示例21：立方体-点光源逐片元
2021-07-18 本文已影响0人
WebGiser
效果
image.png
代码
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8" />
</head>
<body>
<canvas id="webgl" width="600" height="600">
Please use a browser that supports "canvas"
</canvas>
<script src="./lib/webgl-utils.js"></script>
<script src="./lib/webgl-debug.js"></script>
<script src="./lib/cuon-utils.js"></script>
<script src="./lib/cuon-matrix.js"></script>
<script>
let canvas = document.getElementById("webgl");
let gl = getWebGLContext(canvas);
//顶点着色器
let VSHADER_SOURCE =
'attribute vec4 a_Position;\n' +
'attribute vec4 a_Color;\n' +
'attribute vec4 a_Normal;\n' +
'uniform mat4 u_NormalMatrix;\n' +
'uniform mat4 u_MvpMatrix;\n' +
'uniform mat4 u_ModelMatrix;\n' +
'varying vec4 v_Color;\n' +
'varying vec3 v_Position;\n' +
'varying vec3 v_Normal;\n' +
'void main(){\n' +
' gl_Position = u_MvpMatrix * a_Position;\n' +
' v_Position = vec3(u_ModelMatrix * a_Position);\n' +
' v_Normal = normalize(vec3(u_NormalMatrix * a_Normal));\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' +
'uniform vec3 u_LightColor;\n' +
'uniform vec3 u_LightPosition;\n' +
'uniform vec3 u_AmbientLight;\n' +
'varying vec4 v_Color;\n' +
'varying vec3 v_Position;\n' +
'varying vec3 v_Normal;\n' +
'void main(){\n' +
' vec3 normal = normalize(v_Normal);\n'+
// 计算光线方向并归一化
' vec3 lightDirection = normalize(u_LightPosition - v_Position);\n' +
// 计算光线方向和法向量的点积
' float nDotL = max(dot(lightDirection, normal), 0.0);\n' +
// 计算漫反射光的颜色
' vec3 diffuse = u_LightColor * vec3(v_Color) * nDotL;\n' +
// 计算环境光产生的反射光的颜色
' vec3 ambient = u_AmbientLight * v_Color.rgb;\n' +
' gl_FragColor = vec4(diffuse+ambient, v_Color.a);\n' +
'}\n';
//设置缓冲区
function initVertexBuffer(gl) {
// Create a cube
// v6----- v5
// /| /|
// v1------v0|
// | | | |
// | |v7---|-|v4
// |/ |/
// v2------v3
let vertices = new Float32Array([
2.0, 2.0, 2.0, -2.0, 2.0, 2.0, -2.0, -2.0, 2.0, 2.0, -2.0, 2.0, // v0-v1-v2-v3 front
2.0, 2.0, 2.0, 2.0, -2.0, 2.0, 2.0, -2.0, -2.0, 2.0, 2.0, -2.0, // v0-v3-v4-v5 right
2.0, 2.0, 2.0, 2.0, 2.0, -2.0, -2.0, 2.0, -2.0, -2.0, 2.0, 2.0, // v0-v5-v6-v1 up
-2.0, 2.0, 2.0, -2.0, 2.0, -2.0, -2.0, -2.0, -2.0, -2.0, -2.0, 2.0, // v1-v6-v7-v2 left
-2.0, -2.0, -2.0, 2.0, -2.0, -2.0, 2.0, -2.0, 2.0, -2.0, -2.0, 2.0, // v7-v4-v3-v2 down
2.0, -2.0, -2.0, -2.0, -2.0, -2.0, -2.0, 2.0, -2.0, 2.0, 2.0, -2.0 // v4-v7-v6-v5 back
]);
let colors = new Float32Array([ // Colors
1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, // v0-v1-v2-v3 front
1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, // v0-v3-v4-v5 right
1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, // v0-v5-v6-v1 up
1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, // v1-v6-v7-v2 left
1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, // v7-v4-v3-v2 down
1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0 // v4-v7-v6-v5 back
]);
let normals = new Float32Array([ // Normal
0.0, 0.0, 1.0, 0.0, 0.0, 1.0, 0.0, 0.0, 1.0, 0.0, 0.0, 1.0, // v0-v1-v2-v3 front
1.0, 0.0, 0.0, 1.0, 0.0, 0.0, 1.0, 0.0, 0.0, 1.0, 0.0, 0.0, // v0-v3-v4-v5 right
0.0, 1.0, 0.0, 0.0, 1.0, 0.0, 0.0, 1.0, 0.0, 0.0, 1.0, 0.0, // v0-v5-v6-v1 up
-1.0, 0.0, 0.0, -1.0, 0.0, 0.0, -1.0, 0.0, 0.0, -1.0, 0.0, 0.0, // v1-v6-v7-v2 left
0.0, -1.0, 0.0, 0.0, -1.0, 0.0, 0.0, -1.0, 0.0, 0.0, -1.0, 0.0, // v7-v4-v3-v2 down
0.0, 0.0, -1.0, 0.0, 0.0, -1.0, 0.0, 0.0, -1.0, 0.0, 0.0, -1.0 // v4-v7-v6-v5 back
]);
// Indices of the vertices
let indices = new Uint8Array([
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
]);
//创建缓冲区
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, 3 * FSIZE, 0);
gl.enableVertexAttribArray(a_Position);
let colorBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, colorBuffer);
gl.bufferData(gl.ARRAY_BUFFER, colors, gl.STATIC_DRAW);
let a_Color = gl.getAttribLocation(gl.program, 'a_Color');
gl.vertexAttribPointer(a_Color, 3, gl.FLOAT, false, 3 * FSIZE, 0 * FSIZE);
gl.enableVertexAttribArray(a_Color);
let normalBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, normalBuffer);
gl.bufferData(gl.ARRAY_BUFFER, normals, gl.STATIC_DRAW);
let a_Normal = gl.getAttribLocation(gl.program, 'a_Normal');
gl.vertexAttribPointer(a_Normal, 3, gl.FLOAT, false, 3 * FSIZE, 0 * FSIZE);
gl.enableVertexAttribArray(a_Normal);
let indexBuffer = gl.createBuffer();
gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, indexBuffer);
gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, indices, gl.STATIC_DRAW);
return indices.length;
}
initShaders(gl, VSHADER_SOURCE, FSHADER_SOURCE);
let u_ModelMatrix = gl.getUniformLocation(gl.program, 'u_ModelMatrix');
let modelMatrix = new Matrix4();
modelMatrix.rotate(90, 0, 1, 0);
gl.uniformMatrix4fv(u_ModelMatrix, false, modelMatrix.elements);
let u_MvpMatrix = gl.getUniformLocation(gl.program, 'u_MvpMatrix');
let mvpMatrix = new Matrix4();
mvpMatrix.setPerspective(30, canvas.width / canvas.height, 1, 100);
mvpMatrix.lookAt(6, 6, 14, 0, 0, 0, 0, 1, 0);
mvpMatrix.multiply(modelMatrix);
gl.uniformMatrix4fv(u_MvpMatrix, false, mvpMatrix.elements);
let u_NormalMatrix = gl.getUniformLocation(gl.program, 'u_NormalMatrix');
let normalMatrix = new Matrix4();
normalMatrix.setInverseOf(modelMatrix);
normalMatrix.transpose();
gl.uniformMatrix4fv(u_NormalMatrix, false, normalMatrix.elements);
let u_LightColor = gl.getUniformLocation(gl.program, 'u_LightColor');
gl.uniform3f(u_LightColor, 1.0, 1.0, 1.0);
let u_LightPosition = gl.getUniformLocation(gl.program, 'u_LightPosition');
gl.uniform3f(u_LightPosition, 2.3, 4.0, 3.5);
let u_AmbientLight = gl.getUniformLocation(gl.program, 'u_AmbientLight');
gl.uniform3f(u_AmbientLight, 0.2, 0.2, 0.2);
let n = initVertexBuffer(gl);
gl.clearColor(0.0, 0.0, 0.0, 1.0);
gl.enable(gl.DEPTH_TEST);
gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
gl.drawElements(gl.TRIANGLES, n, gl.UNSIGNED_BYTE, 0);
</script>
</body>
</html>
