Question

我必须通过使用滑块或按钮控制投影的近远平面来解决需要应用正交投影的任务。

物体是旋转的立方体。我已经定义了很多转换函数，比如旋转，缩放。它工作，但当我尝试应用模型视图矩阵和投影矩阵时，它停止工作，html不显示多维数据集。

控制台告诉我，NaN向量存在归一化问题。

这是我的代码：

HTML

<!DOCTYPE html>
<html>

<button id = "ButtonX">Rotate X</button>
<button id = "ButtonY">Rotate Y</button>
<button id = "ButtonZ">Rotate Z</button>
<button id = "ButtonT">Toggle Rotation</button>
<button id="Direction">Change Direction</button>

<div>Traslation on X -1 <input id="slideX" type="range"
    min="-1" max="1" step="0.1" value="0" />
    1 </div>

<div>Traslation on Y -1 <input id="slideY" type="range"
    min="-1" max="1" step="0.1" value="0" />
    1 </div>

<div>Traslation on Z -1 <input id="slideZ" type="range"
    min="-1" max="1" step="0.1" value="0" />
    1 </div>

<div>Scaling on X -1 <input id="ScalingX" type="range"
    min="0" max="1" step="0.1" value="0" />
    1 </div>
<div>Scaling on Y -1 <input id="ScalingY" type="range"
    min="0" max="1" step="0.1" value="0" />
    1 </div>
<div>Scaling on Z -1 <input id="ScalingZ" type="range"
    min="0" max="1" step="0.1" value="0" />
    1 </div>


<button id="Button1">Increase Z</button>
<button id="Button2">Decrease Z</button>


<script id="vertex-shader" type="x-shader/x-vertex">

attribute  vec4 vPosition;
attribute  vec4 vColor;

varying vec4 fColor;

//uniform vec3 theta;

// Point 2 -> Move the matrices
// Per spostare le matrici le abbiamo dovuto dichiarare nel file GLSL come uniform
// le matrici rx ry e rz sono rispettivamente le matrici di rotazione sugli assi
uniform mat4 rx;
uniform mat4 ry;
uniform mat4 rz;

// Points 3 -> Traslation Matrix
uniform mat4 traslation;
// Points 3 -> Scaling Matrix
uniform mat4 scaling;

//Point 4 -> MV and P matrices
uniform mat4 modelView;
uniform mat4 projection;

void main()
{
    // Compute the sines and cosines of theta for each of
    //   the three axes in one computation.
    //vec3 angles = radians( theta );
    //vec3 c = cos( angles );
    //vec3 s = sin( angles );

    // Remember: the matrices are column-major
    /*
    mat4 rx = mat4( 1.0,  0.0,  0.0, 0.0,
            0.0,  c.x,  s.x, 0.0,
            0.0, -s.x,  c.x, 0.0,
            0.0,  0.0,  0.0, 1.0 );

    mat4 ry = mat4( c.y, 0.0, -s.y, 0.0,
            0.0, 1.0,  0.0, 0.0,
            s.y, 0.0,  c.y, 0.0,
            0.0, 0.0,  0.0, 1.0 );


    mat4 rz = mat4( c.z, s.z, 0.0, 0.0,
            -s.z,  c.z, 0.0, 0.0,
            0.0,  0.0, 1.0, 0.0,
            0.0,  0.0, 0.0, 1.0 );
     */

    fColor = vColor;
    gl_Position = scaling *rz * ry * rx * traslation * vPosition ;  // ORDINE : scaling -> rotazione -> traslation
    //gl_Position = scaling *rz * ry * rx * traslation *projection*modelView*vPosition ;
    gl_Position.z = -gl_Position.z;

}
</script>

<script id="fragment-shader" type="x-shader/x-fragment">

precision mediump float;

varying vec4 fColor;

void
main()
{
    gl_FragColor = fColor;

}
</script>

<script type="text/javascript" src="../Common/webgl-utils.js"></script>
<script type="text/javascript" src="../Common/initShaders.js"></script>
<script type="text/javascript" src="../Common/MV.js"></script>
<script type="text/javascript" src="Homework1.js"></script>



<body>
<canvas id="gl-canvas" width="1024" height="1024">
Oops ... your browser doesn't support the HTML5 canvas element
</canvas>
</body>
</html>

JS

"use strict";

var canvas;
var gl;

var numVertices  = 36;

var numChecks = 8;

var program;

var c;

var flag = true;

var direction = true;

var rx;
var ry;
var rz;
var traslation_loc;
var tx = 0 ;
var ty = 0;
var tz = 0;
var scaling_loc;
var sx = 1.0;
var sy = 1.0;
var sz = 1.0;

var pointsArray = [];
var colorsArray = [];


//Point 4
var near = -1;
var far = 1;
var radius = 1.0;
var theta  = 0.0;
var phi    = 0.0;
var dr = 5.0 * Math.PI/180.0;

var left = -1.0;
var right = 1.0;
var ytop = 1.0;
var bottom = -1.0;

var mvMatrix, pMatrix;
var modelView, projection;
var eye;

const at = vec3(0.0, 0.0, 0.0);
const up = vec3(0.0, 1.0, 0.0);
//


var vertices = [
    vec4( -0.5, -0.5,  0.5, 1.0 ),
    vec4( -0.5,  0.5,  0.5, 1.0 ),
    vec4( 0.5,  0.5,  0.5, 1.0 ),
    vec4( 0.5, -0.5,  0.5, 1.0 ),
    vec4( -0.5, -0.5, -0.5, 1.0 ),
    vec4( -0.5,  0.5, -0.5, 1.0 ),
    vec4( 0.5,  0.5, -0.5, 1.0 ),
    vec4( 0.5, -0.5, -0.5, 1.0 )
];

var vertexColors = [
    vec4( 0.0, 0.0, 0.0, 1.0 ),  // black
    vec4( 1.0, 0.0, 0.0, 1.0 ),  // red
    vec4( 1.0, 1.0, 0.0, 1.0 ),  // yellow
    vec4( 0.0, 1.0, 0.0, 1.0 ),  // green
    vec4( 0.0, 0.0, 1.0, 1.0 ),  // blue
    vec4( 1.0, 0.0, 1.0, 1.0 ),  // magenta
    vec4( 0.0, 1.0, 1.0, 1.0 ),  // white
    vec4( 0.0, 1.0, 1.0, 1.0 )   // cyan
];

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

var theta = [45.0, 45.0, 45.0];

//var thetaLoc;






function quad(a, b, c, d) {
     pointsArray.push(vertices[a]);
     colorsArray.push(vertexColors[a]);

     pointsArray.push(vertices[b]);
     colorsArray.push(vertexColors[a]);

     pointsArray.push(vertices[c]);
     colorsArray.push(vertexColors[a]);

     pointsArray.push(vertices[a]);
     colorsArray.push(vertexColors[a]);

     pointsArray.push(vertices[c]);
     colorsArray.push(vertexColors[a]);

     pointsArray.push(vertices[d]);
     colorsArray.push(vertexColors[a]);
}

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 );
}


window.onload = function init() {

    canvas = document.getElementById( "gl-canvas" );

    gl = WebGLUtils.setupWebGL( canvas );
    if ( !gl ) { alert( "WebGL isn't available" ); }

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

    gl.enable(gl.DEPTH_TEST);

    //
    //  Load shaders and initialize attribute buffers
    //
    program = initShaders( gl, "vertex-shader", "fragment-shader" );


    gl.useProgram( program );

    colorCube();




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

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

    // Possiamo commentare quello che riguarda il theta per il punto 2
    //thetaLoc = gl.getUniformLocation(program, "theta");

    // Point 2 - Rotation

    //X AXIS

    rx = gl.getUniformLocation(program, "rx");


    //Y AXIS

    ry = gl.getUniformLocation(program, "ry");



    //Z AXIS

     rz = gl.getUniformLocation(program, "rz");


    // Traslation Matrix

    traslation_loc = gl.getUniformLocation(program , "traslation");

    // Scaling Matrix

    scaling_loc = gl.getUniformLocation(program , "scaling");

    // Projection and Model matrix
    modelView = gl.getUniformLocation( program, "modelView" );
    projection = gl.getUniformLocation( program, "projection" );





    //**************


 document.getElementById("ButtonX").onclick = function(){axis = xAxis;};
 document.getElementById("ButtonY").onclick = function(){axis = yAxis;};
 document.getElementById("ButtonZ").onclick = function(){axis = zAxis;};
 document.getElementById("ButtonT").onclick = function(){flag = !flag;};
 document.getElementById("Direction").onclick = function() { direction = !direction;};
 document.getElementById( "slideX" ).oninput = function(){ tx = parseFloat(event.target.value,10); };
 document.getElementById( "slideY" ).oninput = function(){ ty = parseFloat(event.target.value,10); };
 document.getElementById( "slideZ" ).oninput = function(){ tz = parseFloat(event.target.value,10); };
 document.getElementById( "ScalingX" ).oninput = function(){ sx = parseFloat(event.target.value,10); };
 document.getElementById( "ScalingY" ).oninput = function(){ sy = parseFloat(event.target.value,10); };
 document.getElementById( "ScalingZ" ).oninput = function(){ sz = parseFloat(event.target.value,10); };

 // Point 4
 document.getElementById("Button1").onclick = function(){near  *= 1.1; far *= 1.1;};
 document.getElementById("Button2").onclick = function(){near *= 0.9; far *= 0.9;};

    render();
}

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

    // Point 4
    //*************************************
    eye = vec3(radius*Math.sin(phi), radius*Math.sin(theta),
               radius*Math.cos(phi));

    mvMatrix = lookAt(eye, at , up);
    pMatrix = ortho(left, right, bottom, ytop, near, far);

    gl.uniformMatrix4fv( modelView, false, flatten(mvMatrix) );
    gl.uniformMatrix4fv( projection, false, flatten(pMatrix) );


    //*************************************


    // Point 3 -> Scaling

    var scaling = [sx , 0.0 , 0.0 , 0.0,
                   0.0  , sy, 0.0 , 0.0,
                   0.0 , 0.0 , sz , 0.0,
                   0.0 , 0.0 , 0.0 , 1];
    gl.uniformMatrix4fv(scaling_loc,false,scaling);


    // ****************************************
    //X AXIS - Point 2
    var theta_x_degree  = theta[0];
    var theta_x_radians = theta_x_degree * Math.PI / 180;
    var s_x = Math.sin(theta_x_radians);
    var c_x = Math.cos(theta_x_radians);
    var rx_loc = [ 1.0,  0.0,  0.0, 0.0,
                  0.0,  c_x,  s_x, 0.0,
                  0.0, -s_x,  c_x, 0.0,
                  0.0,  0.0,  0.0, 1.0 ];
    gl.uniformMatrix4fv(rx, false, rx_loc);

    //Y AXIS - Point 2
    var theta_y_degree  = theta[1];
    var theta_y_radians = theta_y_degree * Math.PI / 180;
    var s_y = Math.sin(theta_y_radians);
    var c_y = Math.cos(theta_y_radians);
    var ry_loc = [ c_y, 0.0, -s_y, 0.0,
                  0.0, 1.0,  0.0, 0.0,
                  s_y, 0.0,  c_y, 0.0,
                  0.0, 0.0,  0.0, 1.0 ];
    gl.uniformMatrix4fv(ry, false, ry_loc);


    //Z AXIS - Point 2
    var theta_z_degree  = theta[2];
    var theta_z_radians = theta_z_degree * Math.PI / 180;
    var s_z = Math.sin(theta_z_radians);
    var c_z = Math.cos(theta_z_radians);
    var rz_loc = [ c_z, s_z, 0.0, 0.0,
                  -s_z,  c_z, 0.0, 0.0,
                  0.0,  0.0, 1.0, 0.0,
                  0.0,  0.0, 0.0, 1.0  ];
    gl.uniformMatrix4fv(rz, false, rz_loc);

    // ****************************************

    // Point 3 -> Traslation

    var traslation = [1.0 , 0.0 , 0.0 , 0.0,
                      0.0 , 1.0 , 0.0 , 0.0,
                      0.0 , 0.0 , 1.0 , 0.0,
                       tx , ty , tz , 1.0];

    gl.uniformMatrix4fv(traslation_loc,false,traslation);


    // ****************************************




    // ****************************************

    // Point 1 --> Change and Toggle Rotation
    if((direction)&&(!flag)) theta[axis] += -2.0;
    if((!direction)&&(!flag)) theta[axis] += +2.0;

    if(!direction) {theta[axis] += -2.0; }
    if(direction) {theta[axis] += 2.0 ; }

    // ****************************************

    //gl.uniform3fv(thetaLoc, theta);
    gl.drawArrays( gl.TRIANGLES, 0, numVertices );
    requestAnimFrame(render);
}

Answer 1

我发现了问题，那是var“eye”的初始化。有一个“0”无法计算。

使用WebGL进行正交投影

1 个答案: