Class WalkTracer : LineTracer
{
    Line lastLine; //unused right now
    Sector LastSector; //store last found sector
    double LastStepHeight; //last sector height
    vector3 HitPoint; //place where I found a ledge
    bool HitLedge; //did I find a ledge?
    actor owner; //caller
    int hitcount; //count the number of times there's an intersection
    double MaxStepHeight; //gotten from actor

    override ETraceStatus TraceCallback()
    {

        sector NextSector = Results.HitSector;
        if (!NextSector) return TRACE_skip; //if sector has not changed, continue tracing

        if(NextSector != LastSector) //sector has changed
        {
            //count the number of times i encounter a new sector
            hitcount++;
            console.printf('HIT %i', hitcount);

            vector3 hitpos = Results.HitPos;

            //get the floor height at this point
            double NextStepHeight = NextSector.floorplane.ZatPoint(hitpos.XY);
            //difference between current and last floor height
            double stepDifference =  NextStepHeight - LastStepHeight;

            //store last sector
            LastSector = NextSector;

            //store last step height
            LastStepHeight = NextStepHeight;


            if ( stepDifference > MaxStepHeight ) {
                HitLedge = true;
                return TRACE_Stop;

            } else if (stepDifference < -MaxStepHeight ) {
                HitLedge = true;
                return TRACE_Stop;

            } else {
                return TRACE_skip;
            }

        } else {
            return TRACE_skip;
        }

        if(Results.HitType == TRACE_HitActor)
        {
            return TRACE_skip;
        }

        return TRACE_Stop;
    }

    bool TraceFrom (actor caller, vector3 start, Sector sec, vector3 direction, double maxDist, ETraceFlags traceFlags)
    {
        self.hitcount = 0; //reset count
        self.owner = caller;   //the thing that is doing the trace
        self.MaxStepHeight = caller.MaxStepHeight; //the maximum vertical movement we consider a blocking height

        self.LastSector = sec; //record sector
        self.lastLine = null; //unused

        self.HitLedge = false; //reset hit
        self.LastStepHeight = sec.floorplane.ZatPoint(start.XY); //get starting floor height

        return Trace (start, sec, direction, maxDist, traceFlags);
    }
}