/* CS425  
 * cubevarray.c
 * 
 * This program demonstrates 3D object drawn without 
 * glVertex3fv calls.  This program DOES use a vertex array.
 * A cube is drawn in a 3-D projection.
 */

#include <GL/glut.h>
#include <stdlib.h>

#define MY_STYLE GL_LINE_LOOP
/* use this for solid sides
#define MY_STYLE GL_POLYGON
*/

void init(void) 
{
   glClearColor (0.0, 0.0, 0.0, 0.0);
   glShadeModel (GL_FLAT);
   glEnableClientState(GL_VERTEX_ARRAY);
}

void axes(int max)
{
 /* Leave axes function without vertex arrays. */
   /* set color to cyan */
   glColor3f(0.0, 1.0, 1.0); 
   glBegin(GL_LINES);
   /* draw X-axis */
    glVertex3f(-1.0, 0.0, 0.0);
    glVertex3f(max, 0.0, 0.0);
   /* draw a letter X */
    glVertex3f(max, 0.5, 0.0);
    glVertex3f(max+0.5, -0.5, 0.0);
    glVertex3f(max+0.5, 0.5, 0.0);
    glVertex3f(max, -0.5, 0.0);
   /* draw Y-axis */
    glVertex3f(0.0, -1.0, 0.0);
    glVertex3f(0.0, max, 0.0);
   /* draw a letter Y */
    glVertex3f(-0.25, max+0.5, 0.0);
    glVertex3f(0.0, max+0.25, 0.0);
    glVertex3f(0.0, max+0.25, 0.0);
    glVertex3f(0.25, max+0.5, 0.0);
    glVertex3f(0.0, max+0.25, 0.0);
    glVertex3f(0.0, max+0.05, 0.0);
   /* draw Z-axis */
    glVertex3f(0.0, 0.0, -1.0);
    glVertex3f(0.0, 0.0, max);
   /* draw a letter Z */
    glVertex3f(-0.25, 0.25, max+.05);
    glVertex3f(0.25, 0.25, max+0.05);
    glVertex3f(0.25, 0.25, max+0.05);
    glVertex3f(-0.25, -0.25, max+0.05);
    glVertex3f(-0.25, -0.25, max+0.05);
    glVertex3f(0.25, -0.25, max+0.05);
}

void cube(void)
{
   /* Define vertices for the cube */
   GLfloat cube_vertices[][3] = 
     { 
      /* 0 */ {  5.0,  0.0, 10.0},
      /* 1 */ { 13.0,  0.0, 10.0},
      /* 2 */ { 13.0,  8.0, 10.0},
      /* 3 */ {  5.0,  8.0, 10.0},
      /* 4 */ {  5.0,  8.0,  2.0},
      /* 5 */ { 13.0,  8.0,  2.0},
      /* 6 */ { 13.0,  0.0,  2.0},
      /* 7 */ {  5.0,  0.0,  2.0},
     };

   /* Define faces of the cube using indices */
   GLubyte bottom[] = {7, 6, 1, 0}; 
   GLubyte front[]  = {0, 1, 2, 3}; 
   GLubyte left[]   = {7, 0, 3, 4}; 
   GLubyte right[]  = {1, 6, 5, 2}; 
   GLubyte back[]   = {6, 7, 4, 5}; 
   GLubyte top[]    = {3, 2, 5, 4}; 

   /* initialize pointer to vertex array */
   glVertexPointer(3, GL_FLOAT, 0, cube_vertices);

   /* set color to white */
   glColor3f(1.0, 1.0, 1.0);

   /* draw bottom */
   glDrawElements(MY_STYLE, 4, GL_UNSIGNED_BYTE, bottom);              
   /* draw front */
   glDrawElements(MY_STYLE, 4, GL_UNSIGNED_BYTE, front);              
   /* draw left */
   glDrawElements(MY_STYLE, 4, GL_UNSIGNED_BYTE, left);              
   /* draw right */
   glDrawElements(MY_STYLE, 4, GL_UNSIGNED_BYTE, right);              
   /* draw back */
   glDrawElements(MY_STYLE, 4, GL_UNSIGNED_BYTE, back);              
   /* draw top */
   glDrawElements(MY_STYLE, 4, GL_UNSIGNED_BYTE, top);              
}

void display(void)
{
   glMatrixMode (GL_PROJECTION);
   glLoadIdentity();
   gluPerspective(60.0, 1.0, 1.0, 100.0);

   glMatrixMode (GL_MODELVIEW);
   glLoadIdentity();
   gluLookAt (15.0, 13.0, 40.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0);

   glClear (GL_COLOR_BUFFER_BIT);
   axes(20);
   cube ();
   glFlush ();
}

void reshape (int w, int h)
{
   glViewport (0, 0, (GLsizei) w, (GLsizei) h);
}

/* ARGSUSED1 */
void keyboard(unsigned char key, int x, int y)
{
   switch (key) {
      case 27:    /* escape key */
         exit(0);
         break;
   }
}

int main(int argc, char** argv)
{
   glutInit(&argc, argv);
   glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB);
   glutInitWindowSize (500, 500); 
   glutInitWindowPosition (100, 100);
   glutCreateWindow (argv[0]);
   init ();
   glutDisplayFunc(display); 
   glutReshapeFunc(reshape);
   glutKeyboardFunc (keyboard);
   glutMainLoop();
   return 0;
}