Let's play this game!
hero.x = canvas.width / 2;
hero.y = canvas.height / 2;
reset();
var then = Date.now();
main();