Rope Tool
Overview
Ropes can be used to attach objects together or to hang objects from. They react to objects around them, but will not affect those objects.
The rope tool can be found under RollupBar -> Objects -> Misc -> Rope.
Rope Creation
Turn on follow terrain and snap to objects. Place the rope by using the left mouse button. This works in a similar way as placing a road.
A rope can be edited using the edit rope button in its properties.
You can move points in the normal way, add points by CTRL+left click and remove them by double-clicking.
When in Edit Rope mode, you will notice that a point can be colored green or red. Green means the rope is validly attached, and red means the rope is not attached to anything.
| Attached | Not Attached |
|---|
Properties
Rope Params | Description |
|---|---|
Radius | The radius, or thickness, of the rope. |
Smooth | Defines if the rope will be smoothed out or not. |
Num Segments | The number of segments of geometry used in the rope along its length. |
Num Sides | The number of sides around the circumference of the rope. 4 sides would make it a diamond shaped tube, 8 sides would make it much smoother, etc. |
Texture U Tiling | Texture tiling in the U direction. |
Texture V Tiling | Texture tiling in the V direction. |
CastShadows | Enable shadow casting from the rope. |
Bind Ends Radius | Specifies whether the ends will be automatically attached. |
Bind Radius | The environment around the ends of the rope will be tested using a box of this radius to find places for the rope to attached to. |
Physics Params | |
Subdivide | Turns dynamic subdivision on. |
Max Subdiv Verts | Maximum number of subdivided vertices per segment. |
Physical Segments | Number of rope segments in physics (can be different from the number of segments used for rendering). |
Tension | Specifies tension in the original state. A positive value will cause the rope ends to pull together, negative will add slack to the rope (-0.02 is a good starting point for experiments). |
Friction | The friction effective in a non-strained mode. In a strained mode with dynamic tessellation, this that prevents the rope from slipping until it tilts too much. |
Wind X, Y, Z | Simulated wind, additional to any area-specific winds around. |
Wind Variance | How much the wind varies. Basically a randomization multiplier on top of the base Wind XYZ values. |
Air Resistance | Must be set in order for global environment wind to take effect. Not necessary for simulated Wind XYZ values. |
Water Resistance | How the rope interacts with water effectively damping when under water. |
Check Collisions | Ignore collisions from other objects, bullets, etc. |
Ignore Attachment Collisions | Ignore collisions with the object it is attached to. |
Ignore Player Collisions | Ignore collisions with players. |
Non-shootable | Rope cannot be broken by shooting. Rope will still react to physical impulses from bullets. |
Disabled | Simulation is completely disabled. |
StaticAttachStart | Attach start point to the 'world'. |
StaticAttachEnd | Attach end point to the 'world'. |
Advanced Params | |
Mass | This affects how strongly the rope will react to bullet hits. When interacting with solid physicalized objects, it is always treated as weightless. |
Friction Pull | How strongly the rope opposes movement in its pull direction (when strained with dynamic tessellation). When subdivision is off, it's used as 'twist' damping for attached objects. |
Max Force | The rope will detach itself when this strain limit is breached. |
Solver Iterations | Ropes with very large segment counts (40+) might need this increased (values up to 10k are still viable). |
Max Timestep | Sets the maximum time step the entity is allowed to make (defaults to 0.01). Smaller time steps increase stability (can be required for long and thin objects, for instance), but are more expensive. |
Stiffness | Rope's stiffness against stretching. Might need tweaking for longer ropes. |
Contact Hardness | Hardness of contacts and length enforcement in subdivision mode, when strained and potentially touching other objects in the middle. Higher values make it potentially less stable. |
Damping | Sets the strength of the damping on an object's movement. Most objects can work with 0 damping; if an object has trouble coming to rest, try values like 0.2 - 0.3. |
Sleep Speed | If the object's kinetic energy falls below some limit over several frames, the object is considered "sleeping". This limit is proportional to the square of the sleep speed value. |
Sound Params | |
Name | Name of the sound to be attached. |
Segment | The segment to which the sound is attached. |
PosOffset | The position offset indicates how far a sound is moved away from its original attachment point. |
Please note, that when setting up a sound in FMOD for use with ropes, a new parameter has been added. "Angle" indicates the angle of the nearest joint, unless that joint is at the very beginning or end of the rope.
The angle that the two segments form, from 0-180 degrees, will then affect the sound as the designer decides. When setting up the sound, also pay attention to the sound's speed in km/h.
Dynamic Tessellation/Subdivide
There are two rope simulation modes, with dynamic tessellation on or off. Without dynamic tessellation rope, segments are asset-based and are simulated as rigid sticks. In this mode the rope cannot properly collide with objects when it's tied with both ends and strained.
With dynamic tessellation the rope has SegCount segments (independently of the actual rope asset), and each of them can have a maximum of SubVtxCount internal vertices, created at collision points.
More segments make the rope less likely to tunnel through thin objects, but increase the simulation cost. Refer to the art documentation on how to author rope assets for these two modes.