Help How to handle multiple attachments (rope-rope, rope-rigidbody)?

[josemendez]

I tried to solve collision problems with categories, but I am confused a bit.

Hi!

You don't set categories per particle group, but per control point. These are completely different things: A particle group in a rope is a single particle, the one that's right at the location of a control point - when you attach a group, it only attaches one particle. A control point however controls the properties of multiple particles, those that are closest to it. For instance when you change the thickness or the color of a control point it affects multiple particles, same when you change its collision category.

Seems like I can't set different categories per group?

You can't have multiple categories per group: that wouldn't make sense since filters already can accept/reject collisions with multiple groups.

This works just like Unity's collision layers: you can't have objects be in multiple layers simultaneously, but there's no need to since each layer can ignore any combination of multiple layers.

Changing 1 group category, changes for the whole rope.

No, it changes for particles along the rope closest to that control point.

So seems that I can't ignore collisions between attached groups, but collide with the rest of the rope?

You can: just use different categories and set the filters so that they all collide with everything except the categories you don't want to interfere with each other. For instance if you have a rope with 3 control points (left end, middle, right end) and you want the ends to not collide with the objects they're attached to but collide with other particles in the rope, this is one possible setup:

- left end: category 0, collide with 1.
- middle: category 1, collide with 0.
- right end: category 0, collide with 1.
- colliders attached to the ends: category 2, collide with everything except 0.

Seems that rigidbodies kind of work if I set the rigid body to collide with everything, and the rope group to ignore the rigid body (collision mask does work per particle group), but this trick does not work for rope to rope.

Why wouldn't it work for rope to rope? Collision filters use the same logic for all kinds of collisions. Could you be more specific?

kind regards,