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
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
| <!DOCTYPE html>
<html lang="en">
<head>
<title></title>
<meta charset="UTF-8" />
<meta name="viewport" content="width=device-width, initial-scale=1" />
<style>
* {
margin: 0;
padding: 0;
}
#canvas {
width: 99vw;
height: 99vh;
}
</style>
</head>
<body>
<canvas id="canvas"></canvas>
<script id="vertex-shader-2d" type="notjs">
attribute vec4 a_position;
void main() {
gl_Position = a_position;
}
</script>
<script id="fragment-shader-2d" type="notjs">
precision mediump float;
void main() {
gl_FragColor = vec4(1, 0, 0.5, 1);
}
</script>
<script>
const canvas = document.querySelector("#canvas");
const gl = canvas.getContext("webgl");
const vertexShaderSource =
document.querySelector("#vertex-shader-2d").text;
const fragmentShaderSource = document.querySelector(
"#fragment-shader-2d"
).text;
const vertexShader = createShader(
gl,
gl.VERTEX_SHADER,
vertexShaderSource
);
const fragmentShader = createShader(
gl,
gl.FRAGMENT_SHADER,
fragmentShaderSource
);
function createShader(gl, type, source) {
const shader = gl.createShader(type);
gl.shaderSource(shader, source);
gl.compileShader(shader);
const success = gl.getShaderParameter(shader, gl.COMPILE_STATUS);
if (success) {
return shader;
}
console.log(gl.getShaderInfoLog(shader));
gl.deleteShader(shader);
}
function createProgram(gl, vertexShader, fragmentShader) {
const program = gl.createProgram();
gl.attachShader(program, vertexShader);
gl.attachShader(program, fragmentShader);
gl.linkProgram(program);
const success = gl.getProgramParameter(program, gl.LINK_STATUS);
if (success) return program;
console.log(gl.getProgramInfoLog(program));
gl.deleteProgram(program);
}
const program = createProgram(gl, vertexShader, fragmentShader);
const positionAttributeLocation = gl.getAttribLocation(
program,
"a_position"
);
const positionBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, positionBuffer);
const positions = [0, 0, 0, 0.5, 0.7, 0];
gl.bufferData(
gl.ARRAY_BUFFER,
new Float32Array(positions),
gl.STATIC_DRAW
);
gl.viewport(0, 0, gl.canvas.width, gl.canvas.height);
gl.clearColor(0, 0, 0, 0);
gl.clear(gl.COLOR_BUFFER_BIT);
gl.useProgram(program);
gl.enableVertexAttribArray(positionAttributeLocation);
const size = 2;
const type = gl.FLOAT;
const normalize = false;
const stride = 0;
const offset = 0;
gl.vertexAttribPointer(
positionAttributeLocation,
size,
type,
normalize,
stride,
offset
);
const primitiveType = gl.TRIANGLES;
const count = 3;
gl.drawArrays(primitiveType, offset, count);
</script>
</body>
</html>
|
