Timer.h

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#ifndef VRECKO_TIMER_H
#define VRECKO_TIMER_H

// More reliable (and slightly less precise) version of a timer than that from the OSG.
// ------------------------------------------------------------------------------------
// Uses timeGetTime() function instead of QueryPerformanceCounter().
// Calculates time with 1 ms precision and works correctly even on multicore multiprocessor
// machines unlike QPC, which can jump back and forth randomly. The jumps we experienced
// were usually in the range of 50 ms, but much higher values were also reported
// on the internet forums.


#include <vrecko/Export>
#include <osg/Timer>

namespace vrecko {

/* Could be derived from osg::Timer IF the tick() method was virtual :(

   Therefore it was directly copied from osg::Timer and changed a bit.
   The interface is identical to osg::Timer (at least in OSG 2.4.0). */


class VRECKO_EXPORT Timer  {
    public:

        Timer();
        ~Timer();

        static Timer* instance();

        osg::Timer_t tick() const;

        void setStartTick() { _startTick = tick(); }
        void setStartTick(osg::Timer_t t) { _startTick = t; }
        osg::Timer_t getStartTick() const { return _startTick; }

        inline double time_s() const { return delta_s(_startTick, tick()); }

        inline double time_m() const { return delta_m(_startTick, tick()); }

        inline double time_u() const { return delta_u(_startTick, tick()); }

        inline double time_n() const { return delta_n(_startTick, tick()); }
        
        inline double delta_s( osg::Timer_t t1, osg::Timer_t t2 ) const { return (double)(t2 - t1)*_secsPerTick; }

        inline double delta_m( osg::Timer_t t1, osg::Timer_t t2 ) const { return delta_s(t1,t2)*1e3; }

        inline double delta_u( osg::Timer_t t1, osg::Timer_t t2 ) const { return delta_s(t1,t2)*1e6; }

        inline double delta_n( osg::Timer_t t1, osg::Timer_t t2 ) const { return delta_s(t1,t2)*1e9; }
        
        inline double getSecondsPerTick() const { return _secsPerTick; }

    protected :
        osg::Timer_t _startTick;
        double  _secsPerTick;
};


};

#endif