artisynth.core.femmodels

Class EmbeddedFem

java.lang.Object

artisynth.core.femmodels.EmbeddedFem

public class EmbeddedFem
extends java.lang.Object

Useful functions for creating embedded finite element models

Field Summary

Fields

Modifier and Type	Field and Description
static int	DEFAULT_SAMPLES

Constructor Summary

Constructors

Constructor and Description
EmbeddedFem()

Method Summary

Modifier and Type	Method and Description
static void	adjustMassAndStiffness(FemModel3d fem, PolygonalMesh surface) Adjusts mass and stiffness of a FEM model based on a given surface mesh.
static void	adjustMassAndStiffness(FemModel3d fem, PolygonalMesh surface, int nSamplesPerElement) Adjusts mass and stiffness of a FEM model based on a given surface mesh.
static ScalarNodalField	computeNodalField(FemModel3d fem, Function3x1 func, FemElementSampler sampler, int nSamplesPerElement) Computes a best-fitting scalar nodal field, computing node values by minimizing the squared error between a sampled function, and the one interpolated via nodes and shape functions.
static ScalarSubElemField	computeSubElemField(FemModel3d fem, Function3x1 func) Compute a field by simply evaluating the function at integration points
static ScalarSubElemField	computeSubElemField(FemModel3d fem, Function3x1 func, FemElementSampler sampler, int nSamplesPerElement) Compute a field by sampling a function over the FEM model and using least-squares to fit the FEM element shape functions independently over each element.
static FemModel3d	createBoundingFem(FemModel3d fem, PolygonalMesh mesh, RigidTransform3d trans, int minRes, double maxElemWidth) Creates a regular finite element grid that bounds a supplied surface
static FemModel3d	createBoundingFem(FemModel3d fem, PolygonalMesh mesh, RigidTransform3d trans, int minRes, double maxElemWidth, double margin) Creates a FEM model that bounds a given surface
static FemModel3d	createBoundingFem(FemModel3d fem, PolygonalMesh mesh, RigidTransform3d trans, Vector3i res) Creates a FEM model that bounds a given surface
static FemModel3d	createBoundingFem(FemModel3d fem, PolygonalMesh mesh, RigidTransform3d trans, Vector3i res, double margin) Creates a FEM model that bounds a given surface
static MaterialBundle	createMaterialBundle(FemModel3d fem, FemMaterial mat, ScalarFieldComponent density) Creates a material bundle based on a supplied material and a volume density function.
static FemModel3d	createVoxelizedFem(FemModel3d fem, PolygonalMesh mesh, RigidTransform3d trans, int minRes, double maxElemWidth) Creates a FEM model that surrounds a given surface, using a lego-brick-like pattern (like voxels).
static FemModel3d	createVoxelizedFem(FemModel3d fem, PolygonalMesh mesh, RigidTransform3d trans, int minRes, double maxElemWidth, double margin) Creates a FEM model that surrounds a given surface, using a lego-brick-like pattern (like voxels).
static FemModel3d	createVoxelizedFem(FemModel3d fem, PolygonalMesh mesh, RigidTransform3d trans, Vector3i res) Creates a FEM model that surrounds a given surface, using a lego-brick-like pattern (like voxels).
static FemModel3d	createVoxelizedFem(FemModel3d fem, PolygonalMesh mesh, RigidTransform3d trans, Vector3i res, double margin) Creates a FEM model that surrounds a given surface, using a lego-brick-like pattern (like voxels).
static java.lang.Class<? extends DirectSolver>	getSolverClass() Check sparse matrix solver type for use in computing best-fitting node values
static void	removeFractionalElements(FemModel3d fem, DistanceGrid dq, double margin, double frac) Removes elements containing less than the given fraction of volume
static void	removeOutsideElements(FemModel3d fem, PolygonalMesh mesh, double margin) Removes elements outside a given mesh plus margin
static void	removeOutsideElements(FemModel3d fem, PolygonalMesh mesh, int nsamples, double margin) Removes elements outside a given mesh plus margin
static void	restoreFaceCompatibility(FemModel3d fem) Restores element face-face compatibility by inserting pyramid and tet elements
static void	setMasses(FemModel3d fem, Function3x1 density, FemElementIntegrator integrator) Numerically integrates the density function over each element to compute masses concentrated at the nodes.
static void	setMasses(FemModel3d fem, ScalarFemField density, double scale) Sets node and element masses based on a supplied density function by integrating over each element to compute masses concentrated at the nodes.
static void	setSolverClass(java.lang.Class<? extends DirectSolver> clazz) Set sparse matrix solver for use in computing best-fitting node values
static void	trimBoundaryHexes(FemModel3d fem, DistanceGrid sd, double margin) Divide boundary hex elements and remove portions unused
static void	trimBoundaryHexes(FemModel3d fem, PolygonalMesh mesh, double margin) Divide boundary hex elements and remove portions unused

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

DEFAULT_SAMPLES

public static int DEFAULT_SAMPLES

Constructor Detail

EmbeddedFem

public EmbeddedFem()

Method Detail

setSolverClass

public static void setSolverClass(java.lang.Class<? extends DirectSolver> clazz)

Set sparse matrix solver for use in computing best-fitting node values

Parameters:

clazz - solver class type

getSolverClass

public static java.lang.Class<? extends DirectSolver> getSolverClass()

Check sparse matrix solver type for use in computing best-fitting node values

Returns:

solver class type

setMasses

public static void setMasses(FemModel3d fem,
                             Function3x1 density,
                             FemElementIntegrator integrator)

Numerically integrates the density function over each element to compute masses concentrated at the nodes.

Parameters:

fem - model

density - density function

integrator - integrator object for integrating density over elements

setMasses

public static void setMasses(FemModel3d fem,
                             ScalarFemField density,
                             double scale)

Sets node and element masses based on a supplied density function by integrating over each element to compute masses concentrated at the nodes.

Parameters:

fem - model

density - density function

scale - scale for density function

createMaterialBundle

public static MaterialBundle createMaterialBundle(FemModel3d fem,
                                                  FemMaterial mat,
                                                  ScalarFieldComponent density)

Creates a material bundle based on a supplied material and a volume density function. The material's stress/stiffness contributions will be scaled by the density

Parameters:

fem - model

mat - material to use for bundle

density - density function

Returns:

generated material bundle

computeNodalField

public static ScalarNodalField computeNodalField(FemModel3d fem,
                                                 Function3x1 func,
                                                 FemElementSampler sampler,
                                                 int nSamplesPerElement)

Computes a best-fitting scalar nodal field, computing node values by minimizing the squared error between a sampled function, and the one interpolated via nodes and shape functions.

Parameters:

fem - model containing nodes

func - function to sample

sampler - method of sampling from elements

nSamplesPerElement - number of samples per element

Returns:

best-fitting nodal field

computeSubElemField

public static ScalarSubElemField computeSubElemField(FemModel3d fem,
                                                     Function3x1 func,
                                                     FemElementSampler sampler,
                                                     int nSamplesPerElement)

Compute a field by sampling a function over the FEM model and using least-squares to fit the FEM element shape functions independently over each element.

Parameters:

fem - finite element model over which to create field

func - function to sample

sampler - sampling object

nSamplesPerElement - number of samples to take per element

Returns:

computed field

computeSubElemField

public static ScalarSubElemField computeSubElemField(FemModel3d fem,
                                                     Function3x1 func)

Compute a field by simply evaluating the function at integration points

Parameters:

fem - finite element model over which to create field

func - function to sample

Returns:

computed field

adjustMassAndStiffness

public static void adjustMassAndStiffness(FemModel3d fem,
                                          PolygonalMesh surface,
                                          int nSamplesPerElement)

Adjusts mass and stiffness of a FEM model based on a given surface mesh. Does this by adjusting the node/ element masses based on integrating the FEM's density within the mesh volume, and adjusts stiffness by creating a scalar field to modulate the stiffness/tangent contributions.

Parameters:

fem - model to adjust

surface - surface-mesh for determining inside-outside

nSamplesPerElement - number of samples per element for numerical integration

adjustMassAndStiffness

public static void adjustMassAndStiffness(FemModel3d fem,
                                          PolygonalMesh surface)

Adjusts mass and stiffness of a FEM model based on a given surface mesh. Does this by adjusting the node/ element masses based on integrating the FEM's density within the mesh volume, and adjusts stiffness by creating a scalar field to modulate the stiffness/tangent contributions.

Parameters:

fem - model to adjust integration

createBoundingFem

public static FemModel3d createBoundingFem(FemModel3d fem,
                                           PolygonalMesh mesh,
                                           RigidTransform3d trans,
                                           int minRes,
                                           double maxElemWidth)

Creates a regular finite element grid that bounds a supplied surface

Parameters:

fem - model to populated, created if null

mesh - surface to bound

trans - orientation of grid

minRes - minimum number of elements along each dimension

maxElemWidth - maximum element width along any dimension

Returns:

populated or created model

createBoundingFem

public static FemModel3d createBoundingFem(FemModel3d fem,
                                           PolygonalMesh mesh,
                                           RigidTransform3d trans,
                                           int minRes,
                                           double maxElemWidth,
                                           double margin)

Creates a FEM model that bounds a given surface

Parameters:

fem - model to populate, one is created if null

mesh - surface to bound

trans - orientation of bounding model (or uses OBB of mesh if null)

minRes - minimum number of elements along any direction

maxElemWidth - maximum width of an element along any direction

margin - extra space in model to surround mesh

Returns:

created or populated model

createBoundingFem

public static FemModel3d createBoundingFem(FemModel3d fem,
                                           PolygonalMesh mesh,
                                           RigidTransform3d trans,
                                           Vector3i res)

Creates a FEM model that bounds a given surface

Parameters:

fem - model to populate, one is created if null

mesh - surface to bound

trans - orientation of bounding model (or uses OBB of mesh if null)

res - element resolution

Returns:

created or populated model

createBoundingFem

public static FemModel3d createBoundingFem(FemModel3d fem,
                                           PolygonalMesh mesh,
                                           RigidTransform3d trans,
                                           Vector3i res,
                                           double margin)

Creates a FEM model that bounds a given surface

Parameters:

fem - model to populate, one is created if null

mesh - surface to bound

trans - orientation of bounding model (or uses OBB of mesh if null)

res - element resolution

margin - extra space in model to surround mesh

Returns:

created or populated model

createVoxelizedFem

public static FemModel3d createVoxelizedFem(FemModel3d fem,
                                            PolygonalMesh mesh,
                                            RigidTransform3d trans,
                                            int minRes,
                                            double maxElemWidth)

Creates a FEM model that surrounds a given surface, using a lego-brick-like pattern (like voxels). Note that properties of the FEM are NOT adjusted to account for empty space along the boundary elements. For that, use adjustMassAndStiffness(FemModel3d, PolygonalMesh, int)

Parameters:

fem - model to populate (one is created if null)

mesh - mesh to surround/voxelize

trans - orientation for voxels (uses OBB of mesh if null)

minRes - minimum number of elements along any direction

maxElemWidth - maximum element with along any direction

Returns:

populated or created FEM

createVoxelizedFem

public static FemModel3d createVoxelizedFem(FemModel3d fem,
                                            PolygonalMesh mesh,
                                            RigidTransform3d trans,
                                            int minRes,
                                            double maxElemWidth,
                                            double margin)

Creates a FEM model that surrounds a given surface, using a lego-brick-like pattern (like voxels). Note that properties of the FEM are NOT adjusted to account for empty space along the boundary elements. For that, use adjustMassAndStiffness(FemModel3d, PolygonalMesh, int)

Parameters:

fem - model to populate (one is created if null)

mesh - mesh to surround/voxelize

trans - orientation for voxels (uses OBB of mesh if null)

minRes - minimum number of elements along any direction

maxElemWidth - maximum element with along any direction

margin - margin for surrounding mesh

Returns:

populated or created FEM

createVoxelizedFem

public static FemModel3d createVoxelizedFem(FemModel3d fem,
                                            PolygonalMesh mesh,
                                            RigidTransform3d trans,
                                            Vector3i res)

Creates a FEM model that surrounds a given surface, using a lego-brick-like pattern (like voxels). Note that properties of the FEM are NOT adjusted to account for empty space along the boundary elements. For that, use adjustMassAndStiffness(FemModel3d, PolygonalMesh, int)

Parameters:

fem - model to populate (one is created if null)

mesh - mesh to surround/voxelize

trans - orientation for voxels (uses OBB of mesh if null)

res - element resolution for original grid

Returns:

populated or created FEM

createVoxelizedFem

public static FemModel3d createVoxelizedFem(FemModel3d fem,
                                            PolygonalMesh mesh,
                                            RigidTransform3d trans,
                                            Vector3i res,
                                            double margin)

Creates a FEM model that surrounds a given surface, using a lego-brick-like pattern (like voxels). Note that properties of the FEM are NOT adjusted to account for empty space along the boundary elements. For that, use adjustMassAndStiffness(FemModel3d, PolygonalMesh, int)

Parameters:

fem - model to populate (one is created if null)

mesh - mesh to surround/voxelize

trans - orientation for voxels (uses OBB of mesh if null)

res - element resolution for original grid

margin - margin for surrounding mesh

Returns:

populated or created FEM

removeOutsideElements

public static void removeOutsideElements(FemModel3d fem,
                                         PolygonalMesh mesh,
                                         double margin)

Removes elements outside a given mesh plus margin

Parameters:

fem - model to remove elements from

mesh - surface outside which to remove elements

margin - margin distance outside mesh to consider (if < 0, once is computed based on a half element size)

removeOutsideElements

public static void removeOutsideElements(FemModel3d fem,
                                         PolygonalMesh mesh,
                                         int nsamples,
                                         double margin)

Removes elements outside a given mesh plus margin

Parameters:

fem - model to remove elements from

mesh - surface outside which to remove elements

nsamples - number of samples to choose from within the element

margin - margin distance outside mesh to consider (if < 0, once is computed based on a half element size)

removeFractionalElements

public static void removeFractionalElements(FemModel3d fem,
                                            DistanceGrid dq,
                                            double margin,
                                            double frac)

Removes elements containing less than the given fraction of volume

Parameters:

fem - model to modify

dq - distance grid

margin - margin to keep outside distance field

frac - fraction below which to remove elements

trimBoundaryHexes

public static void trimBoundaryHexes(FemModel3d fem,
                                     PolygonalMesh mesh,
                                     double margin)

Divide boundary hex elements and remove portions unused

Parameters:

fem - model to trim

mesh - surface for determining inside/outside

margin - margin to preserve around model

trimBoundaryHexes

public static void trimBoundaryHexes(FemModel3d fem,
                                     DistanceGrid sd,
                                     double margin)

Divide boundary hex elements and remove portions unused

Parameters:

fem - model to trim

sd - signed-distance field for determining inside/outside

margin - margin to preserve around model

restoreFaceCompatibility

public static void restoreFaceCompatibility(FemModel3d fem)

Restores element face-face compatibility by inserting pyramid and tet elements

Parameters:

fem - model to fix