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# SDL_Surface

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Hi! I use SDL_Image for loading SDL_Surfaces. Unfortunately all my images seem to be 8 bit only. What''s wrong. I''ve setup the display mode correctly. Thanks for any advice! _____ ... you got me on my knees, Layla

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I'd like yo help you, but you don't provide much informations. Do you mind posting some code ? like the SDL_SetVideoMode() part and IMG_Load() part ?

Also, are you sure the files you are loading aren't 8 bit ? because if it's the case, setting the video mode to any color depth won't change a thing.

Sorry if it doesn't help you, but I can't think of anything else at the moment

Matt

edit: there was a second 'and' between SDL_SetVideoMode() and IMG_Load()

[edited by - lemurion on March 30, 2004 12:02:48 PM]

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I often use SDL, and I think as LEMURION, I think that it should come from your screen settings or your file format...

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If you specify your screen surface to only have 8 bpp then try and display a 32 bpp image then it will look extremely crappy. If your using 8 bit images then make sure your screen surface is at least 8 bbp resolution, otherwise make sure you are matching the resolution of your images to the resolution of your screen surface,.

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Thanks for your replies! It''s great to find the people willing to help me. I''ve been thinking about the problem for a long time but my lack of knowledge about SDL didn''t let me solve it...

OK. Here I post the source code for functions which initialize the display and load an image. Probably, there is a lot of SDL stuff which is actually useless. I''d be thankful if you find any bugs and finally - if you help me solve this color-depth problem.

bool	Engine::InitDisplay (string title, int width, int height, int bpp, bool fullscreen) {    Uint32 flags = 0;    int rgb_size[3];	    if(!m_bInitialized)  {	// Initialize only once        // Init all the SDL stuff        if(SDL_Init(SDL_INIT_VIDEO|SDL_INIT_TIMER|SDL_INIT_AUDIO) < 0)  {            /* LOG */ Log.Send("Error : SDL not initialized!");			m_bDone = true;            return false;   //return now, nothing else should be called        }    }	m_bFullscreen = fullscreen;        if(m_bFullscreen) flags |= SDL_FULLSCREEN;	// Fullscreen?	// Check if we are choosing a correct bpp    if(bpp != -1 && bpp != 8 && bpp != 16 && bpp != 24 && bpp != 32)    {        /* LOG */ Log.Send("Error : invalid BPP (%d), must be 8,16,24 or 32, trying the best BPP.", bpp);        m_bDone = true;		return false;    }    else    //this choosed correct BPP    {        if(bpp == -1) bpp = SDL_GetVideoInfo()->vfmt->BitsPerPixel;  //Try desktop resolution						int ok;        ok = SDL_VideoModeOK(width, height, bpp, flags);        		if(!ok) {            /* LOG */ Log.Send("Error : couldn''t set video %dx%dx%d", width, height, bpp);			m_bDone = true;            return false;   //return now        }    }	m_BPP = bpp;    // Buffer sizes    switch (m_BPP)    {        case 8:            rgb_size[0] = 3;            rgb_size[1] = 3;            rgb_size[2] = 2;            break;        case 16:            rgb_size[0] = 5;            rgb_size[1] = 5;            rgb_size[2] = 6;            break;        default:            rgb_size[0] = 8;            rgb_size[1] = 8;            rgb_size[2] = 8;            break;    }    // Set key GL attributes	// RGB Colors    SDL_GL_SetAttribute(SDL_GL_RED_SIZE, rgb_size[0]);    SDL_GL_SetAttribute(SDL_GL_GREEN_SIZE, rgb_size[1]);    SDL_GL_SetAttribute(SDL_GL_BLUE_SIZE, rgb_size[2]);    SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);    SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 8);   // 8 bit depth buffer    SDL_GL_SetAttribute(SDL_GL_STENCIL_SIZE, 0);    SDL_GL_SetAttribute(SDL_GL_ACCUM_RED_SIZE, 0);    SDL_GL_SetAttribute(SDL_GL_ACCUM_GREEN_SIZE, 0);    SDL_GL_SetAttribute(SDL_GL_ACCUM_BLUE_SIZE, 0);    SDL_GL_SetAttribute(SDL_GL_ACCUM_ALPHA_SIZE, 0);     flags |= SDL_OPENGLBLIT | SDL_NOFRAME | SDL_DOUBLEBUF | SDL_HWSURFACE;    // Create SDL screen and update settings based on returned screen    m_Screen = SDL_SetVideoMode(width, height, bpp, flags);    if(!m_Screen)    {        /* LOG */ Log.Send("\n........ Error : failed to create screen''s surface");        		m_bDone = true;        return false;   // Too bad..     }        m_Width  = width;    m_Height = height;    m_Title  = title;    InitOpenGL();	// Initialize OpenGL setting for the engine	if (!SDL_GetVideoInfo()) {		// Check once again if everything is correct		/* LOG */ Log.Send("Error : couldn''t obtain video info.");		return false;	}    m_bInitialized = true;    //If it makes it to the end it has been initialized	m_bPaused = false;		m_bDone   = false;		/* LOG */ Log.Send("Video mode initialized : %dx%dx%d Fullscreen : %d", width, height, bpp, fullscreen);    return true;  // Everything went pretty well! :D}bool tImage::OpenFromFile(string filename) {	// Function that creates an image based on a graphics file	// Formats supported : BMP, PNM, XPM, XCF, PCX, GIF, JPG, PNG, TIF, LBM	SDL_Surface *Surface;	Release();		// Clean everything up    Surface = IMG_Load(filename.c_str());	/* LOG */ Log.Send("Loading image : %s", filename.c_str() );	m_FileName = filename;    if(!Surface)	{		/* LOG */ Log.Send("....Error : couldn''t load image from %s", filename.c_str);		return false;	}	bool flag;	flag = OpenFromSurface(Surface, 0, 0, Surface->w, Surface->h);	TC.FreeImage (Surface);		// We don''t need that any more   	return flag;		// Woow! Everything OK. }bool tImage::OpenFromSurface(SDL_Surface *SrcSurface, int x, int y, int w, int h) {	// The function opens our beautiful image from SDL_Surface. It copies	// pixel data from a specified surface	SDL_Rect	rect;	SDL_Surface *Surface;	SDL_Surface *screen;	rect.x = x;	rect.y = y;	rect.w = w;	rect.h = h;	Surface = SDL_CreateRGBSurface(SDL_HWSURFACE | SDL_SRCCOLORKEY | SDL_SRCALPHA, rect.w, rect.h, 32 /*SrcSurface->format->BitsPerPixel*/,	    screen->format->Rmask, screen->format->Gmask, screen->format->Bmask, screen->format->Amask);	// Transparency	unsigned long int key = SrcSurface->format->colorkey;	SDL_SetAlpha(SrcSurface, SDL_SRCALPHA, 255);	SDL_SetColorKey(SrcSurface, SDL_SRCCOLORKEY, SDL_MapRGB(Surface->format,		m_TransparencyRGB[0], m_TransparencyRGB[1], m_TransparencyRGB[2]) );    			SDL_BlitSurface(SrcSurface,&rect,Surface,NULL);	SrcSurface->format->colorkey = key;	 // Surface conversion    SDL_Surface *temp = Surface;	    Surface = SDL_DisplayFormatAlpha(temp);		if(Surface)    {       // TC.FreeImage(temp);    } else	{		 // Can''t convert		/* LOG */ Log.Send("....Error : couldn''t convert image!");        Surface = temp;    }	if (Surface)	{		m_Image = Surface;		// Assing the surface		ReloadTexture();		// Now let OpenGL cope with THE THING	} else {		/* LOG */ Log.Send("....Error : image''s loading failed!");		return false;	}	// We are not attached	m_pSrcImage	= NULL;	// Assing class'' members	m_RegionX = 0;	m_RegionY = 0;	m_RegionWidth = m_Image->w;	m_RegionHeight = m_Image->h;	Log.Send("....Image succesfully created!");		return true;}

Also, there is something totally messed up with transparency. You see - the rendering part is taken by OpenGL. SDL is used to load images only - not to display them. I just want to use SDL functions to create an RGBA data which is then used to create OpenGL textures.

GREEEAAT THANX!

------------------

... you got me on my knees, Layla

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If you just want to load images, why not use DevIL?

You have a small bug where you use c_str instead of c_str(), but that''s irrelevant.

I can''t see any obvious mistakes but there''s too much code for now. Are you absolutely sure your input file is in the correct format? And how do you know your images are 8 bit only - where''s the proof or symptoms of this?

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Hi! Thanks for your help. Let''s get straight into explenations...

quote:

I can''t see any obvious mistakes but there''s too much code for now. Are you absolutely sure your input file is in the correct format? And how do you know your images are 8 bit only - where''s the proof or symptoms of this?

Yeah, I am 100% sure that my images are 32 bit (some are 24). Anyway - I found something which might be helpful. A kind of a tip - do you see a line in OpenFromSurface(...) where there is a call to SDL_DisplayFormatAlpha ? I remember that once I made something somewhere around it (I know it sounds silly) and suddenlly the images became 32 bit but the colors where messed up. Doesn''t make things clearer a bit?

Bye, thanx!

-----------

... you got me on my knees, Layla

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Well, if i''m not mistaken, doing
SDL_Surface *temp = Surface;Surface = SDL_DisplayFormatAlpha(temp);//is the same asSurface = SDL_DisplayFormatAlpha(Surface);// because temp is pointing at the same memory location as Surface// what you should do is:SDL_Surface *temp;temp = SDL_DisplayFormatAlpha(Surface);// and then use temp// or you can use temp before this line and doSDL_Surface *Surface;Surface = SDL_DisplayFormatAlpha(temp);

hope that helps !
Matt

PS: Yippy ! my 100th post !

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Thanks, lemurion. I''ll check it out and let you know if it helped.

... you got me on my knees, Layla

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Ehh... It''s still not what I''ve been looking for. :/

Do you have any idea why do I get these 8 bit images??

Thx

----

... you got me on my knees, Layla

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output the bpp every step of the way, so we can see what''s causing the change. or if there is a change...

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