So I have been playing around with canvas. Trying to simulate random falling objects, drawing the background image is no problem and not the 2nd img that is supposed to simulate a rain drop.
I can get the drop to e down at a random x but now I am not really sure on how to loop the drop image x times set by the variable noOfDrops.
I left my loop mented out, the working code with just one drop falling randomly is:
<!DOCTYPE html>
<html lang="en">
<head>
<title>Canvas Regn</title>
<script type="text/javascript">
var ctx;
var imgBg;
var imgDrops;
var x = 0;
var y = 0;
var noOfDrops = 50;
var fallingDrops = [];
function setup() {
var canvas = document.getElementById('canvasRegn');
if (canvas.getContext) {
ctx = canvas.getContext('2d');
setInterval('draw();', 36);
imgBg = new Image();
imgBg.src = 'dimma.jpg';
imgDrops = new Image();
imgDrops.src = 'drop.png';
/*for (var i = 0; i < noOfDrops; i++) {
var fallingDr = imgDrops[i];
fallingDr.x = Math.random() * 600;
fallingDrops.push(fallingDr);
}*/
}
}
function draw() {
drawBackground();
ctx.drawImage (imgDrops, x, y); //The rain drop
y += 3; //Set the falling speed
if (y > 450) { //Repeat the raindrop when it falls out of view
y = -25 //Account for the image size
x = Math.random() * 600; //Make it appear randomly along the width
}
}
function drawBackground(){
ctx.drawImage(imgBg, 0, 0); //Background
}
</script>
</head>
<body onload="setup();">
<canvas id="canvasRegn" width="600" height="450"style="margin:100px;"></canvas>
</body>
</html>
If anyone has some good ideas on how to implement that, I would appreciate it alot.
So I have been playing around with canvas. Trying to simulate random falling objects, drawing the background image is no problem and not the 2nd img that is supposed to simulate a rain drop.
I can get the drop to e down at a random x but now I am not really sure on how to loop the drop image x times set by the variable noOfDrops.
I left my loop mented out, the working code with just one drop falling randomly is:
<!DOCTYPE html>
<html lang="en">
<head>
<title>Canvas Regn</title>
<script type="text/javascript">
var ctx;
var imgBg;
var imgDrops;
var x = 0;
var y = 0;
var noOfDrops = 50;
var fallingDrops = [];
function setup() {
var canvas = document.getElementById('canvasRegn');
if (canvas.getContext) {
ctx = canvas.getContext('2d');
setInterval('draw();', 36);
imgBg = new Image();
imgBg.src = 'dimma.jpg';
imgDrops = new Image();
imgDrops.src = 'drop.png';
/*for (var i = 0; i < noOfDrops; i++) {
var fallingDr = imgDrops[i];
fallingDr.x = Math.random() * 600;
fallingDrops.push(fallingDr);
}*/
}
}
function draw() {
drawBackground();
ctx.drawImage (imgDrops, x, y); //The rain drop
y += 3; //Set the falling speed
if (y > 450) { //Repeat the raindrop when it falls out of view
y = -25 //Account for the image size
x = Math.random() * 600; //Make it appear randomly along the width
}
}
function drawBackground(){
ctx.drawImage(imgBg, 0, 0); //Background
}
</script>
</head>
<body onload="setup();">
<canvas id="canvasRegn" width="600" height="450"style="margin:100px;"></canvas>
</body>
</html>
If anyone has some good ideas on how to implement that, I would appreciate it alot.
Share Improve this question asked Oct 29, 2012 at 20:53 TobbeTobbe 492 gold badges2 silver badges8 bronze badges1 Answer
Reset to default 8Your loop is actually pretty close. The biggest problem you would have is that you can't just maintain 1 x and 1 y value, you have to maintain that per image. So I modified your loop a bit to push an object on the array that has an x,y, and speed value. The speed value gives you nice randomization of the movement, so everything doesn't e down at the same speed:
var ctx;
var imgBg;
var imgDrops;
var x = 0;
var y = 0;
var noOfDrops = 50;
var fallingDrops = [];
function drawBackground(){
ctx.drawImage(imgBg, 0, 0); //Background
}
function draw() {
drawBackground();
for (var i=0; i< noOfDrops; i++)
{
ctx.drawImage (fallingDrops[i].image, fallingDrops[i].x, fallingDrops[i].y); //The rain drop
fallingDrops[i].y += fallingDrops[i].speed; //Set the falling speed
if (fallingDrops[i].y > 450) { //Repeat the raindrop when it falls out of view
fallingDrops[i].y = -25 //Account for the image size
fallingDrops[i].x = Math.random() * 600; //Make it appear randomly along the width
}
}
}
function setup() {
var canvas = document.getElementById('canvasRegn');
if (canvas.getContext) {
ctx = canvas.getContext('2d');
imgBg = new Image();
imgBg.src = "http://lorempixel./600/600/sports/";
setInterval(draw, 36);
for (var i = 0; i < noOfDrops; i++) {
var fallingDr = new Object();
fallingDr["image"] = new Image();
fallingDr.image.src = 'http://lorempixel./10/10/sports/';
fallingDr["x"] = Math.random() * 600;
fallingDr["y"] = Math.random() * 5;
fallingDr["speed"] = 3 + Math.random() * 5;
fallingDrops.push(fallingDr);
}
}
}
setup();
Here is a fiddle demo: http://jsfiddle/L4Qfb/21/