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
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
|
<!DOCTYPE html>
<head>
<meta charset="utf-8"/>
<title>Циркулярен диск</title>
<script src="webgl-fmi.js"></script>
<script id="vshader" type="x-shader/x-vertex">
// отвън се подава само ъгъла
attribute float aAngle;
#define PI 3.14159
#define eps 0.0001
#define TEETH 35.0
#define RADIUS 0.7
#define TEETH_DEPTH 0.1
#define LEDGE_MODIFIER 2.0
void main ()
{
float r = RADIUS + mod(aAngle, 2.0 * PI / TEETH) / ((360.0 / TEETH - 1.0) * PI / 180.0) * TEETH_DEPTH;;
float angle = aAngle - LEDGE_MODIFIER * r;
gl_Position = vec4(r*cos(angle)/1.5,r*sin(angle),0,1);
}
</script>
<script id="fshader" type="x-shader/x-fragment">
precision mediump float;
uniform vec3 uColor;
void main( )
{
gl_FragColor = vec4(uColor,1);
}
</script>
<script>
function start( )
{
gl = getContext("picasso");
glprog = getProgram("vshader","fshader");
aAngle = gl.getAttribLocation(glprog,"aAngle");
uColor = gl.getUniformLocation(glprog,"uColor");
gl.clearColor(1,1,1,1);
gl.clear(gl.COLOR_BUFFER_BIT);
// точки по зъбното колело
var n = 360;
// n ъгъла от 0 до 2*pi
var data = [ ];
for(var i=0; i<n; i++)
data.push(2*Math.PI*i/n);
console.log(data);
var buf = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER,buf);
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(data), gl.STATIC_DRAW);
gl.uniform3f(uColor,0.3,0.7,0.2);
gl.enableVertexAttribArray(aAngle);
gl.vertexAttribPointer(aAngle,1,gl.FLOAT,false,0,0);
// рисуване на назъбения профил
// (ама назъбеността да се прави с шейдъра)
gl.drawArrays(gl.LINE_LOOP,0,n);
}
</script>
</head>
<body onload="start()">
<h2>Циркулярен диск</h2>
<noscript>
Искаме JavaScript, но няма!
</noscript>
<canvas id="picasso" width="600" height="400" style="border: solid;">
Искаме canvas, но няма!
</canvas>
</body>
|
