VuoSmooth.h

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#ifndef VUOSMOOTH_H
#define VUOSMOOTH_H
 
typedef struct _VuoSmoothInertia
{
    bool moving;
    bool updateNeededAfterSetPosition;
    VuoGenericType1 positionLastFrame;
    VuoGenericType1 velocity;
    VuoGenericType1 target;
    VuoGenericType1 positionWhenTargetChanged;
    VuoGenericType1 velocityWhenTargetChanged;
    VuoReal timeLastFrame;
    VuoReal timeWhenTargetChanged;
    VuoReal duration;
} *VuoSmoothInertia;
 
static VuoSmoothInertia VuoSmoothInertia_make(VuoGenericType1 initialPosition)
{
    VuoSmoothInertia s = (VuoSmoothInertia)calloc(1,sizeof(struct _VuoSmoothInertia));
    VuoRegister(s, free);
    s->positionLastFrame = initialPosition;
    return s;
}
 
static void VuoSmoothInertia_setPosition(VuoSmoothInertia s, VuoGenericType1 position)
{
    s->positionLastFrame = position;
    s->moving = false;
    s->velocity = VuoGenericType1_makeFromJson(NULL);
    s->updateNeededAfterSetPosition = true;
}
 
static void VuoSmoothInertia_setTarget(VuoSmoothInertia s, VuoReal time, VuoGenericType1 target)
{
    s->target = target;
    s->positionWhenTargetChanged = s->positionLastFrame;
    s->velocityWhenTargetChanged = s->velocity;
    s->timeWhenTargetChanged = time;
    s->moving = true;
}
 
static void VuoSmoothInertia_setDuration(VuoSmoothInertia s, VuoReal duration)
{
    s->duration = MAX(duration, 0.00001);
}
 
static bool VuoSmoothInertia_step(VuoSmoothInertia s, VuoReal time, VuoGenericType1 *calculatedPosition)
{
    bool movedDuringThisStep = false;
 
    if (s->updateNeededAfterSetPosition)
    {
        movedDuringThisStep = true;
        *calculatedPosition = s->positionLastFrame;
        s->updateNeededAfterSetPosition = false;
    }
 
    if (s->moving)
    {
        movedDuringThisStep = true;
        VuoReal timeSinceLastFrame = time - s->timeLastFrame;
        if (timeSinceLastFrame != 0)
        {
            double timeSinceTargetChanged = MIN(time - s->timeWhenTargetChanged, s->duration);
            double curviness = s->duration/(3.*timeSinceLastFrame);
            VuoGenericType1 p1 = VuoGenericType1_add(s->positionWhenTargetChanged, VuoGenericType1_multiply(s->velocityWhenTargetChanged, timeSinceLastFrame*curviness));
            *calculatedPosition = VuoGenericType1_bezier3(s->positionWhenTargetChanged, p1, s->target, s->target, timeSinceTargetChanged/s->duration);
 
            s->velocity = VuoGenericType1_multiply(VuoGenericType1_subtract(*calculatedPosition, s->positionLastFrame), 1./timeSinceLastFrame);
            s->positionLastFrame = *calculatedPosition;
 
            if (time - s->timeWhenTargetChanged > s->duration)
            {
                s->moving = false;
                s->velocity = VuoGenericType1_makeFromJson(NULL);
            }
        }
    }
 
    s->timeLastFrame = time;
 
    return movedDuringThisStep;
}
 
#endif