我正在开发一款游戏，我想知道为什么“螃蟹”(一个实体)不能像“怪物”(也是一个实体)一样被杀死。我的意思是，如果我触摸妖精怪物，我就会得到一分，但我只是走过螃蟹。 我尝试添加一个 if..else，但随后玩家每秒获得数千分。 我做错了什么？
// Create the canvas
var canvas = document.createElement("canvas");
var ctx = canvas.getContext("2d");
canvas.width = 512;
canvas.height = 480;
document.body.appendChild(canvas);
// Background image
var bgReady = false;
var bgImage = new Image();
bgImage.onload = function() {
bgReady = true;
};
bgImage.src = "images/background.png";
// Hero image
var heroReady = false;
var heroImage = new Image();
heroImage.onload = function() {
heroReady = true;
};
heroImage.src = "images/hero.png";
// Monster image
var monsterReady = false;
var monsterImage = new Image();
monsterImage.onload = function() {
monsterReady = true;
};
monsterImage.src = "images/monster.png";
// Crab image
var crabReady = false;
var crabImage = new Image();
crabImage.onload = function() {
crabReady = true;
};
crabImage.src = "images/old/hero.png";
// Game objects
var hero = {
speed: 300 // movement in pixels per second
};
var monster = {};
var crab = {};
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 = 32 + (Math.random() * (canvas.width - 64));
monster.y = 32 + (Math.random() * (canvas.height - 64));
// Throw the crab somewhere on the screen randomly
crab.x = 32 + (Math.random() * (canvas.width - 64));
crab.y = 32 + (Math.random() * (canvas.height - 64));
};
// Update game objects
var update = function(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 (crabReady) {
ctx.drawImage(crabImage, crab.x, crab.y);
}
// Score
ctx.fillStyle = "rgb(250, 250, 250)";
ctx.font = "24px Helvetica";
ctx.textAlign = "left";
ctx.textBaseline = "top";
ctx.fillText("Mobs killed: " + monstersCaught, 32, 32);
};
// The main game loop
var main = function() {
var now = Date.now();
var delta = now - then;
update(delta / 1000);
render();
then = now;
// Request to do this again ASAP
requestAnimationFrame(main);
};
// Cross-browser support for requestAnimationFrame
var w = window;
requestAnimationFrame = w.requestAnimationFrame || w.webkitRequestAnimationFrame || w.msRequestAnimationFrame || w.mozRequestAnimationFrame;
// Let's play this game!
var then = Date.now();
reset();
main();<!DOCTYPE html>
<html>
<head>
<title>Underbound</title>
<link rel="stylesheet" type="text/css" href="style.css">
</head>
<body>
<div class="game">
<script src="js/game.js"></script>
</div>
</body>
</html>最佳答案
因为你只是检查英雄是否与怪物发生碰撞。
hero.x <= (monster.x + 32) && monster.x <= (hero.x + 32) && hero.y <= (monster.y + 32) && monster.y <= (hero.y + 32)
相反，您可能应该创建一个函数来检查它们是否发生冲突:
function isColliding(a, b) {
return a.x <= (b.x + 32) && b.x <= (a.x + 32) &&
a.y <= (b.y + 32) && b.y <= (a.y + 32);
}
if (isColliding(hero, monster)) { ...
然后还可以检查它们是否与crab发生碰撞。
if (isColliding(hero, crab)) { ...
如果你将所有“怪物”放入一个数组中，然后检查数组中的每个怪物，那么它会更可持续(直到你有很多怪物)。
至于快速获得大量积分的问题:你必须将怪物(或螃蟹)从游戏区域中移走，并在更新阶段停止检查碰撞，否则玩家将继续与螃蟹碰撞并获得积分。
对此的一个解决方案是为你的怪物提供一个active(或类似的属性)。默认情况下，这是 true，但是当玩家与它们碰撞时，这将是 false。然后，您只需绘制它们并在 active 为 true 时检查碰撞。
关于javascript - 为什么 "crab"(一个实体)不像 "monster"(也是一个实体)那样可触摸？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/35161046/