/****************************************************************************
*                   colour.c
*
*  This module implements routines to manipulate colours.
*
*  from Persistence of Vision Raytracer 
*  Copyright 1992 Persistence of Vision Team
*---------------------------------------------------------------------------
*  Copying, distribution and legal info is in the file povlegal.doc which
*  should be distributed with this file. If povlegal.doc is not available
*  or for more info please contact:
*
*       Drew Wells [POV-Team Leader] 
*       CIS: 73767,1244  Internet: 73767.1244@compuserve.com
*       Phone: (213) 254-4041
* 
* This program is based on the popular DKB raytracer version 2.12.
* DKBTrace was originally written by David K. Buck.
* DKBTrace Ver 2.0-2.12 were written by David K. Buck & Aaron A. Collins.
*
*****************************************************************************/


#include "frame.h"
#include "vector.h"
#include "povproto.h"

#define FABS(x) ((x) < 0.0 ? (0.0 - (x)) : (x))

DBL Colour_Distance (colour1, colour2)
COLOUR *colour1, *colour2;
{
   return (FABS (colour1->Red - colour2->Red)
      + FABS (colour1->Green - colour2->Green)
      + FABS (colour1->Blue - colour2->Blue));
}

void Add_Colour (result, colour1, colour2)
COLOUR *result, *colour1, *colour2;
{
   result->Red = colour1->Red + colour2->Red;
   result->Green = colour1->Green + colour2->Green;
   result->Blue = colour1->Blue + colour2->Blue;
   result->Alpha = colour1->Alpha + colour2->Alpha;
}

void Scale_Colour (result, colour, factor)
COLOUR *result, *colour;
DBL factor;
{
   result->Red = colour->Red * factor;
   result->Green = colour->Green * factor;
   result->Blue = colour->Blue * factor;
   result->Alpha = colour->Alpha * factor;
}

void Clip_Colour (result, colour)
COLOUR *result, *colour;
{
   if (colour -> Red > 1.0)
      result -> Red = 1.0;
   else if (colour -> Red < 0.0)
      result -> Red = 0.0;
   else result -> Red = colour -> Red;

      if (colour -> Green > 1.0)
         result -> Green = 1.0;
      else if (colour -> Green < 0.0)
         result -> Green = 0.0;
      else result -> Green = colour -> Green;

      if (colour -> Blue > 1.0)
         result -> Blue = 1.0;
      else if (colour -> Blue < 0.0)
         result -> Blue = 0.0;
      else result -> Blue = colour -> Blue;

      if (colour -> Alpha > 1.0)
         result -> Alpha = 1.0;
      else if (colour -> Alpha < 0.0)
         result -> Alpha = 0.0;
      else result -> Alpha = colour -> Alpha;
}