There should be further clarification in the docs on how to use Clumps on *animated* geometry. I'm in the middle of a production right now and we have huge issues with fur on animated geometry, when we try to use clumps.


Dragos

digitallysane
There should be further clarification in the docs on how to use Clumps on *animated* geometry. I'm in the middle of a production right now and we have huge issues with fur on animated geometry, when we try to use clumps.

Could you post a simplified example illustrating the issues? The main ideas to remember when using animated geometry with fur are:

1) Use a Rest Position SOP on the skin geometry before animation is applied.
2) The “rest” and “clumporigin” attributes and number of clump hairs should not be animated.
3) Use a Fur SOP to generate the clump curves instead of other methods (eg. Scatter SOP).

derrick
2) The and “clumporigin” attributes and number of clump hairs should not be animated.

This part is not mentioned at all in the docs (or I missed it, so I was using the suggested $TX, $TY and $TZ).

This can be helped by 1. a more developed documentation for fur on animated geom and 2. some docs on the internal workings of clumping / fur sop, as it wasn't so obvious for me that I shouldn't animate the attribute (thanks Gene)

Also, the Fur SOP gives a message when fed the clumps (“Skin attribute ”rest“ is shadowed by another attribute” (or “N” or “uv” etc) ). What should be done with the attributes passed down the stream by the Fur SOP which generates the clumps?

Dragos

digitallysane
Also, the Fur SOP gives a message when fed the clumps (“Skin attribute ”rest“ is shadowed by another attribute” (or “N” or “uv” etc) ). What should be done with the attributes passed down the stream by the Fur SOP which generates the clumps?

The CVEX shaders used by the Fur SOP will look for attributes from the clump, guide, and skin geometries, in that order (the warning will be generated if you provide the attribute on more than one of the geometries).

I recommend only specifying attributes unique to the clumps on the clump geometry. Unless you have created some custom clump attributes, this will only be “clumporigin”. On the Fur SOP used to generate the clump hairs, set the “Skin Attributes” value to “clumporigin” and clear the “Guide Attributes” value.

derrick
On the Fur SOP used to generate the clump hairs, set the “Skin Attributes” value to “clumporigin” and clear the “Guide Attributes” value.

Here http://www.sidefx.com/docs/houdini9.1/fur/clumping [sidefx.com] it says to put clumporigin in the Guide Attributes field. What you say makes more sense but then there is a bug in the docs.

Dragos

digitallysane
Here http://www.sidefx.com/docs/houdini9.1/fur/clumping [sidefx.com] it says to put clumporigin in the Guide Attributes field. What you say makes more sense but then there is a bug in the docs.

Yes, that was a bug in the documentation and should now be fixed.

I seem to have followed most of the instructions fairly well, but my procedural shader is not picking up the clumping. Also, if I plan to animate and cant put $TX $TY $TZ in clumporigins value, what should I place there?

we're also having trouble getting clumping to work. It works in the viewport but not in the render…

uen
Also, if I plan to animate and cant put $TX $TY $TZ in clumporigins value, what should I place there?

Since for animation you already placed a rest sop up in the chain (look into the Fur docs for that), you can use $RESTX, $RESTY, $RESTZ.
Frankly, I think it's a mistake that SESI insists in suggesting the position values in the help for clumporigin instead of the rest position ones. It will hit newcomers again and again.

Dragos

Hi all,

Thanks to Dragos for the tip, Acctually in the documentation the animation part comes laterso so I didnt l know about the rest s sop portion. But I will give that a try . I'm still having some issues with the Fur procedural It doesnt reflect the furstyle setting s I have set. The vei viewport will reflect twhat I set in the furstyle but the fur procedural wont. Any one have a idea why?

Hi all,

I converted my guide harirs into wire objects and did a dynamic sim on them and tried giving tg them an initial pose . buit when I try to render the fur the rendered fur doesn ‘'t follow the guides direction at all.

Things I checked already:

My fur procedural does have the guide geometry feeding into it so that s not the issue.
Also the fur procedural was working with the guide hairs before the intial pose was set up .

Things I’m willing to consider:

If there is a better workflow for styling hair that I will try to animate along with a a character please point me n the right direction .

Hi,

I'm trying to get through the fur tutorials (the first I've attacked), but I'm having some trouble. Well to be honest, the first tutorials were the video introductions to the UI. I guess this proves how fresh I am. Though I have around 11 years experience working with just about every 3D program, including one that was proprietary, I haven't been in Houdini since version 4 (2001?), and then only for a one week training at SideFX. I'm sure if I had used it in production back then, I would be in a much better head-space… oh well. I hope I am a good test for these tutorials.

In the “Basic fur setup” tutorial, I can't get the custom width parameter (created in the attribCreate node) to have any effect on the render output.

In the “Using guide hairs” tutorial, when I plug the guides reference object in to the hair shader, it causes an error in the render:

fur: “The two sources have unmatched geometry.”

I have attached a file which should illustrate both of these issues.

I have triple checked my work, but as a Novice, I'm sure it is possible I am still overlooking something. Could it be both of these problems stem from how I used the extract tool? This is the only part which I really don't understand (I was hoping to avoid black-boxes in Houdini) The text reads:

Select the SKIN_OUT node in the network editor, and select the grid in the viewport, then click ‘Extract’ on the Modify shelf tab.

The problem is, I can't seem to figure out how to select “the grid” (I'm using a sphere) in the viewport. I'm in the sub-object level here. Why should I have to select one in the network editor and one in the viewport. I ultimately shift-selected both in the network editor. It worked and created the nodes, but perhaps something broke somewhere? I checked the merge nodes in the skin and guides reference objects and they are identical. How can you tell which one uses which “out” node. Perhaps this is where the mistake is?


It seems like things would be more intuitive if there was a “shader out” node, or something. At least I could see the flow in the network editor instead of having to rig nulls as outputs which then go back up to object level just so the shader can reference something lower. It would get rid of all the flag work-flows as well, assuming there is a way to access all the info the shader needs there. I'm rambling now…


Ok, I'm ready to learn something new.


Cheers,

- Rafe


P.S. is there a search feature for this forum? I posted this in the apprentice area before I found this thread.

Yes, right at the top of the forum, press Search.

Hi Again,

I just wanted to make a semi-off-topic comment without further cluttering my last post.

The quality and look and feel of the documentation/help system in Houdini blows everything else out of the water. I have never turned to help docs as my first option before. Usually I don't bother until I need SDK reference, instead turning to friends or Google or websites.

Did you guys even bother making a paper manual?

Having scene files with the tutorials would be the topping on the cake. It would have saved me from typing most of my last post.

Nice work!

- Rafe

- Rafe ………

Good to see you have finally picked up Houdini , read the docs though !!.Thats why they are there.
Are you still working with Steve R ?.He mentioned Houdini and testing it when I last spoke to him !. I take it your the “Trial Monkey ” !.

regards

rob east

circusmonkey
- Rafe ………

Good to see you have finally picked up Houdini , read the docs though !!.Thats why they are there.
Are you still working with Steve R ?.He mentioned Houdini and testing it when I last spoke to him !. I take it your the “Trial Monkey ” !.

regards

rob east

Hey Rob!

Nope, the only monkeys here are in the trees outside. It's (sort of) unrelated. Honestly though, you shouldn't have posted. Now you're going to start getting questions in your email :wink:.

- Rafe

Hi everyone I would like to calculate the distance between the guide hairs I'm using and the geometry the fur is being generated on then use that calculation to prevent the fur from penetrating the surface during animation.

Why do it this way? I want to try animating the guide geometry with a lag chop instead of a wire dop. in that case I don't want to use Rbd's and would like to rig up some type of repelling system. I'm not really creating a fur look, its actually hair for a horse's mane.

Any advice would be appreciated greatly!