ami.js/src/shaders/helpers/shaders.helpers.unpack.js

<p align="center"> <img src="https://cloud.githubusercontent.com/assets/214063/23213764/78ade038-f90c-11e6-8208-4fcade5f3832.png" width="60%"> </p>

import ShadersBase from '../shaders.base';

/**
 * Set of methods to unpack values from [r][b][g][a] -> float
 */
class Unpack extends ShadersBase {
  /**
   * Constructor
   */
  constructor() {
    super();
    this.name = 'unpack';

    // default properties names
    this._packedData = 'packedData';
    this._offset = 'offset';
    this._unpackedData = 'unpackedData';

    this._base._uniforms ={
      uNumberOfChannels: {
        value: 1,
      },
      uBitsAllocated: {
        value: 16,
      },
      uPixelType: {
        value: 0,
      },
    };
  }

  api(
    baseFragment = this._base, packedData = this._packedData,
    offset = this._offset, unpackedData = this._unpackedData) {
    this._base = baseFragment;
    return this.compute(packedData, offset, unpackedData);
  }

  compute(packedData, offset, unpackedData) {
    this.computeDefinition();
    this._base._functions[this._name] = this._definition;
    return `${this._name}(${packedData}, ${offset}, ${unpackedData});`;
  }

  computeDefinition() {
    // fun stuff
    let content = '';
    if (this._base._uniforms.uNumberOfChannels.value === 1) {
      switch (this._base._uniforms.uBitsAllocated.value) {
        case 1:
        case 8:
          content = this.upack8();
          break;

        case 16:
          content = this.upack16();
          break;

        case 32:
          content = this.upack32();
          break;

        default:
          content = this.upackDefault();
          break;
      }
    } else {
      content = this.upackIdentity();
    }

    this._definition = `
void ${this._name}(in vec4 packedData, in int offset, out vec4 unpackedData){

${content}

}  
    `;
  }

  upack8() {
    this._base._functions['uInt8'] = this.uInt8();

    return `
uInt8(
  packedData.r,
  unpackedData.x);
    `;
  }

  upack16() {
    this._base._functions['uInt16'] = this.uInt16();

    return `
uInt16(
  packedData.r * float( 1 - offset) + packedData.b * float(offset),
  packedData.g * float( 1 - offset) + packedData.a * float(offset),
  unpackedData.x);
    `;
  }

  upack32() {
    if (this._base._uniforms.uPixelType.value === 0) {
      this._base._functions['uInt32'] = this.uInt32();

      return `
uInt32(
  packedData.r,
  packedData.g,
  packedData.b,
  packedData.a,
  unpackedData.x);
      `;
    } else {
      this._base._functions['uFloat32'] = this.uFloat32();

      return `
uFloat32(
  packedData.r,
  packedData.g,
  packedData.b,
  packedData.a,
  unpackedData.x);
      `;
    }
  }

  upackIdentity() {
    return `
unpackedData = packedData;
      `;
  }

  uInt8() {
    return `
void uInt8(in float r, out float value){
  value = r * 255.;
}
    `;
  }

  uInt16() {
    return `
void uInt16(in float r, in float a, out float value){
  value = r * 255. + a * 255. * 256.;
}
    `;
  }

  uInt32() {
    return `
void uInt32(in float r, in float g, in float b, in float a, out float value){
  value = r * 255. + g * 255. * 256. + b * 255. * 256. * 256. + a * 255. * 256. * 256. * 256.;
  // value = r * 255. + g * 65025. + b * 16581375. + a * 4228250625.;
}
    `;
  }

  uFloat32() {
    return `
void uFloat32(in float r, in float g, in float b, in float a, out float value){

  // create arrays containing bits for rgba values
  // value between 0 and 255
  value = r * 255.;
  int bytemeR[8];
  bytemeR[0] = int(floor(value / 128.));
  value -= float(bytemeR[0] * 128);
  bytemeR[1] = int(floor(value / 64.));
  value -= float(bytemeR[1] * 64);
  bytemeR[2] = int(floor(value / 32.));
  value -= float(bytemeR[2] * 32);
  bytemeR[3] = int(floor(value / 16.));
  value -= float(bytemeR[3] * 16);
  bytemeR[4] = int(floor(value / 8.));
  value -= float(bytemeR[4] * 8);
  bytemeR[5] = int(floor(value / 4.));
  value -= float(bytemeR[5] * 4);
  bytemeR[6] = int(floor(value / 2.));
  value -= float(bytemeR[6] * 2);
  bytemeR[7] = int(floor(value));

  value = g * 255.;
  int bytemeG[8];
  bytemeG[0] = int(floor(value / 128.));
  value -= float(bytemeG[0] * 128);
  bytemeG[1] = int(floor(value / 64.));
  value -= float(bytemeG[1] * 64);
  bytemeG[2] = int(floor(value / 32.));
  value -= float(bytemeG[2] * 32);
  bytemeG[3] = int(floor(value / 16.));
  value -= float(bytemeG[3] * 16);
  bytemeG[4] = int(floor(value / 8.));
  value -= float(bytemeG[4] * 8);
  bytemeG[5] = int(floor(value / 4.));
  value -= float(bytemeG[5] * 4);
  bytemeG[6] = int(floor(value / 2.));
  value -= float(bytemeG[6] * 2);
  bytemeG[7] = int(floor(value));

  value = b * 255.;
  int bytemeB[8];
  bytemeB[0] = int(floor(value / 128.));
  value -= float(bytemeB[0] * 128);
  bytemeB[1] = int(floor(value / 64.));
  value -= float(bytemeB[1] * 64);
  bytemeB[2] = int(floor(value / 32.));
  value -= float(bytemeB[2] * 32);
  bytemeB[3] = int(floor(value / 16.));
  value -= float(bytemeB[3] * 16);
  bytemeB[4] = int(floor(value / 8.));
  value -= float(bytemeB[4] * 8);
  bytemeB[5] = int(floor(value / 4.));
  value -= float(bytemeB[5] * 4);
  bytemeB[6] = int(floor(value / 2.));
  value -= float(bytemeB[6] * 2);
  bytemeB[7] = int(floor(value));

  value = a * 255.;
  int bytemeA[8];
  bytemeA[0] = int(floor(value / 128.));
  value -= float(bytemeA[0] * 128);
  bytemeA[1] = int(floor(value / 64.));
  value -= float(bytemeA[1] * 64);
  bytemeA[2] = int(floor(value / 32.));
  value -= float(bytemeA[2] * 32);
  bytemeA[3] = int(floor(value / 16.));
  value -= float(bytemeA[3] * 16);
  bytemeA[4] = int(floor(value / 8.));
  value -= float(bytemeA[4] * 8);
  bytemeA[5] = int(floor(value / 4.));
  value -= float(bytemeA[5] * 4);
  bytemeA[6] = int(floor(value / 2.));
  value -= float(bytemeA[6] * 2);
  bytemeA[7] = int(floor(value));

  // compute float32 value from bit arrays

  // sign
  int issigned = 1 - 2 * bytemeR[0];
  //   issigned = int(pow(-1., float(bytemeR[0])));

  // exponent
  int exponent = 0;

  exponent += bytemeR[1] * int(pow(2., 7.));
  exponent += bytemeR[2] * int(pow(2., 6.));
  exponent += bytemeR[3] * int(pow(2., 5.));
  exponent += bytemeR[4] * int(pow(2., 4.));
  exponent += bytemeR[5] * int(pow(2., 3.));
  exponent += bytemeR[6] * int(pow(2., 2.));
  exponent += bytemeR[7] * int(pow(2., 1.));

  exponent += bytemeG[0];


  // fraction
  float fraction = 0.;

  fraction = float(bytemeG[1]) * pow(2., -1.);
  fraction += float(bytemeG[2]) * pow(2., -2.);
  fraction += float(bytemeG[3]) * pow(2., -3.);
  fraction += float(bytemeG[4]) * pow(2., -4.);
  fraction += float(bytemeG[5]) * pow(2., -5.);
  fraction += float(bytemeG[6]) * pow(2., -6.);
  fraction += float(bytemeG[7]) * pow(2., -7.);

  fraction += float(bytemeB[0]) * pow(2., -8.);
  fraction += float(bytemeB[1]) * pow(2., -9.);
  fraction += float(bytemeB[2]) * pow(2., -10.);
  fraction += float(bytemeB[3]) * pow(2., -11.);
  fraction += float(bytemeB[4]) * pow(2., -12.);
  fraction += float(bytemeB[5]) * pow(2., -13.);
  fraction += float(bytemeB[6]) * pow(2., -14.);
  fraction += float(bytemeB[7]) * pow(2., -15.);

  fraction += float(bytemeA[0]) * pow(2., -16.);
  fraction += float(bytemeA[1]) * pow(2., -17.);
  fraction += float(bytemeA[2]) * pow(2., -18.);
  fraction += float(bytemeA[3]) * pow(2., -19.);
  fraction += float(bytemeA[4]) * pow(2., -20.);
  fraction += float(bytemeA[5]) * pow(2., -21.);
  fraction += float(bytemeA[6]) * pow(2., -22.);
  fraction += float(bytemeA[7]) * pow(2., -23.);

  value = float(issigned) * pow( 2., float(exponent - 127)) * (1. + fraction);
}
    `;
  }
}

export default new Unpack();