// a tool for interactively creating lookup tables.
// mutterer@unistra.fr

var l = newArray(0,0,80,100,160,100,255,255,0,0,80,150,160,150,255,255,0,0,80,180,160,180,255,255);
var col = newArray("red","green","blue");
var reds=newArray(256);
var greens=newArray(256);
var blues=newArray(256);
var active = 0;
var s = setup();

macro "Spline Lut Tool - C000T0f15L" {
	getCursorLoc(x, y, z, modifiers);
	if (y>256){
		i=floor(x/85);
		if (i<3) {
			overlay(i);
			active = i;
		} 
	}
	else while (modifiers&16!=0) {
		getCursorLoc(x, y, z, modifiers);
		c=closest(x,y);
		l[active*8+c*2]=(c==0)*0+(c==1)*maxOf(0,minOf(x,l[active*8+2*2]))+(c==2)*minOf(255,maxOf(x,l[active*8+2]))+(c==3)*255;
		l[active*8+c*2+1]=255-maxOf(0,minOf(255,y));
		overlay(active);
		wait(50);
	}
}

function setup() {
	newImage("Spline Lut", "8-bit ramp", 256, 256, 1);
	run("Canvas Size...", "width=256 height="+getHeight+30+" position=Top-Center zero");
	overlay(0);
	return true;
}

function overlay(c) {
	Overlay.remove;
	lx = newArray(4);
	ly = newArray(4);
	for (i=0;i<3;i++){
		for (j=0;j<4;j++) {
			lx[j] = l[i*8+j*2];
			ly[j] = 255-l[i*8+j*2+1];
			if (i==c) {
				makeOval(lx[j]-3, ly[j]-3, 6, 6);
				Roi.setStrokeWidth(5);
				Overlay.addSelection(col[i]);
			}
		}
		makeSelection("polyline", lx,ly);
		run("Fit Spline");
		Overlay.addSelection(col[i]);
		getSelectionCoordinates(xc, yc);
		yc = Array.resample(yc,256);
		for (k=0;k<yc.length;k++) yc[k] = maxOf(0,minOf(255,255-yc[k]));
		if (i==0) reds = yc;	
		else if (i==1) greens = yc;	
		else if (i==2) blues = yc;	
	}
	setLut (reds, greens, blues);
	for (i=0;i<3;i++){
		makeRectangle(85*i,256,85,30);
		Overlay.addSelection("",0,col[i]);
	}
	run("Select None");
}

function closest(x,y) {
	d=500;
	c=-1;
	lx = newArray(4);
	ly = newArray(4);
	for (j=0;j<4;j++) {
		lx[j] = l[active*8+j*2];
		ly[j] = 255-l[active*8+j*2+1];
		di = sqrt ((x-lx[j])*(x-lx[j])+(y-ly[j])*(y-ly[j]));
		if (di<d) {
			d=di;
			c =j;
		}
	}
	return c;
}