This determines how strongly the cloth object resists deformation. The Overall Stiffness is independent of the resolution of the mesh. If the materialuv attribute is used to specify cloth UV coordinates are specified on the mesh, then the effect of stiffness is also independent of the orientations of the triangles and quads in the mesh. The default setting for the Overall Stiffness works the best if you model the simulation geometry to real size. If you don’t model your geometry in meters, then make sure that you set the correct units of length in the Hip File Options. This should be done before you create your DOP network. When using real-size models, you should make sure that you have your length units set correctly before you create your DOP network: You should set the correct Unit Length in Edit > Preferences > Hip File Options before you create your DOP network.

This value should lie between 0 and 1. The Overall Damping Ratio controls the rate of energy loss as a result of the rate of deformation. A value of 0 means that there is no loss of energy due to internal damping forces. A value of 1 means that the object is critically damped, in which case the object comes to rest in the quickest possible way without oscillating. The higher the damping ratio, the less the cloth oscillates and the quicker the object’s motion will come to rest. The effect of damping is independent of your geometry’s resolution.

This is the mass per square meter. The mass density can be made lower or higher in parts of the object using the primitive attribute surfacemassdensity, which works as a multiplier for the parameter.

These values should lie between 0 and 1 and act as modifiers to the Overall Stiffness for specific types of deformation. The Relative Stiffness parameters determine the relative strengths of the internal forces that counteract planar shape changes and bending. Together, the Relative Stiffness contributions for stretch and shear determine the resistance against changes within the local cloth surface plane. The contribution for Weak Bend and Strong Bend determine how strongly the object resists bending. The Weak Bend model can be used to create thin silky kinds of cloth sheets. The Strong Bend model can be used to create a strong resistance against bending, for example, for leather or thick rubber. The effect of Relative Stiffness is independent of the amount of detail and the shapes of the triangles and quadrangles your simulation geometry.

The stretch and shear contributions of Relative Stiffness work in the directions of the cloth material UV’s. These UV coordinates can be specified by the materialuv vertex or point attribute. When no UV coordinates are specified, the material directions are determined by the polygon edges. The Visualization tab of the Cloth Object has an option that allows you to see which UV directions are being currently used by the cloth object.

These values should lie between 0 and 1 and act as modifiers to the Overall Damping Ratio. The Relative Damping Ratio parameters allow you to determine separately how much energy loss is introduced by the rate of changes in planar shape (stretch + shear) and the rate of bending.

These values allow you to very the strength of the internal stress within the cloth surface separately for the U and V directions. The U and V directions can be provided using the vertex and point attributes materialuv. For example, to make the cloth more stretchy in the U direction than in the V direction, you could set a lower value (say 0.5) for the U component of the Anisotropic Strength while keeping the V component unchanged.

This is the rest angle along edges between two primitives that belong to separate panels. Panels are connected by pinning together two cloth objects using a stitch constraint or by specifying separate per-vertex rest positions within a single cloth object. The seam angle does not affect the rest angle for polygons that lie within a single panel. If you want to make parts of the object have different rest angles, then you can locally multiply the rest angle using the primitive attribute seamangle.

This geometry determines the initial simulated state of the object. It determines the initial position and velocity for each of the points.

This is the geometry that is used for the computation of internal forces and for collision detection. Your cloth geometry should satisfy guidelines that ensure a fast-running and good looking simulation.

In many cases, you can use the Remesh SOP to help you create a suitable simulation mesh. When using triangulated geometry, it is recommended that you provide a materialuv point or vertex attribute to specify the directions of the cloth fabric.

This option allows you to specify and animate the target positions that are used by the simulation inside the SOP network (without having to use a SOP solver). The option defines whether the target positions should be imported from a SOP geometry node at each frame. When enabled, the solver will copy target positions from the point attribute targetP of the SOP geometry node onto the attribute targetP on the simulation geometry at each frame. If no targetP exists, then the P attribute from the SOP geometry node is copied instead.

The path to the SOP node that will serve as the source of the target positions. The positions should be stored in an attribute with the name targetP. If this attribute is not found, the P attribute is used as a fallback.

This coefficient determines how strongly the finite element solver tries to make the point positions match the target point positions. The solver creates an imaginary potential force for this purpose.

This coefficient determines how strongly the finite element solver tries to make the point velocities match the target point velocities. The solver creates an imaginary dissipation force for this purpose.

If enabled, the geometry in this object will collide with all other objects. These other objects may belong to the same solver or they may be be Static Objects, RBD Objects, or the Ground Plane. When the Collision Detection parameter on the Static Object is set to Use Volume Collisions, then the polygon vertices will be tested for collision against the signed distance field (SDF) of the Static Object. When Collision Detection is set to Use Surface Collisions, then geometry-based continuous collision detection is used. The geometry-based collisions collide points against polygons, and edges against edges.

When geometry-based collisions are used, only polygons and tetrahedrons in the Static Object are considered. Other types of primitives, for example spheres, are be ignored. The geometry of the external objects (e.g. Static Object) is treated as being one-sided; only the outsides of the polygons, determined by the winding order, oppose collisions.

When volume-based collisions are enabled, only points will be colliding against the volumes, not the interiors of polygons and tetrahedrons. When colliding against small volumes, this may mean that you need to increase the number of points on your mesh to get accurate collision results.

When enabled, this object will collide with other objects that have the same solver. These collisions are handled using continuous collision detection, based on the geometry (polygons and/or tetrahedrons). For collisions between objects on the same solver, the polygons are treated as two-sided. Both sides of the polygons collide. The surface of a tetrahedral mesh only collides on one side: the outside.

If disabled, then no two polygons within this object can collide with each other.

If disabled, then no two polygons that belong on the same connected component may collide with each other.

This option only has an effect when fracturing is enabled on the solver. If disabled, then no two polygons that belong on the same fracture part may collide with each other. Fracture parts are controlled by the integer-valued fracturepart primitive attribute.

This is the radius of an imaginary padding layer around the polygons. This layer consists of the region of space that has a distance of at most Collision Radius to some polygon. For two-sided collision surfaces, such as cloth geometry, the layer applies to both sides of each polygon (back and front). For one-sided collision surfaces, such as polygons in a Static Object, the collision radius is applied only on the front side of the polygons. The Finite Element Solver tries to ensure that the layers for the objects don’t penetrate each other or pass through each other.

For example, when a pair of two-sided polygons collide, one with a thickness of 0.01 and one with a thickness of 0.02, the solver will try to separate polygons of these objects by a distance of 0.03.

The Thickness parameter is one of the very few parameters that is scale dependent. It is very important that you adjust this parameter when you change the scale or amount of detail of your geometry.

Use a Thickness that is significantly smaller than the length of the shortest edge in your simulation geometry. Typically, the Thickness should not exceed 1% percent of the average edge length. To avoid problems with self collisions, you should keep the polygons (and/or tetrahedrons) in your geometry fairly even-sized. Avoid polygons that have very small edges, compared to the average size of the polygons in your cloth geometry.

The coefficient of friction of the object. A value of 0 means the object is frictionless. This governs how much the velocity that is tangential to the contact plane is affected by collisions. When two objects are in contact, then the solver multiplies the friction coefficients of the involved object to get the effective friction coefficient for that contact.

The component of drag in the directions normal to the surface. Increasing this will make the object go along with any wind that blows against it. For realistic wind interaction, the Normal Drag should be chosen larger (about 10 times larger) than the tangent drag.

The component of drag in the direction tangent to the surface. Increasing this will make the object go along with any wind that blows tangent to the object.

The name of the external velocity fields on affectors that the object will respond to. The default is vel, which will make the object react to fluids and smoke when the Tangent Drag and the Normal Drag have been chosen sufficiently large. The Tangent Drag and Normal Drag forces are computed by comparing the object’s velocity with the external velocity.

This offset is added to any velocity that’s read from the velocity field. When there’s no velocity field, then the offset can be used to create a wind force which has constant velocity everywhere. This wind effect is more realistic and more accurate than the wind that is generated by DOP Forces.

Visualize the cloth’s collisionradius.

Color of the cloth collisionradius guide geometry.