webGL创建旋转动画三角形_webgl 三角形 动画-程序员宅基地

技术标签: web  

test.html

<!doctype html>
<html lang="en">
  <head>
    <meta charset="utf-8">
    <title>WebGL Demo</title>
    <link rel="stylesheet" href="./webgl.css" type="text/css">
    <script src="https://cdnjs.cloudflare.com/ajax/libs/gl-matrix/2.8.1/gl-matrix-min.js"
            integrity="sha512-zhHQR0/H5SEBL3Wn6yYSaTTZej12z0hVZKOv3TwCUXT1z5qeqGcXJLLrbERYRScEDDpYIJhPC1fk31gqR783iQ=="
            crossorigin="anonymous" defer>
    </script>
    <script src="test.js" defer></script>
  </head>

  <body>
    <canvas id="glcanvas" width="640" height="480"></canvas>
  </body>
</html>

test.js

var squareRotation = 0.0;

main();

//
// Start here
//
function main() {
    
  const canvas = document.querySelector('#glcanvas');
  const gl = canvas.getContext('webgl');

  // If we don't have a GL context, give up now

  if (!gl) {
    
    alert('Unable to initialize WebGL. Your browser or machine may not support it.');
    return;
  }

  // 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);

    requestAnimationFrame(render);
  }
  requestAnimationFrame(render);
}

//
// initBuffers
//
// Initialize the buffers we'll need. For this demo, we just
// have one object -- a simple two-dimensional square.
//
function initBuffers(gl) {
    

  // Create a buffer for the square's 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 square.

  const positions = [
    0, 0.5,   -0.5, -0.5,   0.5, -0.5
  ];

  // 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 vertices

  const colors = [
    1.0, 0.0, 0.0, 1.0,    // red
    1.0, 0.0, 0.0, 1.0,    // red
    1.0, 0.0, 0.0, 1.0,    // red
    1.0, 0.0, 0.0, 1.0,    // red
  ];

  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,
  };
}

//
// 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
              squareRotation,   // amount to rotate in radians
              [0, 0, 1]);       // axis to rotate around

  // Tell WebGL how to pull out the positions from the position
  // buffer into the vertexPosition attribute
  {
    
    const numComponents = 2;
    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);
  }

  // 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);

  {
    
    const offset = 0;
    const vertexCount = 4;
    gl.drawArrays(gl.TRIANGLE_STRIP, offset, vertexCount);
  }

  // Update the rotation for the next draw

  squareRotation += 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;
}
版权声明:本文为博主原创文章,遵循 CC 4.0 BY-SA 版权协议,转载请附上原文出处链接和本声明。
本文链接:https://blog.csdn.net/while_BLUE_/article/details/109739041

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