Cubehelix_color_MaxMSP/Cubehelix.js

// Cubehelix color scheme for Max/MSP/Jitter
// By Théophile Clet - https://tflcl.xyz
// Based on Dave Green's work: http://www.mrao.cam.ac.uk/~dag/CUBEHELIX/cubetry.html
// Original publication: Green, D. A., 2011, `A colour scheme for the display of astronomical intensity images', Bulletin of the Astronomical Society of India, 39, 289. (2011BASI...39..289G at ADS.) ( http://astron-soc.in/bulletin/11June/289392011.pdf )
// Original js code taken straight from the online example implementation: http://www.mrao.cam.ac.uk/~dag/CUBEHELIX/cubetry.html


autowatch = 0;
inlets = 1;
outlets = 2;

setinletassist(0, "List as input: {makeCubehelixRGB, start[float], rots[float], sign[-1,1], hue[float], gamma[float], levels(int), flip([0,1]}")
setoutletassist(0, "To jit.matrix: outputs the color palette as a 4-plane 1 dim matrix");
setoutletassist(1, "dump out. Outputs paramters used for generation. Bangs when finished.");

function makeCubehelixRGB(start, rots, sign, hue, gamma, levels, flip){
  rots = rots*sign;

  //dumpOut(start, rots, hue, gamma, levels, flip);

  outlet(0, "dim", levels, 1);
  for (var i = 0; i < levels; i++) {

    var fract = CubeHelixFract(i,levels,flip);
    var red = CubeHelixRGB(fract,start,rots,hue,gamma,1);
    var grn = CubeHelixRGB(fract,start,rots,hue,gamma,2);
    var blu = CubeHelixRGB(fract,start,rots,hue,gamma,3);

    if(flip == 1){fract = 1.0-fract;}

    outlet(0, "setcell", i, 0, "val", 1., red, grn, blu);
  }
  outlet(0, "bang");
  outlet(1, "bang");
}

function dumpOut(start, rots, hue, gamma, levels, flip){
  outlet(1, "start", start);
  outlet(1, "rots", rots);
  outlet(1, "hue", hue);
  outlet(1, "gamma", gamma);
  outlet(1, "levels", levels);
  outlet(1, "flip", flip);
}
// ----------------------------------------------------------------------------
// 2017 May 30: make consistent with Fortran
// ----------------------------------------------------------------------------

function CubeHelixRGB(fract,start,rots,hue,gamma,irgb){

    var angle = 2*Math.PI*(start/3.0+1+rots*fract);
    var fract = Math.pow(fract, gamma);
    var amp=hue*fract*(1-fract)/2.0;

    var r=fract+amp*(-0.14861*Math.cos(angle)+1.78277*Math.sin(angle));
    var g=fract+amp*(-0.29227*Math.cos(angle)-0.90649*Math.sin(angle));
    var b=fract+amp*(+1.97294*Math.cos(angle));

    r=Math.max(Math.min(r,1.0),0.0);
    g=Math.max(Math.min(g,1.0),0.0);
    b=Math.max(Math.min(b,1.0),0.0);

    if(irgb == 1){
      return r;
    }
    else if(irgb == 2) {
      return g;
    }
    else {
      return b;
    }
}

// ----------------------------------------------------------------------------

function CubeHelixFract(i,n,flip){
    var fraction = i/(n-1);
    if (flip == 1) {
      fraction = 1 - fraction;
    }
    return fraction;
}