/* Simple program:  Move N sprites around on the screen as fast as possible */+
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+
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#include <stdlib.h>+
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#include <stdio.h>+
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#include <time.h>+
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#include <math.h>+
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+
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#include "SDL.h"+
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+
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#define NUM_SPRITES	100+
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#define MAX_SPEED 	1+
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+
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SDL_Surface *sprite;+
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int numsprites;+
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SDL_Rect *sprite_rects;+
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SDL_Rect *positions;+
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SDL_Rect *velocities;+
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int sprites_visible;+
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int debug_flip;+
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Uint16 sprite_w, sprite_h;+
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+
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/* Call this instead of exit(), so we can clean up SDL: atexit() is evil. */+
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static void+
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quit(int rc)+
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{+
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    SDL_Quit();+
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    exit(rc);+
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}+
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+
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int+
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LoadSprite(char *file)+
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{+
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    SDL_Surface *temp;+
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+
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    /* Load the sprite image */+
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    sprite = SDL_LoadBMP(file);+
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    if (sprite == NULL) {+
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        fprintf(stderr, "Couldn't load %s: %s", file, SDL_GetError());+
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        return (-1);+
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    }+
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+
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    /* Set transparent pixel as the pixel at (0,0) */+
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    if (sprite->format->palette) {+
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        SDL_SetColorKey(sprite, (SDL_SRCCOLORKEY | SDL_RLEACCEL),+
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                        *(Uint8 *) sprite->pixels);+
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    }+
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+
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    /* Convert sprite to video format */+
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    temp = SDL_DisplayFormat(sprite);+
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    SDL_FreeSurface(sprite);+
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    if (temp == NULL) {+
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        fprintf(stderr, "Couldn't convert background: %s\n", SDL_GetError());+
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        return (-1);+
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    }+
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    sprite = temp;+
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+
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    /* We're ready to roll. :) */+
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    return (0);+
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}+
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+
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void+
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MoveSprites(SDL_Surface * screen, Uint32 background)+
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{+
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    int i, nupdates;+
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    SDL_Rect area, *position, *velocity;+
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+
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    nupdates = 0;+
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    /* Erase all the sprites if necessary */+
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    if (sprites_visible) {+
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        SDL_FillRect(screen, NULL, background);+
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    }+
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+
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    /* Move the sprite, bounce at the wall, and draw */+
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    for (i = 0; i < numsprites; ++i) {+
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        position = &positions[i];+
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        velocity = &velocities[i];+
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        position->x += velocity->x;+
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        if ((position->x < 0) || (position->x >= (screen->w - sprite_w))) {+
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            velocity->x = -velocity->x;+
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            position->x += velocity->x;+
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        }+
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        position->y += velocity->y;+
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        if ((position->y < 0) || (position->y >= (screen->h - sprite_w))) {+
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            velocity->y = -velocity->y;+
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            position->y += velocity->y;+
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        }+
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+
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        /* Blit the sprite onto the screen */+
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        area = *position;+
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        SDL_BlitSurface(sprite, NULL, screen, &area);+
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        sprite_rects[nupdates++] = area;+
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    }+
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+
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    if (debug_flip) {+
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        if ((screen->flags & SDL_DOUBLEBUF) == SDL_DOUBLEBUF) {+
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            static int t = 0;+
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+
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            Uint32 color = SDL_MapRGB(screen->format, 255, 0, 0);+
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            SDL_Rect r;+
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            r.x =+
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                (sin((float) t * 2 * 3.1459) + 1.0) / 2.0 * (screen->w - 20);+
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            r.y = 0;+
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            r.w = 20;+
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            r.h = screen->h;+
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+
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            SDL_FillRect(screen, &r, color);+
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            t += 2;+
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        }+
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    }+
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+
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    /* Update the screen! */+
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    if ((screen->flags & SDL_DOUBLEBUF) == SDL_DOUBLEBUF) {+
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        SDL_Flip(screen);+
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    } else {+
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        SDL_UpdateRects(screen, nupdates, sprite_rects);+
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    }+
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    sprites_visible = 1;+
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}+
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+
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/* This is a way of telling whether or not to use hardware surfaces */+
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Uint32+
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FastestFlags(Uint32 flags, int width, int height, int bpp)+
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{+
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    const SDL_VideoInfo *info;+
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+
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    /* Hardware acceleration is only used in fullscreen mode */+
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    flags |= SDL_FULLSCREEN;+
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+
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    /* Check for various video capabilities */+
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    info = SDL_GetVideoInfo();+
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    if (info->blit_hw_CC && info->blit_fill) {+
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        /* We use accelerated colorkeying and color filling */+
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        flags |= SDL_HWSURFACE;+
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    }+
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    /* If we have enough video memory, and will use accelerated+
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       blits directly to it, then use page flipping.+
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     */+
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    if ((flags & SDL_HWSURFACE) == SDL_HWSURFACE) {+
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        /* Direct hardware blitting without double-buffering+
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           causes really bad flickering.+
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         */+
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        if (info->video_mem * 1024 > (height * width * bpp / 8)) {+
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            flags |= SDL_DOUBLEBUF;+
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        } else {+
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            flags &= ~SDL_HWSURFACE;+
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        }+
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    }+
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+
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    /* Return the flags */+
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    return (flags);+
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}+
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+
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int+
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main(int argc, char *argv[])+
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{+
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    SDL_Surface *screen;+
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    Uint8 *mem;+
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    int width, height;+
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    Uint8 video_bpp;+
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    Uint32 videoflags;+
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    Uint32 background;+
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    int i, done;+
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    SDL_Event event;+
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    Uint32 then, now, frames;+
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+
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    /* Initialize SDL */+
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    if (SDL_Init(SDL_INIT_VIDEO) < 0) {+
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        fprintf(stderr, "Couldn't initialize SDL: %s\n", SDL_GetError());+
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        return (1);+
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    }+
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+
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    numsprites = NUM_SPRITES;+
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    videoflags = SDL_SWSURFACE | SDL_ANYFORMAT;+
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    width = 640;+
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    height = 480;+
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    video_bpp = 8;+
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    debug_flip = 0;+
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    while (argc > 1) {+
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        --argc;+
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        if (strcmp(argv[argc - 1], "-width") == 0) {+
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            width = atoi(argv[argc]);+
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            --argc;+
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        } else if (strcmp(argv[argc - 1], "-height") == 0) {+
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            height = atoi(argv[argc]);+
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            --argc;+
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        } else if (strcmp(argv[argc - 1], "-bpp") == 0) {+
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            video_bpp = atoi(argv[argc]);+
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            videoflags &= ~SDL_ANYFORMAT;+
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            --argc;+
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        } else if (strcmp(argv[argc], "-fast") == 0) {+
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            videoflags = FastestFlags(videoflags, width, height, video_bpp);+
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        } else if (strcmp(argv[argc], "-hw") == 0) {+
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            videoflags ^= SDL_HWSURFACE;+
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        } else if (strcmp(argv[argc], "-flip") == 0) {+
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            videoflags ^= SDL_DOUBLEBUF;+
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        } else if (strcmp(argv[argc], "-debugflip") == 0) {+
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            debug_flip ^= 1;+
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        } else if (strcmp(argv[argc], "-fullscreen") == 0) {+
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            videoflags ^= SDL_FULLSCREEN;+
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        } else if (isdigit(argv[argc][0])) {+
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            numsprites = atoi(argv[argc]);+
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        } else {+
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            fprintf(stderr,+
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                    "Usage: %s [-bpp N] [-hw] [-flip] [-fast] [-fullscreen] [numsprites]\n",+
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                    argv[0]);+
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            quit(1);+
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        }+
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    }+
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+
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    /* Set video mode */+
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    screen = SDL_SetVideoMode(width, height, video_bpp, videoflags);+
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    if (!screen) {+
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        fprintf(stderr, "Couldn't set %dx%d video mode: %s\n",+
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                width, height, SDL_GetError());+
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        quit(2);+
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    }+
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+
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    /* Load the sprite */+
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    if (LoadSprite("icon.bmp") < 0) {+
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        quit(1);+
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    }+
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+
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    /* Allocate memory for the sprite info */+
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    mem = (Uint8 *) malloc(4 * sizeof(SDL_Rect) * numsprites);+
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    if (mem == NULL) {+
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        SDL_FreeSurface(sprite);+
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        fprintf(stderr, "Out of memory!\n");+
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        quit(2);+
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    }+
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    sprite_rects = (SDL_Rect *) mem;+
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    positions = sprite_rects;+
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    sprite_rects += numsprites;+
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    velocities = sprite_rects;+
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    sprite_rects += numsprites;+
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    sprite_w = sprite->w;+
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    sprite_h = sprite->h;+
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    srand(time(NULL));+
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    for (i = 0; i < numsprites; ++i) {+
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        positions[i].x = rand() % (screen->w - sprite_w);+
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        positions[i].y = rand() % (screen->h - sprite_h);+
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        positions[i].w = sprite->w;+
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        positions[i].h = sprite->h;+
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        velocities[i].x = 0;+
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        velocities[i].y = 0;+
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        while (!velocities[i].x && !velocities[i].y) {+
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            velocities[i].x = (rand() % (MAX_SPEED * 2 + 1)) - MAX_SPEED;+
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            velocities[i].y = (rand() % (MAX_SPEED * 2 + 1)) - MAX_SPEED;+
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        }+
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    }+
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+
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    /* Clear the background to grey */+
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    background = SDL_MapRGB(screen->format, 0xA0, 0xA0, 0xA0);+
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    SDL_FillRect(screen, NULL, background);+
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    SDL_Flip(screen);+
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+
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    /* Print out information about our surfaces */+
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    printf("Screen is at %d bits per pixel\n", screen->format->BitsPerPixel);+
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    if ((screen->flags & SDL_HWSURFACE) == SDL_HWSURFACE) {+
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        printf("Screen is in video memory\n");+
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    } else {+
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        printf("Screen is in system memory\n");+
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    }+
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    if ((screen->flags & SDL_DOUBLEBUF) == SDL_DOUBLEBUF) {+
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        printf("Screen has double-buffering enabled\n");+
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    }+
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    if ((sprite->flags & SDL_HWSURFACE) == SDL_HWSURFACE) {+
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        printf("Sprite is in video memory\n");+
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    } else {+
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        printf("Sprite is in system memory\n");+
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    }+
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    /* Run a sample blit to trigger blit acceleration */+
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    {+
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        SDL_Rect dst;+
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        dst.x = 0;+
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        dst.y = 0;+
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        dst.w = sprite->w;+
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        dst.h = sprite->h;+
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        SDL_BlitSurface(sprite, NULL, screen, &dst);+
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        SDL_FillRect(screen, &dst, background);+
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    }+
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    if ((sprite->flags & SDL_HWACCEL) == SDL_HWACCEL) {+
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        printf("Sprite blit uses hardware acceleration\n");+
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    }+
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    if ((sprite->flags & SDL_RLEACCEL) == SDL_RLEACCEL) {+
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        printf("Sprite blit uses RLE acceleration\n");+
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    }+
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+
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    /* Loop, blitting sprites and waiting for a keystroke */+
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    frames = 0;+
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    then = SDL_GetTicks();+
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    done = 0;+
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    sprites_visible = 0;+
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    while (!done) {+
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        /* Check for events */+
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        ++frames;+
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        while (SDL_PollEvent(&event)) {+
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            switch (event.type) {+
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            case SDL_MOUSEBUTTONDOWN:+
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                SDL_WarpMouse(screen->w / 2, screen->h / 2);+
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                break;+
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            case SDL_KEYDOWN:+
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                /* Any keypress quits the app... */+
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            case SDL_QUIT:+
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                done = 1;+
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                break;+
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            default:+
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                break;+
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            }+
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        }+
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        MoveSprites(screen, background);+
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    }+
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    SDL_FreeSurface(sprite);+
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    free(mem);+
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+
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    /* Print out some timing information */+
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    now = SDL_GetTicks();+
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    if (now > then) {+
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        double fps = ((double) frames * 1000) / (now - then);+
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        printf("%2.2f frames per second\n", fps);+
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    }+
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    SDL_Quit();+
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    return (0);+
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}+
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