attribute vec3 position;
attribute vec3 normal;
attribute vec4 color;
uniform   mat4 mvpMatrix;
uniform   mat4 invMatrix;
uniform   vec3 lightDirection;
varying   vec4 vColor;

void main(void){
    vec3  invLight = normalize(invMatrix * vec4(lightDirection, 0.0)).xyz;
    float diffuse  = clamp(dot(normal, invLight), 0.1, 1.0);
    vColor         = color * vec4(vec3(diffuse), 1.0);
    gl_Position    = mvpMatrix * vec4(position, 1.0);
}

vec3  invLight = normalize(invMatrix * vec4(lightDirection, 0.0)).xyz;
float diffuse  = clamp(dot(normal, invLight), 0.1, 1.0);
vColor         = color * vec4(vec3(diffuse), 1.0);

// 生成圆环体的函数
function torus(row, column, irad, orad){
    var pos = new Array(), nor = new Array(),
        col = new Array(), idx = new Array();
    for(var i = 0; i <= row; i++){
        var r = Math.PI * 2 / row * i;
        var rr = Math.cos(r);
        var ry = Math.sin(r);
        for(var ii = 0; ii <= column; ii++){
            var tr = Math.PI * 2 / column * ii;
            var tx = (rr * irad + orad) * Math.cos(tr);
            var ty = ry * irad;
            var tz = (rr * irad + orad) * Math.sin(tr);
            var rx = rr * Math.cos(tr);
            var rz = rr * Math.sin(tr);
            pos.push(tx, ty, tz);
            nor.push(rx, ry, rz);
            var tc = hsva(360 / column * ii, 1, 1, 1);
            col.push(tc[0], tc[1], tc[2], tc[3]);
        }
    }
    for(i = 0; i < row; i++){
        for(ii = 0; ii < column; ii++){
            r = (column + 1) * i + ii;
            idx.push(r, r + column + 1, r + 1);
            idx.push(r + column + 1, r + column + 2, r + 1);
        }
    }
    return [pos, nor, col, idx];
}

// 获取attributeLocation并放入数组
var attLocation = new Array();
attLocation[0] = gl.getAttribLocation(prg, ‘position‘);
attLocation[1] = gl.getAttribLocation(prg, ‘normal‘);
attLocation[2] = gl.getAttribLocation(prg, ‘color‘);

// 将attribute的元素个数保存到数组中
var attStride = new Array();
attStride[0] = 3;
attStride[1] = 3;
attStride[2] = 4;

// 生成圆环体的顶点数据
var torusData = torus(32, 32, 1.0, 2.0);
var position = torusData[0];
var normal = torusData[1];
var color = torusData[2];
var index = torusData[3];

// 生成VBO
var pos_vbo = create_vbo(position);
var nor_vbo = create_vbo(normal);
var col_vbo = create_vbo(color);

// 获取uniformLocation并保存到数组中
var uniLocation = new Array();
uniLocation[0] = gl.getUniformLocation(prg, ‘mvpMatrix‘);
uniLocation[1] = gl.getUniformLocation(prg, ‘invMatrix‘);
uniLocation[2] = gl.getUniformLocation(prg, ‘lightDirection‘);

// 各矩阵的生成和初始化
var mMatrix = m.identity(m.create());
var vMatrix = m.identity(m.create());
var pMatrix = m.identity(m.create());
var tmpMatrix = m.identity(m.create());
var mvpMatrix = m.identity(m.create());
var invMatrix = m.identity(m.create());

// 视图x投影坐标变换矩阵
m.lookAt([0.0, 0.0, 20.0], [0, 0, 0], [0, 1, 0], vMatrix);
m.perspective(45, c.width / c.height, 0.1, 100, pMatrix);
m.multiply(pMatrix, vMatrix, tmpMatrix);

// 平行光源的方向
var lightDirection = [-0.5, 0.5, 0.5];

// 计数器自增
count++;

// 用计数器计算角度
var rad = (count % 360) * Math.PI / 180;

// 模型坐标变换矩阵的生成
m.identity(mMatrix);
m.rotate(mMatrix, rad, [0, 1, 1], mMatrix);
m.multiply(tmpMatrix, mMatrix, mvpMatrix);

// 依据模型坐标变换矩阵生成逆矩阵
m.inverse(mMatrix, invMatrix);

// uniform变量
gl.uniformMatrix4fv(uniLocation[0], false, mvpMatrix);
gl.uniformMatrix4fv(uniLocation[1], false, invMatrix);
gl.uniform3fv(uniLocation[2], lightDirection);