【愚公系列】2022年09月 微信小程序-WebGL立体图形的绘制

import drawCube from './drawCube'
Page({
/**

页面的初始数据

*/

data: {

},
/**

生命周期函数--监听页面加载

*/

onLoad: function (options) {

},
/**


生命周期函数--监听页面初次渲染完成

*/

onReady: function () {

wx.createSelectorQuery()

.select('#myCanvas1')

.node()

.exec((res) => {

const canvas = res[0].node

const gl = canvas.getContext('webgl')

if (!gl) {

console.log('webgl未受支持');

return

}

// 检查所有支持的扩展

var available_extensions = gl.getSupportedExtensions();

console.log(available_extensions);
// 清除画布

// 使用完全不透明的黑色清除所有图像，我们将清除色设为黑色，此时并没有开始清除

gl.clearColor(0.0, 0.0, 0.0, 1.0);

// 用上面指定的颜色清除缓冲区

gl.clear(gl.COLOR_BUFFER_BIT);
// 画的是一个正方形

drawCube(gl, canvas)

})

import {

mat4

} from '../../lib/gl-matrix'



var cubeRotation = 0.0;
//

// Start here

//

function drawCube(gl,canvas) {

// Vertex shader program
const vsSource = attribute vec4 aVertexPosition; attribute vec4 aVertexColor; uniform mat4 uModelViewMatrix; uniform mat4 uProjectionMatrix; varying lowp vec4 vColor; void main(void) { gl_Position = uProjectionMatrix * uModelViewMatrix * aVertexPosition; vColor = aVertexColor; };
// Fragment shader program
const fsSource = varying lowp vec4 vColor; void main(void) { gl_FragColor = vColor; };
// Initialize a shader program; this is where all the lighting

// for the vertices and so forth is established.

const shaderProgram = initShaderProgram(gl, vsSource, fsSource);
// Collect all the info needed to use the shader program.

// Look up which attributes our shader program is using

// for aVertexPosition, aVevrtexColor and also

// look up uniform locations.

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'),

},

};
// Here's where we call the routine that builds all the

// objects we'll be drawing.

const buffers = initBuffers(gl);
var then = 0;
// Draw the scene repeatedly

function render(now) {

now *= 0.001;  // convert to seconds

const deltaTime = now - then;

then = now;
drawScene(gl, programInfo, buffers, deltaTime);

canvas.requestAnimationFrame(render);

}

canvas.requestAnimationFrame(render);

}
//

// initBuffers

//

// Initialize the buffers we'll need. For this demo, we just

// have one object -- a simple three-dimensional cube.

//

function initBuffers(gl) {
// Create a buffer for the cube's vertex positions.
const positionBuffer = gl.createBuffer();
// Select the positionBuffer as the one to apply buffer

// operations to from here out.
gl.bindBuffer(gl.ARRAY_BUFFER, positionBuffer);
// Now create an array of positions for the cube.
const positions = [

// Front face

-1.0, -1.0,  1.0,

1.0, -1.0,  1.0,

1.0,  1.0,  1.0,

-1.0,  1.0,  1.0,
// Back face
-1.0, -1.0, -1.0,
-1.0,  1.0, -1.0,
1.0,  1.0, -1.0,
1.0, -1.0, -1.0,

// Top face

-1.0,  1.0, -1.0,

-1.0,  1.0,  1.0,

1.0,  1.0,  1.0,

1.0,  1.0, -1.0,
// Bottom face

-1.0, -1.0, -1.0,

1.0, -1.0, -1.0,

1.0, -1.0,  1.0,

-1.0, -1.0,  1.0,
// Right face
1.0, -1.0, -1.0,
1.0,  1.0, -1.0,
1.0,  1.0,  1.0,
1.0, -1.0,  1.0,

// Left face
-1.0, -1.0, -1.0,
-1.0, -1.0,  1.0,
-1.0,  1.0,  1.0,
-1.0,  1.0, -1.0,

];
// 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.
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(positions), gl.STATIC_DRAW);
// Now set up the colors for the faces. We'll use solid colors

// for each face.
const faceColors = [

[1.0,  1.0,  1.0,  1.0],    // Front face: white

[1.0,  0.0,  0.0,  1.0],    // Back face: red

[0.0,  1.0,  0.0,  1.0],    // Top face: green

[0.0,  0.0,  1.0,  1.0],    // Bottom face: blue

[1.0,  1.0,  0.0,  1.0],    // Right face: yellow

[1.0,  0.0,  1.0,  1.0],    // Left face: purple

];
// Convert the array of colors into a table for all the vertices.
var colors = [];
for (var j = 0; j < faceColors.length; ++j) {

const c = faceColors[j];
// Repeat each color four times for the four vertices of the face
colors = colors.concat(c, c, c, c);
// colors = colors.concat(c);
// colors = colors.concat(c);
// colors = colors.concat(c);
// colors = colors.concat(c);

}
const colorBuffer = gl.createBuffer();

gl.bindBuffer(gl.ARRAY_BUFFER, colorBuffer);

gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(colors), gl.STATIC_DRAW);
// Build the element array buffer; this specifies the indices

// into the vertex arrays for each face's vertices.
const indexBuffer = gl.createBuffer();

gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, indexBuffer);
// This array defines each face as two triangles, using the

// indices into the vertex array to specify each triangle's

// position.
const indices = [

0,  1,  2,      0,  2,  3,    // front

4,  5,  6,      4,  6,  7,    // back

8,  9,  10,     8,  10, 11,   // top

12, 13, 14,     12, 14, 15,   // bottom

16, 17, 18,     16, 18, 19,   // right

20, 21, 22,     20, 22, 23,   // left

];
// Now send the element array to GL
gl.bufferData(gl.ELEMENT_ARRAY_BUFFER,

new Uint16Array(indices), gl.STATIC_DRAW);
return {

position: positionBuffer,

color: colorBuffer,

indices: indexBuffer,

};

}
//

// Draw the scene.

//

function drawScene(gl, programInfo, buffers, deltaTime) {

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, 0.0, -6.0]);  // amount to translate
mat4.rotate(modelViewMatrix,  // destination matrix

modelViewMatrix,  // matrix to rotate

cubeRotation,     // amount to rotate in radians

[0, 0, 1]);       // axis to rotate around (Z)
mat4.rotate(modelViewMatrix,  // destination matrix

modelViewMatrix,  // matrix to rotate

cubeRotation * .7,// amount to rotate in radians

[0, 1, 0]);       // axis to rotate around (Y)
// Tell WebGL how to pull out the positions from the position

// buffer into the vertexPosition attribute

{

const numComponents = 3;

const type = gl.FLOAT;

const normalize = false;

const stride = 0;

const offset = 0;

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

gl.vertexAttribPointer(

programInfo.attribLocations.vertexPosition,

numComponents,

type,

normalize,

stride,

offset);

gl.enableVertexAttribArray(

programInfo.attribLocations.vertexPosition);

}
// Tell WebGL how to pull out the colors from the color buffer

// into the vertexColor attribute.

{

const numComponents = 4;

const type = gl.FLOAT;

const normalize = false;

const stride = 0;

const offset = 0;

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

gl.vertexAttribPointer(

programInfo.attribLocations.vertexColor,

numComponents,

type,

normalize,

stride,

offset);

gl.enableVertexAttribArray(

programInfo.attribLocations.vertexColor);

}
// gl.ARRAY_BUFFER: 包含顶点属性的Buffer，如顶点坐标，纹理坐标数据或顶点颜色数据。

// gl.ELEMENT_ARRAY_BUFFER: 用于元素索引的Buffer。
// Tell WebGL which indices to use to index the vertices

gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, buffers.indices);
// Tell WebGL to use our program when drawing
gl.useProgram(programInfo.program);
// Set the shader uniforms
gl.uniformMatrix4fv(

programInfo.uniformLocations.projectionMatrix,

false,

projectionMatrix);

gl.uniformMatrix4fv(

programInfo.uniformLocations.modelViewMatrix,

false,

modelViewMatrix);
{

// 6个面，12个三角形，每个三角3个顶点，共36个顶点

const vertexCount = 36;

const type = gl.UNSIGNED_SHORT;

const offset = 0;

gl.drawElements(gl.TRIANGLES, vertexCount, type, offset);

}
// Update the rotation for the next draw
cubeRotation += deltaTime;

}
//

// Initialize a shader program, so WebGL knows how to draw our data

//

function initShaderProgram(gl, vsSource, fsSource) {

const vertexShader = loadShader(gl, gl.VERTEX_SHADER, vsSource);

const fragmentShader = loadShader(gl, gl.FRAGMENT_SHADER, fsSource);
// Create the shader program
const shaderProgram = gl.createProgram();

gl.attachShader(shaderProgram, vertexShader);

gl.attachShader(shaderProgram, fragmentShader);

gl.linkProgram(shaderProgram);
// If creating the shader program failed, alert
if (!gl.getProgramParameter(shaderProgram, gl.LINK_STATUS)) {

alert('Unable to initialize the shader program: ' + gl.getProgramInfoLog(shaderProgram));

return null;

}
return shaderProgram;

}
//

// creates a shader of the given type, uploads the source and

// compiles it.

//

function loadShader(gl, type, source) {

const shader = gl.createShader(type);
// Send the source to the shader object
gl.shaderSource(shader, source);
// Compile the shader program
gl.compileShader(shader);
// See if it compiled successfully
if (!gl.getShaderParameter(shader, gl.COMPILE_STATUS)) {

alert('An error occurred compiling the shaders: ' + gl.getShaderInfoLog(shader));

gl.deleteShader(shader);

return null;

}
return shader;

}
export default drawCube