/* $Id: rail.c,v 1.98 2008/04/06 22:59:38 pb Exp $ */

#include <math.h>
#include <stdlib.h>

#define GL_GLEXT_PROTOTYPES

#include <GL/gl.h>
#include <GL/glext.h>
#include <GL/glut.h>
#include <sys/time.h>
#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include <float.h>

static int screen_width, screen_height;
GLint display_list;

float v[] = {
	20,0,-100,
	0,20,-100,
	-20,0,-100,
	0,-20,-100
};
unsigned short i[] = { 0, 1, 2, 
		       1, 2, 3 };
GLsizei tsci[] = { 3, 3 };
unsigned short *tsfi[] = { i, i+3 };
unsigned int tsin = sizeof(tsci)/sizeof(*tsci);

static void draw(void)
{
    glEnableClientState(GL_VERTEX_ARRAY);
    glInterleavedArrays(GL_V3F, 0, v);
    glMultiDrawElements(GL_TRIANGLES, tsci, GL_UNSIGNED_SHORT,
			(void *)tsfi, tsin);
}

static void drawfunc(void)
{
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    glPushMatrix();

    // Render some triangles directly in red
    glColor3f(.5, 0, 0);
    draw();

    glTranslatef(0, -50, 0);

    // Render the same triangles from a display list, in green
    glColor3f(0, .5, 0);
    glCallList(display_list);

    glPopMatrix();
    glutSwapBuffers();
}

static void idle_visible()
{
    glutPostRedisplay();
}

/* new window size or exposure */
static void reshape(int width, int height)
{
  float h = (float) height / (float) width;
  float s = 1.0;

  screen_width = width;
  screen_height = height;

  glViewport(0, 0, (GLint) width, (GLint) height);
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();
  glFrustum(-s, s, -h*s*1.5, h*s*.5, 1.5, 500);
  glMatrixMode(GL_MODELVIEW);
  glLoadIdentity();
}

static void init()
{
  float ambient[3] = { 1, 1, 1 };

  glClearColor(.5, .5, .9, 1.0);

  glEnable(GL_LIGHTING);
  glEnable(GL_LIGHT0);
  glLightfv(GL_LIGHT0, GL_DIFFUSE, ambient);

  display_list = glGenLists(1);
  glNewList(display_list, GL_COMPILE);
  draw();
  glEndList();

  glEnable(GL_COLOR_MATERIAL);
  glColorMaterial(GL_FRONT, GL_AMBIENT_AND_DIFFUSE);
}

void visible(int vis)
{
    glutIdleFunc(idle_visible);
}

int main(int argc, char *argv[])
{
    glutInit(&argc, argv);

    glutInitDisplayMode(GLUT_RGB|GLUT_DEPTH|GLUT_DOUBLE);
    glutInitWindowPosition(0, 0);
    glutInitWindowSize(200, 200);
    glutCreateWindow("Test glMultiDrawElements");

    glutDisplayFunc(drawfunc);
    glutReshapeFunc(reshape);
    glutVisibilityFunc(visible);

    printf("Vendor: %s\n", glGetString(GL_VENDOR));
    printf("Renderer: %s\n", glGetString(GL_RENDERER));
    printf("Version: %s\n", glGetString(GL_VERSION));
    printf("Extensions: %s\n", glGetString(GL_EXTENSIONS));
    printf("GLU Version: %s\n", gluGetString(GLU_VERSION));
    printf("GLU Extensions: %s\n", gluGetString(GLU_EXTENSIONS));

    fflush(stdout);

    init();
    glutMainLoop();
    return 0;
}