/***********************************************************************
 * On a CSU CS department Sun workstation, compile with
 *
 *   gcc -o rotatebox rotatebox.c -I/s/parsons/l/sys/Mesa-3.0/include -L/s/parsons/l/sys/Mesa-3.0/lib/SunOS -lm -lMesaGL -lMesaGLw -lMesaGLU -lglut -lXm -lXt -lX11 -lXi
 *
 * To run this on a Sun, you may need to define your LD_LIBRARY_PATH 
 * environmental variable.  You can do this by placing this line in your
 * .cshrc file in your home directory:
 *
 *  setenv LD_LIBRARY_PATH /s/parsons/l/sys/Mesa-3.0/lib/SunOS
 *
 * On a CSU CS department Linux workstation, compile with
 *
 *   gcc -o rotatebox rotatebox.c -L/usr/X11R6/LessTif/Motif1.2/lib -L/usr/X11R6/lib -lm -lMesaGLw -lglut -lGLU -lGL  -lXm -lXt -lX11 -lXi
 *
 * To run this on a Linux machine, you may need to define your LD_LIBRARY_PATH 
 * environmental variable.  You can do this by placing this line in your
 * .cshrc file in your home directory:
 *
 *  setenv LD_LIBRARY_PATH /s/parsons/l/sys/Mesa-3.0/lib/Linux
 **********************************************************************/

/* Normal Includes */
#include <stdio.h>
#include <math.h>

/* OpenGL Includes */
#include <GL/gl.h>
#include <GL/glu.h>
#include <GL/glut.h>

int MouseX,MouseY;
double Phi=0, Theta=0;
void mouseclick(int b, int s, int x, int y);
void mousemove(int x, int y);
void key(unsigned char c, int x, int y);
void display();

main(int argc, char **argv) {
  /* Initialize OpenGL */
  glutInit(&argc,argv); 

  /* We want a double buffered display w/ RGB Color and a Depth Buffer */
  glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);

  /* How big of a window do we want? */
  glutInitWindowSize(200,200);

  /* Where do we want the window? */
  glutInitWindowPosition(100,100);

  /* Make the window, call it whatever the name of our program is */
  glutCreateWindow(argv[0]);

  /* What function should be notified of mouse events? */
  glutMouseFunc(mouseclick);

  /* What function should be notified of mouse events? */
  glutMotionFunc(mousemove);

  /* What function should be notified of Keyboard Events? */
  glutKeyboardFunc(key);

  /* What function gets called to redraw the screen? */
  glutDisplayFunc(display);

  /* What color is the background? */
  glClearColor(0,0,0,0);

  /* Lets set up the Projection Matrix */
  glMatrixMode(GL_PROJECTION);

  /* Reset it */
  glLoadIdentity();

  /* Set up the projection Matrix for Orthographic or Perspective: */
  /* glOrtho(-10,10,-10,10,1,100); */
  gluPerspective(75,1,1,100);

  /* Choose a Shading Model: */
  glShadeModel(GL_FLAT);
  /* glShadeModel(GL_SMOOTH); */
  
  /* Enable the Z-Buffer */
  glEnable(GL_DEPTH_TEST);

  /* Let the program begin! */
  glutMainLoop();
}

/* Mouse Click handler */
void mouseclick(int b, int s, int x, int y) {
  MouseX = x;
  MouseY = y;
  printf("MOUSE CLICK: Button: %d Status: %d Location: (%d,%d)\n",b,s,x,y);
}

/* Mouse Move handler */
void mousemove(int x, int y) {
  Theta += .02 * (MouseX - x);
  Phi -= .02 * (MouseY - y);

  if (Phi >= M_PI_2 || Phi <= -M_PI_2)
    Phi += .02 * (MouseY - y);

  printf("MOUSE MOVE: Location: (%d,%d)\n",x,y);
  MouseX = x;
  MouseY = y;

  /* Tell GL we need to Re Display */
  glutPostRedisplay();
}

/* Keyboard Handler */
void key(unsigned char c, int x, int y) {
  printf("KEY: %c (%d) Location (%d,%d)\n",c,c,x,y);
}

/* Redraw Handler */
void display() {
  double Camx, Camy, Camz;

  /* Lets set up the modelview matrix: */
  glMatrixMode(GL_MODELVIEW);

  /* Reset it */
  glLoadIdentity();

  /* Compute the Camera Location */
  Camx=cos(Phi)*sin(Theta) * 5;
  Camy=sin(Phi) * 5;
  Camz=cos(Theta)*cos(Phi) * 5;

  /* Tell it where we are, where we are looking, and where is up */
  gluLookAt(Camx,Camy,Camz,
            0,0,0,
            0,1,0);

  /* Clear the screen */
  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

  /* Begin Drawing Quadrilaterals */
  glBegin(GL_QUADS);

  /* Quad 1 */
  glColor3f(0.0,0.7,0.1);   /* Greenish */
  glVertex3f(-1.0,1.0,1.0);
  glVertex3f(1.0,1.0,1.0);
  glVertex3f(1.0,-1.0,1.0);
  glVertex3f(-1.0,-1.0,1.0);

  /* Quad 2 */
  glColor3f(0.9,1.0,0.1);  /* Yellowish */
  glVertex3f(-1.0,1.0,-1.0);
  glVertex3f(1.0,1.0,-1.0);
  glVertex3f(1.0,-1.0,-1.0);
  glVertex3f(-1.0,-1.0,-1.0);

  /* Quad 3 */
  glColor3f(0.2,0.2,1.0);  /* Blueish */
  glVertex3f(-1.0,1.0,1.0);
  glVertex3f(1.0,1.0,1.0);
  glVertex3f(1.0,1.0,-1.0);
  glVertex3f(-1.0,1.0,-1.0);

  /* Quad 4 */
  glColor3f(0.7,0.0,0.1);  /* Reddish */
  glVertex3f(-1.0,-1.0,1.0);
  glVertex3f(1.0,-1.0,1.0);
  glVertex3f(1.0,-1.0,-1.0);
  glVertex3f(-1.0,-1.0,-1.0);

  /* Done Drawing Quadrilaterals */
  glEnd();
  
  /* Display to the screen what we have drawn */
  glutSwapBuffers();
}