效果
image.png
代码
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title></title>
<script src="./cuon-matrix.js"></script>
</head>
<body>
<canvas id="canvas" width="600" height="600" style="border: 1px solid #ff0000;"></canvas>
<script>
let canvas = document.getElementById('canvas');
let gl = canvas.getContext('webgl');
// 顶点着色器
let VSHADER_SOURCE =
"attribute vec4 a_Position;\n" +
"attribute vec4 a_Color;\n" +
"uniform mat4 u_MvpMatrix;\n" +
"varying vec4 v_Color;\n" +
"void main(){\n" +
"gl_Position = u_MvpMatrix * a_Position;\n" +
"v_Color = a_Color;\n" +
"}\n";
// 片元着色器
let FSHADER_SOURCE =
"#ifdef GL_ES\n" +
"precision mediump float;\n" +
"#endif\n" +
"varying vec4 v_Color;\n" +
"void main(){\n" +
" gl_FragColor = v_Color;\n" +
"}\n";
// 初始化着色器
function initShaders(gl, vSource, fSource) {
let vShader = gl.createShader(gl.VERTEX_SHADER);
gl.shaderSource(vShader, vSource);
gl.compileShader(vShader);
let fShader = gl.createShader(gl.FRAGMENT_SHADER);
gl.shaderSource(fShader, fSource);
gl.compileShader(fShader);
let program = gl.createProgram();
gl.attachShader(program, vShader);
gl.attachShader(program, fShader);
gl.linkProgram(program);
gl.useProgram(program);
gl.program = program;
}
// 设置定点位置-缓冲区对象
function initVertexBuffers(gl) {
// v6----- v5
// /| /|
// v1------v0|
// | | | |
// | |v7---|-|v4
// |/ |/
// v2------v3
let vertices = new Float32Array([
1.0, 1.0, 1.0, -1.0, 1.0, 1.0, -1.0, -1.0, 1.0, 1.0, -1.0, 1.0, // v0-v1-v2-v3 front
1.0, 1.0, 1.0, 1.0, -1.0, 1.0, 1.0, -1.0, -1.0, 1.0, 1.0, -1.0, // v0-v3-v4-v5 right
1.0, 1.0, 1.0, 1.0, 1.0, -1.0, -1.0, 1.0, -1.0, -1.0, 1.0, 1.0, // v0-v5-v6-v1 up
-1.0, 1.0, 1.0, -1.0, 1.0, -1.0, -1.0, -1.0, -1.0, -1.0, -1.0, 1.0, // v1-v6-v7-v2 left
-1.0, -1.0, -1.0, 1.0, -1.0, -1.0, 1.0, -1.0, 1.0, -1.0, -1.0, 1.0, // v7-v4-v3-v2 down
1.0, -1.0, -1.0, -1.0, -1.0, -1.0, -1.0, 1.0, -1.0, 1.0, 1.0, -1.0 // v4-v7-v6-v5 back
]);
let colors = new Float32Array([ // Colors
0.4, 0.4, 1.0, 0.4, 0.4, 1.0, 0.4, 0.4, 1.0, 0.4, 0.4, 1.0, // v0-v1-v2-v3 front(blue)
0.4, 1.0, 0.4, 0.4, 1.0, 0.4, 0.4, 1.0, 0.4, 0.4, 1.0, 0.4, // v0-v3-v4-v5 right(green)
1.0, 0.4, 0.4, 1.0, 0.4, 0.4, 1.0, 0.4, 0.4, 1.0, 0.4, 0.4, // v0-v5-v6-v1 up(red)
1.0, 1.0, 0.4, 1.0, 1.0, 0.4, 1.0, 1.0, 0.4, 1.0, 1.0, 0.4, // v1-v6-v7-v2 left
1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, // v7-v4-v3-v2 down
0.4, 1.0, 1.0, 0.4, 1.0, 1.0, 0.4, 1.0, 1.0, 0.4, 1.0, 1.0 // v4-v7-v6-v5 back
]);
let indices = new Uint8Array([ // Indices of the vertices
0, 1, 2, 0, 2, 3, // front
4, 5, 6, 4, 6, 7, // right
8, 9, 10, 8, 10, 11, // up
12, 13, 14, 12, 14, 15, // left
16, 17, 18, 16, 18, 19, // down
20, 21, 22, 20, 22, 23 // back
]);
// 创建顶点位置缓冲区对象
let vertexBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, vertexBuffer);
gl.bufferData(gl.ARRAY_BUFFER, vertices, gl.STATIC_DRAW);
let fsize = vertices.BYTES_PER_ELEMENT;
let a_Position = gl.getAttribLocation(gl.program, 'a_Position');
gl.vertexAttribPointer(a_Position, 3, gl.FLOAT, false, fsize * 0, fsize * 0);
gl.enableVertexAttribArray(a_Position);
// 创建颜色缓冲区
let colorBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, colorBuffer);
gl.bufferData(gl.ARRAY_BUFFER, colors, gl.STATIC_DRAW);
let fsize2 = colors.BYTES_PER_ELEMENT;
let a_Color = gl.getAttribLocation(gl.program, 'a_Color');
gl.vertexAttribPointer(a_Color, 3, gl.FLOAT, false, fsize2 * 0, fsize * 0);
gl.enableVertexAttribArray(a_Color);
// 创建顶点索引缓冲区
let indicesBuffer = gl.createBuffer();
gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, indicesBuffer);
gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, indices, gl.STATIC_DRAW);
return indices.length;
}
initShaders(gl, VSHADER_SOURCE, FSHADER_SOURCE);
let n = initVertexBuffers(gl);
gl.clearColor(0, 0, 0, 1);
// 开启隐藏面消除（深度检测）
gl.enable(gl.DEPTH_TEST);
gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
// 设置mvp矩阵：模型矩阵、视图矩阵、投影矩阵
let modelMatrix = new Matrix4();
//modelMatrix.setTranslate(0.75, 0, 0);
let viewMatrix = new Matrix4();
viewMatrix.setLookAt(3, 3, 7, 0, 0, 0, 0, 1, 0);
let projectMatrix = new Matrix4();
projectMatrix.setPerspective(30, canvas.width / canvas.height, 1, 100);
let mvpMatrix = new Matrix4();
mvpMatrix.set(projectMatrix).multiply(viewMatrix).multiply(modelMatrix);
let u_MvpMatrix = gl.getUniformLocation(gl.program, 'u_MvpMatrix');
gl.uniformMatrix4fv(u_MvpMatrix, false, mvpMatrix.elements);
gl.drawElements(gl.TRIANGLES, n, gl.UNSIGNED_BYTE, 0);
</script>
</body>
</html>
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