/*
 * Graphic module for the Gnome Graphics Project
 *
 * See the .h file for more information on how to use this library
 *
 * Changes:
 *
 * When       What
 * ---------  ----------------------------------------------------
 *
 * Todo:
 */

#include <GL/glut.h>
#include <GL/gl.h>
#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include <math.h>

#include "gnomegr.h"

#ifndef CALLBACK
#define CALLBACK
#endif /* CALLBACK */

typedef void (CALLBACK *glucallback)();

/*
 * Some must-have global variables 
 */
static t_program_start startup_routine;
static int screen_width, screen_height;

/*
 * [ END of Some must-have global variables ]
 */



/*
 * DEBUG:
 *
 * Check for openGL error, if there was one, print it on the screen
 * This routine is used during debugging of this library.
 */
/*
static void checkgl()
{
    int e;

    e = glGetError();
    if (e != GL_NO_ERROR)
    {
        printf("Gl error: 0x%x\n", e);
    }
}
*/

/*
 * OpenGL initialization
 */
static void schematic_init(void)
{
    glDisable(GL_DEPTH_TEST);
    glClearColor(1.0, 1.0, 1.0, 0.0);
}


/*
 * OpenGL initialization
 */
static void init(void)
{
    schematic_init();
}


/*---------- Tesselation callbacks - for drawing the track -----------*/


/*
 * See comments in the .h file
 */
void Render(const GnomeBitmap *canvas_ptr)
{
  glPixelStorei(GL_UNPACK_ALIGNMENT, 1);

  /* Initialize the screen */
  glClearColor(1.0, 1.0, 1.0, 1.0);  /* Background color is white */
  glClear(GL_COLOR_BUFFER_BIT);
  
  /* Render the bitmap */
  glColor3f(0.0, 0.0, 0.0);  /* Bitmap is drawn in black */
  glRasterPos2i(0, 0);
  glBitmap(canvas_ptr->width, canvas_ptr->height, 0, 0, 0, 0, canvas_ptr->bits);
  glFinish();
  
  /* Display the result */
  glutSwapBuffers ();
}

static void display_cb(void)
{
}

/* ---------- GLUT callbacks --------------*/
/*
 * glut callback that to notify change in the screen size
 * Setup the projection matrix.
 */
static void reshape_cb (int w, int h)
{
    /* Reset the viewport... */
    glViewport(0, 0, w, h);

    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    glOrtho(0.0, (GLfloat)w, 0.0, (GLfloat)h, -1.0, 1.0);
    glMatrixMode(GL_MODELVIEW);
}


/*
 * A hack:
 *   this routine is setup by InitGnomeGr to call the users
 *   main_loop (startup_routine) function.
 *   This hack is here because glutMainLoop must be called, but
 *   it never returns
 */
void timer_cb(int id)
{
    startup_routine();
}

/* ---------- [ End GLUT callbacks ] --------------*/

void InitGr(
    const GnomeBitmap *canvas_ptr,
    t_program_start start)
{
    int argc = 1;
    char *argv[] = {""};

    startup_routine = start;

    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB);
    glutInitWindowSize(canvas_ptr->width, canvas_ptr->height);
    screen_width = canvas_ptr->width;
    screen_height = canvas_ptr->height;
    glutInitWindowPosition(0, 0);
    glutCreateWindow ("Gnome Graphics 2004");

    init();

    glutTimerFunc(100, timer_cb, 0);
    glutDisplayFunc(display_cb);
    glutReshapeFunc(reshape_cb);
    glutMainLoop();
}