ColorTranslator.cc

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//=============================================================================
//
//  CLASS ColorTranslator - IMPLEMENTATION
//
//=============================================================================


//== INCLUDES =================================================================


#include "ColorTranslator.hh"
#include <iostream>


//== NAMESPACES ===============================================================


namespace ACG {


//== IMPLEMENTATION ========================================================== 


void
ColorTranslator::
initialize()
{
  glGetIntegerv( GL_RED_BITS,   &red_bits_   );
  glGetIntegerv( GL_GREEN_BITS, &green_bits_ );
  glGetIntegerv( GL_BLUE_BITS,  &blue_bits_  );
  glGetIntegerv( GL_ALPHA_BITS,  &alpha_bits_ );

  if (red_bits_   > 8)  red_bits_   = 8;
  if (green_bits_ > 8)  green_bits_ = 8;
  if (blue_bits_  > 8)  blue_bits_  = 8;
  if (alpha_bits_ > 8)  alpha_bits_ = 8;

  red_mask_    = ((1 << red_bits_)   - 1);
  green_mask_  = ((1 << green_bits_) - 1);
  blue_mask_   = ((1 << blue_bits_)  - 1);
  alpha_mask_  = ((1 << alpha_bits_) - 1);

  red_shift_   = 8 - red_bits_;
  green_shift_ = 8 - green_bits_;
  blue_shift_  = 8 - blue_bits_;
  alpha_shift_ = 8 - alpha_bits_;

  red_round_   = 1 << (red_shift_   - 1);
  green_round_ = 1 << (green_shift_ - 1);
  blue_round_  = 1 << (blue_shift_  - 1);
  alpha_round_ = 1 << (alpha_shift_ - 1);

  initialized_ = true;
}

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


Vec4uc
ColorTranslator::
index2color(unsigned int _idx) const 
{
  assert(initialized());
  unsigned char  r, g, b, a;
  unsigned int   idx(_idx+1);
  
  b = ((idx & blue_mask_)  << blue_shift_)  | blue_round_;  
  idx >>= blue_bits_;
  g = ((idx & green_mask_) << green_shift_) | green_round_;  
  idx >>= green_bits_;
  r = ((idx & red_mask_)   << red_shift_)   | red_round_;  
  idx >>= red_bits_;
  a = ((idx & alpha_mask_) << alpha_shift_) | alpha_round_;
  idx >>= alpha_bits_;

  if (!idx) 
    return  Vec4uc(r, g, b, a);

  else 
  {
    std::cerr << "Can't convert index " << _idx << " to RGBA\n";
    return Vec4uc(0, 0, 0, 0);
  }
}

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


int
ColorTranslator::
color2index(Vec4uc _rgba) const
{
  assert(initialized());
  unsigned int result;

  result =   _rgba[3] >> alpha_shift_;
  result <<= red_bits_;
  result =   _rgba[0] >> red_shift_;
  result <<= green_bits_;
  result |=  _rgba[1] >> green_shift_;
  result <<= blue_bits_;
  result |=  _rgba[2] >> blue_shift_;    

  return (result-1);
}


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


unsigned int
ColorTranslator::max_index() const 
{
  assert(initialized());
  if (red_bits_+green_bits_+blue_bits_+alpha_bits_ == 32)
    return 0xffffffff;
  else
    return (1 << (red_bits_+green_bits_+blue_bits_+alpha_bits_))-1;
}


//=============================================================================
} // namespace ACG
//=============================================================================