FadeFilter.h

Go to the documentation of this file.

#ifndef FADE_FILTER_H
#define FADE_FILTER_H

#include <vreckoDP/PHANToM/PHANToM_Device.h>

#ifdef COMPILE_PHANTOM_DEVICE

namespace vreckoDP_PHANToM {

/* PHANToM filter to fade-in or fade-out the forces and keep them at zero level in the meantime.
   Can be used alone to fade in the force on the start of the program,
   or as a base class from which other filter is inherited. */
class FadeForceFilter : public PHANToMFilter {
public:
    FadeForceFilter(const char* abName = "FadeFilter");

    virtual bool loadXMLParameters(XERCES_CPP_NAMESPACE_QUALIFIER DOMNode *parameters);
    virtual void postInitialize(void);

    virtual void apply(PHANToMSTATE &pState, osg::Vec3 &force, osg::Vec3 &torque);

protected:
// Parameters loaded from the Parameters element:
    double defaultFadeTimeInSecs;
    bool bFadeInFromStart;

    enum FadeState {
        Normal, // nothing is done
        FadingOut, // fading out
        Lowered, // forces are at zero level
        FadingIn // fading in
    };

    FadeState fadeState;
    double fadeTimeInSecs;
    osg::Timer_t fadeTimeInTicks;
    osg::Timer_t fadeStart; // [in Timer tick units]


    void startFade(bool bFadeIn, double newFadeTimeInSecs = -1);
        // If [bFadeIn] is "false", we are fading out.
        // This method will also take in account any previous fade that might be currently in progress.
        // If [fadeTimeInSecs] is negative, the [defaultFadeTimeInSecs] will be used.

    inline float currentFadeFactor(osg::Timer_t currentTick) { // returns 0.0 - 1.0
        checkFadingForEnd(currentTick);

        if (fadeState == Normal)
            return 1.0f;
        if (fadeState == Lowered)
            return 0.0f;

        if (fadeState == FadingIn)
            return (float)(currentTick - fadeStart) / (float)fadeTimeInTicks;
        
        // => this must be a fade-out
        return 1.0f - ((float)(currentTick - fadeStart) / (float)fadeTimeInTicks);
    }

    inline void checkFadingForEnd(osg::Timer_t currentTick) {
        if ((fadeState == Normal) || (fadeState == Lowered))
            return; // all OK

        if (currentTick > fadeStart + fadeTimeInTicks) {
            // fading passed the end -> stop fading
            if (fadeState == FadingIn)
                fadeState = Normal;
            else
                fadeState = Lowered;
        }
    }
};

}

#endif


#endif