Thank you for the detailled hip, that's very kind of you :) Makes me feel very humble too, as it obviously will take time to understand all this. I do very little steps :) My knowledge of Vex is very new and poor, that's why I splitted in vex + vop.
If I'm no wrong, the super clever line might be this one : int pt1 = min(neighbours(input, pt0)); Min neighbor is what ? the closest neighbour to pt0 ? The neighbor with the smallest index ? At a moment, I was thinking using the Normal (@axis ) to find the P1. Assuming that @axis position is on P0 and is pointing toward P1. But I'm unable to translate this. P0+@axis =P1 The conversion Local to Space is loosing me a bit. Is this an invert matrix thing (like in ice ) ? I realise I've been wrong route with the arrays. Yes I end up with array per points which makes it very confusing. Thank you a lot for providing this, it's a hell of an effort to understand, but the exercice in itself is very educative even if I only get portions of it :) On Thu, Mar 3, 2016 at 4:40 AM, Christopher Crouzet < christopher.crou...@gmail.com> wrote: > You can think of each geometry attribute as an array which length equals > the number of points (if dealing with points). VOPs simply iterate over > these points and process the graph for each of them. Since each attribute > is an array, at any time you can pick the value of any element with `Get > Attribute` provided you know the point number. This is so straightforward > that you can even do this outside of VOP/VEX, with the `point` expression > for example. > > Sometimes it can be useful to define attributes that can themselves hold > arrays, for example a list of neighbours, to then pass these down to other > nodes for further processing. That's why they added that feature in H14, > but otherwise there's no real need to directly create arrays yourself. > Shamefully, I haven't used Fabric Engine yet but from what you're saying > maybe they're just presenting the data differently by providing you with > the whole points data as an array instead of letting you directly work on a > per-point context? In any case, there's plently of good reasons to use > Fabric Engine but this definitely isn't one of them—just wrap your head > around how Houdini works instead, everything will eventually start to make > sense :) > > Olivier, assuming that two poins are neighbour based on their point number > is quite a risky bet. Instead, there is a `Neighbour VOP` node for that so > you can pick P1 as being the first neighbour of P0. But then, to reflect > the sorting order of your points, it'd be better to retrieve the array of > all the neighbours and retrieve only the neighbour with the smallest point > number. > > I've made an example scene for you—everything is happening in the node > named `rotate_each_prim`, where you'll find an `angle` parameter to play > with. I tried to keep the code as simple as possible and documented every > line to help you understanding it. > > An issue is that the `Sort SOP` node fails when for example sorting the > points of the grid along the X axis since many points in that grid share > the same position in X, leaving no hint for the `Sort SOP` node to > prioritize one point over the other. In fact, sorting points by an axis > might be troublesome even on more organic geometries, so basing this effect > on the `Sort SOP` alone won't be enough to have predictible results, and > you'll end up with primitives rotating in a different direction than their > neighbours. > > > On 3 March 2016 at 05:43, Anto Matkovic <a...@matkovic.com> wrote: > >> Nope. I think the only way to create an array directly in VOP, is pcfind >> (pcopen that returns array), or array version of point neighbors. Or, to >> stack the 'append' node several times :). There are examples how to loop >> over arrays of indices, later in network, here: >> >> https://www.sidefx.com/index.php?option=com_content&task=view&id=3148&Itemid=412 >> By the way, had to do some pretty interesting networks :) for Kristinka >> Hair for H - while everything worked at the end of day, anyway. >> >> If you're around arrays and nodes, Fabric is waiting for You.... >> >> >> ------------------------------ >> *From:* Olivier Jeannel <facialdel...@gmail.com> >> *To:* "softimage@listproc.autodesk.com" <softimage@listproc.autodesk.com> >> >> *Sent:* Wednesday, March 2, 2016 1:29 PM >> *Subject:* OT Houdini build Array VOP question (and a bit of rant) >> >> Hello serious list :) >> >> I'm a bit confused with houdini vop array. >> While I managed to do it in vex, I would like to make a build array (like >> build array from set) of the pointposition (P) in VOP. >> >> I understand you need to for-loop on each Ptnum and probably append the P >> values and this will buid an array of P. >> But you know what ? Well I can't manage to make it work. >> >> I found no example on the net (sideFX, odforce). >> The doc is just words, no schemes, no graphics. >> The examples hips are bizarre, not so simple, and use the old loop node. >> >> So I'm wondering if someone from here could provide a screen shot of how >> that should be connected ? >> >> Thank you :) >> >> >> ------ >> Softimage Mailing List. >> To unsubscribe, send a mail to softimage-requ...@listproc.autodesk.com >> with "unsubscribe" in the subject, and reply to confirm. >> >> >> ------ >> Softimage Mailing List. >> To unsubscribe, send a mail to softimage-requ...@listproc.autodesk.com >> with "unsubscribe" in the subject, and reply to confirm. >> > > > > -- > Christopher Crouzet > *http://christophercrouzet.com* <http://christophercrouzet.com> > > > ------ > Softimage Mailing List. > To unsubscribe, send a mail to softimage-requ...@listproc.autodesk.com > with "unsubscribe" in the subject, and reply to confirm. >
------ Softimage Mailing List. To unsubscribe, send a mail to softimage-requ...@listproc.autodesk.com with "unsubscribe" in the subject, and reply to confirm.
