examples/packed-arrays.html

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    <title>twgl.js - packed-arrays</title>
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      canvas {
          display: block;
          width: 100vw;
          height: 100vh;
      }
      #b {
        position: absolute;
        top: 10px;
        width: 100%;
        text-align: center;
        z-index: 2;
      }
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  <body>
    <canvas id="c"></canvas>
    <div id="b"><a href="http://twgljs.org">twgl.js</a> - packed-arrays</div>
  </body>
  <script id="vs" type="notjs">
uniform mat4 u_worldViewProjection;
uniform vec3 u_lightWorldPos;
uniform mat4 u_world;
uniform mat4 u_viewInverse;
uniform mat4 u_worldInverseTranspose;

attribute vec4 a_position;
attribute vec3 a_normal;
attribute vec2 a_texcoord;

varying vec4 v_position;
varying vec2 v_texCoord;
varying vec3 v_normal;
varying vec3 v_surfaceToLight;
varying vec3 v_surfaceToView;

void main() {
  v_texCoord = a_texcoord;
  v_position = (u_worldViewProjection * a_position);
  v_normal = (u_worldInverseTranspose * vec4(a_normal, 0)).xyz;
  v_surfaceToLight = u_lightWorldPos - (u_world * a_position).xyz;
  v_surfaceToView = (u_viewInverse[3] - (u_world * a_position)).xyz;
  gl_Position = v_position;
}
  </script>
  <script id="fs" type="notjs">
precision mediump float;

varying vec4 v_position;
varying vec2 v_texCoord;
varying vec3 v_normal;
varying vec3 v_surfaceToLight;
varying vec3 v_surfaceToView;

uniform vec4 u_lightColor;
uniform vec4 u_diffuseMult;
uniform sampler2D u_diffuse;
uniform vec4 u_specular;
uniform float u_shininess;
uniform float u_specularFactor;

vec4 lit(float l ,float h, float m) {
  return vec4(1.0,
              abs(l),//max(l, 0.0),
              (l > 0.0) ? pow(max(0.0, h), m) : 0.0,
              1.0);
}

void main() {
  vec4 diffuseColor = texture2D(u_diffuse, v_texCoord) * u_diffuseMult;
  vec3 a_normal = normalize(v_normal);
  vec3 surfaceToLight = normalize(v_surfaceToLight);
  vec3 surfaceToView = normalize(v_surfaceToView);
  vec3 halfVector = normalize(surfaceToLight + surfaceToView);
  vec4 litR = lit(dot(a_normal, surfaceToLight),
                    dot(a_normal, halfVector), u_shininess);
  vec4 outColor = vec4((
  u_lightColor * (diffuseColor * litR.y +
                u_specular * litR.z * u_specularFactor)).rgb,
      diffuseColor.a);
  gl_FragColor = outColor;
}
  </script>
  <script src="../3rdparty/chroma.min.js"></script>
  <script type="module">
    import * as twgl from '../dist/6.x/twgl-full.module.js';
    twgl.setDefaults({attribPrefix: "a_"});
    const m4 = twgl.m4;
    const gl = document.querySelector("#c").getContext("webgl");
    const programInfo = twgl.createProgramInfo(gl, ["vs", "fs"]);

// ------------------------------------------------------------------
// This is all the code needed to automatically pack unpacked arrays
// It's not included in TWGL because packing unpacked arrays seems
// like overkill. Do you really gain much? If you're really going
// for perf it seems like you'd pack offline

    function isArrayBuffer(a) {
      return a && a.buffer && a.buffer instanceof ArrayBuffer;
    }

    function getGLTypeForArray(array, arrayName) {
      if (isArrayBuffer(array)) {
        return twgl.getGLTypeForTypedArray(array);
      }

      if (isArrayBuffer(array.data)) {
        return twgl.getGLTypeForTypedArray(array.data);
      }

      let Type = array.type;
      if (!Type) {
        if (arrayName === "indices") {
          Type = Uint16Array;
        } else {
          Type = Float32Array;
        }
      }
      return twgl.getGLTypeForTypedArray(new Type(0));
    }

    function getNormalizationForGLType(gl, type) {
      switch (type) {
        case gl.BYTE:
        case gl.UNSIGNED_BYTE:
          return true;
        default:
          return false;
      }
    }

    function getNumBytesForGLType(type) {
      switch (type) {
        case gl.BYTE:           return 1;  // eslint-disable-line
        case gl.UNSIGNED_BYTE:  return 1;  // eslint-disable-line
        case gl.SHORT:          return 2;  // eslint-disable-line
        case gl.UNSIGNED_SHORT: return 2;  // eslint-disable-line
        case gl.INT:            return 4;  // eslint-disable-line
        case gl.UNSIGNED_INT:   return 4;  // eslint-disable-line
        case gl.FLOAT:          return 4;  // eslint-disable-line
        default:
          throw "unknown gl type";
      }
    }

    const texcoordRE = /coord|texture/i;
    const colorRE = /color|colour/i;

    function guessNumComponentsFromName(name, length) {
      let numComponents;
      if (texcoordRE.test(name)) {
        numComponents = 2;
      } else if (colorRE.test(name)) {
        numComponents = 4;
      } else {
        numComponents = 3;  // position, normals, indices ...
      }

      if (length % numComponents > 0) {
        throw "Can not guess numComponents for attribute '" + name + "'. Tried " +
              numComponents + " but " + length +
              " values is not evenly divisible by " + numComponents +
              ". You should specify it.";
      }

      return numComponents;
    }

    const defaultAttribPrefix = "a_";
    function createPackedBufferInfoFromArrays(gl, arrays) {
      // compute size of array needed and offsets
      let offset      = 0;
      let maxElements = 0;

      const attribs = {};

      Object.keys(arrays).forEach(function(arrayName) {
        if (arrayName === "indices") {
          return;
        }
        const array = arrays[arrayName];
        const attribName = array.attrib || array.name || array.attribName || (defaultAttribPrefix + arrayName);
        const glType = getGLTypeForArray(array, arrayName);
        const attrib = {
          numComponents: array.numComponents || array.size || guessNumComponentsFromName(arrayName),
          type:          glType,
          normalize:     array.normalize !== undefined ? array.normalize : getNormalizationForGLType(gl, glType),
          offset:        offset,
        };
        attribs[attribName] = attrib;
        const sizeInBytes = attrib.numComponents * getNumBytesForGLType(glType);
        // should we handle padding? For example RGB8 is 3 bytes and will need padding
        offset += sizeInBytes;
        // should we check that all lengths are the same?
        const length = array.length || array.data.length;
        const numElements = length / attrib.numComponents;
        maxElements = Math.max(maxElements, numElements);
      });

      const stride = offset;
      const arrayBuffer = new ArrayBuffer(stride * maxElements);
      const buffer = gl.createBuffer();
      gl.bindBuffer(gl.ARRAY_BUFFER, buffer);

      Object.keys(arrays).forEach(function(arrayName) {
        if (arrayName === "indices") {
          return;
        }
        const array = arrays[arrayName];
        const attribName = array.attrib || array.name || array.attribName || (defaultAttribPrefix + arrayName);
        const attrib = attribs[attribName];
        attrib.buffer = buffer;
        attrib.stride = stride;
        const data = array.length ? array : array.data;
        const length = data.length;
        const numComponents = attrib.numComponents;
        const numElements = length / numComponents;
        const Type = twgl.getTypedArrayTypeForGLType(attrib.type);
        const view = new Type(arrayBuffer, attrib.offset);
        const localStride = stride / getNumBytesForGLType(attrib.type);
        let offset = 0;
        let index = 0;
        for (let elem = 0; elem < numElements; ++elem) {
          for (let component = 0; component < numComponents; ++component) {
            view[offset + component] = data[index++];
          }
          offset += localStride;
        }
      });

      gl.bufferData(gl.ARRAY_BUFFER, arrayBuffer, gl.STATIC_DRAW);

      const bufferInfo = {
        attribs: attribs,
      };
      const indices = arrays.indices;
      if (indices) {
        bufferInfo.indices = twgl.createBufferFromArray(gl, indices, "indices");
        bufferInfo.numElements = indices.length || indices.data.length;
        bufferInfo.elementType = (indices instanceof Uint32Array) ?  gl.UNSIGNED_INT : gl.UNSIGNED_SHORT;
      } else {
        bufferInfo.numElements = maxElements;
      }

      return bufferInfo;
    }

// end of packing code
// -------------------------------------------------------

    const shapes = [
      createPackedBufferInfoFromArrays(gl, twgl.primitives.createCubeVertices(2)),
      createPackedBufferInfoFromArrays(gl, twgl.primitives.createSphereVertices(1, 24, 12)),
      createPackedBufferInfoFromArrays(gl, twgl.primitives.createPlaneVertices(2, 2)),
      createPackedBufferInfoFromArrays(gl, twgl.primitives.createTruncatedConeVertices(1, 0, 2, 24, 1)),
      createPackedBufferInfoFromArrays(gl, twgl.primitives.createCresentVertices(1, 1, 0.5, 0.1, 24)),
      createPackedBufferInfoFromArrays(gl, twgl.primitives.createCylinderVertices(1, 2, 24, 2)),
      createPackedBufferInfoFromArrays(gl, twgl.primitives.createDiscVertices(1, 24)),
      createPackedBufferInfoFromArrays(gl, twgl.primitives.createTorusVertices(1, 0.4, 24, 12)),
    ];

    function rand(min, max) {
      return min + Math.random() * (max - min);
    }

    // Shared values
    const lightWorldPosition = [1, 8, -10];
    const lightColor = [1, 1, 1, 1];
    const camera = m4.identity();
    const view = m4.identity();
    const viewProjection = m4.identity();

    const tex = twgl.createTexture(gl, {
      min: gl.NEAREST,
      mag: gl.NEAREST,
      src: [
        255, 255, 255, 255,
        192, 192, 192, 255,
        192, 192, 192, 255,
        255, 255, 255, 255,
      ],
    });

    const objects = [];
    const drawObjects = [];
    const numObjects = 100;
    const baseHue = rand(0, 360);
    for (let ii = 0; ii < numObjects; ++ii) {
      const uniforms = {
        u_lightWorldPos: lightWorldPosition,
        u_lightColor: lightColor,
        u_diffuseMult: chroma.hsv((baseHue + rand(0, 60)) % 360, 0.4, 0.8).gl(),
        u_specular: [1, 1, 1, 1],
        u_shininess: 50,
        u_specularFactor: 1,
        u_diffuse: tex,
        u_viewInverse: camera,
        u_world: m4.identity(),
        u_worldInverseTranspose: m4.identity(),
        u_worldViewProjection: m4.identity(),
      };
      drawObjects.push({
        programInfo: programInfo,
        bufferInfo: shapes[ii % shapes.length],
        uniforms: uniforms,
      });
      objects.push({
        translation: [rand(-10, 10), rand(-10, 10), rand(-10, 10)],
        ySpeed: rand(0.1, 0.3),
        zSpeed: rand(0.1, 0.3),
        uniforms: uniforms,
      });
    }

    function render(time) {
      time *= 0.001;
      twgl.resizeCanvasToDisplaySize(gl.canvas);
      gl.viewport(0, 0, gl.canvas.width, gl.canvas.height);

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

      const projection = m4.perspective(30 * Math.PI / 180, gl.canvas.clientWidth / gl.canvas.clientHeight, 0.5, 100);
      const eye = [1, 4, -20];
      const target = [0, 0, 0];
      const up = [0, 1, 0];

      m4.lookAt(eye, target, up, camera);
      m4.inverse(camera, view);
      m4.multiply(projection, view, viewProjection);

      objects.forEach(function(obj) {
        const uni = obj.uniforms;
        const world = uni.u_world;
        m4.identity(world);
        m4.rotateY(world, time * obj.ySpeed, world);
        m4.rotateZ(world, time * obj.zSpeed, world);
        m4.translate(world, obj.translation, world);
        m4.rotateX(world, time, world);
        m4.transpose(m4.inverse(world, uni.u_worldInverseTranspose), uni.u_worldInverseTranspose);
        m4.multiply(viewProjection, uni.u_world, uni.u_worldViewProjection);
      });

      twgl.drawObjectList(gl, drawObjects);

      requestAnimationFrame(render);
    }
    requestAnimationFrame(render);

  </script>
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