Re: [AD] SF.net SVN: alleg:[12120] allegro/branches/4.9/addons/iio/png.c

[Elias Pschernig <elias.pschernig@xxxxxxxxxx>]

Evert Glebbeek wrote:
> On 24 Apr 2009, at 18:33 , elias@xxxxxxxxxx wrote:
> > Log Message:
> > -----------
> > Replaced al_map_rgba/al_put_pixel with direct memory access in  
> > png.c, faster and easier to read.
>
> [snip]
>
> > -               al_put_pixel(i, y, c);
> > +               *(rgba++) = pal[pix].r;
> > +               *(rgba++) = pal[pix].g;
> > +               *(rgba++) = pal[pix].b;
>
> This doesn't look like it's endianesse safe (as described in the  
> lock_bitmap example). Haven't tested it; I can test on my iBook later.

I wouldn't be sure in the 24-bit case, but for the 32-bit case you're right. 
Probably. Maybe we should add one additional endian-safe bitmap formats, like 
OpenGL? Something like:

ALLEGRO_PIXEL_FORMAT_RGBA_8888_LE

And it would make sure that in memory, the pixels are laid out as first red, 
then green, then blue, then alpha? It certainly would be less error-prone to use 
when doing lots of direct-access pixel manipulation. And it also would emphasize 
the endianness of (most of) the other formants.

The real problem I tried to solve was that in my game I can't allow 
al_set_target_bitmap to be called on my bitmaps else the performance drops 
horrendously (because 1000ds of FBOs for tiny bitmaps somehow kill the NVidia 
drivers) - but Trent's most recent commit gives me an idea how to fix that in a 
different way...

--
Elias Pschernig <elias@xxxxxxxxxx>