Question

我试图在WebGL中为大学项目创建一个uv-sphere，但是我在正确声明顶点索引方面遇到了问题（我认为）。我正在关注此http://www.songho.ca/opengl/gl_sphere.html，我认为我的代码与此处显示的代码非常相似。这就是我声明顶点/索引/法线/纹理坐标的方式：

this.vertices = [];
        this.indices = [];
        this.normals = [];
        this.texCoords = [];

        let horizontalAng = 0;
        let horizontalDiff = (2 * Math.PI) / this.horizontalDiv;

        let verticalAng = Math.PI / 2;
        let verticalDiff = - (Math.PI / this.verticalDiv);


        for (var i = 0; i <= this.verticalDiv; i++) {

            let cosVert = Math.cos(verticalAng);
            let sinVert = Math.sin(verticalAng);

            for (var j = 0; j <= this.horizontlDiv; j++) {

                let cosHor = Math.cos(horizontalAng);
                let sinHor = Math.sin(horizontalAng);

                // z = (r * cos(verticalAng)) * cos(horizontalAng)
                // x = (r * cos(verticalAng)) * sin(horizontalAng)
                // y = r * sin(veritcalAng)

                let x = cosVert * sinHor;
                let y = sinVert;
                let z = cosVert * cosHor;

                this.vertices.push(x, y, z);
                this.normals.push(x, y, z);

                this.texCoords.push(j / this.horizontalDiv);
                this.texCoords.push(i / this.verticalDiv);

                horizontalAng += horizontalDiff;
            }

            verticalAng += verticalDiff;
        }


        for (var i = 0; i < this.verticalDiv; i++) {
            k1 = i * (this.horizontalDiv + 1);   
            k2 = k1 + this.horizontalDiv + 1;   

            for (var j = 0; j < this.horizontalDiv; j++) {

                if (i != 0) {
                    this.indices.push(k1);
                    this.indices.push(k2);
                    this.indices.push(k1 + 1);
                }

                if (i != (this.verticalDiv - 1)) {
                    this.indices.push(k1 + 1);
                    this.indices.push(k2);
                    this.indices.push(k2 + 1);
                }

                k1++;
                k2++;
            }
        }
    ```

Answer 1

该代码有几种错字

它没有声明k1或k2。

horizontalDiv在horizontlDiv处的拼写错误

class Foo {
  constructor(horizontalDiv, verticalDiv) {
    this.horizontalDiv = horizontalDiv;
    this.verticalDiv = verticalDiv;
    
    this.vertices = [];
    this.indices = [];
    this.normals = [];
    this.texCoords = [];

    let horizontalAng = 0;
    let horizontalDiff = (2 * Math.PI) / this.horizontalDiv;

    let verticalAng = Math.PI / 2;
    let verticalDiff = -(Math.PI / this.verticalDiv);


    for (var i = 0; i <= this.verticalDiv; i++) {

      let cosVert = Math.cos(verticalAng);
      let sinVert = Math.sin(verticalAng);

      for (var j = 0; j <= this.horizontalDiv; j++) {

        let cosHor = Math.cos(horizontalAng);
        let sinHor = Math.sin(horizontalAng);

        // z = (r * cos(verticalAng)) * cos(horizontalAng)
        // x = (r * cos(verticalAng)) * sin(horizontalAng)
        // y = r * sin(veritcalAng)

        let x = cosVert * sinHor;
        let y = sinVert;
        let z = cosVert * cosHor;

        this.vertices.push(x, y, z);
        this.normals.push(x, y, z);

        this.texCoords.push(j / this.horizontalDiv);
        this.texCoords.push(i / this.verticalDiv);

        horizontalAng += horizontalDiff;
      }

      verticalAng += verticalDiff;
    }


    for (var i = 0; i < this.verticalDiv; i++) {
      let k1 = i * (this.horizontalDiv + 1);
      let k2 = k1 + this.horizontalDiv + 1;

      for (var j = 0; j < this.horizontalDiv; j++) {

        if (i != 0) {
          this.indices.push(k1);
          this.indices.push(k2);
          this.indices.push(k1 + 1);
        }

        if (i != (this.verticalDiv - 1)) {
          this.indices.push(k1 + 1);
          this.indices.push(k2);
          this.indices.push(k2 + 1);
        }

        k1++;
        k2++;
      }
    }
  }
}

const f = new Foo(10, 10);

const m4 = twgl.m4;
const gl = document.querySelector('canvas').getContext('webgl');

const vs = `
attribute vec4 position;
attribute vec3 normal;
attribute vec2 texcoord;
uniform mat4 matrix;
varying vec4 v_color;
void main() {
  gl_Position = matrix * position;
  v_color = vec4(0, 0, 1, 1);
  
  // comment in next line to show normals
  //v_color = vec4(normal * .5 + .5, 1);
  
  // comment in next line to show texcoords
  //v_color = vec4(texcoord, 0, 1);
}
`;
const fs = `
precision mediump float;
varying vec4 v_color;
void main() {
  gl_FragColor = v_color;
}
`;

// compile shaders, link program, look up locations
const programInfo = twgl.createProgramInfo(gl, [vs, fs]);

// calls gl.createBuffer, gl.bindBuffer, gl.bufferData
const bufferInfo = twgl.createBufferInfoFromArrays(gl, {
  position: f.vertices,
  normal: f.normals,
  texcoord: f.texCoords,
  indices: f.indices,
});

let matrix = m4.perspective(Math.PI * 0.25, 2, 0.1, 100);
matrix = m4.translate(matrix, [0, 0, -5]);

gl.useProgram(programInfo.program);
// calls gl.bindBuffer, gl.enableVertexAttribArray, gl.vertexAttribPointer
twgl.setBuffersAndAttributes(gl, programInfo, bufferInfo);
// calls gl.uniformXXX
twgl.setUniforms(programInfo, {
  matrix,
});
// calls gl.drawArrays or gl.drawElements
twgl.drawBufferInfo(gl, bufferInfo);

canvas { border: 1px solid black; }

<script src="https://twgljs.org/dist/4.x/twgl-full.min.js"></script>
<canvas></canvas>

声明紫外线球的指数

1 个答案: