MountainCar.cpp

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/*
 *  MountainCar.cpp
 *  hog2
 *
 *  Created by Nathan Sturtevant on 11/29/10.
 *  Copyright 2010 University of Denver. All rights reserved.
 *
 */
 
#include "MountainCar.h"
#include <math.h>
 
MountainCarEnvironment::MountainCarEnvironment()
{
    minPosition = -1.2;
    maxPosition = 0.6;
    minVelocity = -0.07;
    maxVelocity = 0.07;
    goalPosition = 0.5;
    accelerationFactor = 0.001;
    gravityFactor = -0.0025;
    hillPeakFrequency = 3.0;
}
 
void MountainCarEnvironment::GetSuccessors(const MountainCarState &nodeID, std::vector<MountainCarState> &neighbors) const
{
        neighbors.resize(0);
        neighbors.push_back(nodeID);
        neighbors.push_back(nodeID);
        neighbors.push_back(nodeID);
        ApplyAction(neighbors[0], 1);
        ApplyAction(neighbors[1], 0);
        ApplyAction(neighbors[2], -1);
}
 
void MountainCarEnvironment::GetActions(const MountainCarState &nodeID, std::vector<MountainCarAction> &actions) const
{
        actions.resize(0);
        actions.push_back(1);
        actions.push_back(0);
        actions.push_back(-1);
}
 
MountainCarAction MountainCarEnvironment::GetAction(const MountainCarState &s1, const MountainCarState &s2) const
{
        assert(!"GetAction not implemented");
}
 
void MountainCarEnvironment::ApplyAction(MountainCarState &s, MountainCarAction a) const
{
        s.speed += a * accelerationFactor + GetSlope(s.loc) * (gravityFactor);
        if (s.speed > maxVelocity) {
                s.speed = maxVelocity;
        }
        if (s.speed < minVelocity)
        {
                s.speed = minVelocity;
        }
        s.loc += s.speed;
        if (s.loc > maxPosition)
        {
                s.loc = maxPosition;
        }
        if (s.loc < minPosition)
        {
                s.loc = minPosition;
        }
        if (s.loc == minPosition && s.speed < 0)
        {
                s.speed = 0;
        }
}
 
double MountainCarEnvironment::GetHeightAtPosition(double queryPosition) const
{
        return -sin(hillPeakFrequency * (queryPosition));
}
 
double MountainCarEnvironment::GetSlope(double queryPosition) const
{
        /*The curve is generated by cos(hillPeakFrequency(x-pi/2)) so the 
         * pseudo-derivative is cos(hillPeakFrequency* x) 
         */
        return cos(hillPeakFrequency * queryPosition);
}
 
 
void MountainCarEnvironment::GetNextState(const MountainCarState &s1, MountainCarAction a, MountainCarState &s2) const
{
        s2 = s1;
        ApplyAction(s2, a);
}
 
bool MountainCarEnvironment::InvertAction(MountainCarAction &a) const
{
        a = -a;
        return false; // actions aren't really invertable
}
 
double MountainCarEnvironment::HCost(const MountainCarState &node1, const MountainCarState &node2) const
{ return 0; }
 
double MountainCarEnvironment::GCost(const MountainCarState &node1, const MountainCarState &node2) const
{
        return 1;
}
 
double MountainCarEnvironment::GCost(const MountainCarState &node, const MountainCarAction &act) const
{
        return 1;
}
 
bool MountainCarEnvironment::GoalTest(const MountainCarState &node, const MountainCarState &goal) const
{
        return fgreater(node.loc, goalPosition);
}
 
uint64_t MountainCarEnvironment::GetStateHash(const MountainCarState &node) const
{
        return (((int)(node.loc*1000))<<10) + node.speed*1000;
}
 
uint64_t MountainCarEnvironment::GetActionHash(MountainCarAction act) const
{
        return act+1;
}
 
void MountainCarEnvironment::OpenGLDraw() const
{
//      minPosition = -1.2;
//    maxPosition = 0.6;
        glBegin(GL_LINE_STRIP);
        glColor3f(0, 1.0, 0);
        for (double x = minPosition; x < maxPosition; x += 0.1)
        {
                glVertex3f(x, GetHeightAtPosition(x), 0);
        }       
        glEnd();
}
 
void MountainCarEnvironment::OpenGLDraw(const MountainCarState&) const { }
void MountainCarEnvironment::OpenGLDraw(const MountainCarState&, const MountainCarState&, float) const { }
void MountainCarEnvironment::OpenGLDraw(const MountainCarState&, const MountainCarAction&) const { }