Attribute Wrangle Run Over Points

[sessionbeer]

Hello,

I don't understand how I do this and was hoping someone could help me. With this basic script in a Wrangle, set to run over 'Points', it works as expected. When I switch it to run over 'Primitives', nothing happens and it breaks. Could someone please explain how I do the equivalent when it is set to run over 'Primitives' please? For a bigger script I require it to run over primitives, or at least I believe so.

v@new_pos;
getattribute(@OpInput2, @new_pos, "point", "P", @ptnum, @vtxnum);
vector blend = lerp(@P, @new_pos, ch("blend"));
@P = set(blend);

Cheers

[Guest mantragora]

Do you want to blend Point position with Primitive position in Over Primitives mode?

[sessionbeer]

Yea, I think that's what I'm trying to achieve.

[Guest mantragora]

1. There are more points that primitives, how do you want to interpolate data between points?

2. If you go over primitives, than you are not getting all point positions, because it will not loop automatically over each point in getattribute(), only over one point in each primitive. You need to get all point positions from each primitive and loop over it.

Thats for start

[anim]

well, there is a minor detail

you can't set primitive position using wrangle, so @P = anything; will not do anything

you have to set positions of all it's points

[sessionbeer]

Maybe it's easier to explain with a scene so below is a stripped down version.

When you play the scene and look inside (solver1/mover) - you'll notice that the points move at different speeds. My wrangle node is trying to get the previous frame point position, and the add a vertex to the new point position. But for some reason it isn't working correctly. On the other side I have dropped a tail Sop down and that is working correctly, so I'm not sure where I'm going wrong? I maybe of course, be going about this entirely wrong so I would appreciate some advice.

Thanks

 

https://dl.dropboxusercontent.com/u/2802779/Wrangler_A1.hip