# Martin B

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1. ## Scaling geometry in CopyToPoints operation

If your points have a float @pscale atribute then CopyToPoints will automatically scale to that amount. I think it will also work with vector called @scale, and scale them in x/y/z. Make a pointWrangle and try either of the below to see it working f@pscale = rand(@ptnum); v@scale = rand(@ptnum);
2. ## Self moving/motivated RBD objects?

Hi there, I'm trying to make a load of vegtables roll along the ground (might have to go up inclines, around bends etc), but in a purposeful motivated way, think zombie vegetables. I've been playing with various RBD sims and am getting some ok movement but there's a large variety of odd shaped veg, some skid and some end up stalling. Also working in some slighly strange movements like a cucumber but its moving end over end instead of rolling. So I was thinking of trying to set something up along the lines of one of those balls you get for pets that has a little motor inside it https://www.youtube.com/watch?v=gBGwoxU8yEs But I wasn't sure how to approach it... In my head it would be animating the centre of mass to be lower and in front of the direction I want them to travel. Or is there a simpler way to cheat it? Any pointers would be greatly appreaciated, I'm comfortable in Houdini but dynamics isn't my forte. Cheers Martin
3. ## Self moving/motivated RBD objects?

Ah brilliant, can't believe I didn't know about Rich Lords blog. Thanks ever so much for tokeru as well, such a wealth of information!
4. ## alembic [SOLVED] per-particle attributes Maya to Houdini via Alembic

Don't worry, you have to list the attributes in the alembic export window but I was naming the wrong. They also seem to go into the detailed field in houdini instead of the primitive list like above, but reckon I can figure it out now
5. ## alembic [SOLVED] per-particle attributes Maya to Houdini via Alembic

Bumping this old thread in the hope that someone sees it. I'm having trouble getting Maya to export PP attributes, P, V and ID are there in Houdini but nothing else. (They're not there as primitive attrbs that I can promote yet) So I think I'm missing something on the Maya side, but there's not really any options on the Alembic export. I'm trying to bring across some of the firework's examples that are in the Content Browser for a quick turn around job. Cheers Martin
6. ## Finding out how many edges are connected to a point? (and a few other questions...)

Hi there, I want to rebuild an old tree model that uses cards with opacity maps and swap them for geo. Conveniently each 'card' is a pyramid with the centre point next to the branch. So the idea is to find the centre point of each card by the fact that is has 4 edges connected to it while the outer points only have 3. Then average the vector between the centre and 4 edge points, which will give me an 'up' vector, which I can then use to rotate some geometry around it. How would you go about this? I'm fairly new to Houdini, so I know the steps I want to take but actually executing them is proving difficult. And assuming there's a few thousand leaves on the tree this has to be relatively economical to run. Should I instance geo onto the leaves (with random scale/offset/noise), or would using curves/fur make more sense? Its a pine tree kind of thing so has spines more than leaves. Below is a simplified version of what I'm trying to achieve. Thanks for any pointers. Cards on branch Replaced with geo.
7. ## Finding out how many edges are connected to a point? (and a few other questions...)

Thanks for the direction. I made some headway and learnt some cool stuff but ended up using a fur system straight on the branches. Its come out pretty good for what I need so going to go that route.
8. ## Hair Shader question for white/blonde hair...

I posted this over on www.sidefx.com but this site seems to get more love. Still pretty new to Houdini but done some searching around on this topic and could use some input. Hi there, I'm trying to shade a fairly long haired dog which has almost white hair with lots of blonde/yellow coming through on the denser area's, especially when backlit. I'm almost getting there with the inbuilt Hair Shader but was wondering how others are doing this? At the minute I can turn on Transmit Objects which produces a nice backlit effect but is incredibly heavy to render. Is this essentially path tracing dual scattering? The other option is to only use Transmit Lights to get some transmission and use the Fake Caustic options under opacity to lift the darker shadows, which renders quickly but doesn't have the depth of going the full Transmission route. Are there any ways to cheat the dual scattered look? I've had a read of the papers but its a bit beyond me… Any help is much appreciated Martin
9. ## Hair Shader question for white/blonde hair...

He's some crops from the other day, Beauty, DIFF and TRANS. No texture maps, just white hairs and the transmission pushed to yellow. Its had a fair bit more work done to it since, texture maps, getting more control over tip/root blending, figuring out the specular and wet mouth stuff, not a million miles off the live action dog, bit more love and some comp work should be good.
10. ## Hair Shader question for white/blonde hair...

For those interested I went with having Transmit Objects turned on and dropping the refraction limit right down, this gave 90% of the transmission effect I was getting with a higher limit but rendered in half the time, and then graded that AOV up in comp, along with a little bit of the fake caustics I managed to get a pretty nice soft looking hair with loads of scatter.
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