wm4mathmcr.h

windows ce 下的3D桌面

// Wild Magic Source Code
// David Eberly
// http://www.geometrictools.com
// Copyright (c) 1998-2007
//
// This library is free software; you can redistribute it and/or modify it
// under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation; either version 2.1 of the License, or (at
// your option) any later version.  The license is available for reading at
// either of the locations:
//     http://www.gnu.org/copyleft/lgpl.html
//     http://www.geometrictools.com/License/WildMagicLicense.pdf
//
// Version: 4.0.0 (2006/06/28)

#ifndef WM4MATHMCR_H
#define WM4MATHMCR_H

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

// Fast conversion from a IEEE 32-bit floating point number F in [0,1] to a
// a 32-bit integer I in [0,2^L-1].
//
//   fFloat = F
//   iLog = L
//   iInt = I

#define WM4_SCALED_FLOAT_TO_INT(fFloat,iLog,iInt)\
{ \
    int iShift = 150 - iLog - ((*(int*)(&fFloat) >> 23) & 0xFF); \
    if ( iShift < 24 ) \
    { \
        iInt = ((*(int*)(&fFloat) & 0x007FFFFF) | \
            0x00800000) >> iShift; \
        if ( iInt == (1 << iLog) ) \
        { \
            iInt--; \
        } \
    } \
    else \
    { \
        iInt = 0; \
    } \
}

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

#endif