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Solaris and Karma » What relation about light and texture?
- KaiStavginski
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Hi, we already have a fix for that, it's just not in an 18.5 build yet. I'll try to backport & test it today.
Technical Discussion » Importing `houdini.env` into the shell
- KaiStavginski
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You can set variables from a bash script if you just source it. But the houdini.env file doesn't exactly contain shell commands.
In bash you could do something like this:
grep -v “#” just filters out comment lines
grep “=” filters for lines actually containing an assigment
xargs -L1 echo export just prints each line with “export” prepended.
So you get output like
export HOUDINI_NO_SPLASH=1
Wrapping the whole command in $() will execute the whole thing as a shell command.
Bash also requires that there's no space around the =. Just make sure of that in your file, I didn't take care of that in the one-liner.
In bash you could do something like this:
$(cat houdini.env | grep -v "#" | grep "=" | xargs -L1 echo export)
grep -v “#” just filters out comment lines
grep “=” filters for lines actually containing an assigment
xargs -L1 echo export just prints each line with “export” prepended.
So you get output like
export HOUDINI_NO_SPLASH=1
Wrapping the whole command in $() will execute the whole thing as a shell command.
Bash also requires that there's no space around the =. Just make sure of that in your file, I didn't take care of that in the one-liner.
Technical Discussion » How can I retrieve the length of a curve?
- KaiStavginski
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Technical Discussion » Houdini clumping bugs and how to solve them
- KaiStavginski
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Hi Fabio,
thanks for sending more details, that's very useful. I also see an influx of experienced artists now and more and more studios picking up the tools, which is great.
Good to hear you were able to get good performance with VEX as well.
I might start with a normal direction threshold as well. After all we already have that in Hair Generate! I also found that our geodesic distance methods aren't quite ready for this use case, hopefully we can take that a bit further in the not too distance future.
Cheers,
Kai
thanks for sending more details, that's very useful. I also see an influx of experienced artists now and more and more studios picking up the tools, which is great.
Good to hear you were able to get good performance with VEX as well.
I might start with a normal direction threshold as well. After all we already have that in Hair Generate! I also found that our geodesic distance methods aren't quite ready for this use case, hopefully we can take that a bit further in the not too distance future.
Cheers,
Kai
Technical Discussion » Houdini clumping bugs and how to solve them
- KaiStavginski
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Hi,
this is like the best bug report ever, lots of effort on the video alone! Thanks for that.
The first bug, with hairs finding clumps by any point on the curve, is fixed in tomorrow's build. I'm very surprised that wasn't found before, but it was a one line fix.
With the thin geometry problem, I'm taking a bit more time to get the right solution. It'd be great to hear what you did (geodesic distance, normal direction cutoff, something else) and how performance & quality are in production.
Cheers,
Kai
this is like the best bug report ever, lots of effort on the video alone! Thanks for that.
The first bug, with hairs finding clumps by any point on the curve, is fixed in tomorrow's build. I'm very surprised that wasn't found before, but it was a one line fix.
With the thin geometry problem, I'm taking a bit more time to get the right solution. It'd be great to hear what you did (geodesic distance, normal direction cutoff, something else) and how performance & quality are in production.
Cheers,
Kai
Technical Discussion » HDA and versions, not very clear how it works
- KaiStavginski
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Another note - making breaking changes is really the only reason to bump up the version. Don't overuse it when you just make some additions to the .hda. In houdini itself we only end up with 4 different versions after many years of breaking changes.
Technical Discussion » HDA and versions, not very clear how it works
- KaiStavginski
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In other words, what you saw in Ari's video would only kick in if you had multiple copies of a single version.
Try it, make a copy of your ms_versions_test__0_2.hdalc, and install that as well. Now you have two copies of your 0.4 definition, one from each of the files. Now only one of them can be set to green with Use This Definition, this is set globally for your hip file. In practice, this is mostly useful when you have a local copy open for editing and maybe a copy somewhere on central server.
On the other hand, the version (0.1, 0.2, ..) you pick in the parameter pane's asset bar is stored per node instance. All the nodes you set to e.g. 0.4 there will use the the 0.4 version that's green in the Asset Manager. This makes it possible to use different versions of an HDA in the same scene, maybe because a new version changes some behavior, and your existing setup requires the old behavior. Hopefully that clarifies how the two interfaces complement each other.
Try it, make a copy of your ms_versions_test__0_2.hdalc, and install that as well. Now you have two copies of your 0.4 definition, one from each of the files. Now only one of them can be set to green with Use This Definition, this is set globally for your hip file. In practice, this is mostly useful when you have a local copy open for editing and maybe a copy somewhere on central server.
On the other hand, the version (0.1, 0.2, ..) you pick in the parameter pane's asset bar is stored per node instance. All the nodes you set to e.g. 0.4 there will use the the 0.4 version that's green in the Asset Manager. This makes it possible to use different versions of an HDA in the same scene, maybe because a new version changes some behavior, and your existing setup requires the old behavior. Hopefully that clarifies how the two interfaces complement each other.
Technical Discussion » Vellum Hair Simulation Problem
- KaiStavginski
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Hi,
the main issue is that the head transform happens at the very top. I moved that all the way down and set up the guide deform SOP.
From you screenshot I see a resample SOP after guide deform - general rule of thumb, never resample animated guides. It'll resample differently on each frame and will destroy motion blur among other things.
You'll see that the scene is like 20x faster, even the simulation, because nodes only become time dependent at the very bottom, just before sim & hairgen.
the main issue is that the head transform happens at the very top. I moved that all the way down and set up the guide deform SOP.
From you screenshot I see a resample SOP after guide deform - general rule of thumb, never resample animated guides. It'll resample differently on each frame and will destroy motion blur among other things.
You'll see that the scene is like 20x faster, even the simulation, because nodes only become time dependent at the very bottom, just before sim & hairgen.
Technical Discussion » Transfer Groups Bleeding Into Other Objects [SOLVED]
- KaiStavginski
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Hard to solve in general, when you have a single piece of with parts that are close to one another.
But you have separate pieces, and you're already doing a for-each loop - why not do the transfer in there as well?
But you have separate pieces, and you're already doing a for-each loop - why not do the transfer in there as well?
Solaris and Karma » How to import camera in Solaris?
- KaiStavginski
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Solaris and Karma » Drag unselected objects in the edit lop?
- KaiStavginski
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I should make clear that this dragging of unselected primitives only works in physics mode. Is that what you're using?
Solaris and Karma » Drop node silently fails on Instances
- KaiStavginski
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Hi Peter,
that should work in tomorrow's build, along with some other internal approvements.
that should work in tomorrow's build, along with some other internal approvements.
Technical Discussion » Would like help from Kai on Shaders
- KaiStavginski
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@Christopher_R,
all you need to get a basic AOV is the bind export VOP. Set Layer Export is only needed when layering multiple shaders.
Can you get your export_customDiffuse to work at all?
You have to set up a corresponding image plane of the same data type on the Mantra ROP as well, maybe that part is missing in your setup?
@pickled I believe we already have an RFE for that. My main obstacle with adding that sort of functionality is the resulting UI clutter. I may tackle that sort of stuff for the next release (after 18).
all you need to get a basic AOV is the bind export VOP. Set Layer Export is only needed when layering multiple shaders.
Can you get your export_customDiffuse to work at all?
You have to set up a corresponding image plane of the same data type on the Mantra ROP as well, maybe that part is missing in your setup?
@pickled I believe we already have an RFE for that. My main obstacle with adding that sort of functionality is the resulting UI clutter. I may tackle that sort of stuff for the next release (after 18).
Technical Discussion » Would like help from Kai on Shaders
- KaiStavginski
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Technical Discussion » Skin UVs to Hair
- KaiStavginski
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In that screenshot of the network editor it looks like you tried to attribpromote the uv attribute, did that not help?
I would have suggested promoting ‘uv’ to a vertex or point attribute.
I would have suggested promoting ‘uv’ to a vertex or point attribute.
Houdini Indie and Apprentice » H 16.5 Hair (Simulation) Dynamics
- KaiStavginski
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This seems to behave much better when you set “Reference Matching” to 0. I think maybe there's some weird interaction with the non-1 spatial scale there. I'll look into that.
Technical Discussion » guide/ hair interpolation
- KaiStavginski
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Yeah it should be pretty easy for us to implement such a thing.
I think you could even hack it yourself by setting a different clumpid primitive attribute value on each object's guides. Then you can control the inter-object blending using the Clump Crossover parameter on the hair generate object.
I'm still planning to implement something that actually pushes apart the guides when you use the Part Guides SOP. Just haven't gotten to it. It's pretty straight forward to do it now though with the Guide Bend SOP and it's ability to take a direction attribute, just not a one-click solution yet.
I think you could even hack it yourself by setting a different clumpid primitive attribute value on each object's guides. Then you can control the inter-object blending using the Clump Crossover parameter on the hair generate object.
I'm still planning to implement something that actually pushes apart the guides when you use the Part Guides SOP. Just haven't gotten to it. It's pretty straight forward to do it now though with the Guide Bend SOP and it's ability to take a direction attribute, just not a one-click solution yet.
Houdini Indie and Apprentice » 16.5 Hairgen slow ??
- KaiStavginski
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I'm guessing the fact it took longer without args is just a coincidence? Did you run multiple times?
Did you run that first, maybe? Could be disk caching.
Just to throw in some more numbers - HairSOP2.hiplc took 16.75 seconds on my i7 5960x. It seems like we're having some trouble on threadripper - or maybe on windows. I'll see if I can find out more.
Did you run that first, maybe? Could be disk caching.
Just to throw in some more numbers - HairSOP2.hiplc took 16.75 seconds on my i7 5960x. It seems like we're having some trouble on threadripper - or maybe on windows. I'll see if I can find out more.
Houdini Indie and Apprentice » Cant get Hair Brushes to work
- KaiStavginski
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Doudini
After some more tests I noticed that the Brush Tools dont work correct on Unclosed Geometry. After doing polyfill the brushes lift option and surface brush work. Smooth brush still seems to have issues and I miss Wacom Pressure options to control strength etc. (I know can customize the wrangles inside the guidegroom) But there should be some better default artist friendly options.
Also I Hope one day houdini will get a real brush engine instead of faking things with the stroke SOP, The paint SOP could need some optimization too, espcially for wacom tablets. It feels very limited and clumsy to change settings etc.
I'm glad you found that this was partly due to open geometry. This is probably something we can fix internally, as most operators that rely on generating VDBs (as these do) should close the geometry as a preprocess step.
We do have some limitations still with the stroke SOP & state which we hope to address. But the tools that are in place should of course work out of the box, so please report any remaining issues as bugs.
Houdini Indie and Apprentice » 16.5 Hairgen slow ??
- KaiStavginski
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I'd appreciate any scene files for these cases - 40 seconds to generate 4 millions hairs is longer than expected on a 1950X.
It takes about 28 seconds on my 8-Core i7 5960x with 8 segments and max guide count of 10. It's true that scatter relaxation is relatively slow, it accounts for 8 of those 28 seconds.
It's not as fast as I'd like it to be. Part of it is due to the fact that everything is implemented as HDAs and mostly using VEX. That allows you to dive in and modify things or learn from the system, but comes with many little overheads and isn't as flexible as a full C++ implementation, where we can do smarter caching for example.
You could try to reduce Max Guide Count or guide segment count. You could also enable “Assume Uniform Segment Count” if all guides have the same number of segments, I found that this takes another 5 seconds off.
It's also true that you don't have to pay this cost all the time - hair isn't regenerated from scratch every time you edit something.
I can promise you that a future update (possibly next release) will make the system quite a bit faster.
It takes about 28 seconds on my 8-Core i7 5960x with 8 segments and max guide count of 10. It's true that scatter relaxation is relatively slow, it accounts for 8 of those 28 seconds.
It's not as fast as I'd like it to be. Part of it is due to the fact that everything is implemented as HDAs and mostly using VEX. That allows you to dive in and modify things or learn from the system, but comes with many little overheads and isn't as flexible as a full C++ implementation, where we can do smarter caching for example.
You could try to reduce Max Guide Count or guide segment count. You could also enable “Assume Uniform Segment Count” if all guides have the same number of segments, I found that this takes another 5 seconds off.
It's also true that you don't have to pay this cost all the time - hair isn't regenerated from scratch every time you edit something.
I can promise you that a future update (possibly next release) will make the system quite a bit faster.
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