/*
  Copyright (C) 1997-2011 Sam Lantinga <slouken@libsdl.org>

  This software is provided 'as-is', without any express or implied
  warranty.  In no event will the authors be held liable for any damages
  arising from the use of this software.

  Permission is granted to anyone to use this software for any purpose,
  including commercial applications, and to alter it and redistribute it
  freely.
*/
/* Simple program:  Move N sprites around on the screen as fast as possible */

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include <time.h>
#include <math.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 =
                (int)((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 > (Uint32)(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 | SDL_RESIZABLE;
    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((unsigned int)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;
        }
    }

    /* Clear the background to grey */
    background = SDL_MapRGB(screen->format, 0xA0, 0xA0, 0xA0);
    SDL_FillRect(screen, NULL, background);
    SDL_Flip(screen);

    /* 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_VIDEORESIZE:
                screen = SDL_SetVideoMode(event.resize.w, event.resize.h, video_bpp, videoflags);
                break;
            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) {
        double fps = ((double) frames * 1000) / (now - then);
        printf("%2.2f frames per second\n", fps);
    }
    SDL_Quit();
    return (0);
}