Hi,
I have a modified version of the trail example where I have copied a bunch of circles to each trail point. Just wondering how I skin each trail individually? The point count of the particle system creating the trails is changing per frame.
Hello @smurf
It’s currently not possible to set on the Skin POP a varying number of primitives to group. For now, you could use the GLSL Advanced POP to manually create the skin primitives.
I’ll take a look. Thanks Guillaume
for later down the line , skinning based on attribute (like Partid ) , would be handy …
Thanks, we’ve noted the suggestion down.
Hi Guillaume, I had a look at the docs Experimental:Write GLSL POPs - Derivative
I also had a look at the GLSL Advanced example in the file “POPs examples - Second release”… and I am finding it hard to piece together how to proceed. Are there any other reference materials to do this kind of thing? Or any chance of getting a simple example file to get started? No probs if not. Thanks!
Hello @smurf,
Echoing Guillaume, we’ll plan to make this easier in the future, for now a workaround to be able to use the skin POP is to use the line divide to resample each line strip to have the same number of points, which allows to use Groups of N prims on Skin POP, see attached.
trail_sm_lineDivide.toe (2.5 MB)
edit: you might notice some flipping in the tubes along the line strips in the file above, it’s because the copy POP uses an up vector, also something we plan on improving, having line metrics POP output an orientation frame that doesn’t flip
Otherwise regarding GLSL examples, in the alpha 6 release zip here Alpha 6 - now available - #3 you’ll find a GLSL folder in the Examples folder which tries to demonstrate how to use the GLSL POPs, let us know if you have any questions.
we’re planning on making the doc easier to start with, and do more examples, right now it’s mostly just a list of the built-in functions
Hi Vincent, Thanks for the example file, much appreciated! I will also take a look GLSL folder in the alpha 6 release. I am looking forward to the improved orientation frame you mentioned too.
Cheers!
With the example file, I occasionally get streaks of lines that seem to go to the origin. If I make the lifespan of the particles extremely long so they do not die - I do not get these streaks. Is there a way to have particles dying and not get the streaks, so the sim is a more optimised? This happens on the Line Divide Pop. Thanks!
Is this a bug? Thanks!
It looks like there’s a bug with the Line Divide POP when there are only one point in the trail initially. We will look into this, thanks.
Amazing, Thanks again @Guillaume.L ! In the meantime I will look into ways of culling one point trails. Cheers!
trail_sm_lineDivide_cull_1vertls.toe (2.5 MB)
In case you’re wondering, here’s a way to cull the 1 vert line strips with a single delete POP, using the _NumVertsPrim built-in attribute.
edit: another temporary workaround is to switch the interpolation mode to cardinal on the line divide instead of linear which is not affected by the bug
Thanks for the example file @vincentDev ! I had overlooked the intrinsic attributes (if that is what you call them). I made an extra attribute on the Line Strip Metrics - LineStripLength and was using that. Your method is more efficient, thanks!
The next build, which is coming in the next 2 days, will allow 1-point line strips, and handle them properly.
great news! Thanks @greg !
I responded that a fixed build is coming shortly, but we are testing more changes in an Alpha 6.2 which is not finalized, but if you are in a hurry to get it, a Windows pre-release version is in this here, which we will replace:
< deleted since Alpha 6.2 is now generally released >
I’ll take a look. Thanks @greg !
I would like to use the curve POP node as a starting point (for the scale factor on a copy POP), then edit the curve. I came up with a method of converting the curve to chops then doing a raw edit on a locked chop. Is this the best or most direct method for manually editing a curve? Thanks!
