gluLookAt Problem

#include <GL/glut.h>
#include <stdlib.h>
#include <math.h>
#include <iostream>
#include <fstream>
using namespace std;

//fstream output("data.txt",ios::out);

double dt = 0.05; // this is the time step
float coeF = 0.5;
float verysmall = 0.001;
float totaltime = 0.0;
float gravity = 0.1;
GLfloat near = 0.1,far = 20.0;
GLfloat startdispz = -1.0;

const float DEG2RAD = 3.14159/180;

class ball
{
    private:
        // ax acceleration in x, px position in x, vx velocity in x
        double ax,ay,az,px,py,pz,vx,vy,vz,size;

    public:
        ball()
        {
            px=0.0;py=0.0;
        }
        ball(double dummyvx, double dummyvy,double dummyvz)
        {
            px=0;   py=0.1; pz=0;   size=0.1;
            vx=dummyvx; vy=dummyvy; vz=dummyvz; ay=gravity;
        }
        double getpx(){return px;}  double getpy(){return py;}  double getpz(){return pz;}
        double getvx(){return vx;}  double getvy(){return vy;}  double getvz(){return vz;}
        double getballsize(){return size;}

        double getspeed(){return  sqrt(py*py + px*px + pz*pz);}

        void evolve()
        {
            //cout << "vy" << vy << "\n";
            vy += (-gravity*dt);                            // equation for the y component of v
            px += vx*dt;    py += vy*dt;    pz += vz*dt;    // equations for all 3 components of p
            totaltime += dt;                                // update total time
            //output << totaltime << " " << px << " "   << py << " "  << pz << "\n";
            //cout << totaltime << " " << py  << " " << pz << "\n";
            //terminate when we hit the ground i.e pz < 0

            if(py < size)
            {
                py = size;
                vy = -vy*coeF;

                //cout << "The ball has hit the ground\n";
                //vx=0; vy=0;   vz=0;
                //output.close();
                //exit(0);
            }
        }
};

// ball start at origin with velocity vector as in the constructor
ball golfball(0.0, 0.4, 0.8);

void init(void)
{
    glClearColor(1.0,1.0,1.0,0.0);
}

void drawCircle(float Radius, int numPoints)
{
    glBegin( GL_LINE_LOOP );
    for( int i=0; i<numPoints; i++ )
    {
        float Angle = i * (2.0*M_PI/numPoints);
        float X = cos( Angle )*Radius;
        float Y = sin( Angle )*Radius;
        glVertex2f( X, Y );
    }
    glEnd();
}

void display(void)
{
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluPerspective(40,1,near,far);

    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
    gluLookAt(0.0, 2.0, -3.0, 0.0, 0.0, 10.0, 0.0, 1.0, 0.0);

    glClear(GL_COLOR_BUFFER_BIT);

    glPushMatrix();
        glColor3f (0.0, 0.0, 0.0);
        glTranslatef(golfball.getpx(),golfball.getpy(),startdispz - golfball.getpz());
        glutSolidSphere(golfball.getballsize(),20,20);
    glPopMatrix();

    glPushMatrix();
        glColor3f (0.0, 1.0, 0.0);
        glTranslatef(0,0.0,-7.5);
        glRotatef(90, 1.0, 0.0, 0.0);
        drawCircle(0.1,24);
        glRotatef(-90, 1.0, 0.0, 0.0);
    glPopMatrix();

    glFlush();
    glutSwapBuffers();
}

void keyboard(unsigned char key, int x, int y)
{
    switch (key)
    {
        case 'q':
        exit(0);
    }
}

void evolve(int a)
{
    // evolve system here
    golfball.evolve();
    glutPostRedisplay();
    glutTimerFunc(20,evolve,20);
}

int main(int argc, char** argv)
{
   glutInit(&argc, argv);
   glutInitDisplayMode (GLUT_DOUBLE | GLUT_RGB);
   glutInitWindowSize (800, 800);
   glutCreateWindow (argv[0]);   init();
   glutKeyboardFunc (keyboard);
   //  glutIdleFunc(evolve);
   glutTimerFunc(100,evolve,100);
   glutDisplayFunc (display);
   cout << "Hello All on CG6301\n";
   cout << "This program models projectile motion, the golf ball moves under gravity(no friction)\n";
   cout << "The file is closed and the program terminates when the ball is deemed to have hit the ground \n";
   cout << "The lab questions ask you to determine how accurately we have modelled the system\n";

   glutMainLoop();
   return 0;
}