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About lugnut

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  • Name
    John Baumann
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    New York City
  1. Bacterial Growth with Bullet

    Thanks for the link Tesan- The hip visualizes data of bacterial movement but unfortunately doesn't show replication and most importantly for me isn't procedural. Might come in handy though! -jb
  2. Bacterial Growth with Bullet

    Trying to do bacterial growth with bullet, I can grow the bacteria rods with the v@scale attrib and then replace the extended rods with two split bacteria, that then grow and split: replicate_bac_8-31.mp4 The problem is that the rods don't get pushed around like I would like. They wind up all oriented the same and pile up on each other. I am sure it is due to how I am sourcing the split prims... When I simply spawn the rods and then grow them they push each other around properly: spawn_bac_8-31.mp4 Here is the hip file with both the grow and split and the spawn: bac_replicate_rnd_01.hiplc There's an old post on this topic that has a good reference for the bacterial replication, but no attempts at using bullet: I also tried going back to 18.5 and using intrinsic transforms instead of what I suppose is the naive method of copying to points, - and using the reset bullet id trick instead of the @scale attrib as in H9.X - but the results were pretty much the same, here's the hip for that: bac_rnd_18-5_01.hiplc And also some other nice ref showing how the bacteria can twist and make strands ( ultimately the goal is to show a similar effect): elife-32976-video3.mp4 I would appreciate any insight into this - a lot of this bullet stuff still seems like voodoo. For instance I am merging the new prims with existing prims and then deleting the old prims just to get the bullet attribs on them, I couldn't find any information about how to properly initialize new bullet prims for example. So thanks for any attention to this -jb
  3. Upshot is just setting scaleinheritance to 1 for the entire chain works for me, only individual joints scale and none of their children. Thanks Matt for getting me off the path of trying to set it for separate points (which seems to render the scaleinheritance attrib ineffective?). For context attached a scaled down version of what I'm doing - a stretchable spline IK body with a not-stretched head - to at least add to the kinefex examples on the forum. kinefx_notopscale.hiplc I still have to do a little extra work if I want to scale all of the joints of the body with a single parameter- I guess a separate rigpose for scaling with the scale parameters linked and then a skeletonblend? Although setting scaleinheritance to 1 on the chain works on this I suppose there are scenarios where you would want to have inheritance behavior vary down the chain ... possibly breaking up the chain and using the parent constraint vop later?.. I am just getting into the rig vops, tho -jb
  4. yes, that works (setting it for every joint/point) , but you if you set scaleinheritance to 4 for only children of the joint and not the joint being scaled, ( so that the other points have scaleinheritance set to 0) it seems to have no effect. Or even if only the first joint is set to 4. I was trying to have the scale inherited at the beginning of the chain but not inherited farther down the chain. So it looks like scaleinheritance wont allow me to do that? kinefx_scalemode_2.hiplc
  5. Title says it - is there any way to have a parented joint not inherit the scale of its parent joint? I tried setting scaleinheritance attrib to 4 both before and after the rig pose - no success. I assume there is a rig vop or wrangle solution. I made a naive attempt of getting the transforms, extracting the scale and replacing it with scale from an inverted transform but that didn't work either. Any ideas?
  6. Get An Attribute equal to Frame

    Sorry! In my mind it was easier than reality - I forgot you need a solver sop to retain the frame value. Attaching a file. capture_frame_w_solver.hipnc
  7. Bulk rename

  8. Attribute Transfer by ptnum

    You have just described the functionality of the Attribute Copy node. Plug the second set into the first input and the first set into the second. The default settings will do just what you want, setting the Cd attrib on the points
  9. Get An Attribute equal to Frame

    Not sure if this is what you are asking but if you want to save a frame or time when something happens for the first time this is a simple way to do it: Let say you want to save the frame when a point reaches a certain height. First set with attribute create or wrangle: i@theFrame = -1; then in another wrangle: if(i@theFrame<0 && @P.y> someHeight) @theFrame = @Frame; the theFrame attrib will only be set to hold the frame number one time: when the is greater than the threshold and it hasn't already been set
  10. Wire constraint network Question

    Ah thanks! should have tried that!
  11. Wire constraint network Question

    Hi all- Building a procedural constraint network for wires by connecting the interior points in a grid. It works fine for some grid dimensions, but not others, where the sim blows up. shown below a 5x5 and a 6x6 grid. A 15x15 grid will work fine, but a 6x6 one won't. Curious! I'm building zero-length constraints from the interior points and setting the anchor points as follows: int wirepts[] = nearpoints(1,@P,.0001); foreach (int wpt; wirepts) { if(wpt != wirepts[0]) { int pt1 = addpoint(0,v@P); int pt2 = addpoint(0,v@P); setpointattrib(0,"anchor_id",pt1,wirepts[0]); setpointattrib(0,"anchor_id",pt2,wpt); int newprim = addprim(0,"polyline",pt1,pt2); setprimattrib(0,"constraint_name",newprim, "WireGlue"); setprimattrib(0,"constraint_type",newprim, "position"); } } setpointgroup(0,"delete",@ptnum,1,"set"); I delete the original points later - I'm not using the first of the nearpoints to avoid a prim with the same anchor points, I thought that might be the problem, but it didn't seem to matter. Does anybody know the reason why this happens? Am I missing something? Thanks - I'm including a sample file. wireGridConstraints.hiplc
  12. Copy collision cd to geo

  13. I'm doing a simple "flicker" animation where I use a COP blend node with the factor param controlled by CHOPs to turn frames on and off. I can render to a flipbook, but the composite ROP just gives me black frames? Anybody know why this happens and if there is a workaround ( besides saving from mplay)? BTW the replacing the blend with a switch COP dosen't work at all, I'm assuming because the switch is not cooking the input, is that correct? Thanks for any info
  14. OBJ transform to SOP lvl

    I don't think there's much of a difference performance-wise between transforms at object versus sop level. So you might just copy the channels from your object to a transform sop and delete the ones at the object level. Otherwise you can use an object merge in another object and set transform to "Into This Object".