/* Hilbert curve drawing program
 * by Josh Holtrop
 */

/* includes */
#include <SDL/SDL.h>
#include <GL/gl.h>
#include <GL/glu.h>

/* constants */
#define SEGMENTS 16
#define WIDTH	 800
#define HEIGHT	 600

/* functions */
void usage(void);
void initgl(void);
void display(void);
void mainloop(void);
void drawHilbert();

/* global variables */
int level = 2;
float size = 0.4;
SDL_Surface * sdlScreen;
int winWidth = WIDTH;
int winHeight = HEIGHT;
int displayList = -1;

int	main(int argc, char *argv[])
{
	int i;
	for (i = 1; i < argc; i++)
	{
		if (!strncmp("-l", argv[i], 2))
		{
			sscanf(argv[i] + 2, "%d", &level);
			if (level < 1)
				usage();
		}
		else if (!strncmp("-s", argv[i], 2))
		{
			sscanf(argv[i] + 2, "%f", &size);
			if (size < 0.01 || size > 0.99)
				usage();
		}
		else
		{
			usage();
		}
	}

	if (SDL_Init(SDL_INIT_VIDEO))
	{
		printf("Failed to initialize SDL!\n");
		return 1;
	}

	atexit(SDL_Quit);

	SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
	if (!(sdlScreen = SDL_SetVideoMode(WIDTH, HEIGHT, 16, SDL_OPENGL | SDL_RESIZABLE)))
	{
		printf("Failed to set video mode!\n");
		SDL_Quit();
		return 2;
	}
	SDL_WM_SetCaption(argv[0], argv[0]);

	initgl();
	mainloop();

	return 0;
}

void mainloop(void)
{
	SDL_Event event;
	display();
	while (SDL_WaitEvent(&event))
	{
		switch (event.type)
		{
			case SDL_QUIT:
				return;
			case SDL_KEYDOWN:
				switch (event.key.keysym.sym)
				{
					case SDLK_ESCAPE:
						return;
					default:
						break;
				}
				break;
			case SDL_VIDEORESIZE:
				break;
		}
	}
}

void initgl(void)
{
	glClearColor (0.0, 0.0, 0.0, 0.0);
	glEnable(GL_DEPTH_TEST);
	glShadeModel(GL_SMOOTH);
	glViewport(0, 0, winWidth, winHeight);
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	gluPerspective(60.0, (GLfloat)winHeight/(GLfloat)winWidth, 1.0, 30.0);
	glMatrixMode(GL_MODELVIEW);
	glLoadIdentity();
	glTranslatef(0.0, 0.0, -3.6);
}

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

	if (displayList >= 0)
	{
		glCallList(displayList);
	}
	else
	{
		displayList = glGenLists(1);
		if (displayList < 0)
		{
			fprintf(stderr, "Error allocating display list!\n");
			exit(132);
		}
		glNewList(displayList, GL_COMPILE_AND_EXECUTE);
		drawHilbert();
		glEndList();
	}

	SDL_GL_SwapBuffers();
}

void drawHilbert()
{
}

void usage(void)
{
	printf("Options:\n"
	       "    -l<level>   level of Hilbert curve to draw (1-?)\n"
		   "    -s<size>    radius of Hilbert curve (0.01-0.99)\n");
	exit(42);
}