我在这个代码中有一个错误导致船在从地球返回后在太空中飞得越来越快。我想不出这个。
我将速度设置为0.1，使其在空间中超级慢。当你点击星球时，我会运行一个功能，将画布移出屏幕，并使用zindex将div标签添加到堆栈的顶部。当你着陆并返回轨道时，船只会稍微快一点。在做了大约10-15次之后，船的移动远远大于设定的0.1速度。我将包含html，js和css，以便您可以运行它来进行测试。
以下是整个代码。
// Canvas Context's
var canvasMS = document.getElementById('MainScreen_cvs');
var ctxMain = canvasMS.getContext('2d');
var canvasShip = document.getElementById('Ship_cvs');
var ctxShip = canvasShip.getContext('2d');
var PlanetDiv = document.getElementById('PlanetDiv');
var OrbitReturn = document.getElementById('OrbitReturn');
var canvasPlanets = document.getElementById('Planets_cvs');
var ctxPlanets = canvasPlanets.getContext('2d');
var canvasHUD = document.getElementById('HUD_cvs');
var ctxHUD = canvasHUD.getContext('2d');
var canvasSurface = document.getElementById('Surface_cvs');
var ctxSurface = canvasSurface.getContext('2d');
// ----------------------------------End Canvas Context
var Player1;
var Planet1;
var planetClicked;
var gameWidth = canvasMS.width;
var gameHeight = canvasMS.height;
var mouseX = 10000;
var mouseY = 10000;
var SpaceMapX = 10;
var SpaceMapY = 10;
var SurfaceMap = 0;
var SurfaceMap2 = -1600;
var inSpace = true;
var onSurface = false;
var requestAnimFrame = window.requestAnimationFrame ||
window.webkitRequestAnimationFrame ||
window.mozRequestAnimationFrame ||
window.msRequestAnimationFrame ||
window.oRequestAnimationFrame;
// Load Images
var imgMap = new Image();
imgMap.src = 'images/bg1.png';
var imgButtons = new Image();
imgButtons.src = 'images/button_sprite.png';
var imgBlueWindow = new Image();
imgBlueWindow.src = 'images/blue_window.png';
var imgSprite = new Image();
imgSprite.src = 'images/sprite.png';
var imgPlanets = new Image();
imgPlanets.src = 'images/earthlike_p1.png';
var imgBluesky1 = new Image();
imgBluesky1.src = 'images/bluesky1.png';
var imgBluesky2 = new Image();
imgBluesky2.src = 'images/bluesky2.png';
imgMap.addEventListener('load',init,false);
// ------------- End Loading Images
//-------------------- Create Game Objects ----------------
function CreateGameObjects(){
Player1 = new Ship();
Planet1 = new Planet();
};
//---------------END CREATING GAME OBJECTS------------------
function init(){ //----------------------------------------------- GAME INITIALIZATION
document.addEventListener('keydown',checkKeyDown,false);
document.addEventListener('keyup',checkKeyUp,false);
document.addEventListener("mousedown", checkMouseDown, false);
document.addEventListener("mouseup", checkMouseUp, false);
CreateGameObjects();
Loop();
};
function Loop() { // ---------------- Main Game Loop
clearCtx();
DrawGameObjects();
requestAnimFrame(Loop);
};
function planetSurface(){
if(onSurface){
clearCtx();
HUD();
Player1.draw();
if(mouseY < 21 && mouseX > 693){
ReturntoOrbit();
}
planetClicked.drawSurfaceImg();
var CloseButton = '<button style="float:right;" type="button">Return to Orbit</button>' ;
OrbitReturn.innerHTML = CloseButton;
requestAnimFrame(planetSurface);
}
};
function DrawGameObjects(){
Player1.draw();
Planet1.draw();
HUD();
};
function HUD(){
canvasHUD.style.zIndex = "100";
if (onSurface){
ctxHUD.fillStyle = "#000";
ctxHUD.fillText("locSurface: " + planetClicked.locSurface, 20,30);
}
if (inSpace)
ctxHUD.fillStyle = "#fff";
ctxHUD.fillText("Speed: " + Player1.speed, 60,60);
ctxHUD.fillText("drawX: " + Player1.drawX, 600,40);
ctxHUD.fillText("drawY: " + Player1.drawY, 600,30);
// ctxHUD.fillText("Planet Clicked: " + Planet1.isClicked, 600,50);
}
//----------------------------------------------------------- Objects
/************************************************************************************/
//--------------------------------- SPACE SHIP --------------------------------------
function Ship(){
this.srcX = 0;
this.srcY = 0;
this.srcW = 60;
this.srcH = 60;
this.drawX = 20 ;
this.drawY = 50 ;
this.speed = 0;
this.surfaceSpeed = 10;
this.drift = 0.45;
this.w = 16;
this.h = 16;
this.isUpKey = false;
this.isDownKey = false;
this.isLeftKey = false;
this.isRightKey = false;
this.isSpacebar = false;
this.direction = "n/a";
this.isMoving = false;
this.isClicked = false;
this.surfX = 350;
this.surfY = 200;
};
Ship.prototype.draw = function() {
if(inSpace)
ctxShip.drawImage(imgSprite,this.srcX,this.srcY,this.srcW,this.srcH,this.drawX,this.drawY,this.w,this.h);
if(onSurface)
ctxShip.drawImage(imgSprite,this.srcX,this.srcY,this.srcW,this.srcH,this.surfX,this.surfY,this.w,this.h);
this.checkPos(planetClicked);
};
Ship.prototype.checkPos = function (PlanetX){
if(inSpace){
this.srcY = 0;
this.srcW = 60;
this.w = 16;
this.h = 16;
this.speed = 0.1;
//----------------------------- Move Ship and Map based on the speed of the ship.
if(this.isLeftKey){
this.drawX -= this.speed;
if(SpaceMapX >= 1){
SpaceMapX -= this.speed;
}
}
if(this.isRightKey){
this.drawX += this.speed;
if(SpaceMapX <= 2190)SpaceMapX += this.speed;
}
if(this.isDownKey){
this.drawY += this.speed;
if(SpaceMapY <= 2490)SpaceMapY += this.speed;
}
if (this.isUpKey) {
this.drawY -= this.speed;
if(SpaceMapY >= 1){
SpaceMapY -= this.speed;
}
}
if (SpaceMapY < 0) {SpaceMapY = 0;}
if (SpaceMapX < 0 ) {SpaceMapX = 0}
//--------------------------------------------------------------------END
//-----------------------------------Change Ship Graphic based on direction and map boundaries.
if(this.isUpKey) this.srcX = 360;
if(this.isDownKey) this.srcX = 120;
if(this.isLeftKey) this.srcX = 240;
if(this.isRightKey) this.srcX = 0;
if(this.isUpKey && this.isLeftKey) this.srcX = 300;
if(this.isUpKey && this.isRightKey) this.srcX = 420;
if(this.isDownKey && this.isLeftKey) this.srcX = 180;
if(this.isDownKey && this.isRightKey) this.srcX = 60;
if (this.drawX <= 5) this.drawX = 5;
if (this.drawY <= 5) {this.drawY = 5};
if (this.drawY >= 480) {this.drawY = 480};
if (this.drawX >= 780) {this.drawX = 780};
//----------------------------------------------------------------END
ctxMain.drawImage(imgMap,SpaceMapX,SpaceMapY,gameWidth,gameHeight,0,0,gameWidth,gameHeight);
}
if (onSurface) {
this.srcY = 240;
this.srcW = 92;
this.w = 93;
this.h = 60;
if(this.isLeftKey){
PlanetX.locSurface -= this.surfaceSpeed;
SurfaceMap += this.surfaceSpeed;
SurfaceMap2 += this.surfaceSpeed;
PlanetX.MapDirection = -1;
this.srcX = 93;
}
if(this.isRightKey){
PlanetX.locSurface += this.surfaceSpeed;
SurfaceMap -= this.surfaceSpeed;
SurfaceMap2 -= this.surfaceSpeed;
PlanetX.MapDirection = 1;
this.srcX = 0;
}
}
};
//------------------------------END OF SPACE SHIP ------------------------------------
//----------------------------- PLANET OBJECT INFO ------------------------------------
function Planet(){
this.srcX = 0;
this.srcY = 0;
this.srcW = 100;
this.srcH = 100;
this.w = 50;
this.h = 50;
this.coordX = 100;
this.coordY = 100;
this.planetType = "Small Earthlike Planet."
this.drawX = this.coordX - SpaceMapX;
this.drawY = this.coordY - SpaceMapY;
this.surfaceIMG = imgBluesky1;
this.isClicked = false;
this.locSurface = 0;
};
Planet.prototype.draw = function(){
this.drawX = this.coordX - SpaceMapX;
this.drawY = this.coordY - SpaceMapY;
ifClicked(this);
if(this.isClicked){
PlanetDiv.style.display = "block";
var LandPlanetDivButton = '<button id="LandPlanetDivButton" type="button" onclick="landOnSurface();">Land On Surface</button>';
var ClosePlanetDivButton = '<button id="ClosePlanetDivButton" type="button" onclick="ClosePlanetDiv();">Close (x)</button><br/><p id="PlanetDivText">' ;
PlanetDiv.style.zIndex = "2";
HideCanvas();
planetClicked = this;
PlanetDiv.innerHTML = LandPlanetDivButton + ClosePlanetDivButton + this.planetType; + '</p>';
}
ctxPlanets.drawImage(imgPlanets,this.srcX,this.srcY,this.srcW,this.srcH,this.drawX,this.drawY,this.w,this.h);
};
Planet.prototype.drawSurfaceImg = function(){
if(SurfaceMap2 >= 0) SurfaceMap2 = -1600;
if(SurfaceMap2 < -1600) SurfaceMap2 = -1;
if(SurfaceMap >= 1600) SurfaceMap = 0;
if(SurfaceMap < 0) SurfaceMap = 1599;
ctxSurface.drawImage(this.surfaceIMG, 0, 0, 1600, gameHeight, SurfaceMap, 0, 1600, gameHeight);
ctxSurface.drawImage(this.surfaceIMG, 0, 0, 1600, gameHeight, SurfaceMap2, 0, 1600, gameHeight);
};
//----------------------------- END OF PLANET OBJECT -----------------------------------
//-----end Objects
function randomFromTo(from,to){
return Math.floor(Math.random()*(to-from+1)+from);
};
function closestNum(Num, a){
var num = Num + (gameWidth/2);
var closest = a[0];
var difference = Math.abs (num - closest);
for (var i = 0; i < a.length; i++) {
var difference2 = Math.abs (num - a[i]);
if (difference2 < difference) {
difference = difference2;
closest = a[i];
}
}
return closest;
};
function sortNum(a)
{
var swapped;
do{
swapped = false;
for (var i=0; i < a.length-1; i++) {
if (a[i] > a[i+1]) {
var temp = a[i];
a[i] = a[i+1];
a[i+1] = temp;
swapped = true;
}
}
}while (swapped);
};
function ifClicked(obj){
if(mouseX >= obj.drawX && mouseX <= obj.drawX + obj.w){
if(mouseY >= obj.drawY && mouseY <= obj.drawY + obj.h){
obj.isClicked = true;
}
}
else{
obj.isClicked = false;
}
};
function clearCtx() {
ctxMain.clearRect(0,0,gameWidth,gameHeight);
ctxShip.clearRect(0,0,gameWidth,gameHeight);
ctxPlanets.clearRect(0,0,gameWidth,gameHeight);
ctxHUD.clearRect(0,0,gameWidth,gameHeight);
ctxSurface.clearRect(0,0,gameWidth,gameHeight);
};
function checkKeyDown(e){
var keyID = e.keyCode || e.which;
if(keyID === 38 || keyID === 87){ // up arrow or W key
Player1.isUpKey = true;
Player1.direction = "North";
Player1.isMoving = true;
e.preventDefault();
}
if(keyID === 39|| keyID === 68){ // right arrow or D key
Player1.isRightKey = true;
Player1.direction = "East"
Player1.isMoving = true;
e.preventDefault();
}
if(keyID === 40 || keyID === 83){ // down arrow or S key
Player1.isDownKey = true;
Player1.direction = "South";
Player1.isMoving = true;
e.preventDefault();
}
if(keyID === 37 || keyID === 65){ // left arrow or A key
Player1.isLeftKey = true;
Player1.direction = "West";
Player1.isMoving = true;
e.preventDefault();
}
};
function checkKeyUp(e){
var keyID = e.keyCode || e.which;
if(keyID === 38 || keyID === 87){ // up arrow or W key
Player1.isUpKey = false;
Player1.isMoving = false;
e.preventDefault();
}
if(keyID === 39|| keyID === 68){ // right arrow or D key
Player1.isRightKey = false;
Player1.isMoving = false;
e.preventDefault();
}
if(keyID === 40 || keyID === 83){ // down arrow or S key
Player1.isDownKey = false;
Player1.isMoving = false;
e.preventDefault();
}
if(keyID === 37 || keyID === 65){ // left arrow or A key
Player1.isLeftKey = false;
Player1.isMoving = false;
e.preventDefault();
}
};
function clearMouse(){
mouseX = 10000;
mouseY = 10000;
};
function checkMouseDown(e) {
var mX = (e.clientX - (canvasMS.offsetLeft - canvasMS.scrollLeft));
var mY = (e.clientY - (canvasMS.offsetTop - canvasMS.scrollTop));
if(mX <= gameWidth && mX >= 0) mouseX = mX;
if(mY <= gameHeight && mY >= 0) mouseY = mY;
//mouseIsDown = true;
};
function checkMouseUp(e){
//mouseIsDown = false;
clearMouse();
};
function ClosePlanetDiv (){
PlanetDiv.style.zIndex = "-2";
PlanetDiv.innerHTML = "";
PlanetDiv.style.display = "none";
ShowCanvas();
};
function HideCanvas(){
canvasShip.style.marginTop = "-10000px";
canvasPlanets.style.marginTop = "-10000px";
};
function ShowCanvas(){
canvasShip.style.marginTop = "-500px";
canvasPlanets.style.marginTop = "-500px";
};
function landOnSurface(){
ClosePlanetDiv();
inSpace = false;
onSurface = true;
Player1.srcX = 0;
planetSurface();
canvasSurface.style.display = "block";
OrbitReturn.style.display = "block";
};
function ReturntoOrbit(){
OrbitReturn.style.display = "none";
canvasSurface.style.display = "none";
inSpace = true;
onSurface = false;
Loop();
};
<!doctype html>
<html lang='en'>
<head>
<meta charset="utf-8">
<title>Space Explorer</title>
<link rel="stylesheet" type="text/css" href="style.css">
<script src="Functions.js"></script>
</head>
<body>
<canvas id="MainScreen_cvs" width="800" height="500"></canvas>
<div id="PlanetDiv"></div>
<canvas id="Surface_cvs" width="800" height="500"></canvas>
<canvas id="Ship_cvs" width="800" height="500"></canvas>
<canvas id="Planets_cvs" width="800" height="500"></canvas>
<canvas id="HUD_cvs" width="800" height="500"></canvas>
<div id="OrbitReturn"></div>
<div id="log">
<h1 style="color:blue;">Recent updates will be logged here when made live.</h1>
<hr />
<h3> Wednesday August 3, 2016 </h3>
<ul>
<li> HTML file completed. Working on getting JS files started.</li>
<li> JS files created. </li>
<li>Basic ship & flight functions in place. Basic star map initialized.</li>
</ul>
<hr />
</div>
<script type="text/javascript" src="game.js"></script>
</body>
</html>
body {
background: #303030;
}
#MainScreen_cvs {
position: relative;
display: block;
background: #777777 ;
margin: 30px auto 0px;
z-index: 1;
}
#Surface_cvs{
position: relative;
display: none;
z-index: 1;
margin: -500px auto 0px;
}
#Ship_cvs, #Planets_cvs, #HUD_cvs {
display: block;
position: relative;
margin: -500px auto 0px;
z-index: 1;
}
#log {
display: block;
position: absolute;
top: 560px;
left: 233px;
background: #ffffff;
overflow: scroll;
width: 800px;
height: 300px;
z-index: 3;
}
#OrbitReturn{
display: block;
position: relative;
width: 800px;
height: 500px;
z-index: 3;
margin: -500px auto 0px;
}
#PlanetDiv {
display: block;
position: relative;
width: 800px;
height: 500px;
background-image: url("images/Sky.jpg");
z-index: -2;
margin: -500px auto 0px;
}
#ClosePlanetDivButton{
float: right;
}
#LandPlanetDivButton{
position: absolute;
top: 400px;
left: 325px;
font-size: 20px;
}
#PlanetDivText{
text-indent: 50px;
font-size: 20px;
}
答案 0 :(得分：0)
Ship.prototype.checkPos正在发生一些事情。每次降落在地球上，看起来就像检查暂停一样，然后在你进入轨道时启动。但这一次他checkPos的速度越来越快。
我可以继续盯着它，但你可以从那里弄明白。我把一个console.log（＆＃39; checkPos＆＃39;）放在该功能的顶部，看着它暂停并重启。
Ship.prototype.checkPos = function(PlanetX) {
console.log('checkPos');
if (inSpace) {
...
我认为可能就在这里
function ReturntoOrbit() {
OrbitReturn.style.display = "none";
canvasSurface.style.display = "none";
inSpace = true;
onSurface = false;
//Loop(); <--- this little guy. Get rid of him.
};