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jamesr

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jamesr last won the day on October 31 2018

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About jamesr

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    James
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  1. Here's an example to go along, if it helps. prim_l_x_w.hip
  2. Does anyone know of a hotkey/option to mirror a component selection on a symmetrical mesh? I've found myself selecting stuff in the viewport quite a bit the last few days, but can't seem to find anything. Edit: I had forgotten about Attribute Mirror SOP, which is pretty useful for what I'm after, however if someone knows an answer to the above question that'd be cool too.
  3. Grains and constraints not visible ?

    Because vellum configure grains hda does not create constraints between particles
  4. Opacity from Attribute Transfer

    There's a few ways to do this. Here is a simple one using a SOP Solver in the AutoDopNetwork. This way allows a nice fade in/out over time by accumulating a value into an attribute called "illume". The disadvantage of doing the fading like this in a SOP solver is that you need to sim each time you want to adjust the fading. Alternatively, you could also store the frame where the sphere first contacts or has enough influence on a particle, and then post-sim use that to control fading on/off. Changed/added nodes in gold. ParticlesTest_v032_jamesr1.hip ParticlesTest_v032_jamesr2.hip
  5. popdrag - slower particle in selected radius

    Sure. In your note you say "by bouncing from the surface" you mean act like a normal collider, just inside right? Like have the particles bounce around the inside? That's how I read it. Added/changed nodes are in gold. pop_inside_issue_jamesr.hip
  6. Can't Get Rid of Particle Stepping

    Whenever you're running into issues like this, it helps to throw down a Timeshift SOP, uncheck "integer frames", and break the connection in the "Frame" parameter. Use the ladder to scrub forward/back in like 0.1 increments. If the source moves smoothly no matter how granular the unit which which you're scrubbing is, you should be good. When you're simulating and you're caching to RAM, houdini has everything it needs to access subframe data (which is why you're seeing correct results when you don't cache your source). When you cache to disk, by default it saves on whole frames. When the cache is read back in, you only have access to what was written to disk, so when you're running a particle sim with say 5 substeps, and houdini looks up frame 1001.2 of the incoming source, there won't be anything there. The Time Blend SOP will interpolate between frames for you. In most cases, it is necessary to have an i@id attribute on your points, since especially for particle simulations the point count may not be stable, and the Time Blend SOP won't work correctly. Unless there is significant motion in between whole frames, it's not necessarily required to write substeps to disk.
  7. pop replicate 1st vs 2nd input

    The second input is "Reference Stream". You will notice a difference if you are merging the replicated points back in. In the left input, there will be double what you expect With it in the right input, the points will be replicated based on the input, but when you merge them back in there will be the correct amount. Check this example, I think it will help. popreplicate_second_input.hip
  8. popdrag - slower particle in selected radius

    Hi, your issue is in the pop drag node. You have "@falloff" in the activation slider, which is deactivating the whole node, because that expression isn't valid for that parameter. Think of activation as like a "global" parameter for the node. It can't be changed per particle, it's either on or off. Instead, you should leave Activation to 1 and use "VEXpressions" to multiply the drag (airresist) by your custom attribute. Also, you have "0.798" as the point number for your distance lookup in the VOP where you set the f@falloff attribute. You should be careful that it is set to the correct point number. Nodes changed are in red. particles_issue_jamesr.hip
  9. Exporting Material Diffuse Animation

    You can use COPs for this
  10. SDF from density in Dops

    It'd be cool to hear from the source, but here's what I figured out fog_to_sdf_dops.hip
  11. And the demo file doesn't work?
  12. Are you using layer mixing in your material? Or are you just trying to write custom aovs?
  13. Split geometry to parts by proximity

    Could you just ray the target points that are on each target onto your source starting geometry and call those the starting points? Then you have the target attribute/group already on the points, and already once they are minpos'd onto the source geo, they will always be as close as they can be to that target.
  14. Split geometry to parts by proximity

    Hmmm if all you care about is distance to the target geometry, you should be able to just assign an integer attribute called like "target" or something, and use nearpoint() and point() to get the closest one. int pt_near = nearpoint(1, v@P); i@target = point(1, "target", pt_near); and do stuff to your particles from there. You could even make them into groups if you wanted string groupname = sprintf("target_%d", i@target); setpointgroup(0, groupname, i@ptnum, 1, "set"); Maybe I'm missing something? close_point_targets.hip
  15. Here's your same setup, only one line different. See inside the SOP solver. Also to see color better you should unpack. SOP Solver Problem_james2.hip
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