I'm having a problem whit my code.
I draw some circles in a circular path and I expect when to click on them to return something other than 0 in firebug console but that's not happening;
I don't know what is wrong with my code and i hope someone will tell me.
Here's my code:
var canvas, ctx;
var circle_data = [];
function circles(x, y, radius) {
this.x = x;
this.y = y;
this.radius = radius;
circle_data.push(this);
}
circles.prototype = {
draw: function (context) {
context.beginPath();
context.arc(this.x, this.y, this.radius / 5, 0, 2 * Math.PI, false);
context.fillStyle = "red";
context.fill();
}
}
function draw() {
ctx.translate(250, 250);
for (var n = 0; n < 10; n++) {
var radi = (Math.PI / 180);
var x = Math.sin(radi * n * 36) * 70;
var y = Math.cos(radi * n * 36) * 70;
var radius = 50;
var thiscircle = new circles(x, y, radius);
thiscircle.draw(ctx);
}
}
function mouseDown(e) {
var img_data = ctx.getImageData(e.pageX, e.pageY, 1, 1);
console.log(img_data.data[3]);
}
function init() {
canvas = document.getElementById('canvas'),
ctx = canvas.getContext('2d');
canvas.addEventListener('mousedown', mouseDown, false);
}
init();
It dosen't matter is i use data[3];
I tried whit console.log(img_data.data[0]+" "+img_data.data[1]+" "+img_data.data[2]);
Still getting 0 0 0
Your detecting the mouse position relative to the page and not the canvas, you need to get the position of the canvas on the page and subtract that from the X and Y of the mouse to find you position relative to the canvas. I use functions similar to the ones below when working with canvas.
getOffsetPosition = function(obj){
/*obj is the Canvas element*/
var offsetX = offsetY = 0;
if (obj.offsetParent) {
do {
offsetX += obj.offsetLeft;
offsetY += obj.offsetTop;
}while(obj = obj.offsetParent);
}
return [offsetX,offsetY];
}
getMouse = function(e,canvasElement){
OFFSET = getOffsetPosition(canvasElement);
mouse_x = (e.pageX || (e.clientX + document.body.scrollLeft + document.documentElement.scrollLeft)) - OFFSET[0];
mouse_y = (e.pageY || (e.clientY + document.body.scrollTop + document.documentElement.scrollTop)) - OFFSET[1];
return [mouse_x,mouse_y];
}
The following code works.
<!DOCTYPE HTML>
<html>
<head>
<meta charset="utf-8">
<title>Untitled Document</title>
</head>
<body>
<canvas id="canvas" width="500" height="500" style="background-color:#999999;"></canvas>
</body>
<script>
var canvas,ctx;
var circle_data = [];
function circles(x,y,radius)
{
this.x = x;
this.y = y;
this.radius = radius;
circle_data.push(this);
}
circles.prototype = {
draw: function(context){
context.beginPath();
context.arc(this.x, this.y, this.radius / 5, 0, 2* Math.PI, false);
context.fillStyle = "red";
context.fill();
}
}
getOffsetPosition = function(obj){
/*obj is the Canvas element*/
var offsetX = offsetY = 0;
if (obj.offsetParent) {
do {
offsetX += obj.offsetLeft;
offsetY += obj.offsetTop;
}while(obj = obj.offsetParent);
}
return [offsetX,offsetY];
}
getMouse = function(e,canvasElement){
OFFSET = getOffsetPosition(canvasElement);
mouse_x = (e.pageX || (e.clientX + document.body.scrollLeft + document.documentElement.scrollLeft)) - OFFSET[0];
mouse_y = (e.pageY || (e.clientY + document.body.scrollTop + document.documentElement.scrollTop)) - OFFSET[1];
return [mouse_x,mouse_y];
}
function draw(){
ctx.translate(250, 250);
for (var n = 0; n < 10; n++) {
var radi = (Math.PI/180);
var x = Math.sin(radi*n*36)*70;
var y = Math.cos(radi*n*36)*70;
var radius = 50;
var thiscircle = new circles(x,y,radius);
thiscircle.draw(ctx);
}
}
function mouseDown(e)
{
var pos = getMouse(e,ctx.canvas);
var img_data = ctx.getImageData(pos[0],pos[1],1,1);
console.log(img_data.data[3]);
}
function init() {
canvas = document.getElementById('canvas'),
ctx = canvas.getContext('2d');
draw();
canvas.addEventListener('mousedown', mouseDown, false);
}
init();
</script>
</html>
Related
How do I get the following script to work? I wanted to be able to move the ship to the mouse coordinates. The space itself should move and the ship should stay in the centerview.
Would be great if you can modify the script as everybody writes his functions different.
Finally if the button is clicked I want the ship to move to that destination
I tried it when it worked and the ship never moved and I don't know if it has to do with the prototype.update function or not.
Is prototype.update or .render the same as if I would write this.update or this.render?
<script>
function domanDown(evt)
{
switch (evt)
{
case 38: /* Up arrow was pressed or button pressed*/
offsetY+=100 ;
break;
case 40: /* Down arrow was pressed or button pressed*/
offsetY-=100;
break;
case 37: /* Left arrow was pressedor button pressed*/
offsetX+=100;
break;
case 39: /* Right arrow was pressed or button pressed*/
offsetX-=100;
break;
}
}
window.requestAnimationFrame = function() {
return window.requestAnimationFrame ||
window.webkitRequestAnimationFrame ||
window.mozRequestAnimationFrame ||
window.msRequestAnimationFrame ||
window.oRequestAnimationFrame ||
function(f) {
window.setTimeout(f,1e3/60);
}
}();
var Obj = function (x,y,sp,size){
this.size = size;
this.x = x;
this.y = y;
this.color = sp;
this.selected = 0;
}
var Planet_Class = function (x,y,sp){
this.type = 'Planet_Class';
this.depot = 11;
this.xtype = new Obj(x,y,sp,10);
w.objects.push(this);
Planet_Class.prototype.update =function () {
}
Planet_Class.prototype.render =function () {
ctx.save();
ctx.beginPath();
ctx.fillStyle = this.xtype.color;
ctx.fillRect(this.xtype.x, this.xtype.y,this.xtype.size,this.xtype.size);
ctx.fill();
ctx.restore();
}
}
var Usership = function(x,y,sp){
this.depot = 10;
this.type = 'Usership';
this.xtype = new Obj(x,y,sp,10);
w.objects.push(this);
Usership.prototype.update =function (x,y) {
this.xtype.x = x || 20;
this.xtype.y = y || 20;
}
Usership.prototype.render =function () {
ctx.save();
ctx.beginPath();
ctx.fillStyle = this.xtype.color;
ctx.fillRect(this.xtype.x, this.xtype.y,this.xtype.size,this.xtype.size);
ctx.fill();
ctx.restore();
}
}
var World = function(){
this.objects = new Array();
this.count = function(type,sp){
var cnt = 0;
for(var k = 0;k<this.objects.length;k++)
cnt++;
return cnt;
}
}
renderWorld = function(){
requestAnimationFrame(renderWorld);
var spliceArray = Array();
ctx.beginPath();
objcnt = w.objects.length;
ctx.clearRect(0, 0, canvas.width, canvas.height);
ctx.fillStyle = "white";
ctx.fill();
i = 0;
while(i < objcnt){
w.objects[i].update();
w.objects[i].render();
if(w.objects[i].depot < 1)
spliceArray.push(i);
i++;
}
for(var k = 0;k<spliceArray.length;k++)
{
w.objects.splice(spliceArray[k],1); }
}
function r1(max,min){
return (Math.floor(Math.random() * (max - min)) + 1);
}
canvas = document.getElementById("canvas");
ctx = canvas.getContext("2d"),
width = 1024,
height = 768;
offsetX = (canvas.width/2)-300; /Startpoint x for the Ship
offsetY = (canvas.height/2)-300; /Startpoint y for the Ship
generateshipx = -offsetX + (canvas.width/2);
generateshipy = -offsetY + (canvas.height/2);
mX = generateshipx;
mY = generateshipy;
w = new World();
new Usership(generateshipx,generateshipy,'green');
for(i=1;i<4;i++){
new Planet_Class(r1(600,2),r1(600,2),'red');
}
canvas.addEventListener("click", function (e) {
mX = e.pageX- canvas.offsetLeft -offsetX) ;
mY = e.pageY - canvas.offsetTop -offsetY) ;
});
renderWorld();
</script>
<html>
<head>
</head>
<body style="background-color:black;">
<canvas style="z-index:1" width="1024" height="768" id="canvas"></canvas>
<input type="button" style="z-index:2; position:absolute; top:300; left:10" value="uo" onCLick="domanDown(38)()">
<input type="button" style="z-index:2; position:absolute; top:340; left:10" value="down" onCLick="domanDown(40)">
<input type="button" style="z-index:2; position:absolute; top:380; left:10" value="left" onCLick="domanDown(37)">
<input type="button" style="z-index:2; position:absolute; top:420; left:10" value="right" onCLick="domanDown(39)">
<input type="button" style="z-index:2; position:absolute; top:460; left:10" value="move" onCLick="moveObj()">
</body>
</html>
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<style>
body {
background-color: black;
}
canvas {
position: absolute;
margin-left: auto;
margin-right: auto;
left: 0;
right: 0;
cursor: crosshair;
border: solid 1px white;
border-radius: 10px;
}
</style>
</head>
<body>
<canvas id="canvas"></canvas>
<script type="application/javascript">
var canvasWidth = 180;
var canvasHeight = 160;
var canvas = null;
var ctx = null;
var bounds = null;
var isRotating = false;
var isMoving = false;
var pan = {
x: 0.0,
y: 0.0
};
var target = {
x: 0.0,
y: 0.0,
dist: 0.0
};
var ship = {
x: (canvasWidth * 0.5)|0,
y: (canvasHeight * 0.5)|0,
width: 10.0,
height: 10.0,
rotation: 0.0,
deltaRotation: 0.0
};
var stars = [];
stars.length = 100;
window.onload = function() {
canvas = document.getElementById("canvas");
canvas.width = canvasWidth;
canvas.height = canvasHeight;
ctx = canvas.getContext("2d");
bounds = canvas.getBoundingClientRect();
for (var i = 0; i < stars.length; ++i) {
stars[i] = {
x: (Math.random() * 4 * canvasWidth - 2 * canvasWidth)|0,
y: (Math.random() * 4 * canvasHeight - 2 * canvasHeight)|0
};
}
loop();
}
window.onmousedown = function(e) {
isRotating = true;
isMoving = false;
target.x = pan.x + e.clientX - bounds.left;
target.y = pan.y + e.clientY - bounds.top;
}
function loop() {
// Tick
// Rotate to face target
if (isRotating) {
// Vector creation
var tX = ship.x - target.x;
var tY = ship.y - target.y;
var tL = Math.sqrt(tX**2 + tY**2);
var fX = Math.sin(ship.rotation);
var fY = -Math.cos(ship.rotation);
var sX = Math.sin(ship.rotation + Math.PI * 0.5);
var sY = -Math.cos(ship.rotation + Math.PI * 0.5);
// Normalization
tX = tX / tL;
tY = tY / tL;
// Left or right?
var a = 1.0 - Math.abs(tX * fX + tY * fY);
ship.rotation += 0.075 * (sX * tX + sY * tY < 0.0 ? 1.0 : -1.0);
if (a < 0.01) {
target.dist = tL;
isRotating = false;
isMoving = true;
}
}
// Accelerate to target
if (isMoving) {
ship.x += Math.sin(ship.rotation) * 1.0;
ship.y -= Math.cos(ship.rotation) * 1.0;
if (--target.dist < 0.0) {
isMoving = false;
}
}
// Render
// Update pan coordinates
pan.x = ship.x - canvasWidth * 0.5;
pan.y = ship.y - canvasHeight * 0.5;
// Draw background
ctx.fillStyle = "#222222";
ctx.fillRect(0,0,canvasWidth,canvasHeight);
ctx.fillStyle = "white";
for (var i = 0; i < stars.length; ++i) {
ctx.fillRect(
stars[i].x - pan.x,
stars[i].y - pan.y,
2,
2
);
}
// Draw ship
ctx.strokeStyle = "white";
ctx.fillStyle = "darkred";
ctx.translate(canvasWidth * 0.5,canvasHeight * 0.5);
ctx.rotate(ship.rotation);
ctx.beginPath();
ctx.moveTo(-ship.width * 0.5,ship.height * 0.5);
ctx.lineTo(ship.width * 0.5,ship.height * 0.5);
ctx.lineTo(0.0,-ship.height * 0.5);
ctx.lineTo(-ship.width * 0.5,ship.height * 0.5);
ctx.fill();
ctx.stroke();
ctx.rotate(-ship.rotation);
ctx.translate(-canvasWidth * 0.5,-canvasHeight * 0.5);
requestAnimationFrame(loop);
}
</script>
</body>
</html>
I wrote this game from a tutorial i read online, it was working just fine, until i messed it up, my developer tools console says theres a reference error but i just cant see it, please help, the error i get through my we developer console is "Uncaught ReferenceError: Draw is not defined(anonymous function) # games.html:228 "
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title>Gamedev Canvas Workshop</title>
<style>
* { padding: 0; margin: 0; }
canvas { background: #eee;
display: block;
margin: 0 auto;
}
#checking {
margin-left:650px;
}
#checking1 {
margin-left:650px;
}
#checking2 {
margin-left:650px;
}
#checking3 {
margin-left:650px;
}
</style>
</head>
<body>
<canvas id="myCanvas" width="480" height="320"></canvas>
<br/>
<div id ="checking">Current Position</div>
<div id ="checking1">Nothings Moving Bro</div>
<br/>
<div id ="checking3">Color State</div>
<div id ="checking2">Nope, still nothing</div>
<script>
// JavaScript code goes here
var checking1 = document.getElementById("checking1");
var canvas = document.getElementById("myCanvas");
var ctx = canvas.getContext("2d");
var x = canvas.width/2;
var y = canvas.height-30;
var ballRadius = 20;
var dx = 2;
var dy = -2;
var paddleheight = 10;
var paddlewidth = 50;
var paddleX = (canvas.height - paddlewidth)/2;
var RightKeyPressed = false;
var LeftKeyPressed = false;
document.addEventListener("keydown", keyDownHandler,false);
document.addEventListener("keyup",keyUpHandler,false);
function keyDownHandler(e){
if(e.keycode == 39){
RightKeyPressed = true;
}else if(e.keycode == 37){
LeftKeyPressed = true;
}
}
function keyUpHandler(e){
if(e.keycode == 39){
RightKeyPressed = false;
}else if(e.keycode == 37){
LeftKeyPressed = false;
}
function randomInt(min,max){
return Math.floor(Math.random() * (max - min))+ min; }
function paddle(){
ctx.beginPath;
ctx.rect(paddleX,canvas.height - paddleheight,paddlewidth,paddleheight);
ctx.fillStyle="#0095DD";
ctx.fill();
ctx.closePath;
}
function drawball(){
ctx.clearRect(0,0,canvas.width,canvas.height);
ctx.beginPath();
ctx.arc(x,y,ballRadius,0,Math.PI*2,false);
ctx.fillStyle = "rgb(0,149,221)";
ctx.fill();
ctx.closePath();
}
function Draw(){
ctx.clearRect(0,0,canvas.width,canvas.height);
drawball();
paddle();
if(y + dy > canvas.height - 20 || y + dy < ballRadius){
var cx = randomInt(0,255);
var cy = randomInt(0,255);
var cz = randomInt(0,255);
ctx.fillStyle = "rgb(cx,cy,cz)";
ctx.fill();
dy = -dy;
}
if ( x + dx > canvas.width - 20 || x + dx < ballRadius){
var cx = randomInt(0,255);
var cy = randomInt(0,255);
var cz = randomInt(0,255);
ctx.fillStyle = "rgb(cx,cy,cz)";
ctx.fill();
dx = -dx; }
x += dx;
y += dy
var color = ctx.fillStyle;
checking1.innerHTML = " x: " + x + "y: " + y ;
checking2.innerHTML = color ;
}
}
if(RightKeyPressed && paddleX < canvas.width - 50 ){
paddleX += 7;
}else if(LeftKeyPressed && paddleX > 0){
paddleX -= 7;
}
setInterval(Draw,10);
</script>
</body>
</html>
Your code throws the error because it cannot find the function Draw():
setInterval(Draw, 10);
This is because your function is not in the same scope. Your code structure is like this:
function keyUpHandler(e) {
...
function Draw(){
//Codes here
}
...
}
...
setInterval(Draw, 10);
Since the Draw() function is inside the keyUpHandler(e), it cannot be seen from any outside function (that is functions that are on a higher level/scope).
Hope this clears your mind :)
Check out this fiddle , you closing bracket of function keyDownHandlercode is wrong
var checking1 = document.getElementById("checking1");
var canvas = document.getElementById("myCanvas");
var ctx = canvas.getContext("2d");
var x = canvas.width / 2;
var y = canvas.height - 30;
var ballRadius = 20;
var dx = 2;
var dy = -2;
var paddleheight = 10;
var paddlewidth = 50;
var paddleX = (canvas.height - paddlewidth) / 2;
var RightKeyPressed = false;
var LeftKeyPressed = false;
document.addEventListener("keydown", keyDownHandler, false);
document.addEventListener("keyup", keyUpHandler, false);
function keyDownHandler(e) {
if (e.keycode == 39) {
RightKeyPressed = true;
} else if (e.keycode == 37) {
LeftKeyPressed = true;
}
}
function keyUpHandler(e) {
if (e.keycode == 39) {
RightKeyPressed = false;
} else if (e.keycode == 37) {
LeftKeyPressed = false;
}
}
function randomInt(min, max) {
return Math.floor(Math.random() * (max - min)) + min;
}
function paddle() {
ctx.beginPath;
ctx.rect(paddleX, canvas.height - paddleheight, paddlewidth, paddleheight);
ctx.fillStyle = "#0095DD";
ctx.fill();
ctx.closePath;
}
function drawball() {
ctx.clearRect(0, 0, canvas.width, canvas.height);
ctx.beginPath();
ctx.arc(x, y, ballRadius, 0, Math.PI * 2, false);
ctx.fillStyle = "rgb(0,149,221)";
ctx.fill();
ctx.closePath();
}
function zan(){
alert('test');
}
function Draw() {
ctx.clearRect(0, 0, canvas.width, canvas.height);
drawball();
paddle();
if (y + dy > canvas.height - 20 || y + dy < ballRadius) {
var cx = randomInt(0, 255);
var cy = randomInt(0, 255);
var cz = randomInt(0, 255);
ctx.fillStyle = "rgb(cx,cy,cz)";
ctx.fill();
dy = -dy;
}
if (x + dx > canvas.width - 20 || x + dx < ballRadius) {
var cx = randomInt(0, 255);
var cy = randomInt(0, 255);
var cz = randomInt(0, 255);
ctx.fillStyle = "rgb(cx,cy,cz)";
ctx.fill();
dx = -dx;
}
x += dx;
y += dy
var color = ctx.fillStyle;
checking1.innerHTML = " x: " + x + "y: " + y;
checking2.innerHTML = color;
}
if (RightKeyPressed && paddleX < canvas.width - 50) {
paddleX += 7;
} else if (LeftKeyPressed && paddleX > 0) {
paddleX -= 7;
}
setInterval(Draw, 10);
You probably forgot to close your keyuphandler function (currently you have like 3 function inside it until you finally close it at line 193).
add a function closure at about line 88 to close your keyuphandler.
Than you have a extra function closure at line 193 remove that and it works
(by function closure i mean brackets {} )
I have completed code that has a user click a button (to the right of the canvas), then the image is added to the canvas and is constrained to only move around the circumference of a circle. In order to move the image the user just needs to click the image and then move the mouse. To release the image the user simply needs to click where the image goes on the canvas.
Here is a fiddle showing what the current code does.
http://jsfiddle.net/smacnabb/68awv7sq/9/
Question: I am looking to be able to have the images that move around the circumference of the circle rotate while moving around the circumference of the circle.
This is what I mean:
Here is a fiddle for the code I added to try and make this happen
http://jsfiddle.net/smacnabb/68awv7sq/11/
in the handlemousemove method, it calls state.draw() every time the mouse move i'm passing mouseX, mouseY to state.draw.
state.draw() is in addstate method and this was the code I added to make the image rotate
var dx = mouseX - centerX;
var dy = mouseY - centerY;
var radianAngle = Math.atan2(dy, dx);
context.save();
context.translate(centerX, centerY);
context.rotate(radianAngle);
if (this.dragging) {
context.strokeStyle = 'black';
context.strokeRect(this.x, this.y, this.width + 2, this.height + 2)
}
context.drawImage(this.image, this.x, this.y);
context.restore();
What am I doing wrong?
You are close...Take a look at this example:
var canvas = document.getElementById("canvas");
var ctx = canvas.getContext("2d");
var $canvas = $("#canvas");
var canvasOffset = $canvas.offset();
var offsetX = canvasOffset.left;
var offsetY = canvasOffset.top;
var radianAngle = 0;
var cx = 225;
var cy = 125;
var radius = 50;
// image loader
var imageURLs = [];
var imagesOK = 0;
var imgs = [];
imageURLs.push("https://dl.dropboxusercontent.com/u/139992952/multple/cars.png");
imageURLs.push("https://dl.dropboxusercontent.com/u/139992952/multple/plane.png");
imageURLs.push("https://dl.dropboxusercontent.com/u/139992952/multple/cars1.png");
imageURLs.push("https://dl.dropboxusercontent.com/u/139992952/multple/plane1.png");
loadAllImages(start);
function loadAllImages(callback) {
for (var i = 0; i < imageURLs.length; i++) {
var img = new Image();
imgs.push(img);
img.onload = function() {
imagesOK++;
if (imagesOK >= imageURLs.length) {
callback();
}
};
img.onerror = function() {
alert("image load failed");
}
img.crossOrigin = "anonymous";
img.src = imageURLs[i];
}
}
var imagesY = 20;
var targets = [];
var selectedTarget = -1;
function start() {
var n = imgs.length / 2;
for (var i = 0; i < n; i++) {
var target = imgs[i + n];
ctx.drawImage(target, 15, imagesY);
targets.push({
x: 15,
y: imagesY,
width: target.width,
height: target.height,
image: imgs[i]
});
imagesY += target.height + 10;
}
}
function handleMouseDown(e) {
e.preventDefault();
x = parseInt(e.clientX - offsetX);
y = parseInt(e.clientY - offsetY);
for (var i = 0; i < targets.length; i++) {
var t = targets[i];
if (x >= t.x && x <= t.x + t.width && y >= t.y && y <= t.y + t.height) {
selectedTarget = i;
draw(x, y);
}
}
}
function handleMouseMove(e) {
if (selectedTarget < 0) {
return;
}
e.preventDefault();
mouseX = parseInt(e.clientX - offsetX);
mouseY = parseInt(e.clientY - offsetY);
draw(mouseX, mouseY);
}
function draw(mouseX, mouseY) {
var dx = mouseX - cx;
var dy = mouseY - cy;
var radianAngle = Math.atan2(dy, dx);
// Drawing code goes here
var img = targets[selectedTarget].image;
ctx.clearRect(100, 0, canvas.width, canvas.height);
// draw the circle
ctx.beginPath();
ctx.arc(cx, cy, radius, 0, Math.PI * 2);
ctx.closePath();
ctx.stroke();
// draw the image rotated around the circumference
ctx.save();
ctx.translate(cx, cy);
ctx.rotate(radianAngle);
ctx.drawImage(img, radius - img.width / 2, -img.height / 2);
ctx.restore();
}
$("#canvas").mousedown(function(e) {
handleMouseDown(e);
});
$("#canvas").mousemove(function(e) {
handleMouseMove(e);
});
body{ background-color: ivory; }
canvas{border:1px solid red;}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
<h4>Select an icon on left by clicking<br>
Then move mouse to have icon rotate around circle</h4>
<canvas id="canvas" width=350 height=350></canvas>
This is a script for filling canvas' grid squares with red color.
I'm looking for tips how to optimize my script to fill squares continuously, without chopping like here:
I tried to separate and merge some functions, but can't find a solution.
Here's the updated jsFiddle and my code:
HTML:
<canvas id="plan" width="501px" height="301px"></canvas>
JavaScript (updated):
var canvas = document.getElementById('plan');
var context = canvas.getContext('2d'),
wt = canvas.width,
ht = canvas.height;
var down = false;
var draw = function (e) {};
window.onload = grid();
var oldPos = {
mX: 0,
mY: 0
};
var dPos = {
mX: 0,
mY: 0
};
var curPos = {
mX: 0,
mY: 0
};
draw.to = function (X, Y) {
oldPos = getMousePos(canvas, e); //update position
var mposX = X,
mposY = Y;
mposX = mposX - mposX % 5;
mposY = mposY - mposY % 5;
context.fillStyle = "red";
context.fillRect(mposX + 0.5, mposY + 0.5, 5, 5);
};
draw.single = function (e) {
oldPos = getMousePos(canvas, e);
var mpos = getMousePos(canvas, e);
mpos.mX = mpos.mX - mpos.mX % 5;
mpos.mY = mpos.mY - mpos.mY % 5;
context.fillStyle = "red";
context.fillRect(mpos.mX + 0.5, mpos.mY + 0.5, 5, 5);
};
draw.move = function (e) {
if (down) {
curPos = getMousePos(canvas, e);
dPos.mX = Math.abs(curPos.mX - oldPos.mX); // distance between old & new (delta X)
dPos.mY = Math.abs(curPos.mY - oldPos.mY); // delta Y
if (dPos.mX >= 5 || dPos.mY >= 5) { // if the distance is bigger than 5px hz OR 5px vertical
lightIntermediateSquares(oldPos.mX, oldPos.mY, curPos.mX, curPos.mY); // ^ connect them
} else {
draw.single(e); // simple
}
}
};
draw.start = function (e) {
e.preventDefault();
down = true;
draw.single(e);
};
draw.stop = function (e) {
down = false;
};
function lightIntermediateSquares(startX, startY, endX, endY) {
for (var pct = 0; pct <= 1; pct += 0.03) {
var dx = endX - startX;
var dy = endY - startY;
var X = startX + dx * pct;
var Y = startY + dy * pct;
draw.to(X, Y); // is it okay?
}
}
function grid() {
context.strokeStyle = "#f0f0f0";
var h = 2.5,
p = 2.5;
context.strokeRect(0.5, 0.5, 5, 5);
for (i = 0; i < wt; i += p) {
p *= 2;
context.drawImage(canvas, p, 0);
}
for (i = 0; i < ht; i += h) {
h *= 2;
context.drawImage(canvas, 0, h);
}
}
function getMousePos(canvas, e) {
var rect = canvas.getBoundingClientRect();
return {
mX: e.clientX - rect.left - 1,
mY: e.clientY - rect.top - 1
};
}
canvas.addEventListener('mouseup', draw.stop, false);
canvas.addEventListener('mousedown', draw.start, false);
canvas.addEventListener('mousemove', draw.move, false);
canvas.addEventListener('mouseout', draw.stop, false);
Here's how to light the missing squares
Calculate a line between the previous mousemove and the current mousemove position.
Then walk that line using interpolation and color any grid squares that the line crosses.
// walk along a line from the last mousemove position
// to the current mousemove position.
// Then color any cells we pass over on our walk
for(var pct=0;pct<=1;pct+=0.06){
var dx = mouseX-lastX;
var dy = mouseY-lastY;
var X = parseInt(lastX + dx*pct);
var Y = parseInt(lastY + dy*pct);
if( !(X==lastForX && Y==lastForY) ){
draw.ColorCell(X,Y);
}
Here is code and a Fiddle: http://jsfiddle.net/m1erickson/WvuHL/
<!doctype html>
<html>
<head>
<link rel="stylesheet" type="text/css" media="all" href="css/reset.css" /> <!-- reset css -->
<script type="text/javascript" src="http://code.jquery.com/jquery.min.js"></script>
<style>
body{ background-color: ivory; }
canvas{border:1px solid red;}
</style>
<script>
$(function(){
var canvas=document.getElementById("canvas");
var context=canvas.getContext("2d");
var canvasOffset=$("#canvas").offset();
var offsetX=canvasOffset.left;
var offsetY=canvasOffset.top;
var wt = canvas.width;
var ht = canvas.height;
var down = false;
var lastX=-20;
var lastY=-20;
var points=[];
var draw = function (e) {};
draw.started = false;
var count;
function interpolateLine(startX,startY,endX,endY){
var lastForX;
var lastForY;
//
for(var pct=0;pct<=1;pct+=0.06){
var dx = endX-startX;
var dy = endY-startY;
var X = startX + dx*pct;
var Y = startY + dy*pct;
if( !(X==lastForX && Y==lastForY) ){
draw.ColorCell(X,Y);
}
lastForX=X;
lastForY=Y;
}
}
draw.ColorCell=function(x,y){
var rw = x - 1;
var rh = y - 1;
rw = rw - rw % 5 + 0.5;
rh = rh - rh % 5 + 0.5;
context.fillStyle = "red";
context.fillRect( rw, rh, 5, 5);
};
draw.single = function (e) {
var mouseX=parseInt(e.clientX-offsetX);
var mouseY=parseInt(e.clientY-offsetY);
draw.ColorCell(mouseX,mouseY);
};
// mousemove
draw.move = function (e) {
if(!down){return;}
// get the current mouse position
var mouseX=parseInt(e.clientX-offsetX);
var mouseY=parseInt(e.clientY-offsetY);
// if we haven't moved off this XY, then don't bother processing further
if(mouseX==lastX && mouseY==lastY){return;}
// When running the for-loop below,
// many iterations will not find a new grid-cell
// so lastForX/lastForY will let us skip duplicate XY
var lastForX=lastX;
var lastForY=lastY;
// walk along a line from the last mousemove position
// to the current mousemove position.
// Then color any cells we pass over on our walk
for(var pct=0;pct<=1;pct+=0.06){
var dx = mouseX-lastX;
var dy = mouseY-lastY;
var X = parseInt(lastX + dx*pct);
var Y = parseInt(lastY + dy*pct);
if( !(X==lastForX && Y==lastForY) ){
draw.ColorCell(X,Y);
}
lastForX=X;
lastForY=Y;
}
// set this mouse position as starting position for next mousemove
lastX=mouseX;
lastY=mouseY;
};
// mousedown
draw.start = function (e) {
e.preventDefault();
lastX=parseInt(e.clientX-offsetX);
lastY=parseInt(e.clientY-offsetY);
down = true;
};
// mouseup
draw.stop = function (e) {
e.preventDefault();
down = false;
};
function grid() {
context.strokeStyle = "#f0f0f0";
var h = 2.5;
var p = 2.5;
context.strokeRect(0.5, 0.5, 5, 5);
for (i = 0; i < wt; i += p) {
p *= 2;
context.drawImage(canvas, p, 0);
}
for (i = 0; i < ht; i += h) {
h *= 2;
context.drawImage(canvas, 0, h);
}
}
canvas.addEventListener('mouseup', draw.stop, false);
canvas.addEventListener('mouseout', draw.stop, false);
canvas.addEventListener('mousedown', draw.start, false);
canvas.addEventListener('click', draw.single, false);
canvas.addEventListener('mousemove', draw.move, false);
grid();
}); // end $(function(){});
</script>
</head>
<body>
<canvas id="canvas" width=501 height=301></canvas>
</body>
</html>
I am trying to modified this effect to work within my canvas. However, I can't seem to get the mouse position to work properly. The hover area isn't contained to my canvas.
Here's a CSSdeck of how i tried to implement it: http://cssdeck.com/labs/ukktjtis
Effect:
function hoverText(){
window.requestAnimFrame = (function(){
return window.requestAnimationFrame ||
window.webkitRequestAnimationFrame ||
window.mozRequestAnimationFrame ||
window.oRequestAnimationFrame ||
window.msRequestAnimationFrame ||
function( callback ){
window.setTimeout(callback, 1000 / 60);
};
})();
var canvas = document.getElementById("canvas"),
ctx = canvas.getContext("2d"),
keyword = "MacroPlay Games",
imageData,
density = 3,
mouse = {},
hovered = false,
colors = ["0,120,232", "8,200,255", "30,140,255"],
minDist = 20,
bounceFactor = 0.7;
var W = window.innerWidth, H = window.innerHeight;
canvas.width = W;
canvas.height = H;
document.addEventListener("mousemove", function(e) {
mouse.x = e.pageX-50;
mouse.y = e.pageY+200;
}, false);
// Particle Object
var Particle = function() {
this.w = Math.random() * 10.5;
this.h = Math.random() * 10.5;
this.x = -W;
this.y = -H;
this.free = false;
this.vy = -5 + parseInt(Math.random() * 10) / 2;
this.vx = -4 + parseInt(Math.random() * 8);
// Color
this.a = Math.random();
this.color = colors[parseInt(Math.random()*colors.length)];
this.setPosition = function(x, y) {
this.x = x;
this.y = y;
};
this.draw = function() {
ctx.fillStyle = "rgba("+this.color+","+this.a+")";
ctx.fillRect(this.x, this.y, this.w, this.h);
}
};
var particles = [];
// Draw the text
function drawText() {
ctx.clearRect(0, 0, W, H);
ctx.fillStyle = "#000000";
ctx.font = "100px 'Arial', sans-serif";
ctx.textAlign = "center";
ctx.fillText(keyword, W/2, H/2);
}
// Clear the canvas
function clear() {
ctx.clearRect(0, 0, W, H);
}
// Get pixel positions
function positionParticles() {
// Get the data
imageData = ctx.getImageData(0, 0, W, W);
data = imageData.data;
// Iterate each row and column
for (var i = 0; i < imageData.height; i += density) {
for (var j = 0; j < imageData.width; j += density) {
// Get the color of the pixel
var color = data[((j * ( imageData.width * 4)) + (i * 4)) - 1];
// If the color is black, draw pixels
if (color == 255) {
particles.push(new Particle());
particles[particles.length - 1].setPosition(i, j);
}
}
}
}
drawText();
positionParticles();
// Update
function update() {
clear();
for(i = 0; i < particles.length; i++) {
var p = particles[i];
if(mouse.x > p.x && mouse.x < p.x + p.w && mouse.y > p.y && mouse.y < p.y + p.h)
hovered = true;
if(hovered == true) {
var dist = Math.sqrt((p.x - mouse.x)*(p.x - mouse.x) + (p.y - mouse.y)*(p.y - mouse.y));
if(dist <= minDist)
p.free = true;
if(p.free == true) {
p.y += p.vy;
p.vy += 0.15;
p.x += p.vx;
// Collision Detection
if(p.y + p.h > H) {
p.y = H - p.h;
p.vy *= -bounceFactor;
// Friction applied when on the floor
if(p.vx > 0)
p.vx -= 0.1;
else
p.vx += 0.1;
}
if(p.x + p.w > W) {
p.x = W - p.w;
p.vx *= -bounceFactor;
}
if(p.x < 0) {
p.x = 0;
p.vx *= -0.5;
}
}
}
ctx.globalCompositeOperation = "lighter";
p.draw();
}
}
(function animloop(){
requestAnimFrame(animloop);
update();
})();
}
It's highly advised you use jquery (or some js lib) to avoid cross-browser issues like getting the mouse position.
You can easily get the mouse position in any browser using jquery like this:
// get the position of the canvas relative to the web page
var canvasOffset=$("#canvas").offset();
var offsetX=canvasOffset.left;
var offsetY=canvasOffset.top;
// then in the mouse handler, get the exact mouse position like this:
function handleMouseDown(e){
mouseX=parseInt(e.clientX-offsetX);
mouseY=parseInt(e.clientY-offsetY);
// Put your mousedown stuff here
}
// tell the browser to send mousedown events to the handleMouseDown function
$("#canvas").mousedown(function(e){handleMouseDown(e);});
I personally prefer a library like hammer.js. I've use it for all my projects - check it out, it's pretty good.