🚀 go-pugleaf

I'm posting this for a friend:


Hi there!

I am having a problem with reading and writing bitmap images, and
thought I would poll the assembled gurus out there.

Some background:

I am writing a Pinball game which has a TIFF file background onto
which objects such as flippers, balls, bumpers and lights are
composited.  These objects are initially drawn into NXImages and
then composited where needed onto the view containing the background.

I need to do "hit detection" to determine when the ball has hit an
object, and the fastest and easiest way of doing that appears to be to
have a "shadow" pinball table onto which I draw shadows of things that
the ball can hit.  The background of this shadow table is white, and
walls (which balls just bounce off) are light grey.  Reactive objects
like bumpers and flippers are dark grey.  Whenever I draw an object on
the table (say redrawing a flipped flipper) I redraw its shadow (a
simple dark grey outline) on the shadow table.  Thus whenever I move
the ball(s) I read from the point on the shadow table just ahead of
them, and if it is a wall I do a bounce, if it is a flipper etc. (dark
grey) I work out which object it is, then send a message to that
object saying it has been hit etc.

So what I am saying is that I need to be able to create a bitmap which
I can composite onto, and from which I can read pixel values, very
very fast.  Reading pixel values fast means I need to know where in
memory the bitmap is stored.

Now, to use the NeXT composite methods I need to use NXImages or
Views.  If I want to alter a bitmap image it MUST be an
NXCachedImageRep because if I try to alter a NXBitmapImageRep it just
changes a cached copy, and seeing as I don't know where the cached
copy is, I can't read pixels back from it.  Also, with
NXCachedImageReps I cannot find out where the bitmap is stored in
memory (I can get the offscreen window it is stored in).

Help, I don't know what to do; I can lockFocus on the
NXCachedImageRep, and copy the bit into a newly allocated
NXBitmapImageRep, get the address of *that* bitmap and read the pixel,
but that takes forever.  Has anyone (Ali Ozer?) got any ideas?

Thanks in advance,

Tim Bissel.

PS.  This is being posted for me by a friend, but you can reply to him,
     post replies or try mailing me at ...unido!portland!tim