Hey everyone, I know this is really dating me here, but is anyone else in the whole world using spy in Windows? If so, does it work well? I just switched from Linux to Windows, and I see that a few things don't work:
- if I try to take a file, spy tells me it can't take directories, (but they are not directories!)
- if I try to bang-command (EX: !cp), I get a "Command not found" error
Anyone?
Sean
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Technical Discussion » Anyone using Spy in Windows
- mrCatfish
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Technical Discussion » A simple pscale vex problem I cannot solve.
- mrCatfish
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neutrosophicCheck out the attribute adjust float SOP, this is indeed one of its features. The help for this node is very good too: https://www.sidefx.com/docs/houdini/nodes/sop/attribadjustfloat.html [www.sidefx.com]
Thanks so much for your help everyone. I definitely will look into all of this more and see if I can get my setup running simpler or have a more refined and elegant setup. It feels like I have learnt so much just from this one little project. Now I KNOW this might be pushing it. But would it also be possible to map the clones to values in some gradient noise or something to even further super art direct them? Or is that asking too much?
Technical Discussion » A simple pscale vex problem I cannot solve.
- mrCatfish
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You might also want to spend some time looking at the "attribute adjust integer/float/vector" sops that nicely wrap up almost all of these kinds of random and remapping assignments thingies I used to do in wrangles.
Technical Discussion » How to "switch after collision happens"?
- mrCatfish
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Plug the geo into a solver sop, then add a point vop with the first two subnets wired up into inputs zero and one. Grab the attribute using an "import point attribute" from the first input and do the same for the second input. Pipe into a max and bind export this attribute. Now it won't go back.
Edited by mrCatfish - March 28, 2022 10:54:28
Technical Discussion » How to have multiple RBD objects interact with a FLIP?
- mrCatfish
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If you keyframe the "Creation Frame" and set object name to $OS$F, it will work.
Note that "creation frame" is a list of frames, it is not on/off. So what I did was add a channel, and set frame 1 to a value of 1, frame 7 to a value of 7, frame 18 to a value of 18, etc. You can then box-select all keyframes and set to "constant" slope.
Note that "creation frame" is a list of frames, it is not on/off. So what I did was add a channel, and set frame 1 to a value of 1, frame 7 to a value of 7, frame 18 to a value of 18, etc. You can then box-select all keyframes and set to "constant" slope.
Edited by mrCatfish - March 22, 2022 13:37:21
Technical Discussion » RBD fractured objects issue!
- mrCatfish
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I would first try the bullet world scale parm... scale your sim up 100x. Bullet is notorious for rolling-forever small pieces. This causes the HDA to scale up your sim and all forces, then rescale it back down for you. This sometimes works.
If this doesn't work, then change your collision padding smaller. Often just making it 0 works fine. (Tiny pieces can be turned "inside out" by the collision padding.)
Still no joy? Then add a POP wrangle to first second input of solver to quickly ramp down angular velocity (w): (apologies if I stole this from someone on this forum):
If this doesn't work, then change your collision padding smaller. Often just making it 0 works fine. (Tiny pieces can be turned "inside out" by the collision padding.)
Still no joy? Then add a POP wrangle to first second input of solver to quickly ramp down angular velocity (w): (apologies if I stole this from someone on this forum):
// If speed and torque are less than a value reduce the torque
float spin = length(v@w);
float speed = length(v@v);
if(spin < ch("threshold") || speed < ch("speedthresh") ) {
v@w *= 0.1;
}
// If the speed is less than .1
// stop the objects by making them inactive
if (@speed < .1 && @Frame > 1050) {
@active = 0;
}
Technical Discussion » Non-blocking displayMessage() popup ?
- mrCatfish
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I think you can hijack the system's messaging utilities. For examlple, on Linux in a textport:
I don't see a python equivalent to "unix" so I guess you'll have to use hou.hscript to call it. I know that "unix" command works on windows, but I don't know what its messaging utility is called.
set cmd = "this is my message" unix zenity --info --text \"$cmd\" &
I don't see a python equivalent to "unix" so I guess you'll have to use hou.hscript to call it. I know that "unix" command works on windows, but I don't know what its messaging utility is called.
Technical Discussion » Smoke emitter, along curve
- mrCatfish
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Try this... I have both a lightweight sim and the unsimmed "core". I used the orient along curve SOP to generate a velocity in the direction I wanted (had to flip it in the wrangle just after) and rasterized that along with density. High dissipation and only a tiny bit of temperature to add a touch of buoyancy.
Obviously needs tweaking for look, but this is the basic premise.
Obviously needs tweaking for look, but this is the basic premise.
Edited by mrCatfish - March 15, 2022 10:50:38
Technical Discussion » Smoke emitter, along curve
- mrCatfish
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Personally, I would create geo that looked like these trails, scatter points inside the geo, add a velocity attribute and rasterize density and velocity (maybe add a bit of volume noise), then render that without simming. When you're happy with that, you can then use those two fields to birth a supplementary pyro sim (if required).
Technical Discussion » How to stop the tips of skinned spikes from intersecting?
- mrCatfish
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Have you tried the point relax sop? If both the spikes and the skin have a pscale attribute, and you toggle on "Relax in 3d space" it might work (althought it won't know what's "inside" and what's outside so it may avoid to the wrong side). Problem will be that it will snap (it's not a sim) so it will not bounce back nicely. You could of course bring these points into CHOPs to smooth this out.
Failing that, you can use this code to push your geo out of a volume (this code stolen from someone on this forum a long time ago, sorry I can't find original author):
Failing that, you can use this code to push your geo out of a volume (this code stolen from someone on this forum a long time ago, sorry I can't find original author):
// calculate the volume's gradient vector grad = volumegradient(1, 0, @P); // See how far into the volume the geometry is float dist = volumesample(1, 0, @P); // if the geo is inside the volume, move it along // the volume gradient the value of the distance // inside the volume if(dist <= 0) @P -= normalize(grad) * dist;
Technical Discussion » How do I select points based on their colour?
- mrCatfish
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You could also use in a group expression SOP. There really should be a lot more examples in the dropdown of this SOP, (this being one of them).
@Cd.b>.9
Technical Discussion » fluid sticking to surface
- mrCatfish
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Not quite sure what you are trying to do, but it might be good to do a 2d fluid sim, then creep it onto your 3d surface. I've attached an example.
Edited by mrCatfish - Feb. 16, 2022 10:52:13
Technical Discussion » Houdini's hair interpolation not suited for long hair
- mrCatfish
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I'm not sure if this helps at all, (not a hair guy), but here Kai the developer talks about doing ponytails and admits that long hair grooming tools are lacking: https://www.youtube.com/watch?v=uZtKhMkbxkE&t=2081s [www.youtube.com]
Technical Discussion » Poly strips to curve/spline
- mrCatfish
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My favorite way of doing this is to convert to nurbs surface, use a carve with extract, and then convert back to polys. Not sure if this would work on your really messed up surface though.
Technical Discussion » Accessing Attributes on 2nd Input Geo in a Att. Wrangle
- mrCatfish
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// this grabs width from second input f@origwidth = @opinput1_width; // or... f@origwidth = point(1,"width", 0);
Technical Discussion » Who wanna help bringing VFX RBD+Explosions to the next Level
- mrCatfish
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I'm not sure I understand the problem... you talk about particles but it seems this is a straight up RBD sim?
I think you should get a pyro explosion you like, with a matching RBD sim of the car. You can then time-shift them appropriately. At some point you will want the RBD to influence the sim, but I'd start by blocking it out this way before bringing the RBD sim back into the pyro as a collider.
Then do a particle sim for debris and such with the pyro sim's velocity field as a force to advect your particles. You can then also time-shift this after simming to achieve the desired results.
I think you should get a pyro explosion you like, with a matching RBD sim of the car. You can then time-shift them appropriately. At some point you will want the RBD to influence the sim, but I'd start by blocking it out this way before bringing the RBD sim back into the pyro as a collider.
Then do a particle sim for debris and such with the pyro sim's velocity field as a force to advect your particles. You can then also time-shift this after simming to achieve the desired results.
Technical Discussion » How to do talcum powder simulation
- mrCatfish
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I would do a straight-up old school particle sim for the bulk of it. Then I'd use that sim as a pyro source to do a secondary pyro sim to get the cloudy look you see towards the end.
Technical Discussion » Sparse smoke object boundary
- mrCatfish
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Yes, at the same time please bring back the interactive sizing handles and fix the offset issue, (the actual sim does not respect the boundries... there is a slight offset).
Technical Discussion » Copy transform SOP vary scale per copy (alternative to $CY?)
- mrCatfish
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Ah sorry, I didn't read your post carefully enough. Yeah, I can't see a simple way to do it.
My solution would be to toggle on "Copy Number attribute" , and then put the results in a foreach named primitive loop with "copynum" as the piece attribute. Inside the loop put down a transform with $CEX $CEY $CEZ in the pivot transform and scale that way using the current iteration as a seed.
But yeah, convoluted.
My solution would be to toggle on "Copy Number attribute" , and then put the results in a foreach named primitive loop with "copynum" as the piece attribute. Inside the loop put down a transform with $CEX $CEY $CEZ in the pivot transform and scale that way using the current iteration as a seed.
But yeah, convoluted.
Technical Discussion » Copy transform SOP vary scale per copy (alternative to $CY?)
- mrCatfish
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Use the attribute adjust float SOP to create random pscale (or some other scheme), on the template points, and the copy SOP should just recognize that.
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