This set of parameters is only visible when the MultiBody's → “Simulation” option is set to “Soft body”.
Density
A MultiBody can consist of several objects, but it is not possible to change the objects' masses individually. Therefore, mass is controlled indirectly via this parameter: density = mass / volume.
Resolution
Soft bodies use a voxelization method in order to bend polygons correctly. Imagine an object, where the triangles are bigger than the voxels. In such a case it is likely that the simulation will turn out wrong.
You can enter any positive value.
If you see a warning, but the body behaves correctly, you can ignore the message.
Length stiffness
This parameter ranges between 0.0 and 1,000.0. With increasing values, the body becomes more rigid and is less is deformable along its longitudinal axis.
Volume stiffness
This parameter ranges between 0.0 and 1,000.0. With increasing values, the body becomes more rigid and its volume is less deformable.
Elasticity
You can apply any value between 0.0 and 1.0:
- With 0.0, the body quickly loses all its energy and stops wobbling.
- A value of 1.0 results in a much longer tremble and stronger bounces.
- You can counteract these bounces with “Internal Damping”.
Friction
Object friction occurs when bodies with uneven surfaces interact. “Friction” slows down the interacting objects and can even stop them completely. The maximum value is 1.0. RealFlow takes the average friction of all interacting rigid/soft bodies into account.
Air friction
This is the amount of resistance caused by a surrounding atmosphere. High settings can stop an object completely.
Internal Damping
With high values, a body stops bouncing very fast and it will experience smaller bounces. You can use settings between 0.0 and infinity: a value of 0.5 will stop the entire internal movement after 2 seconds, a value of 1, after 1 second, for example.
Autocollision
When enabled, self-interpenetration of the soft body is avoided. “Autocollision” takes longer to simulate, especially with higher “Resolution” settings.
Plasticity
When enabled, the deformations of the body will not relax or recover, and the object remains in a distorted state like clay.
Velocity
Here, the initial velocity of a soft body is defined. You can use any positive or negative value for the parameter's X, Y, and Z components. “Velocity” is measured in metres per second. Click on “+” for sliders.
Rotation W
Here, the initial angular velocity of a soft body is defined. You can use any positive (clockwise rotation) or negative (counterclockwise rotation) value for the parameter's X, Y, and Z components. “Velocity” is measured in degrees per second. Higher values make the object spin faster. Click on “+” for sliders.
Threshold
This value depends on a body’s change of its initial length to produce a permanent deformation. The range goes from 0.0 to 1.0. A value of 0.5 means that permanent deformation will only happen when the body’s length change is at least 50% of its initial size.
Acquired
The parameter's range goes from 0.0 to 1.0. A setting of 0.5 will keep approximately 50% of the node’s deformation as permanent. The other half is able to relax and turn back to its initial state.
Compression limit
When a soft body with activated “Plasticity” is strongly compressed it might become totally flat, but this is not always wanted. A value of 0.5 means that permanent deformations in one direction can compress the body approximately until the half of its original length in this direction. The range goes from 0.0 to 1.0.
Expansion limit
This parameter is related to a body’s permanent expansion after its deformation and avoids unnatural changes in size. A value of 2.0 means that permanent deformations in one direction can expand the body approximately until it has reached twice its original length in this direction. The range goes from 1.0 to 100.0.