前端 | 学习 WebGL



show

code

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
<canvas id="draw" width="500" height="500"></canvas>

<script>
document.addEventListener('DOMContentLoaded', () => {
    const canvas = document.getElementById('draw');
    const gl = canvas.getContext('webgl');

    gl.clearColor(1, 1, 1, 1);

    const sourceV = `
        attribute vec3 position;
        varying vec4 color;

        void main() {
            gl_Position = vec4(position, 1);
            color = gl_Position * 0.5 + 0.5;
        }
    `;

    const shaderV = gl.createShader(gl.VERTEX_SHADER);
    gl.shaderSource(shaderV, sourceV);
    gl.compileShader(shaderV);

    if (!gl.getShaderParameter(shaderV, gl.COMPILE_STATUS)) {
        console.error(gl.getShaderInfoLog(shaderV));
        throw new Error('Failed to compile vertex shader');
    }

    const sourceF = `
        precision mediump float;
        varying vec4 color;

        void main() {
            gl_FragColor = color;
        }
    `;

    const shaderF = gl.createShader(gl.FRAGMENT_SHADER);
    gl.shaderSource(shaderF, sourceF);
    gl.compileShader(shaderF);

    if (!gl.getShaderParameter(shaderF, gl.COMPILE_STATUS)) {
        console.error(gl.getShaderInfoLog(shaderF));
        throw new Error('Failed to compile fragment shader');
    }

    const program = gl.createProgram();
    gl.attachShader(program, shaderV);
    gl.attachShader(program, shaderF);
    gl.linkProgram(program);

    if (!gl.getProgramParameter(program, gl.LINK_STATUS)) {
        console.error(gl.getProgramInfoLog(program));
        throw new Error('Failed to link program');
    }

    gl.useProgram(program);

    const positionsData = new Float32Array([
    -0.75, -0.65, -1,
     0.75, -0.65, -1,
     0   ,  0.65, -1,
    ]);

    const buffer = gl.createBuffer();
    gl.bindBuffer(gl.ARRAY_BUFFER, buffer);
    gl.bufferData(gl.ARRAY_BUFFER, positionsData, gl.STATIC_DRAW);

    const attribute = gl.getAttribLocation(program, 'position');
    gl.enableVertexAttribArray(attribute);
    gl.vertexAttribPointer(attribute, 3, gl.FLOAT, false, 0, 0);

    gl.clear(gl.COLOR_BUFFER_BIT);
    gl.drawArrays(gl.TRIANGLES, 0, 3);
});
</script>

link