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rich_lord

Learning DOPS, motors, constraints etc

22 posts in this topic

I've done some more tests with motors. This time trying to create a bunch of them procedurally at once. Getting all the name attributes to line up was a little tricky on some of them, but I understand all this so much better after doing this.

 

Getting the axis of the motors to do what I want was also a bit tricky, but I've mostly cracked it now.

 

I've put all 5 hips that make up this video on my tumblr here - http://richardlord.tumblr.com/post/139634705771/hipfile-hipfile-hipfile-hipfile-hipfile. The sims will need to be re-rendered into the ROPs for you to see anything.

 

Thanks! Hope you enjoy!

 

 

 

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Thanks matt - I would love to! I haven't even made a single FEM object yet. I'm crossing my fingers that all the dynamics stuff plays really nicely together.

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Fantastic stuff Richard , i'm also a big fan of your 12 robots in a box animation !

 

You're stuff remind me the era of the MEL Bot war, where we build bots in Mel inside Maya and do virtual fight beetween them.

That would be fun to build this kind of things with Houdini.  

 

SESI should do something like this ...

a Houdini FX license for the winner !

 

http://www.melbotwars.com/index_lo.html

Edited by sebkaine
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That would be very cool if SESI did that sebkaine. I bet we would all learn so much from each others setups too.

 

Just in general I would love to see strange RBD creatures that people have created in Houdini. I wonder if it could be an FX challenge or something?

 

I had never seen MEL Bot war before. I have used maya for 10 years, and still wouldn't know where to start doing something like that in MEL.

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well actually the main part was using rigid bodies like you'r setup, MEL was use to implement some sort of inteligence.

but it was using the old RBD system in maya which is now prehistoric.

 

Well if i had to do a fighting robot in maya i will probably start with nParticles / nHair / nConstrain, but that wil be far less impressive than you're stuff in H.

 

I really love what disney do with the microbot in big hero 6, this idea of having small simple piece that propagate and aggregate intelligently would be a 

great challenge !

 

there is a publication about this :

microbot.pdf

Edited by sebkaine
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sebkaine it would be a intressting challange.... the contest part of sesi website is pretty empty...

even a houdini indie as a win would be nice... :-)

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In case this is useful for anyone, I recently had a few misunderstandings about how pin constraints work in rotation mode. Heres a simple file with a bunch of basic constraints setup with packed primitive, and regular rbd objects. Both SESI and a  helpful chap over in this thread  recommended the conetwist constraint instead - which works well in the tests ive ran so far. 

 

It makes a good hinge joint, and you can layer on a world aligned rotational spring constraint if you want to make it springy. 

 

Here's an example of a few useful setups. The examples colored red are an example of what not to do.... Its a gif so click on the piccie to see the constraints in action. (its not very exciting)

 

hip file

post-7586-0-61944700-1458093969_thumb.gi

Edited by rich_lord
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Getting servos working has been bugging me for a long time. I want to set exact rotation values for them rather than just setting motor forces. 

I finally got them working for both packed and unpacked geo.

you can get the hip from here :- http://richardlord.tumblr.com/post/157323581986/hipfile-got-servos-working-using-both-normal-geo

17_02_16_servo_packed_and_unpacked.gif

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Recently I wanted to make constraints based on impacts. I finally managed it. Here's the basics of the system. It uses a couple of ForeEach SOPs to step through and delete any constraint between the same two rbd's.

Phew! This one was really tricky to work out.

The hip file is available here

17_03_06_constraints_on_impacts.gif

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Thanks very much for these...NOM NOM NOM NOM NOM NOM...

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These are seriously very cool experiments to watch. Thanks for these!

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Very Pain!

I assumed creating constraints at the position of the impact would be easy. NOPE! You have to transform each impact point into the rest position(Easy) AND the rest orientation(NOPE!). Luckily i'd done this about 100 years ago and I vaguely remembered how.

Here's how to do it. You can get the file here

 

17_03_10_constraints_on_impacts_at_impacts.gif

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I made some renders using the constraints on impacts setup I made. The sims are pretty crappy, but the basics of the system seems to work solidly enough. It would just be a matter of tweaking all the settings to get a smoother result.

Each pair of RBDs gets no more than 1 constraint. I think it might work better if I allowed a few more, as the RBDs can spin around on this constraint, which looks a bit unstable.

I posted the hip files for this over here: http://richardlord.tumblr.com/post/159194692191/crappy-sims-of-a-system-that-builds-constraints-at

 

Edited by rich_lord
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I have a hip file I use a bunch which contains some of the common tricks I always need, but constantly forget how to do. I thought i'd share it. Mostly its VEX/VOPS stuff to manipulate point transforms, a lot of it revolves around creating and using the orient attribute. 

I'll update it as I go I imagine. When I discover something new, I plan to throw it in here to prevent it eroding from my brain.

Must give a shout out to mestela - http://www.tokeru.com/cgwiki/index.php?title=HoudiniVex , f1480187 and anim, who have helped me understand these things a bunch (even if they don't realize it). Thanks chaps!

http://richardlord.tumblr.com/post/159277887181/ive-started-collecting-a-bunch-of-tricks-i-use-a

math_file.jpg

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I love springs, but never attempted to make them in Houdini. I spent a few days making a SOP asset to do it.

There's 4 types. 2 with hooks on the ends, 1 terminating in central lines, and another that has no end. There's also ramps for adjusting the radius and the distribution of the coils.

All you need to do is feed it two points and it should just work........ The interface is not that great, some parameters dont do anything for certain spring types.

Its not the fastest, its mostly made in VEX, and there are no uv's. All the stretching and scaling is also done in VEX that gets slow once there's tons of points.

I put the hip here - http://richardlord.tumblr.com/post/159989136826/i-made-a-quick-spring-asset-because-i-love-springs

spring_pic_b.gif

spring_pic.gif

Edited by rich_lord
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