/* Simple program:  Move N sprites around on the screen as fast as possible */

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <ctype.h>

#include <math.h>

#include <time.h>

#include "SDL.h"

#define NUM_SPRITES	100

#define MAX_SPEED 	1

SDL_Surface *sprite;

int numsprites;

SDL_Rect *sprite_rects;

SDL_Rect *positions;

SDL_Rect *velocities;

int sprites_visible;

int debug_flip;

Uint16 sprite_w, sprite_h;

/* Call this instead of exit(), so we can clean up SDL: atexit() is evil. */

static void quit(int rc)

{

	SDL_Quit();

	exit(rc);

}

int LoadSprite(char *file)

{

	SDL_Surface *temp;

	/* Load the sprite image */

	sprite = SDL_LoadBMP(file);

	if ( sprite == NULL ) {

		fprintf(stderr, "Couldn't load %s: %s", file, SDL_GetError());

		return(-1);

	}

	/* Set transparent pixel as the pixel at (0,0) */

	if ( sprite->format->palette ) {

		SDL_SetColorKey(sprite, (SDL_SRCCOLORKEY|SDL_RLEACCEL),

						*(Uint8 *)sprite->pixels);

	}

	/* Convert sprite to video format */

	temp = SDL_DisplayFormat(sprite);

	SDL_FreeSurface(sprite);

	if ( temp == NULL ) {

		fprintf(stderr, "Couldn't convert background: %s\n",

							SDL_GetError());

		return(-1);

	}

	sprite = temp;

	/* We're ready to roll. :) */

	return(0);

}

void MoveSprites(SDL_Surface *screen, Uint32 background)

{

	int i, nupdates;

	SDL_Rect area, *position, *velocity;

	nupdates = 0;

	/* Erase all the sprites if necessary */

	if ( sprites_visible ) {

		SDL_FillRect(screen, NULL, background);

	}

	/* Move the sprite, bounce at the wall, and draw */

	for ( i=0; i<numsprites; ++i ) {

		position = &positions[i];

		velocity = &velocities[i];

		position->x += velocity->x;

		if ( (position->x < 0) || (position->x >= (screen->w - sprite_w)) ) {

			velocity->x = -velocity->x;

			position->x += velocity->x;

		}

		position->y += velocity->y;

		if ( (position->y < 0) || (position->y >= (screen->h - sprite_w)) ) {

			velocity->y = -velocity->y;

			position->y += velocity->y;

		}

		/* Blit the sprite onto the screen */

		area = *position;

		SDL_BlitSurface(sprite, NULL, screen, &area);

		sprite_rects[nupdates++] = area;

	}

	if (debug_flip) {

		if ( (screen->flags & SDL_DOUBLEBUF) == SDL_DOUBLEBUF ) {

			static int t = 0;

			Uint32 color = SDL_MapRGB (screen->format, 255, 0, 0);

			SDL_Rect r;

			r.x = (sin((float)t * 2 * 3.1459) + 1.0) / 2.0 * (screen->w-20);

			r.y = 0;

			r.w = 20;

			r.h = screen->h;

			SDL_FillRect (screen, &r, color);

			t+=2;

		}

	}

	/* Update the screen! */

	if ( (screen->flags & SDL_DOUBLEBUF) == SDL_DOUBLEBUF ) {

		SDL_Flip(screen);

	} else {

		SDL_UpdateRects(screen, nupdates, sprite_rects);

	}

	sprites_visible = 1;

}

/* This is a way of telling whether or not to use hardware surfaces */

Uint32 FastestFlags(Uint32 flags, int width, int height, int bpp)

{

	const SDL_VideoInfo *info;

	/* Hardware acceleration is only used in fullscreen mode */

	flags |= SDL_FULLSCREEN;

	/* Check for various video capabilities */

	info = SDL_GetVideoInfo();

	if ( info->blit_hw_CC && info->blit_fill ) {

		/* We use accelerated colorkeying and color filling */

		flags |= SDL_HWSURFACE;

	}

	/* If we have enough video memory, and will use accelerated

	   blits directly to it, then use page flipping.

	 */

	if ( (flags & SDL_HWSURFACE) == SDL_HWSURFACE ) {

		/* Direct hardware blitting without double-buffering

		   causes really bad flickering.

		 */

		if ( info->video_mem*1024 > (height*width*bpp/8) ) {

			flags |= SDL_DOUBLEBUF;

		} else {

			flags &= ~SDL_HWSURFACE;

		}

	}

	/* Return the flags */

	return(flags);

}

int main(int argc, char *argv[])

{

	SDL_Surface *screen;

	Uint8 *mem;

	int width, height;

	Uint8  video_bpp;

	Uint32 videoflags;

	Uint32 background;

	int    i, done;

	SDL_Event event;

	Uint32 then, now, frames;

	/* Initialize SDL */

	if ( SDL_Init(SDL_INIT_VIDEO) < 0 ) {

		fprintf(stderr, "Couldn't initialize SDL: %s\n",SDL_GetError());

		return(1);

	}

	numsprites = NUM_SPRITES;

	videoflags = SDL_SWSURFACE|SDL_ANYFORMAT;

	width = 640;

	height = 480;

	video_bpp = 8;

	debug_flip = 0;

	while ( argc > 1 ) {

		--argc;

		if ( strcmp(argv[argc-1], "-width") == 0 ) {

			width = atoi(argv[argc]);

			--argc;

		} else

		if ( strcmp(argv[argc-1], "-height") == 0 ) {

			height = atoi(argv[argc]);

			--argc;

		} else

		if ( strcmp(argv[argc-1], "-bpp") == 0 ) {

			video_bpp = atoi(argv[argc]);

			videoflags &= ~SDL_ANYFORMAT;

			--argc;

		} else

		if ( strcmp(argv[argc], "-fast") == 0 ) {

			videoflags = FastestFlags(videoflags, width, height, video_bpp);

		} else

		if ( strcmp(argv[argc], "-hw") == 0 ) {

			videoflags ^= SDL_HWSURFACE;

		} else

		if ( strcmp(argv[argc], "-flip") == 0 ) {

			videoflags ^= SDL_DOUBLEBUF;

		} else

		if ( strcmp(argv[argc], "-debugflip") == 0 ) {

			debug_flip ^= 1;

		} else

		if ( strcmp(argv[argc], "-fullscreen") == 0 ) {

			videoflags ^= SDL_FULLSCREEN;

		} else

		if ( isdigit(argv[argc][0]) ) {

			numsprites = atoi(argv[argc]);

		} else {

			fprintf(stderr, 

	"Usage: %s [-bpp N] [-hw] [-flip] [-fast] [-fullscreen] [numsprites]\n",

								argv[0]);

			quit(1);

		}

	}

	/* Set video mode */

	screen = SDL_SetVideoMode(width, height, video_bpp, videoflags);

	if ( ! screen ) {

		fprintf(stderr, "Couldn't set %dx%d video mode: %s\n",

					width, height, SDL_GetError());

		quit(2);

	}

	/* Load the sprite */

	if ( LoadSprite("icon.bmp") < 0 ) {

		quit(1);

	}

	/* Allocate memory for the sprite info */

	mem = (Uint8 *)malloc(4*sizeof(SDL_Rect)*numsprites);

	if ( mem == NULL ) {

		SDL_FreeSurface(sprite);

		fprintf(stderr, "Out of memory!\n");

		quit(2);

	}

	sprite_rects = (SDL_Rect *)mem;

	positions = sprite_rects;

	sprite_rects += numsprites;

	velocities = sprite_rects;

	sprite_rects += numsprites;

	sprite_w = sprite->w;

	sprite_h = sprite->h;

	srand(time(NULL));

	for ( i=0; i<numsprites; ++i ) {

		positions[i].x = rand()%(screen->w - sprite_w);

		positions[i].y = rand()%(screen->h - sprite_h);

		positions[i].w = sprite->w;

		positions[i].h = sprite->h;

		velocities[i].x = 0;

		velocities[i].y = 0;

		while ( ! velocities[i].x && ! velocities[i].y ) {

			velocities[i].x = (rand()%(MAX_SPEED*2+1))-MAX_SPEED;

			velocities[i].y = (rand()%(MAX_SPEED*2+1))-MAX_SPEED;

		}

	}

	background = SDL_MapRGB(screen->format, 0x00, 0x00, 0x00);

	/* Print out information about our surfaces */

	printf("Screen is at %d bits per pixel\n",screen->format->BitsPerPixel);

	if ( (screen->flags & SDL_HWSURFACE) == SDL_HWSURFACE ) {

		printf("Screen is in video memory\n");

	} else {

		printf("Screen is in system memory\n");

	}

	if ( (screen->flags & SDL_DOUBLEBUF) == SDL_DOUBLEBUF ) {

		printf("Screen has double-buffering enabled\n");

	}

	if ( (sprite->flags & SDL_HWSURFACE) == SDL_HWSURFACE ) {

		printf("Sprite is in video memory\n");

	} else {

		printf("Sprite is in system memory\n");

	}

	/* Run a sample blit to trigger blit acceleration */

	{ SDL_Rect dst;

		dst.x = 0;

		dst.y = 0;

		dst.w = sprite->w;

		dst.h = sprite->h;

		SDL_BlitSurface(sprite, NULL, screen, &dst);

		SDL_FillRect(screen, &dst, background);

	}

	if ( (sprite->flags & SDL_HWACCEL) == SDL_HWACCEL ) {

		printf("Sprite blit uses hardware acceleration\n");

	}

	if ( (sprite->flags & SDL_RLEACCEL) == SDL_RLEACCEL ) {

		printf("Sprite blit uses RLE acceleration\n");

	}

	/* Loop, blitting sprites and waiting for a keystroke */

	frames = 0;

	then = SDL_GetTicks();

	done = 0;

	sprites_visible = 0;

	while ( !done ) {

		/* Check for events */

		++frames;

		while ( SDL_PollEvent(&event) ) {

			switch (event.type) {

				case SDL_MOUSEBUTTONDOWN:

					SDL_WarpMouse(screen->w/2, screen->h/2);

					break;

				case SDL_KEYDOWN:

					/* Any keypress quits the app... */

				case SDL_QUIT:

					done = 1;

					break;

				default:

					break;

			}

		}

		MoveSprites(screen, background);

	}

	SDL_FreeSurface(sprite);

	free(mem);

	/* Print out some timing information */

	now = SDL_GetTicks();

	if ( now > then ) {

		printf("%2.2f frames per second\n",

					((double)frames*1000)/(now-then));

	}

	SDL_Quit();

	return(0);

}