Houdini Exporter

Discussion and Support of Krakatoa Volumetric Particle Rendering, Manipulation and Management Toolkit
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oatz
Posts: 388
Joined: Wed Oct 31, 2007 7:27 pm

Houdini Exporter

Postby oatz » Mon Jul 18, 2016 12:55 pm

I just noticed the Houdini exporter only supports the old pop network. Is this still the case? Is there any chance to update it to include the new pop network and any point system?

Found this, which does the trick. wish there was an official version from Thinkbox. https://www.flipswitchingmonkey.com/201 ... m-houdini/

Evan Spearman
Posts: 39
Joined: Wed Jan 20, 2016 2:25 pm

Re: Houdini Exporter

Postby Evan Spearman » Mon Jul 18, 2016 3:33 pm

Thanks for letting us know about this. I'll look into it.
Evan Spearman
Developer
Thinkbox Software

Evan Spearman
Posts: 39
Joined: Wed Jan 20, 2016 2:25 pm

Re: Houdini Exporter

Postby Evan Spearman » Thu Jun 15, 2017 12:08 pm

A new exporter with support for Houdini 16 is now available on our Github page.
https://github.com/ThinkboxSoftware/Hou ... r/releases
Evan Spearman
Developer
Thinkbox Software

jonmoore
Posts: 2
Joined: Tue Oct 25, 2016 6:31 am

Re: Houdini Exporter

Postby jonmoore » Tue Jul 18, 2017 8:27 am

Hi Evan,

I've installed the new v16 Exporter and all seems fine but I can only get it to export a single frame. How do you tell your exporter to export the whole frame range?

Also, I have another Krakatoa exporter (the Flip Switching Mokey one) which works perfectly but is unfortunately single threaded. Is your exporter multi-threaded? One of the benefits of the FSM exporter is that it's built as a ROP driver (it's a proper Houdini node) and can be set up with Houdini Wedging (similar to Krakatoa partitions), so you can output multiply PRT's overnight with a variation of seed values.

Houdini particles are fully threaded so it's not ideal if caching is throttled by a single threaded operation, but unfortunately your Python exporter isn't compatible with Wedging as it has to be run manually from the Python shell. If it's threaded it will be easy enough to run separately seeded PRT exports manually as a 10 million particle sim exports in approx 1 second per frame (that's to BGEO, the compressed variant of Houdini's native cache format - BGEO.SC would take a little longer but not by much).

yin
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Joined: Tue Jul 18, 2017 12:30 pm
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Re: Houdini Exporter

Postby yin » Tue Jul 18, 2017 3:02 pm

Hi jonmoore,

Our exporter always exports the current frame, but you can manipulate the current frame using Houdini's Python API. You can use something like this to export the entire frame range (copy and paste into the Houdini Python Shell and hit enter):

Code: Select all

import Krakatoa

# The Houdini node to export to PRT
node_to_export = hou.node('/obj/fireworks_particles/import_fireworks')

# Output file names will be '/out/fireworks0001.prt', '/out/fireworks0002.prt', etc.
# The destination folder must already exist
output_prefix = '/out/fireworks'

# Sets `start` variable to the first frame number and `end` to the last frame number
(start, end) = hou.playbar.playbackRange()

# You can set this to a larger number to skip over frames
step = 1

# Go through each frame, running the exporter for each one
for frame_num in range(int(start), int(end) + 1, step):
    hou.setFrame(frame_num)
    filename = output_prefix + str(frame_num).zfill(4) + '.prt'
    Krakatoa.exportParticles(node_to_export, filename)


Hopefully the code shouldn't be too hard to understand.

Unfortunately, our exporter is also single-threaded. I will add your suggestions to our issue tracker.
Jerry Yin
Developer
Thinkbox Software

jonmoore
Posts: 2
Joined: Tue Oct 25, 2016 6:31 am

Re: Houdini Exporter

Postby jonmoore » Tue Jul 18, 2017 3:45 pm

Thanks for your detailed reply and suggestions Yin. Seeing as the Flip Switching Monkey PRT ROP functions well, I'll carry on using that for the moment (it has some other nice features e.g. it allows you to filter and remap the attributes on export so keep the cache size as small as possible).

A multithreaded PRT exporter from Thinkbox would be such a powerful option for Houdin to Krakatoa workflows. With Houdini's particles being multithreaded, a threaded exporter would maximise the utility of using Houdini in tandem with Krakatoa. You guys should take a look at the Flip Switching Monkey exporter. It may be single threaded but it'd great from a UX perspective is it works without Python so it's a little quicker and with it being a standard ROP output driver, it can be wedged (output seed based partitions).

https://www.flipswitchingmonkey.com/houdini-prt-rop/


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