/* 
   grid12.c 
 
   same as grid11  + handle rotation around z

   draw the boundary of the grid on screen; can move left/right/up/down
   via instant calls to glTranslatef(); 
   
   can rotate via instant calls to glRotate()
 

   Laura Toma
*/


#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#include <assert.h>
#ifdef __APPLE__
#include <GLUT/glut.h>
#else
#include <GL/glut.h>
#endif



//these shoudl be read from grid file. hardcode them for now 
int nrows = 472; 
int ncols = 391;



/* forward declarations of functions */
void display(void);
void keypress(unsigned char key, int x, int y);


int main(int argc, char** argv) {

  /* open a window */
  glutInit(&argc, argv);
  glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB | GLUT_DEPTH);
  glutInitWindowSize(500, 500);
  glutInitWindowPosition(100,100);
  glutCreateWindow(argv[0]);

  /* OpenGL init */
  glClearColor(0, 0, 0, 0);   /* set background color black*/
  glColor3f(1.0,1.0,1.0);   /* set draw color white */
  glEnable(GL_DEPTH_TEST); //not necessary in 2D
 
  /* callback functions */
  glutDisplayFunc(display); 
  glutKeyboardFunc(keypress);


  /***** INITIALIZE DISPLAY ***********/
  //clear the screen, need t oclear also the depth buffer 
  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); 
  
  glMatrixMode(GL_MODELVIEW); 
  
  glLoadIdentity(); //clear the matrix

  /* 
     Transform to GL coordinates:  
     
     the GL window is [-1,1]x[-1,1] with the origin in the center. Our grid
     points are in the range (0,0) to (ncols,nrows), so they need to
     be mapped to [-1,1]x [-1,1] 
  */

  //glScalef(2.0/ncols, 2.0/nrows, 1.0);  
  //this makes it square, we don't want that. We want to keep the
  //aspect ratio of the grid

  //pick the maximum of (nrows, ncols) and scale with it 
  //glScalef(2.0/nrows, 2.0/nrows, 1.0);  
  //this stretches it to the whole window
  glScalef(1.5/nrows, 1.5/nrows, 1.0);  


  /* our grid is in upper right quadrant, we need to shift it to get
     it centered in the middle of the window*/
  glTranslatef(-ncols/2.0, -nrows/2.0, 0); 


  /* event handler */
  glutMainLoop();
  return 0;
}



void display(void) {
  //clear the screen, need to clear also the depth buffer 
  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); 
  

  /************** DRAW *****************/
  /* draw grid boundary polygon. we are rendering in object space,
     which is [0,0] x [ncols, nrows] */

  //this is where you write code to draw a grid. Start with the
  //boundary.
  glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
  glBegin(GL_POLYGON);
  glVertex2f(0,0);
  glVertex2f(0,nrows);
  glVertex2f(ncols, nrows);
  glVertex2f(ncols, 0);
  glEnd();



 
  /* execute the drawing commands */
  glFlush();
}

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

  case 'l':
    //move left 
    // pos[0] -= 5;  //move left 5 cols 
    glTranslatef(-5,0,0 ); 
    glutPostRedisplay(); 
    break; 
    
  case 'r': 
    //move right
    //pos[0] += 5; //move right 5 cols 
    glTranslatef(5,0,0 ); 
    glutPostRedisplay(); 
    break;
 
  case 'u': 
    //move up 
    //pos[1] += 5; //move up 5 rows 
    glTranslatef(0,5,0 ); 
    glutPostRedisplay(); 
    break; 
    
  case 'd': 
    //move down 
    //pos[1] -= 5; //move down 5 rows 
    glTranslatef(0,-5,0); 
    glutPostRedisplay(); 
    break; 


 
  case 'z':
    //rotate around z
    /* we are in object system of coordinates; the default rotation is
       wrt the origin (ie lower left corner of the grid), but we want
       to rotate wrt the middle of the grid
    */
    glTranslatef(ncols/2, nrows/2, 0); 
    glRotatef(5, 0,0,1); 
    glTranslatef(-ncols/2, -nrows/2, 0); 
    glutPostRedisplay(); 
    break; 

  case 'Z':
    //rotate around z
    glTranslatef(ncols/2, nrows/2, 0); 
    glRotatef(5, 0,0,-1); 
    glTranslatef(-ncols/2, -nrows/2, 0); 
    glutPostRedisplay(); 
    break; 

  }
}