Serious-Engine/Sources/Engine/Math/Functions.cpp

/* Copyright (c) 2002-2012 Croteam Ltd. 
This program is free software; you can redistribute it and/or modify
it under the terms of version 2 of the GNU General Public License as published by
the Free Software Foundation


This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License along
with this program; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. */

#include "Engine/StdH.h"

#include <Engine/Math/Functions.h>

/////////////////////////////////////////////////////////////////////
// Snapping functions

// does "snap to grid" for given coordinate
void Snap( FLOAT &fDest, FLOAT fStep)
{
  // this must use floor() to get proper snapping of negative values.
  FLOAT fDiv = fDest/fStep;
  FLOAT fRound = fDiv + 0.5f;
  FLOAT fSnap = FLOAT(floor(fRound));
  FLOAT fRes = fSnap * fStep;
  fDest = fRes;
}
// does "snap to grid" for given coordinate
void Snap( DOUBLE &fDest, DOUBLE fStep)
{
  // this must use floor() to get proper snapping of negative values.
  DOUBLE fDiv = fDest/fStep;
  DOUBLE fRound = fDiv + 0.5f;
  DOUBLE fSnap = DOUBLE(floor(fRound));
  DOUBLE fRes = fSnap * fStep;
  fDest = fRes;
}

#if 0
// does "snap to grid" for given angle
void Snap( ANGLE &angDest, ANGLE angStep)
{
  /* Watch out for unsigned-signed mixing!
   All sub-expressions and arguments must be unsigned for this to work correctly!
   Unfortunately, ANGLE is not an unsigned type by default, so we must cast it.
   Also, angStep must be a divisor of ANGLE_180!
   */
  ASSERT(ANGLE_180%angStep == 0);   // don't test with ANGLE_360 ,since it is 0!
  angDest = ANGLE( ((UWORD(angDest)+UWORD(angStep)/2U)/UWORD(angStep))*UWORD(angStep) );
}
#endif

double adSinQuadrants[4][2] =
{
  {1.0, 0.0},
  {-1.0, -90.0},
  {-1.0, 0.0},
  {1.0, -90.0},
};
double adCosQuadrants[4][2] =
{
  {-1.0, -90.0},
  {-1.0, 0.0},
  {1.0, -90.0},
  {1.0, 0.0},
};

FLOAT Sin(ANGLE a)
{
  double aWrapped = WrapAngle(a);
  double aIn90 = fmod(aWrapped, 90.0);
  int iQuadrant = int(aWrapped/90.0);
  double fSin = adSinQuadrants[iQuadrant][0]*
    sin((aIn90+adSinQuadrants[iQuadrant][1])*PI/ANGLE_180);
  return FLOAT (fSin);
}
FLOAT Cos(ANGLE a)
{
  double aWrapped = WrapAngle(a);
  double aIn90 = fmod(aWrapped, 90.0);
  int iQuadrant = int(aWrapped/90.0);
  double fCos = adCosQuadrants[iQuadrant][0]*
    sin((aIn90+adCosQuadrants[iQuadrant][1])*PI/ANGLE_180);
  return FLOAT (fCos);
}
FLOAT Tan(ANGLE a)
{
  return Sin(a)/Cos(a);
}