+- Obi Official Forum (https://obi.virtualmethodstudio.com/forum)
+-- Forum: Obi Users Category (https://obi.virtualmethodstudio.com/forum/forum-1.html)
+--- Forum: Obi Rope (https://obi.virtualmethodstudio.com/forum/forum-4.html)
+--- Thread: Help Rope starts out a bit curled inside itself (/thread-881.html)
Rope starts out a bit curled inside itself - KjetilMV - 08-02-2019
Hi
My rope starts a bit curled after generating. The issue is less apparant with a high rope resolution, but my rope has to be low res because I want a steel wire like behaviour.
I've attached a screenshot fo the curve and here's a vid of extending the rope right after generation: https://imgur.com/a/vNhPZdd
I'm generated the rope with a modified version of the RuntimeRopeGenerator - where I input a manually created ObiCurve.
RE: Rope starts out a bit curled inside itself - josemendez - 08-02-2019
(08-02-2019, 03:48 PM)KjetilMV Wrote: Hi
My rope starts a bit curled after generating. The issue is less apparant with a high rope resolution, but my rope has to be low res because I want a steel wire like behaviour.
I've attached a screenshot fo the curve and here's a vid of extending the rope right after generation: https://imgur.com/a/vNhPZdd
I'm generated the rope with a modified version of the RuntimeRopeGenerator - where I input a manually created ObiCurve.
Hi there,
I don't think I get your question, both the curve and the rope seem perfectly fine to me. Can you elaborate?
RE: Rope starts out a bit curled inside itself - KjetilMV - 08-02-2019
(08-02-2019, 04:02 PM)josemendez Wrote: Hi there,
I don't think I get your question, both the curve and the rope seem perfectly fine to me. Can you elaborate?
If you look at the video, you see it's like some hidden invisible rope falls out when I start extendig it. Like a sudden curl.
It's more pronounced when the rope is short and I'm extending it downwards.
New vid here: https://imgur.com/a/smjxziT
Also, I see now that there's an issue with the rope/UV twisted about its own axis when the length is changing.
RE: Rope starts out a bit curled inside itself - josemendez - 08-02-2019
(08-02-2019, 04:36 PM)KjetilMV Wrote: If you look at the video, you see it's like some hidden invisible rope falls out when I start extendig it. Like a sudden curl.
It's more pronounced when the rope is short and I'm extending it downwards.
New vid here: https://imgur.com/a/smjxziT
Also, I see now that there's an issue with the rope/UV twisted about its own axis when the length is changing.
I see now. This effect is inherent to the discretized nature of the rope: it is made of individual "lumps" of matter. When you increase rope length, the distance between the last 2 particle in the rope increases until a new particle is suddenly added. At this point, the mass of the rope goes up a notch, and this causes a small "jerk" in the simulation. If you have more particles, the relative increase in mass is smaller and so the jerk is less pronounced.
The only way to prevent this in a discrete simulation is to increase rope resolution (ie, use more particles per length unit). If you need the rope to be very rigid, increase the amount of solver subsets/iterations (preferably substeps).
As per the "twisting" uv issue, I'll take a look at it and get back to you asap.
RE: Rope starts out a bit curled inside itself - KjetilMV - 15-02-2019
(08-02-2019, 06:15 PM)josemendez Wrote: I see now. This effect is inherent to the discretized nature of the rope: it is made of individual "lumps" of matter. When you increase rope length, the distance between the last 2 particle in the rope increases until a new particle is suddenly added. At this point, the mass of the rope goes up a notch, and this causes a small "jerk" in the simulation. If you have more particles, the relative increase in mass is smaller and so the jerk is less pronounced.
The only way to prevent this in a discrete simulation is to increase rope resolution (ie, use more particles per length unit). If you need the rope to be very rigid, increase the amount of solver subsets/iterations (preferably substeps).
As per the "twisting" uv issue, I'll take a look at it and get back to you asap.
Thank you. Did you get the chance to look at the twisting issue?