Is there a limit in bitmap size in A5? My A4 program had megatexture bitmap of 3200x3200 but in A5 it seems like it is not possible to make bitmaps larger than about 2000x2000 (2000x2000 works but 2100x2100 does not work).

Usually the limit is a power of 2 so your limit is probably 2048x2048. A4 let you make arbitrary sized ones because it was limited by your ram since a4 is software rendering and memory bitmaps.

5.1 falls back to a memory bitmap if you don't explicitly request a video bitmap via the ALLEGRO_VIDEO_BITMAP flag. So if you don't care, don't set either flag.

Basically it now treats a bitmap without either flag as an "auto" type, where it tries to be accelerated if at all possible. So if you, say, load a small image before creating a display, then create the display, it will automatically upgrade it to a video bitmap. (I think that's what eventually was implemented after long discussions...)

So in a nutshell, with 5.1: if you must have a memory or video bitmap, then you need to explicitly set the appropriate flag.

What happens with CPU's with GPU's incorporated like the one I've got

A3850 AMD A8

?

What about minimum bitmap size?.

In my code I'm drawing a patterned line using al_draw_prim() and creating a 2x2 bitmap works fine in OpenGL but in Direct3D it's obviously bitten by this so, for example, I get:

With OpenGL:
{"name":"patternogl.png","src":"\/\/djungxnpq2nug.cloudfront.net\/image\/cache\/5\/9\/59e729fcbad9359036c818da555c2eb3.png","w":636,"h":474,"tn":"\/\/djungxnpq2nug.cloudfront.net\/image\/cache\/5\/9\/59e729fcbad9359036c818da555c2eb3"}
With Direct3D:
{"name":"patternd3d.png","src":"\/\/djungxnpq2nug.cloudfront.net\/image\/cache\/7\/d\/7d452b88069636c26127045ac9318b24.png","w":637,"h":478,"tn":"\/\/djungxnpq2nug.cloudfront.net\/image\/cache\/7\/d\/7d452b88069636c26127045ac9318b24"}

Is there a way to query (currently it's not possible with al_get_display_option()) the minimum bitmap size? or is it better to always assume a minimum size of 16x16?.

I thought it was related to the minimum texture size as mentioned in the documentation because it clearly coincides with a 16x16 bitmap size.

I'd say that indicating in the documentation that on some cards 16x16 is the minimum supported (and a safe minimum to assume) bitmap size is better if that keeps the code cleaner.

Maybe you ran out of vram?

Ok, I'll try it....

EDIT: So the code tries to make 5x5 bitmaps of 640x640. This crashes when trying to make the 20th bitmap. When changing size to 512x512 all 25 bitmaps can be created.

640x640x19 = 7782400 pixels
512x512x25 = 6553600 pixels

Never tried this in A4 but then I was able to make a single 3200x3200 instead.

3200x3200 = 10240000 pixels

It's pitty the swap from A4 to A5 has generated issues not available in the old A4 version of my game.

Some cards or drivers don't work with < 16x16 and D3D in my experience, that's why the limit is there. It looks like you're drawing the full 16x16 in your example there ken, when you should only use a 2x2 piece of it.

That's a memory bitmap. You'd have to set ALLEGRO_MEMORY_BITMAP in 5.0 to achieve the same effect. But why do you need such a large bitmap?