If it can help, here's a basic scene showing one common approach for making strands: https://filebin.net/6ml27y3atb6qd7iq
On 2 March 2017 at 20:17, Tim Bolland <[email protected]> wrote: > Thank you Andy that's a really helpful summation, I'm going to give it a > go :) > > > ------------------------------ > *From:* [email protected] < > [email protected]> on behalf of Andy Nicholas < > [email protected]> > *Sent:* 02 March 2017 13:12 > > *To:* [email protected] > *Subject:* Re: [Houdini] Working with strands the Softimage way > > > Just to confirm how I'm thinking about this, a strand in Houdini is > typically made up of point positions, not points with arrays as attributes. > You can manually add an attribute to each point position to say which > strand it's part of, there's a node that generates lines that will > then understand this? > > > What I'm saying is that's something you can implement yourself. There are > no nodes in Houdini that understand a point with a vector array is a > strand, and no shaders that will do that automatically either. Again, you > can build that yourself if you like, but it's quite advanced if you're > going to be delving into procedural geometry shaders. > > Otherwise you can create polyline primitives and feed point IDs into it. > This will generate a polygon line (polyline) between the vertices in the > primitive, and in some ways this is just like the point[pointarray] > technique. > > > Yep. A polyline is nothing special. Just an unclosed polygon. As others > have pointed out, you can apply attributes to the points to set things like > width and color. Or you can use something like the PolyWire SOP to generate > your own rendertime geometry. > > The key is how do you create these point clusters and the order. In ICE I > would make strands using a build linearly interpolated array with two > vectors feeding into it. I guess I could try and recreate this using > vex/vops, and maybe that's what I'm after, I just need to find a way to > manipulate all these points in the right order. > > > Easiest way (assuming you already have some animated points) is to use the > Trail SOP with it set to "Connect as Polygons", turn "Close rows" off, and > set "Trail Length" to something like 10. Next stop after that is to take a > look at the Resample SOP. Especially the "Treat Polygons As" parameter, as > that'll let you create interpolated shapes to your trails which is kind > handy. > > A > > > > > On 02/03/2017 12:58, Tim Bolland wrote: > > That's a good point Andy, and in my mind this would make the most sense! > But like you say maybe not the most supported. > > > Just to confirm how I'm thinking about this, a strand in Houdini is > typically made up of point positions, not points with arrays as attributes. > You can manually add an attribute to each point position to say which > strand it's part of, there's a node that generates lines that will > then understand this? > > > Otherwise you can create polyline primitives and feed point IDs into it. > This will generate a polygon line (polyline) between the vertices in the > primitive, and in some ways this is just like the point[pointarray] > technique. > > The key is how do you create these point clusters and the order. In ICE I > would make strands using a build linearly interpolated array with two > vectors feeding into it. I guess I could try and recreate this using > vex/vops, and maybe that's what I'm after, I just need to find a way to > manipulate all these points in the right order. > > I'm rambling a bit here, but hopefully getting somewhere! > > Cheers, > > Tim > > ------------------------------ > *From:* [email protected] > <[email protected]> > <[email protected]> on behalf of Andy Nicholas > <[email protected]> <[email protected]> > *Sent:* 02 March 2017 12:27 > *To:* [email protected] > *Subject:* Re: [Houdini] Working with strands the Softimage way > > Hi Tim, > Did you notice that you can do per-point array attributes in VEX? There's > nothing stopping you setting up position vector arrays on each point, just > like in ICE, and then using a Point Wrangle at the end to use that array to > generate a polyline. The problem is that you then have to write all those > handy ICE nodes like "Simulate Strands", etc. yourself. > > That's why generally, you're better off just trying to use polylines as a > primitive as they're more supported by Houdini's other frameworks (e.g. > wire solver) and constraints. > > A > > > > ------ > Softimage Mailing List. > To unsubscribe, send a mail to [email protected] with > "unsubscribe" in the subject, and reply to confirm. > > > > ------ > Softimage Mailing List. > To unsubscribe, send a mail to [email protected] > with "unsubscribe" in the subject, and reply to confirm. > -- Christopher Crouzet *https://christophercrouzet.com* <https://christophercrouzet.com>
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