[SDL] 8bpp BMP seg faults
Ryan C. Gordon
icculus at linuxgames.com
Sun Jun 17 01:08:18 PDT 2001
> /* Generate The Texture */
> glTexImage2D( GL_TEXTURE_2D, 0, 3, TextureImage->w,
> TextureImage->h, 0, GL_RGB,
> GL_UNSIGNED_BYTE, TextureImage->pixels );
> After that last line is where it bombs. Any suggestions? Thanks!
You are giving OpenGL texture data where each byte represents a pixel
(8-bit), but telling it to read three bytes for every pixel
(GL_RGB). glTexImage2D() is reading past the end of the surface's pixel
data, and probably touching memory your application doesn't own.
If you're loading an 8-bit bitmap, you should use GL_COLOR_INDEX (not
GL_RGB) and set up a pixel map with glPixelMapfv().
That's a pain, though.
Alternately, after loading the 8-bit bitmap, convert the SDL surface to 24
/* this is completely untested. */
SDL_Surface *bmp = SDL_LoadBMP("data/crate.bmp");
if ( (bmp != NULL) && (bmp->format.BitsPerPixel != 24) )
memcpy(fmt, bmp->fmt, sizeof (SDL_PixelFormat));
fmt->palette = NULL;
fmt->BitsPerPixel = 24;
fmt->BytesPerPixel = 3;
/* set anything else... */
tmp = SDL_ConvertSurface(bmp, &fmt, SDL_SWSURFACE);
bmp = tmp;
/* your GL code goes here, now with a surface guaranteed to be 24-bit, so
you can use GL_RGB. */
Hhmmm...that's also a pain. :)
Talk amongst yourselves.
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