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MnCloth Class Reference

OpenMayaFX - API module for effects

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Detailed Description

Class for wrapping N cloth objects.

This class wraps the internal Maya representation of N cloth objects suitable for use with the Nucleus solver.

Examples:

testNobjectNode.h, and testNucleusNode.cpp.

#include <MnCloth.h>

Inheritance diagram for MnCloth:
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List of all members.

Public Member Functions
  MnCloth ()
  Default constructor.
virtual  ~MnCloth ()
  The class destructor.
MStatus  createNCloth ()
  Creates the underlying Maya TnCloth and sets this class to wrap it.
MStatus  setTopology (const int numFaces, int *numVertsPerFace, int *faces, const int numEdges, int *edges)
  sets the topology of the underlying N Object.
MStatus  setPositions (const MFloatPointArray &positions, bool startFrame=true)
  Sets the positions of the vertices of the underlying N cloth object.
MStatus  setVelocities (const MFloatPointArray &velocities)
  Sets the velocities of the vertices of the underlying Ncloth object.
MStatus  setBendRestAngleFromPositions (const MFloatPointArray &positions)
  Sets the the bend rest angle from the list of positions for the underlying N Object This sets the shape that bend resistance is trying to achieve.
MStatus  setLinksRestLengthFromPositions (const MFloatPointArray &positions)
  Sets the the rest length from the list of positions for the underlying N Object.
MStatus  setInputMeshAttractPositions (const MFloatPointArray &positions)
  Sets the positions for input mesh attract.
MStatus  setInputMeshAttractDamping (float damping)
  Defines how springy the effect of Input Mesh Attract is.
MStatus  setInputMeshAttractAndRigidStrength (float *inputAttractArray, float *rigidArray, float *deformArray)
  Sets on a per particle basis, the amount by which each particle is affected by the input mesh attract, rigidity, and deformability.
MStatus  setComputeRestLength (const bool b)
  Sets whether rest lengths will be automatically computed, or overridden manually.
MStatus  setComputeRestAngles (const bool b)
  Sets whether rest angles will be automatically computed, or overridden manually.
MStatus  setThickness (float radius)
  sets a radius on each point of the mesh for collision purposes.
MStatus  setThickness (float *radius)
  sets a radius (thickness) on a per point basis for the mesh for collision purposes.
MStatus  setInverseMass (float invMass)
  sets the mass for every point in this mesh
MStatus  setInverseMass (float *invMass)
  sets the mass on a per point basis in this mesh
MStatus  setBounce (float bounce)
  sets the bounce for every point in this mesh
MStatus  setBounce (float *bounce)
  sets the bounce on a per point basis in this mesh
MStatus  setFriction (float friction)
  sets the friction for every point in this mesh
MStatus  setFriction (float *friction)
  sets the friction on a per point basis for this mesh
MStatus  setDamping (float damping)
  sets the damping for every point in this mesh
MStatus  setDamping (float *damping)
  sets the on a per point basis in this mesh
MStatus  setSelfCollisionFlags (const bool vertToVert, const bool vertToEdge=false, const bool vertToFace=false, const bool edgeToEdge=false, const bool edgeToFace=false)
  Sets how (or if) this object will collide with itself.
MStatus  setCollisionFlags (const bool vertToVert, const bool edgeToEdge=false, const bool faceToFace=false)
  Sets how (or if) this object will collide with other objects.
MStatus  setDisableGravity (const bool b)
  Sets whether gravity will affect this object.
MStatus  setMaxIterations (const int it)
  Sets the number of iterations the solver will perform on various dynamic properties like drag, damping, stretch and bend.
MStatus  setMaxSelfCollisionIterations (const int it)
  Sets the number of iterations the solver will perform for self collisions on this object.
MStatus  setSelfCollisionSoftness (float softness)
  This allows one to lower the repulsive force of self collisions such that some interpenetration within the collide width is allowed.
MStatus  setSelfTrappedCheck (bool on)
  This tracks self collision crossovers and attempts to push the crossed over points back.
MStatus  setSelfCrossoverPush (float val)
  See node documentation.
MStatus  setDragAndLift (float drag, float lift)
  Sets the drag and lift values for the cloth.
MStatus  setTangentialDrag (float tangentialDrag)
  Sets the tangential drag values for the cloth.
MStatus  setStartPressure (float startPressure)
  With the volume tracking pressure method this defines the relative air pressure inside the object at the startframe.
MStatus  setSealHoles (bool seal)
  When the volume tracking pressure method is used this determines if physical holes in the cloth model are treated as being capped or not.
MStatus  setPressure (float pressure)
  Sets the pressure within the cloth.
MStatus  setTrackVolume (bool track)
MStatus  setIncompressibility (float v)
  When the volume tracking pressure model is used this defines how incompressible the internal volume of fluid is.
MStatus  setPressureDamping (float damp)
  Sets the damping value for pressure.
MStatus  setPumpRate (float pump)
  Defines the rate at which air pressure is added to the object.
MStatus  setAirTightness (float airTightness)
  Defines the rate at which air can escape from the object, or how permiable the surface is.
MStatus  setAddCrossLinks (float addCrossLinks)
  For faces with more than 3 vertices this will create additional stretch and bends links such that each vertex is connected to each other vertex.
MStatus  setBendAngleDropoff (float dropoff)
  Defines the way bend resistance changes with the angle.
MStatus  setShearResistance (float resistance)
  Sets the shear resistance.
MStatus  setStretchAndCompressionResistance (float stretchResist, float compressionResist)
  Stretch Resistance:
MStatus  setStretchAndCompressionResistance (float *stretchResist, float *compressionResist)
  Sets the stretch and compression resistance for the mesh on a per vertex basis.
MStatus  setBendAngleScale (float scale)
  Defines the amount by which the rest state of the bend angle is scaled.
MStatus  setRestitutionAngle (float angle)
  Defines how far we can bend across an edge before it will fail to go back to the rest angle when there are no forces acting on the cloth.
MStatus  setRestitutionTension (float tension)
  How far can the links be stretched before they fail to go back to their rest length when there are no forces acting on the cloth.
MStatus  setSelfCollideWidth (float width)
  Sets the self collision width.
MStatus  setBendResistance (float strength)
  Bend resistance measures the amount of attraction to the restAngle, which is defined between cvs on either side of an edge.
MStatus  getNumVertices (unsigned int &numVerts) const
  Returns the number of vertices in the underlying n Cloth.
MStatus  getPositions (MFloatPointArray &positions) const
  gets the positions of the points of the underlying N Object.
MStatus  getVelocities (MFloatPointArray &velocities) const
  gets the velocities of the points of the underlying N cloth object.
MStatus  getThickness (MFloatArray &radius) const
  gets the thickness at each point of the underlying N cloth object.
MStatus  getInverseMass (MFloatArray &inverseMass) const
  gets the inverseMass at each point of the underlying N cloth object.
MStatus  getBounce (MFloatArray &bounce) const
  gets the bounce at each point of the underlying N cloth object.
MStatus  getFriction (MFloatArray &friction) const
  gets the friction at each point of the underlying N cloth object.

Friends
class  MFnNObjectData
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Constructor & Destructor Documentation

MnCloth ( )

Default constructor.

The instance is set to contain nothing.

Member Function Documentation

MStatus createNCloth ( )
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Creates the underlying Maya TnCloth and sets this class to wrap it.

Returns:
MStatus setTopology ( const int  numFaces,
int *  numVertsPerFace,
int *  faces,
const int  numEdges,
int *  edges 
)
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sets the topology of the underlying N Object.

Before calling other methods, this must be the first method you call once the cloth object is created.

Parameters:
[in] numFaces number of faces
[in] numVertsPerFace an array of size numFaces, where each element describes the number of verts on that face
[in] faces an array containing the actual face description. Each element is a vertex index.
[in] numEdges number of edges
[in] edges an array containing the edge description. Each element is a vertex index.
Returns:
MStatus setPositions ( const MFloatPointArray &  positions,
bool  startFrame = true 
)
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Sets the positions of the vertices of the underlying N cloth object.

Parameters:
[in] positions the array containing the position information
[in] startFrame whether this information represents the state of the object at the start frame.
Returns:
Examples:
testNucleusNode.cpp.
MStatus setVelocities ( const MFloatPointArray &  velocities )
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Sets the velocities of the vertices of the underlying Ncloth object.

Parameters:
[in] velocities the array containing the velocity information
Returns:
MStatus setBendRestAngleFromPositions ( const MFloatPointArray &  positions )
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Sets the the bend rest angle from the list of positions for the underlying N Object This sets the shape that bend resistance is trying to achieve.

Parameters:
[in] positions the array containing the position information
Returns:
MStatus setLinksRestLengthFromPositions ( const MFloatPointArray &  positions )
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Sets the the rest length from the list of positions for the underlying N Object.

This sets the shape that the stretch/compression resistance are trying to achieve.

Parameters:
[in] positions the array containing the position information
Returns:
MStatus setInputMeshAttractPositions ( const MFloatPointArray &  positions )
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Sets the positions for input mesh attract.

Parameters:
[in] positions the array containing the position information
Returns:
MStatus setInputMeshAttractDamping ( float  damping )
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Defines how springy the effect of Input Mesh Attract is.

At a value of zero input mesh attract will behave like a spring connection from the input mesh to the output dynamic mesh. The cloth will tend to wiggle about the input mesh position. As the Input Attract Damp is increased to 1 the cloth mesh will still move to the input mesh position but not have the momentum to travel past it, so will no longer occillate about the input position.

Parameters:
[in] damping the damping value
Returns:
MStatus setInputMeshAttractAndRigidStrength ( float *  inputAttractArray,
float *  rigidArray,
float *  deformArray 
)
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Sets on a per particle basis, the amount by which each particle is affected by the input mesh attract, rigidity, and deformability.

High values for the input mesh attract will make points stick closely to the input mesh. High values for the rigidArray will make the object behave like a rigid body.

These arguments actually encode 2 pieces of information in 1. It contains instructions for:

A) The number of iterations and B) The strength of the effect

The number of iterations is the maximum value over the array passed in. The relative strength, measured from 0 to 1, is the normalized value of each element of the array.

For example, if for the inputAttractArray one were to specify a value of 10.0 for the first element, and 1.0 for the rest, it means that the solver should take 10 steps to compute inputMeshAttract, and the first particle has a strength of 1 while the rest have a strength of 0.1.

Parameters:
[in] inputAttractArray values for the input mesh attract
[in] rigidArray values for rigidity
[in] deformArray values for deformability
Returns:
MStatus setComputeRestLength ( const bool  b )
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Sets whether rest lengths will be automatically computed, or overridden manually.

If this is set to false, then you must call setLinksRestLengthFromPositions() to set the rest lengths.

Parameters:
[in] b whether to compute rest lengths
Returns:
MStatus setComputeRestAngles ( const bool  b )
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Sets whether rest angles will be automatically computed, or overridden manually.

If this is set to false, then you must call setBendRestAngleFromPositions() to set the rest lengths.

Parameters:
[in] b whether to compute rest angles
Returns:
MStatus setThickness ( float  radius )
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sets a radius on each point of the mesh for collision purposes.

The bigger the radius/thickness, the more easily things collide.

Parameters:
[in] radius the radius to set
Returns:
MStatus setThickness ( float *  radius )
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sets a radius (thickness) on a per point basis for the mesh for collision purposes.

The bigger the radius, the more easily things collide.

Parameters:
[in] radius the radius to set
Returns:
MStatus setInverseMass ( float  invMass )
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sets the mass for every point in this mesh

Parameters:
[in] invMass the inverse of the mass. A value of 0 means an infinitely heave object.
Returns:
MStatus setInverseMass ( float *  invMass )
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sets the mass on a per point basis in this mesh

Parameters:
[in] invMass the inverse of the mass. A value of 0 means an infinitely heave object.
Returns:
MStatus setBounce ( float  bounce )
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sets the bounce for every point in this mesh

Parameters:
[in] bounce value of bounce to set
Returns:
MStatus setBounce ( float *  bounce )
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sets the bounce on a per point basis in this mesh

Parameters:
[in] bounce value of bounce to set
Returns:
MStatus setFriction ( float  friction )
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sets the friction for every point in this mesh

Parameters:
[in] friction the friction to set
Returns:
MStatus setFriction ( float *  friction )
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sets the friction on a per point basis for this mesh

Parameters:
[in] friction the friction to set
Returns:
MStatus setDamping ( float  damping )
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sets the damping for every point in this mesh

Parameters:
[in] damping the damping value to set
Returns:
MStatus setDamping ( float *  damping )
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sets the on a per point basis in this mesh

Parameters:
[in] damping the damping value to set
Returns:
MStatus setSelfCollisionFlags ( const bool  vertToVert,
const bool  vertToEdge = false,
const bool  vertToFace = false,
const bool  edgeToEdge = false,
const bool  edgeToFace = false 
)
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Sets how (or if) this object will collide with itself.

Parameters:
[in] vertToVert whether to calculate vertex - vertex collisions
[in] vertToEdge whether to calculate vertex - edge collisions
[in] vertToFace whether to calculate vertex - face collisions
[in] edgeToEdge whether to calculate edge - edge collisions
[in] edgeToFace whether to calculate edge - face collisions
Returns:
MStatus setCollisionFlags ( const bool  vertToVert,
const bool  edgeToEdge = false,
const bool  faceToFace = false 
)
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Sets how (or if) this object will collide with other objects.

Parameters:
[in] vertToVert whether to calculate vertex - vertex collisions
[in] edgeToEdge whether to calculate edge - edge collisions
[in] faceToFace whether to calculate face - face collisions
Returns:
MStatus setDisableGravity ( const bool  b )
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Sets whether gravity will affect this object.

Parameters:
[in] b whether to calculate gravity
Returns:
MStatus setMaxIterations ( const int  it )
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Sets the number of iterations the solver will perform on various dynamic properties like drag, damping, stretch and bend.

Higher iterations take longer, and the primary use of this attribute is to keep things from locking up should high iteration values be requested.

Parameters:
[in] it number of iterations
Returns:
MStatus setMaxSelfCollisionIterations ( const int  it )
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Sets the number of iterations the solver will perform for self collisions on this object.

Parameters:
[in] it number of iterations
Returns:
MStatus setSelfCollisionSoftness ( float  softness )
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This allows one to lower the repulsive force of self collisions such that some interpenetration within the collide width is allowed.

This can in some cases reduce jitter due to self collision with low selfCollideIterations. In general its use should be avoided, however.

Parameters:
[in] softness value to set.
Returns:
MStatus setSelfTrappedCheck ( bool  on )
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This tracks self collision crossovers and attempts to push the crossed over points back.

It assumes that the surface is in a good state at the start and attempts to preserve that relative state. It is useful in cases where cloth can get caught between passive objects than interpenetrate (for example an elbow passing through a chest). Rather than get stuck on the wrong side this allows the cloth to push back to the correct side when the passive objects later separate.

Parameters:
[in] on whether to turn on self trapped check.
Returns:
MStatus setSelfCrossoverPush ( float  val )
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See node documentation.

Parameters:
[in] val value for crossover push
Returns:
MStatus setDragAndLift ( float  drag,
float  lift 
)
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Sets the drag and lift values for the cloth.

Parameters:
[in] drag value of drag
[in] lift value of lift
Returns:
MStatus setTangentialDrag ( float  tangentialDrag )
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Sets the tangential drag values for the cloth.

Defines the component of drag tangent to the surface. With a value of zero a flat plane will slice through air with no resistance and only have drag when moving along its normal axis. With a value of 1.0 the effect of drag will be equal in all directions.

Parameters:
[in] tangentialDrag the tangential drag
Returns:
MStatus setStartPressure ( float  startPressure )
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With the volume tracking pressure method this defines the relative air pressure inside the object at the startframe.

Parameters:
[in] startPressure the start pressure
Returns:
MStatus setSealHoles ( bool  seal )
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When the volume tracking pressure method is used this determines if physical holes in the cloth model are treated as being capped or not.

If holes are not sealed, then air can escape out them, which also has the effect of pushing the cloth. For example, this can simulate a rubber balloon that is suddenly released. It also allows for inflow based on motion of the cloth. The opening in a parachute will allow air to flow in as it falls down, causing sideways pressure that inflates it. Note that drag alone cannot achieve this sort of effect

Parameters:
[in] seal whether to seal holes
Returns:
MStatus setPressure ( float  pressure )
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Sets the pressure within the cloth.

This defines a force applied along the surface normal direction

Parameters:
[in] pressure the value of pressure to set
Returns:
MStatus setTrackVolume ( bool  track )
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Parameters:
[in] track whether to track volume
Returns:
MStatus setIncompressibility ( float  v )
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When the volume tracking pressure model is used this defines how incompressible the internal volume of fluid is.

This also will affect how much force is applied to the cloth when air is pumped in. In the case of a balloon higher values of incompressibility will overcome higher stretch resistance. Note that higher incompressibility may require more calculation time.

Parameters:
[in] v how incompressible the cloth is
Returns:
MStatus setPressureDamping ( float  damp )
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Sets the damping value for pressure.

Parameters:
[in] damp value to set
Returns:
MStatus setPumpRate ( float  pump )
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Defines the rate at which air pressure is added to the object.

Parameters:
[in] pump value to set
Returns:
MStatus setAirTightness ( float  airTightness )
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Defines the rate at which air can escape from the object, or how permiable the surface is.

This is in addition to any physical holes in the model, which can be be capped or not using the seal holes method.

Parameters:
[in] airTightness value to set
Returns:
MStatus setAddCrossLinks ( float  addCrossLinks )
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For faces with more than 3 vertices this will create additional stretch and bends links such that each vertex is connected to each other vertex.

If this is off then the links will exactly match the meshes list of edges. For a quad meshes having addCrossLinks off would allow the cloth to shear, unless shear resistance was used.

Parameters:
[in] addCrossLinks value to set
Returns:
MStatus setBendAngleDropoff ( float  dropoff )
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Defines the way bend resistance changes with the angle.

At higher values the bend will resist more at high angles then when the surface is nearly flat.

Parameters:
[in] dropoff value to set
Returns:
MStatus setShearResistance ( float  resistance )
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Sets the shear resistance.

Shear can be thought of as the bend in the plane of the cloth.

Parameters:
[in] resistance value to set
Returns:
MStatus setStretchAndCompressionResistance ( float  stretchResist,
float  compressionResist 
)
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Stretch Resistance:

Defines the amount that the material will resist stretching when under tension. Large values generally require more computation, so they may result in longer simulation times. Note that the scalingRelation attribute affects how this value is defined. Also one may need to additionally make the both collision iterations on the solver and constraint strength values high to keep stretching low.

Compression Resistance:

Defines the amount that the material will resist compression. Note that sometimes it is useful to have this value be lower than the Stretch Resistance, because the mesh resolution is only an approximation to a true surface, which could possibly fold within the length of a triangle. If one has a rest position for a cloth that is not flat and the compression and stretch resistance are both high then this can make cloth appear too stiff because the topology locks up. This problem is most noticable when the faces have relatively high angles relative to each other. Having a low compression resistance allows the material keep from locking up, yet still not appear to stretchy. Large values generally require more computation, so they may result in longer simulation times.

Parameters:
[in] stretchResist value to set for stretch
[in] compressionResist value to set for compression
Returns:
MStatus setStretchAndCompressionResistance ( float *  stretchResist,
float *  compressionResist 
)
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Sets the stretch and compression resistance for the mesh on a per vertex basis.

Parameters:
[in] stretchResist value to set for stretch
[in] compressionResist value to set for compression
Returns:
MStatus setBendAngleScale ( float  scale )
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Defines the amount by which the rest state of the bend angle is scaled.

Parameters:
[in] scale value to set
Returns:
MStatus setRestitutionAngle ( float  angle )
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Defines how far we can bend across an edge before it will fail to go back to the rest angle when there are no forces acting on the cloth.

Parameters:
[in] angle value to set
Returns:
MStatus setRestitutionTension ( float  tension )
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How far can the links be stretched before they fail to go back to their rest length when there are no forces acting on the cloth.

When the tension is greater than the defined value the defined rest length will increase until the tension is equal this value. For very low values the material will pull apart like taffy, yet still resist stretching under mild forces.

Parameters:
[in] tension value to set
Returns:
MStatus setSelfCollideWidth ( float  width )
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Sets the self collision width.

Parameters:
[in] width value to set
Returns:
MStatus setBendResistance ( float  strength )
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Bend resistance measures the amount of attraction to the restAngle, which is defined between cvs on either side of an edge.

Larger values will tend to make the surface more rigid and will take longer to compute.

Parameters:
[in] strength value to set
Returns:
MStatus getNumVertices ( unsigned int &  numVerts ) const
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Returns the number of vertices in the underlying n Cloth.

Parameters:
[out] numVerts Number of vertices.
Returns:
MStatus getPositions ( MFloatPointArray &  positions ) const
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gets the positions of the points of the underlying N Object.

Parameters:
[out] positions the array will be filled with the positions.
Returns:
Examples:
testNucleusNode.cpp.
MStatus getVelocities ( MFloatPointArray &  velocities ) const
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gets the velocities of the points of the underlying N cloth object.

Parameters:
[in] velocities the array will be filled with the positions.
Returns:
MStatus getThickness ( MFloatArray &  radius ) const
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gets the thickness at each point of the underlying N cloth object.

Parameters:
[in] radius the array will be filled with the thickness.
Returns:
MStatus getInverseMass ( MFloatArray &  inverseMass ) const
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gets the inverseMass at each point of the underlying N cloth object.

Parameters:
[in] inverseMass the array will be filled with the inverse masses.
Returns:
MStatus getBounce ( MFloatArray &  bounce ) const
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gets the bounce at each point of the underlying N cloth object.

Parameters:
[in] bounce the array will be filled with the bounce.
Returns:
MStatus getFriction ( MFloatArray &  friction ) const
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gets the friction at each point of the underlying N cloth object.

Parameters:
[in] friction the array will be filled with the friction.
Returns:
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