/*

	boxes.c - Moving Inverted Boxes

	Author Jani Kniivilä

	compile with: gcc -o boxes boxes.c -lSDL -lpthread -ltSGGL

*/

#include <stdio.h>
#include <stdlib.h>

#include <SDL/SDL.h>
#include <tSGGL/SGGL.h>

SDL_Surface	*surface;
gfx_image_t	*output;

#define	WIDTH	640
#define	HEIGHT	480

#define	N_BOXES	250	

typedef struct {
	int	x, y, speed, size;
} box_t;

box_t	boxes[N_BOXES];

void	move_boxes()
{
	int	i;

	for (i = 0; i < N_BOXES; i++)
	{
		boxes[i].y += boxes[i].speed;

		if (boxes[i].y > output->view_bottom)
			boxes[i].y = -boxes[i].size;
		else 
		if (boxes[i].y < -boxes[i].size)
			boxes[i].y = output->view_bottom;
	}
}

void	draw_boxes()
{
	int	i;

	for (i = 0; i < N_BOXES; i++)
	{
		gfx_slow_negate_area(	boxes[i].x, boxes[i].y, 
					boxes[i].x + boxes[i].size, boxes[i].y + boxes[i].size, output);
	}
}

int	fx_init()
{
	int	i;

	if (SDL_Init(SDL_INIT_VIDEO) < 0) return -1;
	atexit(SDL_Quit);

	surface = SDL_SetVideoMode(WIDTH, HEIGHT, 16, SDL_SWSURFACE);
	if (!surface) return -2;

	output = gfx_create_null_image(WIDTH, HEIGHT);	/* create an image without pixel-data */
	if (!output) return -3;
	output->data = (Uint16 *) surface->pixels;	/* redirect the pixels to "screen" */

	for (i = 0; i < N_BOXES; i++)
	{
		boxes[i].x = rand() % output->width;
		boxes[i].y = rand() % output->height;
		boxes[i].size = 5 + (rand() % 40);
		boxes[i].speed = -7 + (3 * (rand() % 5));
		if (boxes[i].speed == 0)
			boxes[i].speed = 1;
	}

	return 0;
}

void	fx_shutdown()
{
	free(output);
}

int	fx_draw_frame()
{
	move_boxes();

	if (SDL_MUSTLOCK(surface))
		SDL_LockSurface(surface);

	gfx_clear(output);
	draw_boxes();

	if (SDL_MUSTLOCK(surface))
		SDL_UnlockSurface(surface);

	SDL_Flip(surface);

	return 0;
}

int	main()
{
	SDL_Event	event;
	int		i, done = 0;

	i = fx_init();
	if (i) return i;

	while (!done)
	{
		fx_draw_frame();

		while (SDL_PollEvent(&event))
		{
			switch (event.type)
			{
				case SDL_QUIT:
				case SDL_KEYDOWN:
				case SDL_MOUSEBUTTONDOWN:
					done = 1;
			}
		}
	}

	fx_shutdown();

	return 0;
}