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SDL_Image loading/format question

Started by Atash Mar 29, 2006 at 9:33 PM 4 replies 1k views

Original Post

Mar 29, 2006 at 9:33 PM

In SDL_Image, when an image is loaded, is it loaded as an RGB or an RGBA surface? Thank you in advance :-) [Edited by - Atash on March 29, 2006 9:55:03 PM]

caseyd

Mar 29, 2006 at 9:55 PM

I'm not sure. I just spent a few minutes looking through some material but couldn't find anything. What I would do is load an image using it and than look at the Pixelformat structure through the format member. Maybe compare the differences to a non RGBA surface. I'm sure that certain values, such as Amask would be different for non-RGBA surfaces.

Atash

Mar 30, 2006 at 10:14 PM

Okay, that brings me to a different issue (because of OGL tex loading functions and... yeah)... When you have an SDL_Surface that has pixel data, is all of that data stored with slots for every single value (RGBA), and when using it in RGB mode you simply skip over the Alpha, or is it that it is ACTUALLY stored in an RGB format?

Thanks in advance!!!

Lazy Foo

Mar 30, 2006 at 11:43 PM

Quote:
Original post by Atash
Okay, that brings me to a different issue (because of OGL tex loading functions and... yeah)... When you have an SDL_Surface that has pixel data, is all of that data stored with slots for every single value (RGBA), and when using it in RGB mode you simply skip over the Alpha, or is it that it is ACTUALLY stored in an RGB format?

Thanks in advance!!!

If all you want is a consistent format when loading the image just convert the loaded surface to RGBA:

        //The format    SDL_PixelFormat format;            //Set format    format.palette = NULL;    format.BitsPerPixel = 32;    format.BytesPerPixel = 4;            //Set mask    #if SDL_BYTEORDER == SDL_BIG_ENDIAN    format.Rmask = 0xFF000000;    format.Gmask = 0x00FF0000;    format.Bmask = 0x0000FF00;    format.Amask = 0x000000FF;    #else    format.Rmask = 0x000000FF;    format.Gmask = 0x0000FF00;    format.Bmask = 0x00FF0000;    format.Amask = 0xFF000000;    #endif            //Set shift    format.Rshift = 8; format.Gshift = 8; format.Bshift = 8; format.Ashift = 8;            //Set loss    format.Rloss = 0; format.Gloss = 0; format.Bloss = 0; format.Aloss = 0;

then convert the surface with that pixel format.

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