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JavaScript - Html5 Canvas Game Drawing
I am trying to create an Asteroids type game using JavaScript along with html5's canvas element for drawing. I have searched around and have looked at examples but I can't figure out what is wrong with my rendering that I do in the game loop that is run every frame. The problem appears to be only that the canvas is not cleared at the beginning of each frame but I feel there might be something wrong also. The code used and shown below only works in Firefox but not Google Chrome or Safari.
Here is a picture of what it renders in Chrome: What is is supposed to look like and is in Firefox: Here is my set up for drawing on the canvas: Code: var canvas = null;
var c2d = null;
//...
window.onload = init;
function init() {
canvas = document.getElementById('canvas');
c2d = canvas.getContext('2d');
setInterval( step, 1000/FPS );
//...
//c2d.setTransform(1,0,0,1,0,0); // reset to identity <--Do I need this?
}
Below is the game loop function. Am I clearing the canvas correctly because it does not clear the screen? Also am I using the save and restore functions correctly? Each asteroid and player drawn is at a different of position and rotation so am I doing it correct to draw them? Code: function step() {
//...
canvas.width = canvas.width; //clear canvas PROBLEM
//Things I have tried:
//canvas.height = canvas.height; //clear canvas
//c2d.clearRect(0, 0, canvas.width, canvas.height);
for (u=0;u<asteroids.length;u++) {
c2d.save();
asteroids[u].draw();
c2d.restore();
}
c2d.save();
player.draw();
c2d.restore();
c2d.strokeStyle = "#000000";
c2d.stroke();
}
Below is the Asteroid and Player drawing functions. The Asteroid is a polygon and the Player is a triangle. Both rotate and are draw correctly but should I be passing a reference to the drawing reference? Code: function Asteroid_draw() {
c2d.translate( this.x, this.y );
c2d.rotate(this.angle);
for (i=0;i<this.points_x.length-1;i++) {
c2d.moveTo(this.points_x[i],this.points_y[i]);
c2d.lineTo(this.points_x[i+1],this.points_y[i+1]);
}
c2d.moveTo(this.points_x[0],this.points_y[0]);
c2d.lineTo(this.points_x[this.points_x.length-1],this.points_y[this.points_x.length-1]);
}
function Player_draw() {
c2d.translate( this.x, this.y );
c2d.rotate(this.angle);
//Points {0,-12}{7,5}{-7,5}
c2d.moveTo(0,-12);
c2d.lineTo(7,5);
c2d.moveTo(7,5);
c2d.lineTo(-7,5);
c2d.moveTo(-7,5);
c2d.lineTo(0,-12);
}
Any help is appreciated. Similar TutorialsHello, Codingforums. I have looked on Google for a solution, done a handful of things, and cannot get my script to draw to the page. Code: <html>
<head>
<script type="text/javascript" src="imageFuncs.js"></script>
<script type="text/javascript">
showImages = function() {
var drawingCanvas = document.getElementById("map");
// Check the element is in the DOM and the browser supports canvas
if (drawingCanvas.getContext) {
var ctx = drawingCanvas.getContext("2d");
var imageSources = new Array("map.jpg");
var images = new Array();
images = loadImages(imageSources);
for (var i = 0; i < images.length; i++) {
var img = new Image();
img.src = images[i].src;
img.onload = function(){
ctx.drawImage(img,0,0,screen.width,screen.height);
}
}
}
}
</script>
</head>
<body onload="showImages()">
<canvas id="map">Your browser does not support canvases...</canvas>
</body>
</html>
The problem appears on the ctx.drawImage(img,0,0,screen.width,screen.height); line. I read that the drawImage method will not draw the image if the images are not loaded, which is why I tried an onload event for img. When I run the code the way it is now, I get a attempt to run compile-and-go script on a cleared scope error from Firebug. When I remove the onload event, the script runs without errors. Either way, no image is drawn on the page. Any help? If it helps, this is the loadImages function that I used to get the array of loaded image objects: Code: function loadImages(sources){
var images = new Array();
var loadedImages = 0;
var numImages = 0;
for (var src in sources) {
numImages++;
}
for (var src in sources) {
images[src] = new Image();
images[src].src = sources[src];
}
return images;
}
I have a Canvas controller Class and a new Sprite Controller class Please note I'm not using GIF sprites these are proper programmable sprites like you get in C game engines So i have a Class that controls my Canvas and the Drawing of my Canvas what i mean by this is if you call a new instance of my Class it will create a new Canvas if you already have a canvas you can get a JSRenderEng Object from your Canvas id Now my problem lies with getting my sprites to draw them self's currently my sprites can only appear in one place in a 100x100 px canvas they load as 98x98 1top 1left so they should be a perfect mathematical square inside the canvas with a 1px border, for some reason its not drawing But here is an explination about the classes The Canvas handles the start of the drawing events by going though the sprites attached to the canvas and then calls there draw method, However i seam to have a problem with this my draw method is being fired but is not rendering on the canvas can any one spot the problem. PHP Code: this.draw = function(){ //this.updateParams(); var context = this._canvas.getContext("2d"); context.beginPath(); context.fillRect( 98, 98, 1, 1 ); context.fillStyle = "#000000"; context.fill(); context.closePath(); } Was putting the width and height and the location in the wrong order (DURRRR) I'm having a problem with the <CANVAS> element in JavaScript. here's what i'm trying to do: I need 3 different canvas elements for writing a signature to. they must all 3 be visible at the same time My problem that i'm having is that i can't seem to get the code to work which will write to more than one canvas. here's my code: Code: <html>
<head>
<script language="javascript">
function WriteSignature(element, event)
{
document.addEventListener("mousemove", PenHandler, true);
document.addEventListener("mouseup", upHandler, true);
event.stopPropagation();
event.preventDefault();
function PenHandler(event)
{
var x = event.clientX;
var y = event.clientY;
// mouse event goes here
var canvas1 = document.getElementById("Canvas1");
var ctx = canvas1.getContext("2d");
var PenSize = 2;
ctx.fillStyle = "Black";
ctx.fillRect (x, y, PenSize, PenSize);
event.stopPropagation();
}
function upHandler(event)
{
document.removeEventListener("mouseup", upHandler, true);
document.removeEventListener("mousemove", PenHandler, true);
event.stopPropagation();
}
}
</script>
</head>
<body>
<Canvas id="Canvas1" Width="400" Height="100" Style="border:2px solid black" onmousedown="WriteSignature(this, event);"></Canvas><br><br>
<Canvas id="Canvas2" Width="400" Height="100" Style="border:2px solid black" onmousedown="WriteSignature(this, event);"></Canvas><br>
</body>
</html>
Code:
<html>
<head>
<title>test</title>
</head>
<body>
<script language = "javaScript">
var clouds = [];
var i = 0;
while(i <= 5) {
var cld = new Image();
cld.onload = function()
{
clouds.push(cld);
}
cld.src = "cloud.png";
i++;
}
document.write(clouds.length);
</script>
</body>
</html>
Where am I messing up clouds.length returns 0. Why? I know this is simple, but it will get more complex. I can search for the code, but I would like feedback as to what I'm doing wrong. This is more than likely going to be a multi stage question. More to come... ------ Also, I would like to say that this is my first post. Thanks in advance to those who reply. Hi there! I found this code, in reply to someone's problem, on this forum. I have altered it to my own needs, as it's an excellent piece of code. However, I would like it to run under HTML5. I believe I need to add "canvas" code to do the same?? I have already changed the doctype! HTML heading etc., Can anyone help? Many, many thanks!! Code: <!doctype html>
<head>
<meta charset=UTF-8" />
<title>Crazy Rally - France</title>
<script type="text/javascript">
var frames = new Array();
//load frames into array
for(var i = 1; i < 417; i++){
frames[i] = new Image(480,320);
frames[i].src = "track" + i + ".png";
}
//playback
var currentFrameNumber = 1;
var fps = 30; // frames / second
const speed = 1000 / fps; // milliseconds
//var speed = 33;
function nextFrame( )
{
document.getElementById("display").src = frames[currentFrameNumber].src;
currentFrameNumber = ( currentFrameNumber + 1 ) % frames.length;
setTimeout( nextFrame, speed );
}
window.onload = nextFrame;
</script>
</head>
<body>
<img id="display" src="track1.png" width="480" height="320">
</body>
</html>
I'm trying to finish off a NotePad/SketchPad app using the HTML5 canvas element and i am getting an error when i try to PUT image data to the canvas. also the getImageData() function for CANVAS is also not working. I would like to get this working soon, because i have a really nice Prototype of a 7 inch Touch screen device i would like to install this to. Error: canvas.putImageData is not a function according to all of the HTML5 canvas tutorials i've read (including the one on Mozilla-Dev), it should be correct, but it's still throwing this error. It makes no sense at all. I remember getting a similar error to this before by using the DOM element identifier - getElementByID() where the "D" is a capital letter when it should have been a lower case. However that doesn't seem to be the case here. Can anyone help me out with this? here's my HTML & JS code The main HTML UI file Code: <html><head>
<meta http-equiv="content-type" content="text/html; charset=ISO-8859-1">
<title>Sketch Book v1.0</title>
<script src="SketchBook.js" type="text/javascript"></script>
<script src="JSxpcom.js" language="text/javascript"></script>
</head>
<body onLoad="Init();">
<div id="SketchPageView">
<canvas id="SketchPage" width="480" height="640" style="background: #C7C1A3; position: absolute; top: 0px; left: 0px;" onmousedown="Draw(this, event);"></canvas>
</div>
<div id="Options" style="position: absolute; visibility: hidden; top: 100px; left: 50px;">
<table cellwidth="100" border="0" cellpadding="0" cellspacing="0" height="50">
<tbody><tr><td><img src="./Image/TL-black.PNG" height="19" width="19"></td><td bgcolor="#bce0f8"><center><b>Options</b></center><img src="./Image/delete.png" style="position:absolute; top: 2px; left: 150px; height: 18; width: 18;" onClick="HideOptions();"></td><td><img src="./Image/TR-black.PNG" height="19" width="19"></td></tr>
<tr><td bgcolor="#bce0f8"></td>
<td bgcolor="#bce0f8">
<div style="border: 1px solid black;">
<table>
<tbody><tr>
<td><center>Pen Size</center></td><td><center>Color</center></td>
</tr>
<tr>
<td>
<select id="GetPenSize" onchange="UpdatePenSize();">
<option value="1">1 px</option>
<option value="2">2 px</option>
<option value="3">3 px</option>
<option value="4">4 px</option>
<option value="5">5 px</option>
</select>
</td>
<td>
<select id="GetPenColor" onchange="UpdatePenColor();">
<option value="Black">Black</option>
<option value="White">White</option>
<option value="Red">Red</option>
<option value="Blue">Blue</option>
<option value="Green">Green</option>
<option value="Brown">Brown</option>
</select>
</td>
</tr>
<tr>
<td><input value="Restore" onclick="RestoreData();" type="button"></td><td><input value="Backup" onclick="BackupData();" type="button"></td>
</tr>
<tr>
<td><input value="Encrypt" onclick="EncryptData();" type="button"></td><td><input value="DeCrypt" onclick="DecryptData();" type="button"></td>
</tr>
</tbody></table>
</div>
</td>
<td bgcolor="#bce0f8"></td></tr>
<tr><td><img src="./Image/BL-black.PNG" height="19" width="19"></td> <td bgcolor="#bce0f8"></td><td align="right"><img src="./Image/BR-black.PNG" height="19" width="19"></td></tr>
</tbody></table>
</div>
<table id="UI" style="position: absolute; top: 0px; left: 412px; visibility: visible;" border="0" cellpadding="0" cellspacing="0" width="40">
<tbody><tr><td><img src="./Image/TL-black.PNG" height="19" width="19"></td><td bgcolor="#bce0f8"></td><td><img src="./Image/TR-black.PNG" height="19" width="19"></td></tr>
<tr><td bgcolor="#bce0f8"></td>
<td bgcolor="#bce0f8" height="600">
<img src="./Image/up.png" style="width: 30px; height: 30px;" onclick="NextNote('up');"><br><br><br><br>
<img src="./Image/plus.png" style="width: 30px; height: 30px;" onclick="NewSketch();"><br><br><br><br>
<img src="./Image/save.png" style="width: 30px; height: 30px;" onclick="SaveSketch();"><br><br><br><br>
<img src="./Image/clear.png" style="width: 30px; height: 30px;" onclick="ClearSketch();"><br><br><br><br>
<img src="./Image/delete.png" style="width: 30px; height: 30px;" onclick="DeleteSketch();"><br><br><br><br>
<img src="./Image/gear.png" style="width: 30px; height: 30px;" onclick="ShowOptions();"><br><br>
<img src="./Image/down.png" style="width: 30px; height: 30px;" onclick="NextNote('down');">
</td>
<td bgcolor="#bce0f8"></td> </tr>
<tr><td><img src="./Image/BL-black.PNG" height="19" width="19"></td> <td bgcolor="#bce0f8"></td> <td align="right"><img src="./Image/BR-black.PNG" height="19" width="19"></td></tr>
</tbody></table>
</body></html>
The JS file (has the CANVAS manipulation code in it) Code: var SketchDataFolder = "c:\\";
var PenSize = "3";
var PenShape = "Circle";
var PenColor = "Black";
var LoadFile = "";
var UIstatus = "visible";
var CurrentNote = 0;
var BGcolor = "#C7C1A3";
var DataPath = "\Data\\";
var FileList = [];
var SystemPath;
var UIstatus = "visible";
var Server = "localhost";
document.onkeyup = ToggleUI;
function Init()
{
// Get the System Path
GetSystemPath("SketchBook.html");
// Load All Filenames of the DataPath directory into an array
GetFileList(SystemPath + DataPath, FileList);
//Load the first Note onto the canvas
// if there are no notes in the directory, don't try to load anything
if(FileList.length > 0)
{
var NxtNote = LoadFromDisk(FileList[CurrentNote]);
// Load the image data onto the canvas
var canvas = document.getElementById("SketchPage");
var context = canvas.getContext("2d");
canvas.putImageData(NxtNote , 0 , 0 );
}
}
function HideOptions()
{
document.getElementById("Options").style.visibility = "hidden";
}
function ToggleUI(e)
{
var KeyID = (window.event) ? event.keyCode : e.keyCode;
var KeyValue = 18;
// Use a key to hide the toolbars so that most of the screen is used for the UI
if(KeyID == KeyValue)
{
if(UIstatus == "visible")
{
UIstatus = "hidden";
document.getElementById("UI").style.visibility = "hidden";
return;
}
if(UIstatus == "hidden")
{
UIstatus = "visible";
document.getElementById("UI").style.visibility = "visible";
}
}
}
function ShowOptions()
{
document.getElementById("Options").style.visibility = "visible";
}
function UpdatePenSize()
{
PenSize = document.getElementById('GetPenSize').value;
}
function UpdatePenShape()
{
PenShape = document.getElementById('GetPenShape').value;
}
function UpdatePenColor()
{
PenColor = document.getElementById('GetPenColor').value;
}
function Draw(element, event)
{
document.addEventListener("mousemove", PenHandler, true);
document.addEventListener("mouseup", upHandler, true);
event.stopPropagation();
event.preventDefault();
function PenHandler(event)
{
var x = event.clientX;
var y = event.clientY;
// mouse event goes here
var canvas = document.getElementById("SketchPage");
var ctx = canvas.getContext("2d");
if (PenShape ="Circle")
{
// This draws a circle
ctx.fillStyle = PenColor;
ctx.beginPath();
ctx.arc(x, y, PenSize, 0, Math.PI*2, true);
ctx.closePath();
ctx.fill();
}
event.stopPropagation();
}
function upHandler(event)
{
document.removeEventListener("mouseup", upHandler, true);
document.removeEventListener("mousemove", PenHandler, true);
event.stopPropagation();
}
}
function SaveSketch()
{
// Get the current file name
var FileName = SystemPath + DataPath + CurrentNote + ".img";
var canvas = document.getElementById("SketchPage");
var context = canvas.getContext("2d");
var ImgData = context.getImageData(0, 0, canvas.width, canvas.height);
alert(ImgData);
// Write the PNG file to the disk
SaveToDisk(FileName, ImageData);
}
function NextNote(Direction)
{
if(Direction == "up")
{
// Display the previoius note
CurrentNote--;
// Make sure you don't incrimnet to a non-existant note
if(CurrentNote <= 0)
{
CurrentNote = FileList.length;
}
var NxtNote = LoadFromDisk(SystemPath + DataPath + FileList[CurrentNote]);
// Load the image data onto the canvas
var canvas = document.getElementById("SketchPage");
var context = canvas.getContext("2d");
canvas.putImageData(NxtNote , 0 , 0 );
return;
}
if(Direction == "down")
{
//Display the Next note
CurrentNote++;
// Make sure you don't incrimnet to a non-existant note
if(CurrentNote > FileList.length)
{
CurrentNote = 0;
}
var NxtNote = LoadFromDisk(SystemPath + DataPath + FileList[CurrentNote]);
// Load the image data onto the canvas
var canvas = document.getElementById("SketchPage");
var context = canvas.getContext("2d");
canvas.putImageData(NxtNote , 0 , 0 );
return;
}
}
function DeleteNote()
{
// Delete The current note
DeleteFile(SystemPath + DataPath + FileList[CurrentNote]);
// Reload the Directory List
// Re-Dim the FileList Array
FileList.length = 0;
GetFileList(SystemPath + DataPath, FileList);
// Load The Previous Note
// Display the previoius note
CurrentNote--;
// Make sure you don't incrimnet to a non-existant note
if(CurrentNote <= 0)
{
CurrentNote = FileList.length;
}
var NxtNote = LoadFromDisk(FileList[CurrentNote]);
// Load the image data onto the canvas
var canvas = document.getElementById("SketchPage");
var context = canvas.getContext("2d");
canvas.putImageData(NxtNote , 0 , 0 );
return;
}
function AddNote()
{
// Add a note to the notebook and at the end of the File List
// **** Later this function should be modified to be an INSERT function rather than just an add
// Just incase the user needs to go back an edit and add more things to their notebook
}
function ClearSketch()
{
// Clear the contents of the Canvas
//Draw a rectangle that covers the canvas
var canvas = document.getElementById("SketchPage");
var ctx = canvas.getContext("2d");
ctx.fillStyle = BGcolor;
ctx.fillRect (0, 0, canvas.width, canvas.height);
}
function Crypt(method)
{
// This function will Encrypt or Decrypt All the NoteData
if(method == "encrypt")
{
return;
}
if(method == "decrypt")
{
return;
}
}
function Archive(method)
{
// This function will Restore or Backup all NoteData to a network resource
if(method == "restore")
{
return;
}
if(method == "backup")
{
return;
}
}
// ******************** These are the XPCOM Functions ************************
function GetSystemPath(ApplicationName)
{
// This function should Detect the system directory of the app
// and return that string as the SystemPath variable
// You must supply the filename of the HTML file that it is being called from
// I suppose later i could add the code to detect the HTML's actual file name
// It's on the ToDo List...
var GetSysPath = self.location;
GetSysPath = GetSysPath + "";
Get = GetSysPath.replace("file:///" , "");
Get = Get.replace(/\//g , "\\");
Get = Get.replace(ApplicationName, "");
SystemPath = Get;
return SystemPath;
}
function DeleteFile(FileName)
{
// Delete a local file
netscape.security.PrivilegeManager.enablePrivilege("UniversalXPConnect");
var aFile = Components.classes["@mozilla.org/file/local;1"].createInstance();
if (aFile instanceof Components.interfaces.nsILocalFile)
{
aFile.initWithPath(FileName);
aFile.remove(false);
}
}
function GetFileList(Directory, FileList)
{
netscape.security.PrivilegeManager.enablePrivilege("UniversalXPConnect");
var _nsILocalFile = Components.classes["@mozilla.org/file/local;1"]
.createInstance(Components.interfaces.nsILocalFile);
// initialize path to work with
_nsILocalFile.initWithPath(Directory);
// get file interface implemenation
// this means that an XPCOM Class can implement multiple interface
var lv_oFile = _nsILocalFile.QueryInterface(Components.interfaces.nsIFile);
var lv_oEntries = lv_oFile.directoryEntries;
while(lv_oEntries.hasMoreElements())
{
var lv_cFile = lv_oEntries.getNext()
.QueryInterface(Components.interfaces.nsIFile).path;
FileList.push(lv_cFile);
}
}
function SaveToDisk(filepath, content) {
try {
netscape.security.PrivilegeManager.enablePrivilege("UniversalXPConnect");
} catch (e) {
alert("Permission to save file was denied.");
}
var file = Components.classes["@mozilla.org/file/local;1"]
.createInstance(Components.interfaces.nsILocalFile);
file.initWithPath( filepath );
if ( file.exists() == false ) {
file.create( Components.interfaces.nsIFile.NORMAL_FILE_TYPE, 420 );
}
var outputStream = Components.classes["@mozilla.org/network/file-output-stream;1"]
.createInstance( Components.interfaces.nsIFileOutputStream );
outputStream.init( file, 0x04 | 0x08 | 0x20, 420, 0 );
var output = content;
var result = outputStream.write( output, output.length );
outputStream.close();
}
function LoadFromDisk(filePath)
{
if(window.Components)
try
{
netscape.security.PrivilegeManager.enablePrivilege("UniversalXPConnect");
var file = Components.classes["@mozilla.org/file/local;1"].createInstance(Components.interfaces.nsILocalFile);
file.initWithPath(filePath);
if (!file.exists())
return(null);
var inputStream = Components.classes["@mozilla.org/network/file-input-stream;1"].createInstance(Components.interfaces.nsIFileInputStream);
inputStream.init(file, 0x01, 00004, null);
var sInputStream = Components.classes["@mozilla.org/scriptableinputstream;1"].createInstance(Components.interfaces.nsIScriptableInputStream);
sInputStream.init(inputStream);
return(sInputStream.read(sInputStream.available()));
}
catch(e)
{
//alert("Exception while attempting to load\n\n" + e);
return(false);
}
return(null);
}
I am learning Javascript and HTML5... I am trying to create a slideshow using canvas with text display of what the current image is. I have done this without canvas but I want to use canvas this time. My idea involves using the file name as the text display. Here is my working slideshow.. Code: <html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<title>Slide Show</title>
<script type="text/javascript">
function MM_swapImgRestore() { //v3.0
var i,x,a=document.MM_sr; for(i=0;a&&i<a.length&&(x=a[i])&&x.oSrc;i++) x.src=x.oSrc;
}
function MM_preloadImages() { //v3.0
var d=document; if(d.images){ if(!d.MM_p) d.MM_p=new Array();
var i,j=d.MM_p.length,a=MM_preloadImages.arguments; for(i=0; i<a.length; i++)
if (a[i].indexOf("#")!=0){ d.MM_p[j]=new Image; d.MM_p[j++].src=a[i];}}
}
function MM_findObj(n, d) { //v4.01
var p,i,x; if(!d) d=document; if((p=n.indexOf("?"))>0&&parent.frames.length) {
d=parent.frames[n.substring(p+1)].document; n=n.substring(0,p);}
if(!(x=d[n])&&d.all) x=d.all[n]; for (i=0;!x&&i<d.forms.length;i++) x=d.forms[i][n];
for(i=0;!x&&d.layers&&i<d.layers.length;i++) x=MM_findObj(n,d.layers[i].document);
if(!x && d.getElementById) x=d.getElementById(n); return x;
}
function MM_swapImage() { //v3.0
var i,j=0,x,a=MM_swapImage.arguments; document.MM_sr=new Array; for(i=0;i<(a.length-2);i+=3)
if ((x=MM_findObj(a[i]))!=null){document.MM_sr[j++]=x; if(!x.oSrc) x.oSrc=x.src; x.src=a[i+2];}
}
</script>
<script type="text/javascript">
var imagePaths = [
"images/Summer.jpg",
"images/Spring.jpg",
"images/Fall.jpg",
"images/Winter.jpg",
"images/Puppies.jpg",
"images/Duck.jpg"
];
var showCanvas = null;
var showCanvasCtx = null;
var img = document.createElement("img");
var currentImage = 0;
window.onload = function () {
showCanvas = document.getElementById('showCanvas');
showCanvasCtx = showCanvas.getContext('2d');
img.setAttribute('width','480');
img.setAttribute('height','360');
}
function nextImage() {
currentImage++; if (currentImage >= imagePaths.length) currentImage = 0;
img.setAttribute('src',imagePaths[currentImage]);
img.onload = function() {
showCanvasCtx.drawImage(img,0,0,480,360);
}
}
function prevImage() {
currentImage--; if (currentImage < 0) currentImage = imagePaths.length-1;
img.setAttribute('src',imagePaths[currentImage]);
img.onload = function() {
showCanvasCtx.drawImage(img,0,0,480,360);
}
}
</script>
<style type="text/css">
<!--
#showCanvas {
background-image: url(images/Summer.jpg);
}
#center {
height: 360px;
width: 491px;
float: right;
}
#slideArea {
height: 381px;
width: 600px;
margin-right: auto;
margin-left: auto;
}
#right {
height: 361px;
width: 52px;
float: right;
}
#left {
float: left;
height: 360px;
width: 52px;
}
#nxtBtn {
width: 57px;
height: 57px;
position: relative;
top: 120px;
}
#bkBtn {
height: 57px;
width: 57px;
position: relative;
top: 120px;
}
#displayText {
width: 600px;
height: 20px;
float: left;
text-align: center;
}
-->
</style>
</head>
<body>
<br />
<div id="slideArea">
<div id="right">
<a href="#" id="nxtBtn"onClick="nextImage()"onMouseOut="MM_swapImgRestore()" onMouseOver="MM_swapImage('Next','','images/arrow-right-B.png',1)"><img src="images/arrow-right-A.png" name="Next" width="51" height="75" border="0"></a>
</div>
<div id="left"> <a href="#" id="bkBtn" onClick="prevImage()"onMouseOut="MM_swapImgRestore()" onMouseOver="MM_swapImage('Left','','images/arrow-left-B.png',1)"><img src="images/arrow-left-A.png" name="Left" width="51" height="75" border="0"></a></div>
<div id="center">
<center>
<canvas id="showCanvas" width="480" height="360" >
Your browser does not support the canvas tag.
<br />
Please upgrade your browser
</canvas>
</center>
</div>
<div id="displayText">Display Text</div>
</div>
</body>
</html>
This is what I came up with so far but it doesn't work. Code: <html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<title>Slide Show</title>
<script type="text/javascript">
function MM_swapImgRestore() { //v3.0
var i,x,a=document.MM_sr; for(i=0;a&&i<a.length&&(x=a[i])&&x.oSrc;i++) x.src=x.oSrc;
}
function MM_preloadImages() { //v3.0
var d=document; if(d.images){ if(!d.MM_p) d.MM_p=new Array();
var i,j=d.MM_p.length,a=MM_preloadImages.arguments; for(i=0; i<a.length; i++)
if (a[i].indexOf("#")!=0){ d.MM_p[j]=new Image; d.MM_p[j++].src=a[i];}}
}
function MM_findObj(n, d) { //v4.01
var p,i,x; if(!d) d=document; if((p=n.indexOf("?"))>0&&parent.frames.length) {
d=parent.frames[n.substring(p+1)].document; n=n.substring(0,p);}
if(!(x=d[n])&&d.all) x=d.all[n]; for (i=0;!x&&i<d.forms.length;i++) x=d.forms[i][n];
for(i=0;!x&&d.layers&&i<d.layers.length;i++) x=MM_findObj(n,d.layers[i].document);
if(!x && d.getElementById) x=d.getElementById(n); return x;
}
function MM_swapImage() { //v3.0
var i,j=0,x,a=MM_swapImage.arguments; document.MM_sr=new Array; for(i=0;i<(a.length-2);i+=3)
if ((x=MM_findObj(a[i]))!=null){document.MM_sr[j++]=x; if(!x.oSrc) x.oSrc=x.src; x.src=a[i+2];}
}
</script>
<script type="text/javascript">
////added this code to be able to pull the display text from "imageName"
var imagePath = ["images/];
var imageName = [
"Summer",
"Spring",
"Fall",
"Winter",
"Puppies",
"Duck"
];
var imagePaths = imagePath + imageName + ".jpg";
/////////////////////
var showCanvas = null;
var showCanvasCtx = null;
var img = document.createElement("img");
var currentImage = 0;
window.onload = function () {
showCanvas = document.getElementById('showCanvas');
showCanvasCtx = showCanvas.getContext('2d');
img.setAttribute('width','480');
img.setAttribute('height','360');
}
function nextImage() {
currentImage++; if (currentImage >= imagePaths.length) currentImage = 0;
img.setAttribute('src',imagePaths[currentImage]);
img.onload = function() {
showCanvasCtx.drawImage(img,0,0,480,360);
}
}
function prevImage() {
currentImage--; if (currentImage < 0) currentImage = imagePaths.length-1;
img.setAttribute('src',imagePaths[currentImage]);
img.onload = function() {
showCanvasCtx.drawImage(img,0,0,480,360);
}
}
</script>
<style type="text/css">
<!--
#showCanvas {
background-image: url(images/Summer.jpg);
}
#center {
height: 360px;
width: 491px;
float: right;
}
#slideArea {
height: 381px;
width: 600px;
margin-right: auto;
margin-left: auto;
}
#right {
height: 361px;
width: 52px;
float: right;
}
#left {
float: left;
height: 360px;
width: 52px;
}
#nxtBtn {
width: 57px;
height: 57px;
position: relative;
top: 120px;
}
#bkBtn {
height: 57px;
width: 57px;
position: relative;
top: 120px;
}
#displayText {
width: 600px;
height: 20px;
float: left;
text-align: center;
}
-->
</style>
</head>
<body>
<br />
<div id="slideArea">
<div id="right">
<a href="#" id="nxtBtn"onClick="nextImage()"onMouseOut="MM_swapImgRestore()" onMouseOver="MM_swapImage('Next','','images/arrow-right-B.png',1)"><img src="images/arrow-right-A.png" name="Next" width="51" height="75" border="0"></a>
</div>
<div id="left"> <a href="#" id="bkBtn" onClick="prevImage()"onMouseOut="MM_swapImgRestore()" onMouseOver="MM_swapImage('Left','','images/arrow-left-B.png',1)"><img src="images/arrow-left-A.png" name="Left" width="51" height="75" border="0"></a></div>
<div id="center">
<center>
<canvas id="showCanvas" width="480" height="360" >
Your browser does not support the canvas tag.
<br />
Please upgrade your browser
</canvas>
</center>
</div>
<div id="displayText">Display Text</div>
</div>
</body>
</htm>
Any help would be greatly appreciated. Hello, I'm new here so.. hi! You'll probably be seeing me a lot. Anyways here's my questions. I am trying to get a function to draw 5 randomly sized and colored rectangles nested within each other. Meaning each rectangle should not go outside the boundaries of the rectangle it is in. The color thing I've got down in a randomColor() function. It's the nesting rectangles inside rectangles that is confusing me (hense me being up for the past 4 hours trying to understand it) I started out with very simple code just making 5 rectangles of reducing sizes nested in each other, then added the Math.random to randomize all the sizes. Now I'm at this point and have lost my way. Please help, or maybe there is just an easier way. I added a bunch of comments in my code so maybe you'll understand what I'm trying to do. Code: function rect() { // rectangle generator
autoctx.clearRect(0, 0, 400, 400); // clear canvas
// declare variables
var x;
var y;
var width;
var height;
var i = 0; // counter
// create random x,y coordinates
x = Math.round(Math.random() * 100);
y = Math.round(Math.random() * 100);
do { // create random size rectangle
width = Math.round(Math.random() * 400);
height = Math.round(Math.random() * 400);
} while (width < 100 || height < 100); // make sure rectangle is big enough
autoctx.fillStyle = randomColor(); // Runs random color generator
autoctx.fillRect(x, y, width, height); // fill first rectangle
do {
x += (Math.round(Math.random() * 15)); // choose new random coordinates within previous rectangle
y += (Math.round(Math.random() * 15)); // choose new random coordinates within previous rectangle
//*********** KEEPS RECTANGLE HEIGHT AND WIDTHS FROM BEING A NEGATIVE NUMBER ***********//
do { //*** WIDTH TESTER ***// validates width to be within previous rectangles width
var testW = 0; // new width tester variable
testW = width - (Math.round(Math.random() * (2 * x))); // store test width
if (testW > 0) {
width = testW; // if test width > 0 store in width
}
} while (testW < 0); // if test width < 0 continue loop
do { //*** HEIGHT TESTER ***// validates height to be within previous rectangles height
var testH = 0; // create height testing variable
testH = height - (Math.round(Math.random() * (2 * y))); // calculate new test height
if (testH > 0) { // if test height is > 0
height = testH; // store as height
}
} while (testH < 0); // if test height < 0 try again
//*** Fills final rectangle values ***//
autoctx.fillStyle = randomColor(); // Runs random color generator
autoctx.fillRect(x, y, width, height);
i++; // add 1 to counter
} while (i < 4); // kick out of loop after the 5th rectangle
}
thanks guys I hope I'm not too confusing or anything, any help would be greatly appreciated! Hi everyone, I am trying to make an image mask using javascript. The basic idea is that the image on the canvas will appear as a black box. When the user hovers over the image a small part of it is revealed. I have attached a picture as an example because its quite hard to explain! Any help would be appreciated! Thanks, Luke HTML5&JS-Game-1 Large JS Into Separate JS Files? Hi, I am a C++ game programmer who attempted to make an HTML5/JS game. Game turned out great (except for some performance issues on old computers). Although the game is good, I am terribly embarrassed about the source. Source is HTML5/JavaScript and its one giant, ugly, and confusing HTML file. I've been researching on Google how to split the 1 large HTML file into smaller separate *.js files but can not get it working. Here is the URL link to the game's folder on my web site: http://16bitsoft.com/T-Crisis3AI--HTML5/ I've tried to split the one HTML file into smaller separate *.js files. Had a "Logic.js" file with all logic global variables and functions in it and I loaded the "Logic.js" file (I think) into main HTML file but the main HTML file can't locate the logic variables and functions??? If your a Jedi Master Ninja Assassin HTML5/JavaScript coder then please try to help! Thanks! JeZ+Lee 16BitSoft Video Game Design Studio www.16BitSoft.com Here is screenshots of the game: How would i draw a line on a page dynamically, like if i were clicking points on a map and i wanted to link them together. How could i do that? i found this, but maybe you know of something better that would not require coordinates Hi, I was wondering - how can I convert something that a user draws inside canvas? Say, they draw a square, how could I convert that to print "You have drawn a square" - this would be posted to a text file. Thanks in advance. Hi Everyone I am trying to write some code to create an object in JS that contains the x,y coords for a shape i wish to draw. I create the shape, and then in a draw function I draw the shape to the screen from the object I created erlier. Trouble it is does not seem to work :S have anyone got and ideas? Code: var myShape = new newShape(200,200);
function init() {
canvas = document.getElementById("canvas");
ctx = canvas.getContext("2d");
return setInterval(draw, 50);
} // init
function newShape(x,y){
this.un_X=x
this.un_Y=y
function drawAll() {
ctx.beginPath();
ctx.arc(un_X,un_Y,30,0,Math.PI*2,true);
ctx.closePath();
ctx.stroke();
} // drawAll
} // newShape
function draw() {
ctx.clearRect(0, 0, WIDTH, HEIGHT);
myShape.drawAll();
} // draw
init();
Thanks in advance Ok so i want to work on an EASY basic game. As simple as Guess what number... But there are some twist... Ok So here is my example... (HTML, i know this.)I'm Guessing a number 1-99. What is it? (java) Lets say its 66 and they guess 53, have the text rusult be in a pop up window be: Too low! (java) Lets say they guess 78, have the text rusult be in a pop up window be: Too high! (java) Lets say they guess 100+, have the text rusult be in a pop up window be: Out of range! (java)But lets say they guess 66, have a text result be in a pop up window be: You've won! (java) I want a text field where you can enter your answer, and it will do the actions above. Can anyone code this? Thanks for reading! This is a simple basic game i want to make. Its a "What Am I" Riddle... The questions is (In HTML which i already know): I'm as light as a feather but no man can hold me for long. What am I? the answer is: Your Breath. (This is where the JAVASCRIPT comes in) Lets say they guess a rock, have a pop up say: Wrong Answer. Please try again. Lets say they guess Your breath -OR- Breath, have a pop up say: Correct! I want a text field where you can enter your answer, and if they choose ANYTHING but the 2 correct answers above, it will display please try again. Can anyone code this please? Thanks for reading. I've been reading a lot of tutorials on the canvas tag and seen a lot of people using JavaScript that looks something like: ctx.beginPath(); ctx.moveTo(25,25); ctx.lineTo(105,25); ctx.fill(); I understand that ctx is just the variable name and I can replace that with any variable I define, however, I'm looking for a list of all of the methods such as (moveTo, lineTo, fill etc...), as well as what they do. I hope I'm explaining this or asking this correctly. Thanks! -Mike Hey everyone, I have been practicing using canvas to make designs. My current code below will load the word the user inputs and makes it bounce around the canvas as well as a text spinner. However, whenever the user inputs a second word, the bounce below stops to start a new one and the text spinner messes up. I was wondering if anyone could help me so when the user inputs another word, that it either reloads a new textspinner or adds another one, as well as just add the word to the canvas without stopped the old one. Here's my current script. Thanks already, Joey Code:
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<script>
var ctx;
var a=0.0;
var as=true;//true a is increasing, false decreasing
var x,y;
var xs = 1;
var ys = 1;
var userWord
var myDiv, t;
var test = 0;
var ds ="";//display string
var sli =0; //spinning letter index;
function init(){
ctx = document.getElementById("myCvs").getContext("2d");
userWord = document.getElementById("userWord").value;
x=Math.floor(Math.random()*801)
y=Math.floor(Math.random()*601);
drawText();
setInterval("onEnterFrame()", 50);
myDiv = document.getElementById("myDiv");
for (i =0; i<=userWord.length;i++){
ds += "*";
}
myDiv.innerHTML =ds;
textSpin();
}
function textSpin(){
myChar = randomChar();
var newString = userWord.slice(0, sli);
newString +=myChar;
newString += ds.slice(sli+1, ds.length-1);
myDiv.innerHTML = newString;
if (myChar == userWord.charAt(sli)){sli++;}
if (sli<userWord.length){
t = setTimeout("textSpin()", 80);
}
}
function randomChar(){
var rc = Math.random()*26 + 97; //random lowercase char code
return String.fromCharCode(rc);
}
function onEnterFrame(){
if(a>1){as = false;}
if(a<0){as = true;}
if(as){
a+=0.01;
}else{
a-=0.01;
}
if(x>800){xs = -1}
if(x<0){xs=1}
if(y>600){ys = -1}
if(y<0){ys=1}
x+=10 *xs;
y+=10 *ys;
drawText();
}
function drawText(){
ctx.font = "20px Times New Roman";
//ctx.fillStyle= "rgb(256,256,256)";
//ctx.fillText("Hello", x, y);
ctx.fillStyle = randomColor();
ctx.fillText(userWord, x,y);
}
function randomColor(){
var r = Math.floor(Math.random()*150)+55;
var g = Math.floor(Math.random()*256)+150;
var b = Math.floor(Math.random()*20)+50;
var a = Math.random();
return "rgba("+ r+ ","+g+","+b+","+ a+")";
}
//function randomFont(){
// var s = Math.floor(Math.random()*100) +100;
// return s; //+ "px Times New Roman";}
</script>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<style type="text/css">
body {
background-color:#000;
}
#myDiv {
color:#FFF;
}
</style>
</head>
<body onLoad=""><center>
<input type="text" id="userWord" value=""> </input><br>
<input type="button" id="enterWord" value="Enter Word" onClick="init()" ></input><br><br>
<div id="myDiv" > </div>
<canvas id="myCvs" width="800px" height="600px" /><br>
<br>
</center>
</body>
</html>
Hi there! How should I write this - better than it's now - so that when I rotate a figure, in the next "frame" it would stay rotated? Second thing - if you run this code, and set the angle for, let's say 180 degrees the figure is being drawn in some random location. How do I fix this? Code: Code:
function GenericFigure(context) {
this.states = ["wait", "moving", "rotating", "stop"];
this.state = this.states[0];
this.ctx = context;
this.sqrW = this.sqrH = 20;
this.ctxW = 200;
this.ctxH = 350;
this.colorsO = {
red : "#ee1515",
green : "#45d137",
blue : "#17a3f3",
orange : "#ff910f",
purple : "#680077"
};
this.colorsA = ["#ee1515", "#45d137", "#17a3f3", "#ff910f", "#680077"];
this.pickColor = function() {
var num = Math.floor(Math.random() * 5);
return this.colorsA[num];
}
}
function Rectangle(context) {
this.inheritFrom = GenericFigure;
this.inheritFrom(context);
this.width = this.sqrW;
this.height = this.sqrH * 3;
this.x = this.ctxW / 2;
this.y = 0;
this.rotation = -1;
this.setRotation = function(angle) {
this.rotation = angle;
}
this.rotate = function() {
this.ctx.clearRect(0, 0, this.ctxW, this.ctxH);
this.ctx.translate(this.x + 2 * this.width, this.y - 2 * this.height + 20);
this.ctx.rotate(this.rotation * Math.PI / 180);
this.ctx.fillRect(this.ctxW / 2, 0, this.width, this.height);
this.ctx.restore();
}
this.moveDown = function() {
this.y += 20;
this.ctx.restore();
this.ctx.clearRect(0, 0, this.ctxW, this.ctxH);
this.ctx.fillRect(this.x, this.y, this.width, this.height);
this.ctx.save();
if(this.rotation > -1) {
this.rotate();
}
l("A");
}
this.draw = function() {
this.ctx.fillStyle = this.pickColor();
this.ctx.save();
this.ctx.fillRect(this.x, this.y, this.width, this.height);
}
}
//a tak można wywołać:
var ctx = document.getElementById("game").getContext("2d");
var rect = new Rectangle(ctx);
rect.draw();
var inte = setInterval(function(){if(rect.y >= rect.ctxH - rect.height){clearInterval(inte);return;}if(rect.y == 60) rect.setRotation(90);rect.moveDown();}, 500);
And the third problem: Code: this.ctx.translate(this.x, 0); I thought, that this line should set orientation point to top left corner of my figure, but it seems, that it doesn't - after rotation my figure is being drawn two heights lower. Again - how do I fix it? Any help will be much appreciated . I just cant wrap my mind around canvas. As far as I can tell theres no logical reason as to why the code would not work. Could someone take a look at it and possibly figure out whats wrong? I'm trying to intialize and draw a canvas with a simple image. I have the functions in a custom namespace in javascript. I am also using Jquery Code: var birdr = new Image();
var birdl = new Image();
$(document).ready(function(){
if(Modernizr.canvas){
var c = document.createElement('canvas');
LK.animLoad();
document.getElementById('backg-canvas').appendChild(c);
$('canvas').attr({'width':'500','height':'500','id':'canvas'});
var context = LK.returnCanvas();
context.drawImage(birdl, 400,487,10,10);
}
});
var LK = {
birdx: 400, //unused (lets just get it to draw the image first :\)
birdy: 487, //unused
animLoad: function(){
birdl.src = "images/bird2.png";
birdr.src = "images/bird.png";
//alert(birdl);
//alert(birdr);
},
returnCanvas: function(ca){
var b_canvas = LK.getCanvas();
var b_context = b_canvas.getContext('2d');
return b_context;
},
getCanvas: function(){
var a_canvas = document.getElementById('canvas');
//alert(a_canvas);
return a_canvas;
}
}
Any help would be greatly appreciate thanks. Btw safari web inspector indicates the canvas is getting properly created and appended to the container div. So that all works fine. Hello guys! I need your help! I want to create a rectangle with a line in the middle with the canvas object. The problem is that the line in the middle gets bigger than the rest of the rectangle. How do I solve this? I believe it has something to do with shadows. If so, how do I turn them off. My code is: <html> <head> <title></title> </head> <body> <canvas id='chart' width='400' height='200'> <script type="text/javascript"> var canvas = document.getElementById('chart'); var ctx = canvas.getContext('2d'); ctx.lineWidth = 10; ctx.strokeRect(0, 0, 400, 200); ctx.moveTo(0, 100); ctx.lineTo(400, 100); ctx.stroke(); </script> </body> </html> |
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