I have a several questions about custom rope's forms:
1. Is there a way to create rope using ObiRope Mesh Renderer without visible segmentations on the rope?
2. Can I use any mesh or shape to create a custom, smooth-looking rope?
3. Are there any limitations related to mesh, shape, material, or anything else?
08-07-2025, 08:33 AM (This post was last modified: 08-07-2025, 08:35 AM by josemendez.)
(08-07-2025, 08:26 AM)quent_1982 Wrote: Hello,
I have a several questions about custom rope's forms:
1. Is there a way to create rope using ObiRope Mesh Renderer without visible segmentations on the rope?
Hi!
Depends on what you mean by "segmentations": the result will be as smooth as your mesh topology allows for (if your mesh has very few triangles, there will be no way to smoothly deform it) and your rope's resolution.
(08-07-2025, 08:26 AM)quent_1982 Wrote: 2. Can I use any mesh or shape to create a custom, smooth-looking rope?
Yes, you can use any mesh as long as it's oriented along a principal axis (X, Y or Z).
(08-07-2025, 08:26 AM)quent_1982 Wrote: 3. Are there any limitations related to mesh, shape, material, or anything else?
There's no restriction to mesh, shape, or material, at least not technical. Some meshes/shapes will look better than others though, eg. if you use a cube to represent a bent rope it won't look very good. In this regard, it is best to follow common sense.
Depends on what you mean by "segmentations": the result will be as smooth as your mesh topology allows for (if your mesh has very few triangles, there will be no way to smoothly deform it) and your rope's resolution.
Yes, you can use any mesh as long as it's oriented along a principal axis (X, Y or Z).
There's no restriction to mesh, shape, or material, at least not technical. Some meshes/shapes will look better than others though, eg. if you use a cube to represent a bent rope it won't look very good. In this regard, it is best to follow common sense.
kind regards,
Thanks! Just to clarify - can I use the shark, as shown in the attached photo, with the Obi Rope Mesh Renderer and have it behave exactly like the default Obi Rope and collisions will work without visual problems?
08-07-2025, 11:04 AM (This post was last modified: 08-07-2025, 11:25 AM by josemendez.)
(08-07-2025, 10:25 AM)quent_1982 Wrote: Thanks! Just to clarify - can I use the shark, as shown in the attached photo, with the Obi Rope Mesh Renderer and have it behave exactly like the default Obi Rope and collisions will work without visual problems?
No. The mesh used for rendering the rope is only used for rendering, it is not taken into account during simulation in any way. Obi is a particle-based engine, everything in it is entirely particle-based including collision detection.
In general, the more your mesh resembles a rope the better. There's certain meshes that are more "rope like" than others. The shark in the example scene is an example of taking this to the limit - though it's longer than wider, a shark is obviously not a rope and has parts that stick out like fins, tail, etc that cannot be accurately approximated as a chain of particles. While it works well for the use case shown in the scene - to represent a hanging shark carcass - the illusion will break down when collision detection takes place, as parts of the mesh will just clip trough nearby geometry. You can work around this to some extent by adjusting rope thickness, but a rope will never be able to provide accurate collision detection for an arbitrary mesh.
The same principle applies to any physical object in any engine: visual and physical shape are often decoupled for practical reasons, it's up to you to decide whether your visual and physical shape choices are a good enough fit for your purpose.
For example, Unity has primitive colliders like boxes, spheres and capsules. If your object is roughly sphere-shaped (say, an apple), you can simulate it using a sphere collider. However using a sphere to simulate a shark may be oversimplifying things, and you might need to use a convex mesh collider - which still doesn't perfectly represent the shape of the shark, but it's closer to it than a sphere. Another example would be player characters: in many games the player is represented using a capsule. This works well in many cases, but if you need detailed collision detection this approach will break down, as character limbs stick out and will be able to clip trough other objects.
If you want to simulate a mesh that's not close in shape to a rope, using a softbody might be a better option as it does not make assumptions about the shape of the object or how particles are laid out to represent it.
(08-07-2025, 11:04 AM)josemendez Wrote: No. The mesh used for rendering the rope is only used for rendering, it is not taken into account during simulation in any way. Obi is a particle-based engine, everything in it is entirely particle-based including collision detection.
In general, the more your mesh resembles a rope the better. There's certain meshes that are more "rope like" than others. The shark in the example scene is an example of taking this to the limit - though it's longer than wider, a shark is obviously not a rope and has parts that stick out like fins, tail, etc that cannot be accurately approximated as a chain of particles. While it works well for the use case shown in the scene - to represent a hanging shark carcass - the illusion will break down when collision detection takes place, as parts of the mesh will just clip trough nearby geometry.
The same principle applies to any physical object in any engine: visual and physical shape are often decoupled for practical reasons, it's up to you to decide whether your visual and physical shape choices are a good enough fit for your purpose.
For example, Unity has primitive colliders like boxes, spheres and capsules. If your object is roughly sphere-shaped (say, an apple), you can simulate it using a sphere collider. However using a sphere to simulate a shark might be oversimplifying things, and you might need to use a convex mesh collider - which still doesn't perfectly represent the shape of the shark, but it's closer to it than a sphere. Another example would be player characters: in many games the player is represented using a capsule. This works well in many cases, but if you need detailed collision detection this approach will break down, as character limbs stick out and will be able to clip trough other objects.
If you want to simulate a mesh that's not close in shape to a rope, using a softbody might be a better option as it does not make assumptions about the shape of the object or how particles are laid out to represent it.
kind regards,
I'll take all of it into consideration, thanks for such detailed answer, appreciate your work!
