/* matrix2.c
 *
 * An example showing matrix maniuplation in OpenGL.
 * Ray S. Babcock, September 23, 1996, Montana State University
 *           revised September 22, 1998 for Vertex Arrays
 *
 * OpenGL(TM) is a trademark of Silicon Graphics, Inc.
 *
 *  This program draws three axes and three planes
 *  with matrix push and pop operations
 *  commented out!
 */

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

void
axes (double r, double g, double b)
{
GLfloat axes_vertices[] = {0.0, 0.0, 0.0,
			   1.0, 0.0, 0.0,
			   0.0, 1.0, 0.0,
			   0.0, 0.0, 1.0};

GLubyte axes_indices[] = {0,1,0,2,0,3};
  
  glColor3f(r,g,b);
  glVertexPointer(3, GL_FLOAT, 0, axes_vertices);
  glDrawElements(GL_LINES, 6, GL_UNSIGNED_BYTE, axes_indices);
}

void
plane(double r, double g, double b)
{
GLfloat plane_vertices[] = {-0.5, -0.5, 0.0,
	      		      0.5, -0.5, 0.0,
			      0.5, 0.5, 0.0,
			      -0.5, 0.5, 0.0};

GLubyte plane_indices[] = {0, 1, 2, 3};

   glColor3f(r,g,b);
   glVertexPointer(3, GL_FLOAT, 0, plane_vertices);
   glDrawElements(GL_POLYGON, 4, GL_UNSIGNED_BYTE, plane_indices);
}

void init(void)
{
   glClearColor (0.8, 0.8, 0.8, 0.0);
   glShadeModel(GL_FLAT);
   glEnable(GL_DEPTH_TEST);
   glEnableClientState(GL_VERTEX_ARRAY);
}


void
display()
{
   glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

   glMatrixMode (GL_PROJECTION);
   glLoadIdentity();
   gluPerspective(15.0, 1.0, 1.0, 100.0);

   glMatrixMode (GL_MODELVIEW);
   glLoadIdentity();
   gluLookAt (4.0, 5.0, 5.0, 0.5, 0.5, 0.0, 0.0, 1.0, 0.0);

   /* glPushMatrix(); */
   glTranslatef(0.0, 0.0, -0.5);
     axes(1.0, 1.0, 0.0);
     plane(1.0,0.0,0.0);

   /* glPopMatrix(); */
   /* glPushMatrix();*/
   glRotatef(90.0, 0.0, 1.0, 0.0);
   glTranslatef(0.0, 0.0, 0.5);
     axes(1.0, 0.0, 1.0);
     plane(0.0,1.0,0.0);

   /* glPopMatrix(); */
   /* glPushMatrix();*/
   glRotatef(90.0, 1.0, 0.0, 0.0);
   glTranslatef(0.0, 0.0, 0.5);
     axes(0.0, 1.0, 1.0);
     plane(0.0,0.0,1.0);

   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:
         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;
}