[GEM-dev] strange behaviors with multipass rendering, setting gemhead order with float number, and image latency

[cyrille henry]

Hello,

I experience strange behaviours I can't explain.
the context is multipass rendering : the render order of each framebuffer is important otherwise you can experience 1 frame latency.
I need to set explicitly the render order of gemhead using the set message, because I use the same abstractions multiple time and they need to be render at different time.
I also need to use floating point number since I do have lot's of different gemhead. (gemhead use to accept only int, but if I remember correctly, this limitation is gone long any, is that right?)

I manage to reproduce my problem in a simple patch, see attachment.

When moving the teapot, you experience 1 frame latency for each pass of the abstraction. (for a total of 14 frames)
But, if you remove the loadbang in the abstraction, everything works as expected.
if you set the same value with the loadbang in the main patch : it works. If you don't set the order position  with loadbang, or with the set message, it also works (since the correct value is explicit in the gemhead object).


And of course, on my big patch, changing the timing of the set message did not help...

When you experience latency, the rendering order is reversed.


I would love to have an explanation.

Thanks for your help
C
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