/*  
   grid2.c  
  
   render grid boundary (as 2 triangles) in 3D with a perspective 
   projection 
 
   can move left/right/up/down and rotate on key press
  
 
   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 
 
GLfloat red[3] = {1.0, 0.0, 0.0}; 
GLfloat green[3] = {0.0, 1.0, 0.0}; 
GLfloat blue[3] = {0.0, 0.0, 1.0}; 
GLfloat black[3] = {0.0, 0.0, 0.0}; 
GLfloat white[3] = {1.0, 1.0, 1.0}; 
GLfloat gray[3] = {0.5, 0.5, 0.5}; 
GLfloat yellow[3] = {1.0, 1.0, 0.0}; 
GLfloat magenta[3] = {1.0, 0.0, 1.0}; 
GLfloat cyan[3] = {0.0, 1.0, 1.0}; 
 
//keep track of global translation and rotation  
GLfloat pos[3] = {0,0,0}; 
GLfloat theta[3] = {0,0,0}; 
 
 
//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);  
  
  
  //set up projection  
  glMatrixMode(GL_PROJECTION); 
  glLoadIdentity(); 
  gluPerspective(60, 1 /* aspect */, 1, 10.0); /* the frustrum is from z=-1 to z=-10 */ /* camera is at (0,0,0) looking along negative y axis */ 
 
 
 /* callback functions */ 
  glutDisplayFunc(display);  
  glutKeyboardFunc(keypress); 
 
 
  /* event handler */ 
  glutMainLoop(); 
  return 0; 
} 
 
 
//render points are in object space [0, cols) x [0, ncols) and z in 
//[0,1]; careful with NODATA 
void draw_terrain() { 
  //this is where you write code to draw a grid. Start with the 
  //boundary. 
  glPolygonMode(GL_FRONT_AND_BACK, GL_LINE); 
  glBegin(GL_TRIANGLES); 
  glColor3fv(red); 
  glVertex3f(0,0, 10); 
  glColor3fv(yellow); 
  glVertex3f(0,nrows, 5); 
  glColor3fv(green); 
  glVertex3f(ncols, nrows, 7); 
  glEnd();  
  glBegin(GL_TRIANGLES); 
  glColor3fv(red); 
  glVertex3f(0,0,10); 
  glColor3fv(green); 
  glVertex3f(ncols, nrows, 7); 
  glColor3fv(blue); 
  glVertex3f(ncols, 0, 9); 
  glEnd(); 
} 
 
 
void display(void) { 
  //clear the screen, need to clear also the depth buffer  
  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);  
   
  glMatrixMode(GL_MODELVIEW); 
  //clear the screen, need to clear also the depth buffer  
   
  glLoadIdentity(); //clear the matrix 
   
  //look from above (z=2) and back (y=-2)
  gluLookAt(0,-2,2, /* eye position */   
	    0,0,0, /* position of reference point indicating center of the scene*/  
	    0,0,1 /* direction of up vector */); 
 
  //user modeling 
  glTranslatef(pos[0], pos[1], pos[2]);  
  glRotatef(theta[0], 1,0,0); 
  glRotatef(theta[1], 0,1,0);  
  glRotatef(theta[2], 0,0,1);  
 
  //now draw the grid  
  /*  
     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(1.8/nrows, 1.8/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, -2);  
 
  /************** DRAW *****************/ 
  //render points in object space [0, ncols) x [0, nrows) and z in [-1,1]; 
  draw_terrain();  
  
  /* 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] -= .1;  //move left 5 cols  
     //glTranslatef(-5,0,0 );  
    glutPostRedisplay();  
    break;  
     
  case 'r':  
    //move right 
   pos[0] += .1; //move right 5 cols  
   // glTranslatef(5,0,0 );  
    glutPostRedisplay();  
    break; 
  
  case 'u':  
    //move up  
    pos[1] += .1; //move up 5 rows  
    //glTranslatef(0,5,0 );  
    glutPostRedisplay();  
    break;  
     
  case 'd':  
    //move down  
    pos[1] -= .1; //move down 5 rows  
    //glTranslatef(0,-5,0);  
    glutPostRedisplay();  
    break;  
 
  case 'f':  
    pos[2] += .1;  
    glutPostRedisplay();  
    break; 
  case 'b':  
    pos[2] -= .1;  
    glutPostRedisplay();  
    break;  
 
 
  case 'x':  
    // glRotatef(5, 1,0,0);  
    theta[0] +=5;  
    glutPostRedisplay();  
    break;  
  case 'X':  
    theta[0] -= 5;  
    glRotatef(-5, 1,0,0);  
    glutPostRedisplay();  
    break;  
 
  case 'y':  
    theta[1] += 5;  
    //glRotatef(5, 0,1,0);  
    glutPostRedisplay();  
    break;  
  case 'Y': 
    theta[1] -= 5;  
    //glRotatef(-5, 0,1,0);  
    glutPostRedisplay();  
    break;  
 
     
  case 'z': 
    //rotate around z 
    theta[2] += 5;  
    /* 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 
    theta[2] -= 5;  
    //glTranslatef(ncols/2, nrows/2, 0);  
    //glRotatef(5, 0,0,-1);  
    //glTranslatef(-ncols/2, -nrows/2, 0);  
    glutPostRedisplay();  
    break;  
 
  } 
}