为 WebGL 3D 对象着色的问题

Question

我正在尝试根据 Mozilla 文档中的文档实现 WebGL 应用程序。

我的代码生成了一个由比例因子塑造的球体。颜色是根据比例因子生成的。形状没问题，就是颜色不对。那么出了什么问题-我不知道。此代码适用于 Android 和 Java。我正在使用最新的 Chrome 浏览器。

代码如下：

export function createHcm3dObject(gl, diagram3D, deltaTheta, deltaPhi) {

let positions = [];
let colors = [];
let alpha = 1.0;

for (let theta = 0; theta < 360; theta += deltaTheta) {
    for (let phi = 0; phi < 180; phi += deltaPhi) {

        //r is scalefactor between 0 and 1 which shapes the sphere
        let r = diagram3D[theta][phi];
        //Color is generated according to the radius (alpha is currently set to 1.0)
        let x1Color = generateColorArray(r, alpha);
        let x1 = r * Math.sin(math3d.toRadians(phi)) * Math.cos(math3d.toRadians(theta));
        let y1 = r * Math.sin(math3d.toRadians(phi)) * Math.sin(math3d.toRadians(theta));
        let z1 = r * Math.cos(math3d.toRadians(phi));

        r = diagram3D[theta + deltaTheta][phi];
        let x2Color = generateColorArray(r, alpha);
        let x2 = r * Math.sin(math3d.toRadians(phi)) * Math.cos(math3d.toRadians(theta + deltaTheta));
        let y2 = r * Math.sin(math3d.toRadians(phi)) * Math.sin(math3d.toRadians(theta + deltaTheta));
        let z2 = r * Math.cos(math3d.toRadians(phi));

        r = diagram3D[theta][phi + deltaPhi];
        let x3Color = generateColorArray(r, alpha);
        let x3 = r * Math.sin(math3d.toRadians(phi + deltaPhi)) * Math.cos(math3d.toRadians(theta));
        let y3 = r * Math.sin(math3d.toRadians(phi + deltaPhi)) * Math.sin(math3d.toRadians(theta));
        let z3 = r * Math.cos(math3d.toRadians(phi + deltaPhi));

        r = diagram3D[theta + deltaTheta][phi + deltaPhi];
        let x4Color = generateColorArray(r, alpha);
        let x4 = r * Math.sin(math3d.toRadians(phi + deltaPhi)) * Math.cos(math3d.toRadians(theta + deltaTheta));
        let y4 = r * Math.sin(math3d.toRadians(phi + deltaPhi)) * Math.sin(math3d.toRadians(theta + deltaTheta));
        let z4 = r * Math.cos(math3d.toRadians(phi + deltaPhi));

        //1. Triangle
        positions.push(x1, y1, z1);
        positions.push(x3, y3, z3);
        positions.push(x4, y4, z4);

        //2. Triangle
        positions.push(x2, y2, z2);
        positions.push(x1, y1, z1);
        positions.push(x4, y4, z4);

        //Colors for 1. Triangle (red,green,blue,alpha=1.0)
        colors.push(x1Color[0], x1Color[1], x1Color[2], x1Color[3]);
        colors.push(x3Color[0], x3Color[1], x3Color[2], x3Color[3]);
        colors.push(x4Color[0], x4Color[1], x4Color[2], x4Color[3]);

        //Colors for 2. Triangle
        colors.push(x2Color[0], x2Color[1], x2Color[2], x2Color[3]);
        colors.push(x1Color[0], x1Color[1], x1Color[2], x1Color[3]);
        colors.push(x4Color[0], x4Color[1], x4Color[2], x4Color[3]);
    }
    //console.log(positions);
    //console.log(colors);
}

// Now pass the list of positions into WebGL to build the
// shape. We do this by creating a Float32Array from the
// JavaScript array, then use it to fill the current buffer.

const positionBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, positionBuffer);
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(positions), gl.STATIC_DRAW);

const colorBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, colorBuffer);
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(colors), gl.STATIC_DRAW);

return {
    position: positionBuffer,
    color: colorBuffer,
    positionSize: positions.length,
    deltaTheta,
    deltaPhi
  };
  };

function generateColorArray(r, alpha) {
let colorQuad = [];
let green = Math.abs(Math.sin(2 * r * Math.PI));
let blue = Math.abs(Math.cos(2 * r * Math.PI));
colorQuad[0] = 0.0;
colorQuad[1] = green;
colorQuad[2] = blue;
colorQuad[3] = alpha;
if (r >= 0.5 / 2) {
    let red = Math.abs(Math.cos(2 * r * Math.PI));
    green = Math.abs(Math.sin(2 * r * Math.PI));
    if (r < 0.5) {
        green = 1.0;
    }
    colorQuad[0] = red;
    colorQuad[1] = green;
    colorQuad[2] = 0.0;
    colorQuad[3] = alpha;
}
if (r >= 0.5) {
    let red = Math.abs(Math.cos(2 * r * Math.PI));
    green = Math.abs(Math.cos(2 * r * Math.PI));
    if (r < 0.75) {
        red = 1.0;
    }
    colorQuad[0] = red;
    colorQuad[1] = green;
    colorQuad[2] = 0.0;
    colorQuad[3] = alpha;
}
if (r >= 0.75) {
    let red = 1.0;
    blue = Math.abs(Math.cos(2 * r * Math.PI));
    colorQuad[0] = red;
    colorQuad[1] = 0.0;
    colorQuad[2] = blue;
    colorQuad[3] = alpha;
}
return colorQuad;
}

反应 Class:

export class Viewer3d extends Component {

state = {
rotX: 0,
rotY: 0,
gl: null,
buffers: null,
programInfo: null,
};

  componentDidMount() {
 this.init();
 }

 init = () => {
console.log("Comp did mount");
const canvas = document.querySelector("#glCanvas");
/** @type {WebGLRenderingContext} */
const gl = canvas.getContext("webgl");
if (!gl) {
  alert(
    "Unable to initialize WebGL. Your browser or machine may not support it."
  );
  return;
}
gl.clearColor(0.0, 0.0, 0.0, 1.0);
gl.clear(gl.COLOR_BUFFER_BIT);

let vs = document.getElementById("vshader").textContent;
let fs = document.getElementById("fshader").textContent;

//console.log(vs+" "+fs);

const shaderProgram = shader.initShaderProgram(gl, vs, fs);

let diagram3D = [];

let deltaTheta = 10;
let deltaPhi = 10;

for (let theta = 0; theta <= 360; theta += deltaTheta) {
  let phiArray = [];
  for (let phi = 0; phi <= 180; phi += deltaPhi) {
    let eleCorr = 90 - phi;
    let thetaCorr = 360 - theta;
    let out = engine.antenna_correction(
      thetaCorr,
      0,
      eleCorr,
      0,
      "012EA34",
      "012EA34"
    );
    let att = out.a;
    let logarithmic = false;

    if (logarithmic) {
      att = 1.0 - (-20.0 * Math.log10(att)) / 40.0;
    }

    phiArray[phi] = att;
  }
  diagram3D[theta] = phiArray;
}

//console.log(diagram3D);

const buffers = hcm3d.createHcm3dObject(
  gl,
  diagram3D,
  deltaTheta,
  deltaPhi
);

const programInfo = {
  program: shaderProgram,
  attribLocations: {
    vertexPosition: gl.getAttribLocation(shaderProgram, "aVertexPosition"),
    vertexColor: gl.getAttribLocation(shaderProgram,"aVertexColor"),
  },
  uniformLocations: {
    projectionMatrix: gl.getUniformLocation(shaderProgram,"uProjectionMatrix"),
    modelViewMatrix: gl.getUniformLocation(shaderProgram,"uModelViewMatrix"),
  },
};

  this.setState({ gl, buffers, programInfo });
  this.drawScene(gl, programInfo, buffers);
 };

drawScene = (gl, programInfo, buffers) => {
gl.clearColor(0.0, 0.0, 0.0, 1.0); // Clear to black, fully opaque
gl.clearDepth(1.0); // Clear everything
gl.enable(gl.DEPTH_TEST); // Enable depth testing
gl.depthFunc(gl.LEQUAL); // Near things obscure far things

// Clear the canvas before we start drawing on it.

gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);

// Create a perspective matrix, a special matrix that is
// used to simulate the distortion of perspective in a camera.
// Our field of view is 45 degrees, with a width/height
// ratio that matches the display size of the canvas
// and we only want to see objects between 0.1 units
// and 100 units away from the camera.

const fieldOfView = (45 * Math.PI) / 180; // in radians
const aspect = gl.canvas.clientWidth / gl.canvas.clientHeight;
const zNear = 0.1;
const zFar = 100.0;
const projectionMatrix = mat4.create();

// note: glmatrix.js always has the first argument
// as the destination to receive the result.
mat4.perspective(projectionMatrix, fieldOfView, aspect, zNear, zFar);

// Set the drawing position to the "identity" point, which is
// the center of the scene.
const modelViewMatrix = mat4.create();

// Now move the drawing position a bit to where we want to
// start drawing the square.

mat4.translate(
  modelViewMatrix, // destination matrix
  modelViewMatrix, // matrix to translate
  [0, 0, -2.5]
);

mat4.rotate(modelViewMatrix, modelViewMatrix, this.state.rotY, [1, 0, 0]);
mat4.rotate(modelViewMatrix, modelViewMatrix, this.state.rotX, [0, 1, 0]);

gl.bindBuffer(gl.ARRAY_BUFFER, buffers.color);
gl.bindBuffer(gl.ARRAY_BUFFER, buffers.position);

gl.vertexAttribPointer(
  programInfo.attribLocations.vertexPosition,
  3,
  gl.FLOAT,
  false,
  0,
  0
);

gl.vertexAttribPointer(
  programInfo.attribLocations.vertexColor,
  4,
  gl.FLOAT,
  false,
  0,
  0
);

gl.enableVertexAttribArray(programInfo.attribLocations.vertexPosition);
gl.enableVertexAttribArray(programInfo.attribLocations.vertexColor);

gl.useProgram(programInfo.program);

gl.uniformMatrix4fv(
  programInfo.uniformLocations.projectionMatrix,
  false,
  projectionMatrix
);
gl.uniformMatrix4fv(
  programInfo.uniformLocations.modelViewMatrix,
  false,
  modelViewMatrix
);

gl.drawArrays(gl.TRIANGLES, 0, buffers.positionSize);
};

 onMouseMove = (evt) => {
if (!mouseDown) {
  return;
}

evt.preventDefault();

let deltaX = evt.clientX - mouseX;
let deltaY = evt.clientY - mouseY;
mouseX = evt.clientX;
mouseY = evt.clientY;
this.rotateScene(deltaX, deltaY);
 };

onMouseDown = (evt) => {
evt.preventDefault();

mouseDown = true;
mouseX = evt.clientX;
mouseY = evt.clientY;
};

onMouseUp = (evt) => {
evt.preventDefault();
mouseDown = false;
 };

 rotateScene = (deltaX, deltaY) => {
this.setState({
  rotX: this.state.rotX + deltaX / 100,
  rotY: this.state.rotY + deltaY / 100,
  });
  this.drawScene(this.state.gl, this.state.programInfo, this.state.buffers);
 };

render() {
return (
  <div className="w3-container w3-padding-16">
    <canvas
      id="glCanvas"
      width={1280}
      height={720}
      onMouseMove={this.onMouseMove}
      onMouseDown={this.onMouseDown}
      onMouseUp={this.onMouseUp}
    ></canvas>
  </div>
   );
 }
}

export default Viewer3d;

片段着色器：

<script id="fshader" type="x-shader/x-fragment">
  precision mediump float;
  varying vec4 vColor;

  void main(void) {
    gl_FragColor = vColor;
  }
</script>

顶点着色器：

<script id="vshader" type="x-shader/x-vertex">
  attribute vec4 aVertexPosition;
  attribute vec4 aVertexColor;

  uniform mat4 uModelViewMatrix;
  uniform mat4 uProjectionMatrix;

  varying vec4 vColor;

  void main(void) {
    gl_Position = uProjectionMatrix * uModelViewMatrix * aVertexPosition;
    vColor = aVertexColor;
  }
</script>

Answer 1

您需要绑定一个缓冲区（比如颜色一个），然后 use vertexAttribPointer 到绑定集 buffer 到颜色属性。然后再次绑定顶点位置 buffer，调用 vertexAttribPointer 到 bind 顶点位置 attribute。伪代码：

gl.bindBuffer(gl.ARRAY_BUFFER, buffers.color);

gl.vertexAttribPointer(programInfo.attribLocations.vertexColor, ...);

gl.bindBuffer(gl.ARRAY_BUFFER, buffers.position);

gl.vertexAttribPointer(programInfo.attribLocations.vertexPosition, ...);

为 WebGL 3D 对象着色的问题

Problems by coloring WebGL 3D Object

webgl