glutil.h

/*
Copyright (c) 2000-2003 Lee Thomason (www.grinninglizard.com)
Grinning Lizard Utilities.

This software is provided 'as-is', without any express or implied 
warranty. In no event will the authors be held liable for any 
damages arising from the use of this software.

Permission is granted to anyone to use this software for any 
purpose, including commercial applications, and to alter it and 
redistribute it freely, subject to the following restrictions:

1. The origin of this software must not be misrepresented; you must 
not claim that you wrote the original software. If you use this 
software in a product, an acknowledgment in the product documentation 
would be appreciated but is not required.

2. Altered source versions must be plainly marked as such, and 
must not be misrepresented as being the original software.

3. This notice may not be removed or altered from any source 
distribution.
*/



#ifndef GRINLIZ_UTIL_INCLUDED
#define GRINLIZ_UTIL_INCLUDED

#ifdef _MSC_VER
#pragma warning( disable : 4530 )
#pragma warning( disable : 4786 )
#endif

#include <math.h>
#include "gltypes.h"
#include "gldebug.h"

namespace grinliz {

template <class T> inline T             Min( T a, T b )         { return ( a < b ) ? a : b; }
template <class T> inline T             Max( T a, T b )         { return ( a > b ) ? a : b; }
template <class T> inline T             Min( T a, T b, T c )    { return Min( a, Min( b, c ) ); }
template <class T> inline T             Max( T a, T b, T c )    { return Max( a, Max( b, c ) ); }
template <class T> inline T             Min( T a, T b, T c, T d )       { return Min( d, Min( a, b, c ) ); }
template <class T> inline T             Max( T a, T b, T c, T d )       { return Max( d, Max( a, b, c ) ); }


template <class T> inline void  Swap( T* a, T* b )      { T temp; temp = *a; *a = *b; *b = temp; }
template <class T> inline bool  InRange( T a, T lower, T upper )        { return a >= lower && a <= upper; }
template <class T> inline T             Clamp( const T& a, T lower, T upper )   
                                                                { 
                                                                        if ( a < lower )
                                                                                return lower;
                                                                        else if ( a > upper )
                                                                                return upper;
                                                                        return a;
                                                                }

template <class A, class B> inline B Interpolate( A x0, B q0, A x1, B q1, A x )
{
        GLASSERT( static_cast<B>( x1 - x0 ) != 0.0f );
        return q0 + static_cast<B>( x - x0 ) * ( q1 - q0 ) / static_cast<B>( x1 - x0 );
}


template <class T> inline T InterpolateUnitX( T q0, T q1, T x )
{
        GLASSERT( x >= (T)0.0 );
        GLASSERT( x <= (T)1.0 );

        return q0*( static_cast<T>(1.0) - x ) + q1*x;
}

template <class T> inline T BilinearInterpolate( T q00, T q10, T q01, T q11, T x, T y )
{
        GLASSERT( x >= (T)0.0 );
        GLASSERT( x <= (T)1.0 );
        GLASSERT( y >= (T)0.0 );
        GLASSERT( y <= (T)1.0 );

        const T one = static_cast<T>(1);
        return q00*(one-x)*(one-y) + q10*(x)*(one-y) + q01*(one-x)*(y) + q11*(x)*(y);
}


template <class T> inline T BilinearInterpolate( const T* q, T x, T y, const T* weight )
{
        GLASSERT( x >= (T)0.0 );
        GLASSERT( x <= (T)1.0 );
        GLASSERT( y >= (T)0.0 );
        GLASSERT( y <= (T)1.0 );

        const T one = static_cast<T>(1);
        const T zero = static_cast<T>(0);
        const T area[4] = { (one-x)*(one-y), (one-x)*(y), (x)*(one-y), x*y };

        T totalWeight = zero;
        T sum = zero;

        for ( unsigned i=0; i<4; ++i ) {
                totalWeight += area[i] * weight[i];
                sum += q[i] * area[i] * weight[i];
        }
        if ( totalWeight == zero )
                return zero;
        return sum / totalWeight;
}


inline long LRint( double val)
{
        #ifdef __GNUC__
                return lrint( val );
        #else
                double v = val + (4503599627370496.0*1.5);      // 2^52
                return ((int*)&v)[0];
        #endif
}


inline long LRintf( float val)
{
        #ifdef __GNUC__
                return lrintf( val );
        #else
                // This could be better. 
                return LRint( (double) val);
        #endif
}


extern float gU8ToFloat[256];

inline float U8ToFloat( U8 v )
{
        return gU8ToFloat[v];
}


/*      A class to store a set of bit flags, and set and get them in a standard way.
        Class T must be some kind of integer type.
*/
template < class T >
class Flag
{
  public:
        Flag()                                                          { store = 0; }
        
        inline void Set( T flag )                       { store |= flag; }
        inline void Clear( T flag )                     { store &= ~flag; }
        inline T IsSet( T flag ) const          { return ( store & flag ); }

        inline U32  ToU32() const                       { return store; }
        inline void FromU32( U32 s )            { store = (T) s; }

        inline void ClearAll()                          { store = 0; }

  private:
        T store;
};      

/*      A strange class: it creates bitmaps used for collision detection. Given
        an unsigned something, this is a utility class to pack bits...starting
        with the highest bit.
*/

template < class T >
class HighBitWriter 
{
  public:
        enum
        {
                MAXBIT = ( sizeof(T)*8-1 ),
                NUMBIT = ( sizeof(T)*8 ),
                ALLSET = T( -1 )
        };

        HighBitWriter( T* _data ) : data( _data ), bitPos( MAXBIT )     {}

        void Skip()
        {
                if ( bitPos == 0 )
                {
                        ++data;
                        bitPos = MAXBIT;
                }
                else
                {
                        --bitPos;
                }
        }

        void Skip_N( unsigned n )
        {
                bitPos -= n % NUMBIT;
                if ( bitPos < 0 )
                {
                        bitPos += NUMBIT;
                        ++data;
                }
                data += n / NUMBIT;
        }
        
        void Push_1()   
        {
                *data |= ( 1 << bitPos );
                Skip();
        }

        void Push_1N( unsigned n )
        {
                // Push bits to T boundary
                while( n && bitPos != MAXBIT )
                {
                        Push_1();
                        --n;
                }

                // Write Full T size
                while( n >= NUMBIT )
                {
                        *data = ALLSET;
                        ++data;
                        n -= NUMBIT;
                }

                // Write the remainder
                while ( n )
                {
                        Push_1();
                        --n;
                }
        }

  private:
        T*      data;
        int bitPos;
};


};      // namespace grinliz

#endif

---