-
Notifications
You must be signed in to change notification settings - Fork 2
/
HTML5 - Beginners - globalAlpha.html
60 lines (50 loc) · 1.26 KB
/
HTML5 - Beginners - globalAlpha.html
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width" />
</head>
<body>
<div id="test"></div>
<canvas id="myCanvas" width="320" height="240" style="border:1px solid #d3d3d3;">
Use different browser.
</canvas>
<script>
var c=document.getElementById("myCanvas");
var ctx=c.getContext("2d");
var posx =0;
var incx=5;
gameloop=setInterval(doGameLoop,16);
function doGameLoop(){
myCanvas.width = window.innerWidth;
myCanvas.height = window.innerHeight-32;
myCanvas.width = window.innerWidth-32;
ctx.fillStyle="rgb(0,0,0)";
ctx.fillRect(0,0,c.width,c.height);
ctx.fillStyle="rgb(255,255,255)";
ctx.fillText("Global Alpha.",10,10);
// Move the blob on the screen
posx+=incx;
if(posx>myCanvas.width-150 || posx<-50){
incx=-incx;
}
ctx.save()
ctx.translate(posx,0);
// Set global alpha to .5
ctx.globalAlpha = .5;
// Draw our blob
for(i=0;i<50;i+=1){
ctx.fillStyle="rgb("+i*4+",0,0)"; ctx.fillRect(randInt(0,100),randInt(0,100),randInt(50,100),randInt(50,100));
}
// restore our global alpha
ctx.globalAlpha = 0;
ctx.restore();
}
//
// Random integer min, Max
function randInt(min,max){
return Math.floor(Math.random()*(max-min)+min);
}
</script>
</body>
</html>