source: orxonox.OLD/orxonox/trunk/src/lib/util/color.cc @ 5010

/*
   orxonox - the future of 3D-vertical-scrollers

   Copyright (C) 2004 orx

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.

   ### File Specific:
   main-programmer: Benjamin Grauer
   co-programmer: ...

   this code has been borrowed from:
   http://www.easyrgb.com/math.php
*/

//#define DEBUG_SPECIAL_MODULE DEBUG_MODULE_

#include "color.h"
#include "vector.h"

using namespace std;




#include <stdio.h>

// Needed by rgb2hsv()
float Color::maxrgb(float r, float g, float b)
{
  float max;

  if( r > g)
    max = r;
  else
    max = g;
  if( b > max )
    max = b;
  return( max );
}


// Needed by rgb2hsv()
float Color::minrgb(float r,float g,float b)
{
  float min;

  if( r < g)
    min = r;
  else
    min = g;
  if( b < min )
    min = b;
  return( min );
}


/* Taken from "Fund'l of 3D Computer Graphics", Alan Watt (1989)
   Assumes (r,g,b) range from 0.0 to 1.0
   Sets h in degrees: 0.0 to 360.;
      s,v in [0.,1.]
*/
Vector Color::RGBtoHSV(const Vector& RGB)
{
  float r = RGB.x;
  float g = RGB.y;
  float b = RGB.z;

  float h=0,s=1.0,v=1.0;
  float max_v,min_v,diff,r_dist,g_dist,b_dist;
  float undefined = 0.0;

  max_v = maxrgb(r,g,b);
  min_v = minrgb(r,g,b);
  diff = max_v - min_v;
  v = max_v;

  if( max_v != 0 )
    s = diff/max_v;
  else
    s = 0.0;
  if( s == 0 )
    h = undefined;
  else {
    r_dist = (max_v - r)/diff;
    g_dist = (max_v - g)/diff;
    b_dist = (max_v - b)/diff;
    if( r == max_v )
      h = b_dist - g_dist;
    else
      if( g == max_v )
        h = 2 + r_dist - b_dist;
    else
      if( b == max_v )
        h = 4 + g_dist - r_dist;
    else
      printf("rgb2hsv::How did I get here?\n");
    h *= 60;
    if( h < 0)
      h += 360.0;
  }
  return Vector(h, s, v);
}

/* Taken from "Fund'l of 3D Computer Graphics", Alan Watt (1989)
   Assumes H in degrees, s,v in [0.,1.0];
   (r,g,b) range from 0.0 to 1.0
*/
Vector Color::HSVtoRGB(const Vector& HSV)
{
  float h = HSV.x;
  float s = HSV.y;
  float v = HSV.z;
  float r=0, g=0, b=0;
  float f,p,q,t;
  int i;

  if( s == 0 ) {
    r = v;
    g = v;
    b = v;
  }
  else {
    if(h == 360.)
      h = 0.0;
    h /= 60.;
    i = (int) h;
    f = h - i;
    p = v*(1-s);
    q = v*(1-(s*f));
    t = v*(1-s*(1-f));
    switch(i) {
      case 0:
        r = v;
        g = t;
        b = p;
        break;
      case 1:
        r = q;
        g = v;
        b = p;
        break;
      case 2:
        r = p;
        g = v;
        b = t;
        break;
      case 3:
        r = p;
        g = q;
        b = v;
        break;
      case 4:
        r = t;
        g = p;
        b = v;
        break;
      case 5:
        r = v;
        g = p;
        b = q;
        break;
      default:
        r = 1.0;
        g = 1.0;
        b = 1.0;
      //printf("hsv2rgb::How did I get here?\n");
      // printf("h: %f, s: %f, v: %f; i:  %d\n",hin,s,v,i);
        break;
    }
  }
  return Vector(r,g,b);
}