雾化（使用w分量）

最新推荐文章于 2024-07-26 20:52:26 发布

directx3d_beginner

最新推荐文章于 2024-07-26 20:52:26 发布

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分类专栏： webgl编程指南学习

本文链接：https://blog.csdn.net/directx3d_beginner/article/details/103308082

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<html>
<head>11</head>
<body>
<canvas id = "test" width = "800" height = "800">canvas </canvas>
<script src = "webgltest/cuon-matrix.js"></script>
<script >
//顶点着色器
var vertexShaderSource =
    'attribute vec4 a_Position;\n' +
    'attribute vec4 a_Color;\n' +
    'uniform mat4 u_mvpMatrix;\n' +
    'uniform mat4 u_ModelMatrix;\n' +               //模型矩阵
   'uniform vec4 u_Eye;\n' +
    'varying vec4 v_Color;\n' +                     //varying变量
   'varying float v_Dist;\n' +
    'void main() {\n' +
    'gl_Position = u_mvpMatrix * a_Position;\n'+
    'v_Color = a_Color;\n' +                                        //将数据传给片元着色器
   //计算顶点与视点的距离(<1)
   'v_Dist = gl_Position.w;\n' +
    '}\n';

//片元着色器
var fragmentShaderSource =
    'precision mediump float;\n' +
   'uniform vec3 u_FogColor; \n' +                   //雾的颜色
   'uniform vec2 u_FogDist; \n' +                   //雾化的起点和终点
    'varying vec4 v_Color;\n' +                     //varying变量
   'varying float v_Dist;\n' +
    'void main() {\n' +
   //计算雾化因子
   'float fogFactor = clamp((u_FogDist.y - v_Dist ) / (u_FogDist.y - u_FogDist.x ), 0.0, 1.0 ); \n' +
   'vec3 color = mix(u_FogColor, vec3(v_Color), fogFactor); \n' +
   'gl_FragColor = vec4(color, v_Color.a); \n' +
    '}\n';

//创建着色器方法，输入参数：渲染上下文，着色器类型，数据源
function createShader(gl, type, source)
{
    //创建着色器对象
    var shader = gl.createShader(type);
    //提供数据源
    gl.shaderSource(shader,source);
    //编译着色器
    gl.compileShader(shader);
    //链接
    var success = gl.getShaderParameter(shader, gl.COMPILE_STATUS);
    if(success)
    {
        return shader;
    }
    console.log(gl.getShaderInfoLog(shader));
    gl.deleteShader(shader);

}
//将顶点着色器和像素着色器链接到一个着色程序
function createProgram(gl, vertexShader, fragmentShader)
{
    var program = gl.createProgram();
    gl.attachShader( program, vertexShader);
    gl.attachShader( program, fragmentShader);
    gl.linkProgram( program );
    var success = gl.getProgramParameter(program, gl.LINK_STATUS);
    if(success)
    {
        console.log("link right");
        return program;
    }
    console.log(gl.getProgramInfoLog(program));
    gl.deleteProgram(program);
}

//创建顶点缓冲区和索引缓冲区

function initVertexBuffers(program,gl) {
// Create a cube
//    v6----- v5
//   /|      /|
// v1------v0|
// | |     | |
// | |v7---|-|v4
// |/      |/
// v2------v3

var vertices = new Float32Array([   // Vertex coordinates
     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
]);

var 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
]);

var 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
]);

var 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
]);

// Create a buffer object
var indexBuffer = gl.createBuffer();
if (!indexBuffer)
return -1;

// Write the vertex coordinates and color to the buffer object
if (!initArrayBuffer(program,gl, vertices, 3, gl.FLOAT, 'a_Position'))
return -1;

if (!initArrayBuffer(program,gl, colors, 3, gl.FLOAT, 'a_Color'))
return -1;

// Write the indices to the buffer object
gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, indexBuffer);
gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, indices, gl.STATIC_DRAW);

return indices.length;
}

function initArrayBuffer(program, gl, data, num, type, attribute) {
var buffer = gl.createBuffer();   // Create a buffer object
if (!buffer) {
    console.log('Failed to create the buffer object');
    return false;
}
// Write date into the buffer object
gl.bindBuffer(gl.ARRAY_BUFFER, buffer);
gl.bufferData(gl.ARRAY_BUFFER, data, gl.STATIC_DRAW);
// Assign the buffer object to the attribute variable
var a_attribute = gl.getAttribLocation(program, attribute);
if (a_attribute < 0) {
    console.log('Failed to get the storage location of ' + attribute);
    return false;
}
gl.vertexAttribPointer(a_attribute, num, type, false, 0, 0);
// Enable the assignment of the buffer object to the attribute variable
gl.enableVertexAttribArray(a_attribute);

return true;
}
    var canvas = document.getElementById("test");
    //创建webgl渲染上下文
    var gl = canvas.getContext("webgl");
    //var gl = WebGLUtils.setupWebGL(canvas);
    if(!gl)
    {
        console.log("wrong");
    }
    else
    {
        console.log("right");
    }
    //初始化着色器

    var vertexShader = createShader(gl,gl.VERTEX_SHADER,vertexShaderSource);
    var fragmentShader = createShader(gl,gl.FRAGMENT_SHADER, fragmentShaderSource);
    var program = createProgram(gl, vertexShader, fragmentShader);
    gl.useProgram(program);
    //创建顶点数组
    var n = initVertexBuffers(program,gl);

   //雾的颜色
   var fogColor = new Float32Array([0.137, 0.231, 0.423]);
   //雾化的起点和终点与视点间的距离[起点距离，终点距离]
   var fogDist = new Float32Array([55, 80]);
   //视点在世界坐标系下的坐标
   var eye = new Float32Array([25, 65,35, 1.0]);

   //获取投影矩阵
   var u_mvpMatrix = gl.getUniformLocation(program, 'u_mvpMatrix');
   var u_ModelMatrix = gl.getUniformLocation(program, 'u_ModelMatrix');
   //雾的参数
   var u_FogColor = gl.getUniformLocation(program, 'u_FogColor');
   var u_FogDist = gl.getUniformLocation(program, 'u_FogDist');
   var u_Eye = gl.getUniformLocation(program, 'u_Eye');

   if (!u_mvpMatrix || !u_ModelMatrix || !u_Eye || !u_FogColor || !u_FogDist) {
    console.log('Failed to get the storage location');

   }
   //设置雾的颜色、起点与终点、视点坐标传给相应的Uniform变量
   gl.uniform3fv(u_FogColor, fogColor);
   gl.uniform2fv(u_FogDist, fogDist);
   gl.uniform4fv(u_Eye, eye);
   //清除颜色
   //在绘制之前，清除深度缓冲区
   gl.clearColor(fogColor[0], fogColor[1], fogColor[2], 1.0);
   //开启隐藏面消除功能
   gl.enable(gl.DEPTH_TEST);

   //模型矩阵
   var modelMatrix = new Matrix4();
   modelMatrix.setScale(10, 10, 10);
   gl.uniformMatrix4fv(u_ModelMatrix, false, modelMatrix.elements);

   var g_near = 1.0, g_far = 1000.0;
   //模型视图投影矩阵
   var mvpMatrix = new Matrix4();
   mvpMatrix.setPerspective(30, canvas.width / canvas.height,g_near, g_far);
   mvpMatrix.lookAt(eye[0], eye[1], eye[2], 0, 2, 0, 0, 1, 0 );
   mvpMatrix.multiply(modelMatrix);
   //将投影矩阵传给u_ProjMatrix变量
   gl.uniformMatrix4fv(u_mvpMatrix, false, mvpMatrix.elements);


   gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
   //绘制正方体
   gl.drawElements(gl.TRIANGLES, n, gl.UNSIGNED_BYTE, 0 );

    </script>
</body>
</html>