Smooth animation on a persistently refreshing canvas
Posted
by
Neurofluxation
on Game Development
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Published on 2011-05-09T06:38:48Z
Indexed on
2012/10/11
15:49 UTC
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Yo everyone!
I have been working on an Isometric Tile Game Engine in HTML5/Canvas for a little while now and I have a complete working game. Earlier today I looked back over my code and thought: "hmm, let's try to get this animated smoothly..."
And since then, that is all I have tried to do.
The problem
I would like the character to actually "slide" from tile to tile - but the canvas redrawing doesn't allow this - does anyone have any ideas....? Code and fiddle below...
Fiddle with it! http://jsfiddle.net/neuroflux/n7VAu/
<html>
<head>
<title>tileEngine - Isometric</title>
<style type="text/css">
* { margin: 0px; padding: 0px; font-family: arial, helvetica, sans-serif; font-size: 12px; cursor: default; }
</style>
<script type="text/javascript">
var map = Array( //land
[[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0]],
[[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0]],
[[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0]],
[[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0]],
[[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0]],
[[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0]],
[[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0]],
[[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0]],
[[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0]],
[[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0],[0,0,0]]
);
var tileDict = Array("http://www.wikiword.co.uk/release-candidate/canvas/tileEngine/land.png");
var charDict = Array("http://www.wikiword.co.uk/release-candidate/canvas/tileEngine/mario.png");
var objectDict = Array("http://www.wikiword.co.uk/release-candidate/canvas/tileEngine/rock.png"); //last is one more
var objectImg = new Array();
var charImg = new Array();
var tileImg = new Array();
var loaded = 0;
var loadTimer;
var ymouse;
var xmouse;
var eventUpdate = 0;
var playerX = 0;
var playerY = 0;
function loadImg(){ //preload images and calculate the total loading time
for(var i=0;i<tileDict.length;i++){
tileImg[i] = new Image();
tileImg[i].src = tileDict[i];
tileImg[i].onload = function(){
loaded++;
}
}
i = 0;
for(var i=0;i<charDict.length;i++){
charImg[i] = new Image();
charImg[i].src = charDict[i];
charImg[i].onload = function(){
loaded++;
}
}
i = 0;
for(var i=0;i<objectDict.length;i++){
objectImg[i] = new Image();
objectImg[i].src = objectDict[i];
objectImg[i].onload = function(){
loaded++;
}
}
}
function checkKeycode(event) { //key pressed
var keycode;
if(event == null) {
keyCode = window.event.keyCode;
} else {
keyCode = event.keyCode;
}
switch(keyCode) {
case 38: //left
if(!map[playerX-1][playerY][1] > 0){
playerX--;
}
break;
case 40: //right
if(!map[playerX+1][playerY][1] > 0){
playerX++;
}
break;
case 39: //up
if(!map[playerX][playerY-1][1] > 0){
playerY--;
}
break;
case 37: //down
if(!map[playerX][playerY+1][1] > 0){
playerY++;
}
break;
default:
break;
}
}
function loadAll(){ //load the game
if(loaded == tileDict.length + charDict.length + objectDict.length){
clearInterval(loadTimer);
loadTimer = setInterval(gameUpdate,100);
}
}
function drawMap(){ //draw the map (in intervals)
var tileH = 25;
var tileW = 50;
mapX = 80;
mapY = 10;
for(i=0;i<map.length;i++){
for(j=0;j<map[i].length;j++){
var drawTile= map[i][j][0];
var xpos = (i-j)*tileH + mapX*4.5;
var ypos = (i+j)*tileH/2+ mapY*3.0;
ctx.drawImage(tileImg[drawTile],xpos,ypos);
if(i == playerX && j == playerY){
you = ctx.drawImage(charImg[0],xpos,ypos-(charImg[0].height/2));
}
}
}
}
function init(){ //initialise the main functions and even handlers
ctx = document.getElementById('main').getContext('2d');
loadImg();
loadTimer = setInterval(loadAll,10);
document.onkeydown = checkKeycode;
}
function gameUpdate() { //update the game, clear canvas etc
ctx.clearRect(0,0,904,460);
ctx.fillStyle = "rgba(255, 255, 255, 1.0)"; //assign color
drawMap();
}
</script>
</head>
<body align="center" style="text-align: center;" onload="init()">
<canvas id="main" width="904" height="465">
<h1 style="color: white; font-size: 24px;">I'll be damned, there be no HTML5 & canvas support on this 'ere electronic machine!<sub>This game, jus' plain ol' won't work!</sub></h1>
</canvas>
</body>
</html>
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