131 replies to this topic

[eetu]

Hello, all

While learning this beast of a software, I bet everyone has accumulated a bunch of more or less interesting tests and stupid tricks on their hard drives.
Here's some of what has been accumulating on mine, before bit rot takes them, hopefully some might inspire others on this same road..




First, one from the mailing list a couple of days ago

>>Tom Nixon wrote:
>> Is there a quick and dirty way to calculate the center of mass of geometry?
>>
> Louis Dunlevy wrote:
> A super duper cheapo way would be to use the attribute promote sop.
> Stick position in the colour and then promote the colour to a detail
> attribute using the avarage method..
>

The average of point positions is not necessarily very close to center
of mass. think of a large cube connected to a small geosphere, average P
would be a lot closer to the sphere.

Here's a quickly knitted vop sop doing it via a volume;
http://eetu.iki.fi/h..._of_gravity.hip

The idea is to take a volume representation of the object, and
take the average of the voxel positions, weighted with voxel opacity.

Of course there are probably 5 more elegant ways to do it, but anyway..

eetu.

Attached Files

•  center_of_gravity.hip   301.51K   626 downloads

[eetu]

Playing with SDF's.



A font object is converted to sdf, and some particles spawned inside.
After that, the inverse of the sdf gradient at the point location is copied to the velocity of the point, every frame.

animation

[eetu]

More volumes.



This time stacking a bunch of fractal images to make up an i3d volume.

anim1

anim2

- and one from real confocal microscope data, from an ear of a mouse, iirc

anim3

[eetu]

This was supposed to become foam
I was wondering how to make those bubbles that stick to each other, and conform to each other's shape..
The end result is probably something a bit closer to bark or something - but i kinda like the look anyway

[eetu]

This was a small shader vopnet to help Karma build some npr shader.



All it really does is turn all reflections black
(well, ok, it only does ray casting which means the hit point need not be shaded, and it doesn't recurse..)

Attached Files

•  karma_ref_occ.hip   274.61K   427 downloads

Edited by eetu, 02 February 2009 - 05:19 PM.

[eetu]

Something a bit older, as with much of these things I was supposed to do something good looking with it,
but as that hasn't happened yet I'll just post these



This ugly thing is a texture map creator test really. The object is hit by particles, and the texture map gets damaged
at the hit location.

anim, and the texture map after getting hit by the particles.

[aracid]

hey man

I really like the volume rendering man:)
keep it coming !

[eetu]

After talking with the lads at Anima Vitae, who were making snow for their Niko movie, I got to thinking about
how to make foot prints in Houdini.



This is a combination of ray sop doing the penetration testing, and chops keeping the mesh distorted.
Add two spoonfuls of smooth sop to get the bulging sides.

anim

[eetu]

This is a small technique test on how to drive a morph by proximity to another object.



It's really just a bunch of expressions on two point sops. (Although I guess many effects are just that, too :)


..more tomorrow

Attached Files

•  proximity_morph_01.hip   414.09K   574 downloads

Edited by eetu, 02 February 2009 - 04:04 PM.

[Andz]

eetu, on Feb 2 2009, 04:55 PM, said:

This is a combination of ray sop doing the penetration testing, and chops keeping the mesh distorted.

anim

... and I thoght we needed ICE for that?!?!?  

Congratulations eetu, great experiments!

[GallenWolf]

Good stuff mate! Keep 'em coming!

[rdg]

GallenWolf, on Feb 3 2009, 05:02 AM, said:

Good stuff mate! Keep 'em coming!

yeah! don't stop!
thanks for sharing.