Oh I see!
Thank you very much :)
m.
cyrille henry escribió:
here is a small patch that show the problem : when gemhead receive a
bang while in double rendering mode, the transformation matrix send is
incorrect.
so, finding a workaround is easy. just replace gemhead with the _gemhead
abstraction that always output the correct transformation matrix.
c
cyrille henry a écrit :
are you sure you send the good patch?
this one is not "very simple" and does involve pix_snap.
c
Matteo Sisti Sette a écrit :
Yes the issue is indeed much simpler and [pix_snap] is not involved.
Attached is a very simple patch with a square and a sphere. The bang
forces a render. If you move the sphere far behind the square and hit
the bang, you can see a "flash" of the red sphere just close to the
eye, as if it was in the opposite position than usual.
Is it normal, and if so, what is the explanation???
Matteo Sisti Sette escribió:
Hi,
I'm working on a patch (not the attached one which is an example
that isolates the problem), where from time to time I need to take a
snapshot of the whole scene and "draw" it as a texture on a
rectangle which is on the background.
(when the patch is finished I think I will be allowed to share it,
for what it's worth)
I have it all working fine, but than I came into a problem:
sometimes, I have to send a message to take the snapshot, and
immediately after, send some other message that changes something on
the scene, which has to happen AFTER the snapshot.
Since I am taking snapshots in the "classic" way, that is, opening a
spigot on the gemlist that comes to the [pix_snap], the snapshot is
actually deferred until the next render; this is a problem because I
need to "defer" any other message that has to take effet just after
the sbapshot; this can be done but i'd like to avoid all the
complications.
I thought that a solution would be to force a render just after any
snapshot, by sending a bang to the gemhead that is rendering
everithing.
However, the result is not what I expected and I really can't
understand why.
That's why I am asking for your help.
So, the attached patch is a simplification, in which I draw an
initially white square and a sphere. If you hit the big bang (sorry
for the pun), a snapshot of the scene is taken via [pix_snap] and it
becomes the texture of the square. You can use the number box to
move the sphere around.
Now, if I make the connection where it says "connect this", what I
am doing is just provoking a bang to the gemhead just after opening
the spigot to the pix_snap. What I would expect is that it should
work exactly the same as before (with the difference that an extra
frame is rendered between two "normal" frames, and that's the moment
the snapshot is taken; but this difference should not be "visible").
However, the observed behaviour is not this. The snapshot that is
taken and "printed" on the texture is not the scene, but some
aberration of it. If you leave the sphere wher it is, it will
usually render and snap an all-black scene; but if you move the
sphere to the back, behind the square, the snapshot will take the
sphere very near to the "eye"......
I really don't understand. Doesn't the bang to the gemhead provoke a
full render of everything just the same as it is rendered when a new
frame occurs? Then why is the scene rendered differently when I do
the bang????
I guess this could be further isolated to something regarding the
bang to gemhead, i.e. without involving pix_snap; of course with a
"fast" enough to see what happens during a single extra frame....
Thanks in advance
By the way, thanks to all who gave me example patches some days ago
which have helped me building this patch.
m.
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http://www.matteosistisette.com
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