XGen VS XGen Interactive

[magillaGuerilla]

I have spent the day evaluating XGen. I created a groom in the regular xGen and then recreated it in XGen Interactive.

Essentially I interpret the basic difference as being Interactive works with brushes and maps (from anywhere) whilst xGenOld works with brushes and Artisan maps. Artisan is pretty shoddy to work with and converting maps to ptex and back is just confusing and redundant.

I liked being able to change the guide density with Interactive. I changed the guide density in XGenOld and lost the whole groom. Undo doesn't seem to work well in either version.

There is no density brush in XGenOld but placing a density map in Interactive had absolutely no effect on the density, I still had to paint out the areas that shouldn't have fur (inside mouths etc). The smooth brush in Interactive only blends shape but not length as it does in XGenOld. The bend brush is gone altogether, this is an extremely important brush and quite tedious to recreate the same effect without it. The elevation brush is also missing, presumably replaced by the 'collide with surface' feature which doesn't really seem to work and causes distortion of the guides as they snap away from the surface after being brushed (or just push on through the surface altogether).

The most noticeable difference is that XGenOld whilst being a bit clunky in it's workflow has a really nice feel when brushing, the guides react as expected and it is very fast to get the shape required whilst in Interactive it is simply horrible to work with. You need to spin the model around to all angles and brush, brush, brush to get something approximating the shape you want. Guide tips seem glued in space and have to be brushed two or three times to get them into the right shape - again this would be helped by having distinct comb and bend brushes.

Also a major drawback with Interactive is that guides on the back side of the model that face the camera get brushed regardless of being completely occluded by a front facing surface that you are working on. I'm working on an animal and the large ears on the reverse side have facing guides to camera - the same would be for working on the back and the legs under the body will also have front facing guides. The workaround is to mask areas, which is tedious and extremely time consuming.

[magillaGuerilla]

haha and now I can't get Interactive to render.


// Error: [curves] procedural_9F418B588B05364A71_curves: invalid number of points (found 0, expected 808080) // 

[magillaGuerilla]

Seems to be due to having two clump modifiers in the stack, turn them off and it renders, turn them on and I get the error.

[bolekCG]

Hi magillaGuerilla

I think it is a bug. You can overcome it by using CUT node with resampling on and cut by 0.001 to "re"generate curves.
Also if you want to use renderDensity multiplier add sculpt node at the top of the tree. Anyway my suggestion for now is to
leave interactive grooming. It is unstable right now. I fought with it for the last month maybe ... since update 3 showed up.
It's great but not production ready yet. I could work for static haircuts or as a guide generator, but it's not fur/hair solution yet.

[magillaGuerilla]

thanks Bolek, it definitely looks promising but I agree it is a bit early to commit to using in production. I'm going to scuttle back to my friend Yeti for this one 🙂

Have you been using the regular Xgen in production?

[Michael_Todd]

In the brush tool options, there is a back face filtering setting, which is on by default. You can adjust the fall off angles to transition the effect depending on the facing angles of the mesh.

Density Masks can be painted or applied as textures on the description base node

Multiple Clumps can be applied and there is no requirement for any particular order for the modifiers to have them render:

The brushes have a "Root to Tip" falloff option so you can use the grab or comb brush to bend the hairs, which is pretty much what the bend brush does for groomable splines. We do have plans to add more brushes though, such as an elevation brush.

The Smooth brush has two modes, Global and Local (hotkey switchable via the N key) which act as implied, Globaly, smoothing out the overal shape of the hairs within the brush radius, form root to tip, or locally, just within the brush radius

The Length Brush also has a smooth mode, N hokey switchable, which can be used to smooth the length transitions

There is also a guide modifier that you can add and create guides, which can then be sculpted, so you can block in the overall shape with guides (or from existing curves) and sculpt those guides

One guide modifier can drive multiple descriptions as well, hooked up via the node editor.

 

There are no ptex dependencies for this system and the only sidecar files are maps and mask you paint or add as textures. Every hair can be cached to an alembic file, including animation, and you can use SeExpr on the parameters via the xgmSeexpr node

[magillaGuerilla]

Thanks for your response Todd,

Can I assume that Xgen has been superseded and Interactive is the focus of development?

backfacing - you are misunderstanding the issue, please re-read. Creature assets have a lot of nooks and crannies to navigate around. Which is also why it is good to be able to deform the mesh (open the mouth for instance) to paint in those difficult areas.

density mask - yes that is where I applied the texture, it did nothing.

multiple clumps - I undertand how it works and that it should work but I didn't conjure that error out of thin air.

root to tip - I played around with that a little, I couldn't understand which way the falloff was supposed to be going. I tweaked it and even fully reversed it and still couldn't get a good feel. It also seems a bit tedious to have to tweak the falloff of a brush rather than just switch to a different brush. Can you create and store your own brushes?

Length brush - smooth in the mode - of course! I missed that.

I am working on a pretty decent machine HP z800 with a Quadro card and I could only work at about a quarter the density of the images you show. It was still pretty laggy and not very responsive.

Obviously I'm not going to get through learning all of the pitfalls and workarounds in a day but be aware this cost me a day's wages to evaluate. I'm keen to keep learning as I am getting more requests from clients to use it.

[Michael_Todd]

The Freeze brush can be used to prevent hairs from being affected. Also, you can use the select brush to select hairs in the areas you want to work on and hide unselected and the brushes will not affect hidden hairs.

The render issues you mention would be good to track down if you could provide an example scene as I can't replicate the problem. Are you using Arnold or Mental Ray?

Cheers

[magillaGuerilla]

I'm using Arnold

[bolekCG]

Hi Magilla, hi Michael

I've never used xgen nor xgen interactive before (in production and/or personal testing). I wanted to learn it. I did some furry creatures in yeti before and maybe I'm a bit used to it ... but it's not the case here- really.
I'm not an expret I always saying that, and I am aware of all current features of xgen interactive and possibilities ( all mentioned in maya help - have read it cover to cover  )
All those things I came across I dropped here https://forums.autodesk.com/t5/maya-forum/interactive-xgen-problems-features-questions-ideas/td-p/70... and
All those showed up in the middle of working on




It was really problematic to get there and unfortunately now i'm not able to cache it and simulate properly. Now I need to switch to classic xgen and try to recreate it .

Could you Michael point me to support team to send whole scene and talk a bit ?

[Anonymous]

Interesting on the node editor output drive.

A question tho, I received a mesh groomed without using guides and it's split into 4 descriptions.

Can I assign a linear guide to the top hierarchy and use that to drive the other 3 descriptions for dynamic simulations?

Thanks

[Anonymous]

bump

[Anonymous]

Honestly, I bumped this, but it really should be stickied, it's one of the few universally relevant Xgen threads and with useful replies to boot. And for how difficult it is to get Xgen related questions answered on here, it might actually be sensible to just build on and expand this single thread in order to consolidate the most useful info into a single thread.

Personally (and I'm just testing this, but it seems solid so far), I've found the method to get best results between Xgen interactive, and XgenOld, is to start with XgenOld, get the shape that you want, while making sure to scale all of the guides to the actual length that you want the hair/fur (best to do the scaling before grooming in the shapes).

Then once you have it more or less perfect, make sure to save, and make an alternative save, then select all the guides, convert them to curves by using the 'guides to curves' tool under the utilities tab of the Xgen window (make sure you're in the 'Xgen' window and not the 'Xgen interactive groom' window. each one has their own window/tools).

Then create an Xgen interactive groom on the same surface that your curves are on.

Create a guide layer in the 'Xgen interactive groom' window, deselect everything, select all of your curves, hold ctrl, then select the guide layer that you created, in the 'Xgen interactive groom' window. Then open the attributes window, the guide layer should be the selection that shows up for the attributes window, Just  make sure you're on the first tab (which should be along the lines of 'guide'). and click the button labeled 'use selected curve as guide'.

If all went right, you should have an interactive groom with all the shaping that you built with XgenOld. Since I'm just messin around with this idea, I'm still partially figuring it out myself. I did play around with it a little to test and wasn't able to use the groom tools on it after, it's possible I may need to delete history or bake it or something before I begin the interactive groom portion, but I'll be sure to update when I get to that point.

Side note: I did initially try this exact project just using interactive groom, and I very much agree with the OP. It's a real pain in terms of detailing, and getting the specific hair, or even hair section, to go in the direction that you want it to, and when you're working in 3D space, that's incredibly annoying. I'm not a programmer, but just from a user perspective, I think a lot of this problem would be solved if you could just groom the guides with interactive groom. But for some reason, in interactive, they seem to be locked.. But if you could, it'd pretty much automate the entire process that I just explained.