WebGl将多个对象添加到一个画布

时间：2015-02-19 19:15:42

标签： javascript html5 webgl

这是我在WebGL中的第一个实验：我正在尝试将一个立方体，八面体和四面体添加到单个画布中。我分别对每个形状进行了编程并对其进行了测试：每个形状都在他们自己的画布中生活。当我尝试将它们加在一起时，就会出现问题。目前我只看到八面体旋转（不，它没有掩盖其他形状，我已经检查过）。当我对八面体进行评论时，我看到立方体和四面体旋转，但是它们的颜色缓冲区已经混淆了并且不是我想要的（当我尝试分离它们的颜色缓冲区时，没有任何渲染到屏幕上）。我意识到我对这些编码的编码方式存在不一致之处，但目前的配置是我能够同时展示这两个对象的唯一方法。现在最近增加的八面体使前两个消失了。

我觉得这个问题与顶点和颜色缓冲区有关，但我没有足够的经验和背景知道要修改的内容。我是否为每个实例化了一个颜色缓冲区？这是有道理的。我尝试了这个，但它对前两个形状并不顺利，因此混合了颜色缓冲区。

如果有人可以建议/帮助我，我将不胜感激。花了无数个小时试图解决这个问题。 

var canvas;
var gl;

var NumVertices  = 36;

var points = [];
var colors = [];

var pointsT = [];
var colorsT = [];

var pointsO = [];
var colorsO = [];

var xAxis = 0;
var yAxis = 1;
var zAxis = 2;

var axis = 0;
var theta = [ 0, 0, 0 ];

var thetaLoc;

window.onload = function init()
{
    canvas = document.getElementById( "gl-canvas" );

    gl = WebGLUtils.setupWebGL( canvas );
    if ( !gl ) { alert( "WebGL is not available" ); }


    // --------------- Cube --------------------------

    colorCube();

    // --------------- Tetrahedron -------------------

    colorTetra();

    // --------------- Octohedron --------------------

    colorOcto();


    gl.viewport( 0, 0, canvas.width, canvas.height );
    gl.clearColor( 0.1, 0.1, 0.1, 1.0 );

    gl.enable(gl.DEPTH_TEST);


    // --------------- Load shaders and initialize attribute buffers

    // --------------- Cube --------------------------
    var program = initShaders( gl, "vertex-shader", "fragment-shader" );
    gl.useProgram( program );

    var cBuffer = gl.createBuffer();
    gl.bindBuffer( gl.ARRAY_BUFFER, cBuffer );
    gl.bufferData( gl.ARRAY_BUFFER, flatten(colors), gl.STATIC_DRAW );

    var vColor = gl.getAttribLocation( program, "vColor" );
    gl.vertexAttribPointer( vColor, 4, gl.FLOAT, false, 0, 0 );
    gl.enableVertexAttribArray( vColor );

    var vBuffer = gl.createBuffer();
    gl.bindBuffer( gl.ARRAY_BUFFER, vBuffer );
    gl.bufferData( gl.ARRAY_BUFFER, flatten(points), gl.STATIC_DRAW );

    var vPosition = gl.getAttribLocation( program, "vPosition" );
    gl.vertexAttribPointer( vPosition, 3, gl.FLOAT, false, 0, 0 );
    gl.enableVertexAttribArray( vPosition );

    thetaLoc = gl.getUniformLocation(program, "theta"); 


    // --------------- Tetrahedron -------------------

    var tcBuffer = gl.createBuffer();
    gl.bindBuffer( gl.ARRAY_BUFFER, tcBuffer );
    gl.bufferData( gl.ARRAY_BUFFER, flatten(colors), gl.STATIC_DRAW );

    var tvColor = gl.getAttribLocation( program, "vColor" );
    gl.vertexAttribPointer( tvColor, 3, gl.FLOAT, false, 0, 0 );
    gl.enableVertexAttribArray( tvColor );

    var tvBuffer = gl.createBuffer();
    gl.bindBuffer( gl.ARRAY_BUFFER, tvBuffer);
    gl.bufferData( gl.ARRAY_BUFFER, flatten(points), gl.STATIC_DRAW );

    var tvPosition = gl.getAttribLocation( program, "vPosition" );
    gl.vertexAttribPointer( tvPosition, 3, gl.FLOAT, false, 0, 0 );
    gl.enableVertexAttribArray( tvPosition );


    // --------------- Octohedron --------------------      

    var ocBuffer = gl.createBuffer();
    gl.bindBuffer( gl.ARRAY_BUFFER, ocBuffer );
    gl.bufferData( gl.ARRAY_BUFFER, flatten(colorsO), gl.STATIC_DRAW );

    var ovColor = gl.getAttribLocation( program, "vColor" );
    gl.vertexAttribPointer( ovColor, 3, gl.FLOAT, false, 0, 0 );
    gl.enableVertexAttribArray( ovColor );

    var ovBuffer = gl.createBuffer();
    gl.bindBuffer( gl.ARRAY_BUFFER, ovBuffer );
    gl.bufferData( gl.ARRAY_BUFFER, flatten(pointsO), gl.STATIC_DRAW );

    var ovPosition = gl.getAttribLocation( program, "vPosition" );
    gl.vertexAttribPointer( ovPosition, 3, gl.FLOAT, false, 0, 0 );
    gl.enableVertexAttribArray( ovPosition );

    render();
}

function render()
{
    gl.clear( gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);

    theta[axis] += 2.0;
    gl.uniform3fv(thetaLoc, theta);

    // Render cube
    gl.drawArrays( gl.TRIANGLES, 0, NumVertices );

    // Render tetrahedron
    gl.drawArrays( gl.TRIANGLES, 0, points.length );

    // Render sphere
    gl.drawArrays( gl.TRIANGLES, 0, pointsO.length );
    requestAnimFrame( render );
}


// DEFINE CUBE

function colorCube()
{
    quad( 1, 0, 3, 2 );
    quad( 2, 3, 7, 6 );
    quad( 3, 0, 4, 7 );
    quad( 6, 5, 1, 2 );
    quad( 4, 5, 6, 7 );
    quad( 5, 4, 0, 1 );
}

function quad(a, b, c, d) 
{
    var vertices = [
        vec3( -0.25, -0.25,  0.25 ),
        vec3( -0.25,  0.25,  0.25 ),
        vec3(  0.25,  0.25,  0.25 ),
        vec3(  0.25, -0.25,  0.25 ),
        vec3( -0.25, -0.25, -0.25 ),
        vec3( -0.25,  0.25, -0.25 ),
        vec3(  0.25,  0.25, -0.25 ),
        vec3(  0.25, -0.25, -0.25 )
    ];

    var vertexColors = [
        [ 0.9, 0.9, 0.2, 1.0 ],  // oarnge
        [ 1.0, 0.0, 0.0, 1.0 ],  // red
        [ 1.0, 1.0, 0.0, 1.0 ],  // yellow
        [ 0.0, 1.0, 0.0, 1.0 ],  // green
        [ 0.0, 0.0, 1.0, 1.0 ],  // blue
        [ 1.0, 0.0, 1.0, 1.0 ],  // magenta
        [ 1.0, 1.0, 1.0, 1.0 ],  // white
        [ 0.0, 1.0, 1.0, 1.0 ]   // cyan
    ];

    // Partion the quad into two triangles in order for
    // WebGL to be able to render it.      
    // vertex color assigned by the index of the vertex

    var indices = [ a, b, c, a, c, d ];

    for ( var i = 0; i < indices.length; ++i ) {
        points.push( vertices[indices[i]] );
        colors.push( vertexColors[indices[i]] );

        //for solid colored faces use 
        //colors.push(vertexColors[a]);    
    }
}

// DEFINE TETRAHEDRON

function colorTetra(){

    var verticesT = [
        vec3(  0.0000,  0.0000, -0.3500 ),
        vec3(  0.0000,  0.3500,  0.1500 ),
        vec3( -0.3500, -0.1500,  0.1500 ),
        vec3(  0.3500, -0.1500,  0.1500 )
    ];

    tetra(verticesT[0], verticesT[1], verticesT[2], verticesT[3]);
}

function makeTetra( a, b, c, color )
{
    // add colors and vertices for one triangle

    var baseColors = [
        vec3(0.7, 0.7, 0.9, 1.0),
        vec3(0.6, 0.8, 0.9, 1.0),
        vec3(0.5, 0.6, 0.9, 1.0),
        vec3(1.0, 1.0, 0.2, 1.0)
    ];

    colors.push( baseColors[color] );
    points.push( a );
    colors.push( baseColors[color] );
    points.push( b );
    colors.push( baseColors[color] );
    points.push( c );
}

function tetra( p, q, r, s )
{
    // tetrahedron with each side using
    // a different color

    makeTetra( p, r, q, 0 );
    makeTetra( p, r, s, 1 );
    makeTetra( p, q, s, 2 );
    makeTetra( q, r, s, 3 );
}


// DEFINE OCTOHEDRON

function colorOcto(){

    var verticesO = [
        vec3(  0.4000, 0.0000, 0.0000 ),        
        vec3(  0.0000, 0.0000, 0.0000 ),
        vec3(  0.0000, 0.4000, 0.0000 ),
        vec3(  0.4000, 0.4000, 0.0000 ),
        vec3(  0.2000, 0.2000, 0.3000 ),
        vec3(  0.2000, 0.2000, -0.3000 )
    ];

    octo(verticesO[0], verticesO[1], verticesO[2], verticesO[3], verticesO[4], verticesO[5]);   
}

function makeOcto( a, b, c, color )
{
    // add colors and vertices for one triangle

    var baseColors = [
        vec3(0.6, 0.6, 0.6, 1.0),
        vec3(0.3, 0.4, 0.9, 1.0),
        vec3(0.9, 0.9, 0.9, 1.0),
    ];

    colorsO.push( baseColors[color] );
    pointsO.push( a );
    colorsO.push( baseColors[color] );
    pointsO.push( b );
    colorsO.push( baseColors[color] );
    pointsO.push( c );
}

function octo( a, b, c, d , e, f)
{
    // tetrahedron with each side using
    // a different color

    makeOcto( a, d, e, 0 );
    makeOcto( a, b, e, 1 );
    makeOcto( b, c, e, 0 );
    makeOcto( c, d, e, 1 );
    makeOcto( a, d, f, 1 );
    makeOcto( a, b, f, 2 );
    makeOcto( b, c, f, 1 );
    makeOcto( c, d, f, 2 );
}

我在这里上传了完整的代码结构：

https://gist.github.com/Carla-de-Beer/10ad7c7309fad48d94df

1 个答案:

答案 0 :(得分：1)

在绘制之前，您需要为每个模型设置程序，然后设置属性和制服。

use program for cube
set attributes for cube
set uniforms for cube
draw cube

use program for tetrahedon
set attributes for tetrahedon
set uniforms for tetrahedon
draw tetrahedon

use program for sphere
set attributes for sphere
set uniforms for sphere
draw sphere
  • 使用program = gl.useProgram
  • 设置属性= gl.enableVertexAttribArray，gl.vertexAttribPointer
  • 设置制服= gl.uniformXXX，gl.activeTexture + gl.bindTexture

See this answer as well

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