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Member Since 08 Mar 2012
Offline Last Active Apr 03 2013 07:58 AM

Topics I've Started

SDL_Layer even slower than SDL?

25 January 2013 - 07:51 AM

Hello everyone,
I'm currently experimenting with SDL for some basic scrolling shooter. Since the moving background reeeally slowed things down, I went online and found "SDL_Layer". The documentation is sparse, but I thought I'd figured it out - until I tried it. With just the background in one layer and a single object in another, it's just as slow as vanilla SDL. Because of the moving background I can't use dirty rects. Unfortunately, Google was not helpful on this topic, so I presume there is something wrong with my code.
Here is what I tried:

    SDL_Surface *screen;
    if ( SDL_Init(SDL_INIT_AUDIO|SDL_INIT_VIDEO) < 0 ) {
        fprintf(stderr, "Unable to init SDL: %s\n", SDL_GetError());

    // Initialize screen
    if( screen == NULL ) {
        fprintf(stderr, "Unable to init video: %s\n", SDL_GetError());

    rmask = 0x00ff0000;
    gmask = 0x0000ff00;
    bmask = 0x000000ff;
    amask = 0xff000000;

    display = SDLayer_CreateRGBLayeredDisplay(SDL_HWSURFACE | SDL_FULLSCREEN, SDLAYER_FLIP, LAYERS, layer_widths, layer_heights,
    		32, rmask, gmask, bmask, amask);

    SDLayer_SetColorKey(display, SDL_SRCCOLORKEY, 0); // without this, only the topmost layer will be visible

    bmpBackground = SDL_LoadBMP("Background.bmp");
    if(bmpBackgroundRewind == NULL) {
    	fprintf(stderr, "Couldn't find a graphic: %s\n", SDL_GetError());

    bmpPlayer = SDL_LoadBMP("Player.bmp");
    if(bmpPlayer == NULL) {
    	fprintf(stderr, "Couldn't find a graphic: %s\n", SDL_GetError());
    SDL_SetColorKey(bmpPlayer, SDL_SRCCOLORKEY, SDL_MapRGB(bmpPlayer->format, 255, 0, 255));

I then enter the main loop, which repeatedly triggers the draw() function:

	SDL_Rect background;
	SDL_Rect dest;
        static int background_y = 0;

        if(++background_y >= HEIGHT) background_y=0;

	// draw a moving background
	background.x = 0;
	background.y = background_y;
	background.w = WIDTH;
	background.h = HEIGHT;
	SDLayer_Blit(bmpBackground, NULL, display, &background, 0);

	background.x = 0;
	background.y = background_y-HEIGHT;
	background.w = WIDTH;
	background.h = HEIGHT;
	SDLayer_Blit(bmpBackground, NULL, display, &background, 0);

	// draw the player
	dest.x = player1.x; dest.y = player1.y;
	dest.w = player1.w; dest.h = player1.h;
	SDLayer_Blit(bmpPlayer, NULL, display, &dest, 1);

	// draw the buffer to the screen

I currently disabled everything else, so it's definitely this bit which is causing the slowness. My laptop isn't the fastest one out there, but the speed I'm currently getting can't be right.


Also, I have a hunch the moving background could somehow be realized with viewports and scrolling factors, but should I even bother? When the program's finished, there will be way more objects to update, and it doesn't even work smoothly for one. Or is there some alternative to blitting that I missed?


Anyways, thanks in advance for any help!




Beginner hoping for a few pointers

11 March 2012 - 06:27 AM

Hello all,

I've now watched this forum for a few days and I think I've come to the right place. I'll come straight to the point:
I have some experience in programming and want to revive an old dream of mine: Creating an oldschool RPG. Here's a list of things that come to mind:
  • "Oldschool": No fancy 3D graphics, no realtime playing - just turn based, tile map.
  • Should be cross-platform - I think the best way is to use Java - any other recommendations?
  • I already made a few simple games - some "shoot' em up", Pong, that stuff; fiddled with bitmaps in Delphi way back on Windows.
  • I'm not sure on whether to use a pre-made engine. While it would speed things up, I'd rather know what goes on "behind the stage", and I don't know if I can achieve that without creating from scratch. Any advice? (Oh, and if I were to use something pre-made, it'd have to be licensed under some form of copyleft so I don't have to struggle with licensing problems.)
  • As mentioned, I made some simpler games with Delphi's VCL. But I really don't know where to begin with this one, and albeit having searched the internet for a long time, I didn't find any tutorials that really addressed my problem. My hope now is that the community in this forum can point me a way to start.
Okay, thanks for reading this, and please point out if I have to give more information. Thanks for your time!


P.S.: Please excuse my English since it's not my native language.