[OpenGL] Template

#include <windows.h>
#include <GL/glut.h>
#include <cmath>
#define M_PI 3.14159265358979323846

float w=600,h=600;
float alfa=0,beta=0;
float x,y,z;
float r=5;
float poz1=0,poz2=0;

const GLdouble left = -5.0;
const GLdouble right = 5.0;
const GLdouble bottom = -5.0;
const GLdouble top = 5.0;
const GLdouble nnear = -5.0;
const GLdouble ffar = 5.0;

int right_button_state = GLUT_UP ;
int middle_button_state = GLUT_UP ;
int left_button_state = GLUT_UP ;

int l_button_x, l_button_y, m_button_x, m_button_y, mr_button;


void Keyboard( unsigned char key, int x, int y )
{
    if ( key == 27 )
        exit( EXIT_SUCCESS );
        switch(key)
        {
        case 'w':
                alfa-=5;
                break;
        case 's':
                alfa+=5;
                break;
        case 'a':
                beta-=5;
                break;
        case 'd':
                beta+=5;
                break;
        case 'z':
                r+=0.1;
                break;
        case 'x':
                r-=0.1;
                break;
        case 'e':
                poz1+=0.1;
                break;
        case 'q':
                poz1-=0.1;
                break;
        }
}
void SpecialKeys(int key, int x, int y)
{
        switch(key)
        {
        case GLUT_KEY_UP:
                alfa+=1;
                break;
        }
}

void Init()
{
    glClearColor( 0.1f, 0.1f, 0.1f, 1.0f );
    glMatrixMode( GL_PROJECTION ) ;
    glLoadIdentity();
        gluPerspective(60,w/h,0.1,100);
        glMatrixMode(GL_MODELVIEW);
        glLoadIdentity();
        glEnable(GL_DEPTH_TEST);

    glutKeyboardFunc( Keyboard );
}

void Camera()
{
        x=-r*cos(alfa*M_PI/180)*sin(beta*M_PI/180);
        y=r*sin(alfa*M_PI/180);
        z=r*cos(alfa*M_PI/180)*cos(beta*M_PI/180);
}

void MouseButton( int button, int state, int x, int y)
{
        if (button == GLUT_LEFT_BUTTON)
    {
        left_button_state = state;
        if (state == GLUT_DOWN)
        {
            l_button_x = x;
                        l_button_y = y;
        }
    }


    if (button == GLUT_MIDDLE_BUTTON)
    {
        middle_button_state = state;
        if (state == GLUT_DOWN)
        {
                        mr_button = y;
        }
    }

        if (button == GLUT_RIGHT_BUTTON)
    {
                right_button_state = state;
        if (state == GLUT_DOWN)
        {
            m_button_x = x; // by nie wracal do punktu wyjscia
                        m_button_y = y;
        }
    }

}

void MouseMotion( int x, int y)//te zmiennie ile razy obroci sie kosta przy przejechaniu mysza przez pole obiektu.
{
    if (left_button_state == GLUT_DOWN)  // zmiana kata
    {
        beta += 50 *(top - bottom) / glutGet( GLUT_WINDOW_WIDTH ) *( x - l_button_x );
                l_button_x = x;
                alfa += 50 *(right - left) / glutGet( GLUT_WINDOW_HEIGHT) *( y - l_button_y );  //normalizacja okna, zachowanie proporcji
                l_button_y = y;

                glutPostRedisplay();
    }

        if (middle_button_state == GLUT_DOWN)
    {
        r += 0.01 * (ffar - nnear) * (y - mr_button); // zmiana promienia
        mr_button = y;
                if (r<1)
                        r=1;
        glutPostRedisplay();
    }

        if (right_button_state == GLUT_DOWN)
    {
        poz1 += 2 *(right - left) / glutGet( GLUT_WINDOW_WIDTH ) *( x - m_button_x );
                m_button_x = x;
                poz2 += 2 *(top - bottom) / glutGet( GLUT_WINDOW_HEIGHT ) *( m_button_y - y );
                m_button_y = y;

                glutPostRedisplay();
    }
}

void Render()
{

glClear( GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);

Camera();
gluLookAt(x+poz1,y,z,poz1,poz2,0,0,cos(alfa*M_PI/180),0); //zmiana polozenia kamer

// CODE HERE

glLoadIdentity();
glutSwapBuffers();
}

void Idle()
{
    Render();
}

int main( int argc, char **argv )
{
        glutInitDisplayMode( GLUT_DOUBLE);
        glutInitWindowSize(w,h);
        glutInitWindowPosition(50,50);
        glutCreateWindow( "OpenGL" );
    Init();
        glutIdleFunc( Idle);
    glutDisplayFunc( Render );
        glutMouseFunc(MouseButton);
        glutMotionFunc(MouseMotion);
        glutSpecialFunc(SpecialKeys);
    glutMainLoop();
    return EXIT_SUCCESS;
}