Message-ID: <3708C68A.7F02EF1@indigo.ie>
From: "B O'Donnell" <odonnllb AT indigo DOT ie>
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Subject: Addendum Re: Problem blitting with Allegro and STB
References: <7e8hkj$4ut$1 AT platane DOT wanadoo DOT fr> <37082B4B DOT A885EAB7 AT xoommail DOT com> <37083607 DOT 268EFC80 AT indigo DOT ie>
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Date: Mon, 05 Apr 1999 15:19:54 +0100
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To: djgpp AT delorie DOT com
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B O'Donnell wrote:
> 
> I have a program which is supposed to do masked blits from one of a
> collection of shapes at one side of the screen to a selected point on
> the screen - aka a map editor.
> 
> I'm using Allegro and an STB Powergraph 64 3D card with 2 MB of memory,
> with Autodetect on the program and 'VBE1' in my allegro.cfg; without the
> 'VBE1' I don't even get this far. I'm working in 640*480*256 mode.
> 
> To start with, the current map is blitted piece by piece on the screen,
> and this works fine. When I select a piece a copy is blitted to the top
> of the screen; again no problem. But when I click on the map...
> 
> Clicking on a location usually produces a copy of the selection at the
> right X-displacement, but the Y is wrong. To simplify slightly, if the Y
> of the selection is 200, the Y of the copy is somewhere regular about
> 200 to 224, whatever I pass to masked_blit.
> 
> If I try to fill a section of identical cells with a different stamp, I
> get a peculiar pattern which ignores the map boundaries. BUT if I wash
> the whole map with one stamp, similar to the first draw, the stamp is
> replicated correctly through the entire map.
> 
> Help would be appreciated.
> 
> Regards
> Brian O'Donnell
> odonnllb AT indigo DOT ie

As I wrote the above, I kept thinking that I _can_ blit from offscreen
to anywhere onscreen,but it was late, so I went to bed.

Today I rewrote the paint routine to copy from the screen to a bitmap in
memory then copy that bitmap back to the screen. This works as intended.
I'm still mystified, and what I have is a workaround rather than a
solution, so I'm still looking for ideas.

Regards
Brian O'Donnell
odonnllb AT indigo DOT ie