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jim c

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About jim c

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  • Website URL http://learning3dfromscratch.blogspot.com/

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  • Name Jim
  1. I have a faerie creature which in real world units is quite small, maybe smaller than the palm of your hand. The original model is modeled in the scale of a normal person, so about 172 cm tall. I've got the model in this scale rigged up and ready to go. So the question is how to bring it into the scene. Does it make sense to scale up the actual scene so that it everything is scaled up relative to the character and then animate that, and then scale it all back down, including the animated character, after the animation is done? The reason for doing this is that I want to get the feeling of size right, so I presume I need to render in real world units. Is this the best approach or is there a better way to do this?
  2. I've got a sky rig that I would like to cache to disk. But when I use a FileCache SOP at the end of the network, cache it, and then turn of the Load From File toggle, nothing comes back. Are there other steps I need to take to get this to work? sky-nocache.hipnc
  3. Thanks for doing this, the video looks like it covers all sorts of really cool techniques. Can't say how nice this is to see.
  4. I've got this growing tree model, and I wanted to animate the growth sequence starting where it pushes through the dirt. Using the GrainSource SOP and the PopGrains DOP I can get some decent results, so I now have some clumpy particles. Once I have those what's the best approach to rendering them? Would it make sense to use them as the source for a voronoi fracture sop and have the particles drive the various pieces? Or is there a better approach?
  5. And here's the result now, a couple of captures of different frames
  6. OK so I more or less figure out how to get this to work. First problem was that when I switched to the UV viewport, the UV's didn't show up so it was difficult to tell what was going on (they were there however, I could export the model and see the uvs in Modo). Next step was to delete all the branch geo as it was being created. Using a delete Sop with an expression that checked against the gen attribute (that's supplied by the Lsystem) pretty much did that. Next I used the UVLayout Sop to layout out the various UV islands that the PolyWire SOP creates more or less horizontally. This is done with UV at the vertex level NOT at the point level. After this was done I used an attr promote sop to calc the max UV value and store in a detail attr. Created a Attr Wrangle Sop to adjust the uv.y value so its gradually increasing as a function of uv.x/maxuv.x value. At this point we've got twisting UVs, not matter what frame we're on! The rest was re-suing the existing technique I'd worked out for the static hand built uv's I'd made in Modo. It's not perfect, when you promote the vertices UVs to point UVs there's some distortion that happens at certain areas, but I can live with that, maybe some clever camera angles to avoid focusing on those spots.
  7. if the grid is flat, then you could use the normal() expression, pass in the grid's path, pick any prim, 0 should be fine, and then use that in the Knife SOP's direction parameter.
  8. Couple of things you can do. Look up "Box Modeling" and you'll see how a simple box can be divided up and manipulated into more complex forms, like a head. To start with that drop down a Box SOP. You can then go to the Polygon shelf and use the cut lines or edges (I can't recall exactly what it's called), but it lets you interactively place new edge loops in your geo. That lets you add more detail to the mesh, where you want it and form there you can use the edit sop (typically in Point mode) to manipulate (transform/rotate/scale) points. If you just model one side, along the x-axis for example, then you can delete the other side, and use the Mirror SOP to mirror over your geo. You can use a series of metaballs all merged together and fed into a VDB Volume and then converted into a mesh (Convert VDB SOP) as another way to set up some core forms, and then use the retopo tools to give proper edge loops. There's the NURBs tools as well, but those are probably more hassle then they are worth.
  9. Thanks, I wasn't thinking along those line, it's a project for my wife, she wanted a magic growing tree Unfortunately it's taken forever to get done. Id be happty to write up the basics of how it works though (most of the core is coming up with some nice L-system code).
  10. I've got a nice little lsystem that is producing a tree. The goal is to animate this process. So I'm going from this to this over around 360 steps. So far so good. The only real problem I'm having is how to best generate UVs while it's "growing". To add nice detailing to the geo I use the UV data to apply some deforms. My problem has been that to get this to work nicely I hand built the UV map in Modo using the last frame of the tree's geo like so: Then I used the UVLayout SOP to layout all the islands horizontally along U, and then gradually increased the V values as they run along the new U coord the to "twist" the UV, which then makes it easier to deform it to this: I don't need to do this to all the geo, just the lower trunk portions, the higher branches don't matter they'll be hidden by all the leaves anyways. So, the question is, how to apply UVs like this for the rest of the previous intermediate frames? I've tried to use a wire deformer to get the final geo into a similar position as the growing geo and then use an attribute transfer SOP for the UVs, but that doesn't work so well. Another idea I had was to use a foreach block to isolate the individual branch pieces and then somehow regenerate uvs for each piece, but while I can get the foreach to work I haven;t figured how to re-apply the UVs. The geo us being created with PolyWire Sop which I think I need to stick with as it gives the best results at joining everything together. I've cached out various pieces, so I have access to the underlying lsystem wires (prior to it being fed to the PolyWire sop) if that helps. Any ideas would be most appreciated! Thanks
  11. I have a chunk of geometry, lets say a tube, that's off in space, and it's been rotated around. I'd like to "normalize" it, to translate it to the origin, and then rotate it such that's point straight up in the Y axis, perform some operations on it, and then put it back in it's original position and orientation. I know how to normalize the translation, but I'm stuck with the rotation stuff. Is there a sop that does this or some vex that would point me in the right direction?
  12. Wow! That's some super cool stuff - the animation features look really, really cool, very curious to see how these work!!! Congrats! The ocean on the twisting strip looks really cool, that's a great demo. Compiled SOPs!? Hardware accelerated SOPs? some really interesting stuff in the release!
  13. Thanks guys, both of these are real interesting ideas.
  14. I'm trying to generated noise that flows along the topology of the geometry. But I'm missing something obvious about how to do that. The red arrows indicate how I'd like the noise to flow. The geo is generated by using the polywire SOP. The only other thing I can think of is using COP to generate a texture map with noise and then read the data from that.
  15. So I broke down and ordered a 970 from macvidcards - fingers crossed, hopefully this will be a nice improvement over the thermal disaster that is the Quadro 4000!