SPAR/AIModule/SparAIModule/Utils/BresenhamCircle.h

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#pragma once

template<class Functor>
void BresenhamCircle(Functor& functor, int radius, bool filled)
{
  if(radius == 0)
  {
    functor(0, 0); // ?
    return;
  }

  int x = 0;
  int y = radius;
  int prevy = radius;
  int h = 1 - radius;

  if(filled)
  {
    for(int i=1; i<2*radius; ++i)
    {
      functor(-radius + i, 0);
    }
  }

  functor(0,  radius);
  functor(0, -radius);
  functor( radius, 0);
  functor(-radius, 0);

  while(y > x+1)
  {
    prevy = y;

    if(h < 0)
    {
      h += 2*x + 3;
    }
    else
    {
      h += 2*(x-y) + 5;
      --y;
    }

    ++x;

    if(filled)
    {
      if(prevy > y && x < y)
      {
        for(int i=1; i<2*x; ++i)
        {
          functor(-x + i,  y);
          functor(-x + i, -y);
        }
      }

      for(int i=1; i<2*y; ++i)
      {
        functor(-y + i,  x);
        functor(-y + i, -x);
      }
    }

    functor( x,  y);
    functor(-x,  y);
    functor( x, -y);
    functor(-x, -y);
    if(x != y)
    {
      functor( y,  x);
      functor(-y,  x);
      functor( y, -x);
      functor(-y, -x);
    }
  }
}