Re: [AD] al_set_target_bitmap question

[Elias Pschernig <elias@xxxxxxxxxx>]

On Sat, 2008-01-05 at 10:25 +0000, Peter Hull wrote:
> In al_set_target_bitmap, is there a restriction on what kind of bitmap
> can be passed? The reason for asking is that the current display is
> all set up with a vtable appropriate for a particular kind of driver
> (say OpenGL, or whatever) then if you pass an arbitrary bitmap that
> vtable might not be appropriate.
> 
> On in other words I'm not sure how al_set_target_bitmap is supposed to
> work. Could someone help?
> 

No, we allow drawing to any kind of bitmap. So if you have some bitmap,
and want to draw a line to it, you do:

al_set_target_bitmap(bmp);
al_line(x, y, tx, ty, color);

To draw to the backbuffer again, you do:

al_set_target_bitmap(al_get_display_backbuffer());

Actually, I don't like that last bit at all, but not sure what would be
a better solution. Maybe just a shortcut:

al_unset_target_bitmap()

or

al_set_backbuffer_target()

About the vtable not being appropriate, each ALLEGRO_BITMAP has its own
ALLEGRO_BITMAP_INTERFACE property and also a pointer to the display it
belongs to, should be enough to figure out what to do I think. But I
never tried to mix different kinds of displays so far - maybe if you can
give a more concrete example showing a possible problem.

-- 
Elias Pschernig <elias@xxxxxxxxxx>