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About jonp

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  • Name Jon
  • Location New York
  1. "Proper" simulation of a tornado: http://news.wisc.edu/a-scientist-and-a-supercomputer-re-create-a-tornado/
  2. Ah, Well I haven't looked at your scene to fully understand what's going on, but I do see you are using a blend CHOP... I have also had problems with flipping when using this node. I fixed it by replacing blend with a stack of composite CHOPS. Theoretically they should work the same way, but the composite chops did not have issues with flipping.
  3. Take a look at the following scene. I don't have access to a commercial license right now so you'll have to recreate it, but it should do what you want. It basically reproduces this advice on stackoverflow: http://stackoverflow.com/questions/15873996/converting-a-direction-vector-to-a-quaternion-rotation You build basis vectors from your normal, then use the built-in VOPs / vex functions to convert a matrix3 to a quaternion. odforce_flipping_geo_orient.hipnc
  4. Your goal is to smoothly blend the orientation of your copied geometry, yes? Could you just build some basis vectors from N, convert that to a matrix, then that to a quaternion.? After you do that interpolation is easy, just use a slerp() function in an attribwrangle.
  5. You can also do it in Houdini, in COPS. See the attached HIP. Navigate to the /img context and look at it with a Composite View pane. blur.hipnc
  6. Galiliean-invariant cosmological hydrodynamical simulations on a moving mesh http://wwwmpa.mpa-garching.mpg.de/~volker/arepo/ Note that the codebase used here was the basis for this amazing simulation: http://www.illustris-project.org/
  7. Great tip, thanks! I didn't know if Houdini would lock up anyways using threading. Fortunately it does not!
  8. Greetings, I have a scripted menu parameter that is built from a filtered, sometimes extremely long list of files. When I select a node with this parameter, the first time I do it there is a very long pause where I cannot do anything in the UI. Subsequent access is faster as I'm caching the results of the first lookup. HOWEVER, the first pause is annoying enough. It would be great if there was a way to build the menu contents as a background process somehow and just have the menu script read from a stored list somewhere that is continuously updated (with a caveat message in the menu saying that the list is still being built). Any ideas on how to elegantly do this? Cheers, Jon
  9. D'oh! Just don't use a polysoup when using uvtexture...
  10. I'm looking for a simple way to "break" the vertices along a column on a sphere where uv.x == 1. The reason is because by default the vertices are fused, therefore there is a repeating pattern in the uv on the border polygons. Is there an easy way to do this?
  11. Ah thank you Alex, I wasn't aware of that before!
  12. Probably shouldn't post anything over Christmas / NYE break...
  13. This appears to be the answer: sin(-35.67 + 40.72) / 2. / sin(abs(40.72) + abs(-35.67)) Generalized to: sin(neg_vfov + pos_vfov) * 0.5 / sin(abs(neg_fov) + abs(pos_vfov))
  14. I posted this on the official forum too, but what the heck... Given a camera that is 2048x1536, 0.971 pixel aspect, I need to set the screen window offset so that the FOV is -45.62 - +45.62 degrees horizontal and -35.67 - +40.72 degrees vertical. What's the trig to calculate the screen window offset, given that the vertical FOV is off-center as described above? Any “teach me how to fish” advice would be very helpful… Cheers, Jon
  15. Greetings, I'm a little unsure of what this variable is for, except maybe showing an anaglyph the OpenGL viewport. Does SOHO use it at all? Is there anything I can do to hack it? For example, making my own custom multiprojection camera rig and using the $EYE variable for custom behavior. -Jon