Open Inventor Release 2024.1.1
 
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PlaneGeometryIntersection Class Reference

VSG extension (Preview feature) [Medical] Class for computing the intersection of geometry with a plane. More...

#include <Medical/nodes/PlaneGeometryIntersection.h>

+ Inheritance diagram for PlaneGeometryIntersection:

Public Member Functions

virtual SoType getTypeId () const
 Returns the type identifier for this specific instance.
 
const SoShapegetShape () const
 Get the shape node that contains the computed vertices and indices.
 
int recompute ()
 Recompute the intersection.
 
 PlaneGeometryIntersection ()
 Constructor.
 
- Public Member Functions inherited from SoSeparator
 SoSeparator ()
 Creates a separator node with default settings.
 
 SoSeparator (int nChildren)
 Constructor that takes approximate number of children.
 
- Public Member Functions inherited from SoGroup
 SoGroup ()
 Creates an empty group node.
 
 SoGroup (int nChildren)
 Constructor that takes approximate number of children.
 
virtual void addChild (SoNode *child)
 Adds a child as last one in group.
 
virtual void insertChild (SoNode *child, int newChildIndex)
 Adds a child so that it becomes the one with the given index.
 
virtual SoNodegetChild (int index) const
 Returns pointer the child node with the given index.
 
virtual int findChild (const SoNode *child) const
 Finds index of given child within group.
 
virtual int getNumChildren () const
 Returns number of children.
 
virtual void removeChild (int index)
 Removes child with given index from group.
 
virtual void removeChild (SoNode *child)
 Removes first instance of given child from group.
 
virtual void removeAllChildren ()
 Removes all children from group.
 
virtual void replaceChild (int index, SoNode *newChild)
 Replaces child with given index with new child.
 
virtual void replaceChild (SoNode *oldChild, SoNode *newChild)
 Replaces first instance of given child with new child.
 
- Public Member Functions inherited from SoNode
virtual void setOverride (const SbBool state)
 Turns the override flag on or off.
 
virtual SbBool isOverride () const
 Returns the state of the override flag.
 
virtual SoNodecopy (SbBool copyConnections=FALSE) const
 Creates and returns an exact copy of the node.
 
virtual void touch ()
 Marks an instance as modified, simulating a change to it.
 
- Public Member Functions inherited from SoFieldContainer
void setToDefaults ()
 Sets all fields in this object to their default values.
 
SbBool hasDefaultValues () const
 Returns TRUE if all of the object's fields have their default values.
 
SbBool fieldsAreEqual (const SoFieldContainer *fc) const
 Returns TRUE if this object's fields are exactly equal to fc's fields.
 
void copyFieldValues (const SoFieldContainer *fc, SbBool copyConnections=FALSE)
 Copies the contents of fc's fields into this object's fields.
 
SoNONUNICODE SbBool set (const char *fieldDataString)
 Sets one or more fields in this object to the values specified in the given string, which should be a string in the Open Inventor file format.
 
SbBool set (const SbString &fieldDataString)
 Sets one or more fields in this object to the values specified in the given string, which should be a string in the Open Inventor file format.
 
void get (SbString &fieldDataString)
 Returns the values of the fields of this object in the Open Inventor ASCII file format in the given string.
 
virtual int getFields (SoFieldList &list) const
 Appends references to all of this object's fields to resultList, and returns the number of fields appended.
 
virtual int getAllFields (SoFieldList &list) const
 Returns a list of fields, including the eventIn's and eventOut's.
 
virtual SoFieldgetField (const SbName &fieldName) const
 Returns a the field of this object whose name is fieldName.
 
virtual SoFieldgetEventIn (const SbName &fieldName) const
 Returns a the eventIn with the given name.
 
virtual SoFieldgetEventOut (const SbName &fieldName) const
 Returns the eventOut with the given name.
 
SbBool getFieldName (const SoField *field, SbName &fieldName) const
 Returns the name of the given field in the fieldName argument.
 
SbBool enableNotify (SbBool flag)
 Notification at this Field Container is enabled (if flag == TRUE) or disabled (if flag == FALSE).
 
SbBool isNotifyEnabled () const
 Notification is the process of telling interested objects that this object has changed.
 
virtual void setUserData (void *data)
 Sets application data.
 
void * getUserData (void) const
 Gets user application data.
 
- Public Member Functions inherited from SoBase
virtual SbName getName () const
 Returns the name of an instance.
 
virtual void setName (const SbName &name)
 Sets the name of an instance.
 
void setSynchronizable (const bool b)
 Sets this to be a ScaleViz synchronizable object.
 
bool isSynchronizable () const
 Gets the ScaleViz synchronizable state of this object.
 
- Public Member Functions inherited from SoRefCounter
void ref () const
 Adds a reference to an instance.
 
void unref () const
 Removes a reference from an instance.
 
void unrefNoDelete () const
 unrefNoDelete() should be called when it is desired to decrement the reference count, but not delete the instance if this brings the reference count to zero.
 
int getRefCount () const
 Returns current reference count.
 
void lock () const
 lock this instance.
 
void unlock () const
 unlock this instance.
 
- Public Member Functions inherited from SoTypedObject
SbBool isOfType (const SoType &type) const
 Returns TRUE if this object is of the type specified in type or is derived from that type.
 
template<typename TypedObjectClass >
SbBool isOfType () const
 Returns TRUE if this object is of the type of class TypedObjectClass or is derived from that class.
 

Static Public Member Functions

static SoType getClassTypeId ()
 Returns the type identifier for this class.
 
static void initClass ()
 Initialize class (called automatically by InventorMedical::init()).
 
static void exitClass ()
 Finish using class (called automatically by InventorMedical::finish()).
 
- Static Public Member Functions inherited from SoSeparator
static SoType getClassTypeId ()
 Returns the type identifier for this class.
 
- Static Public Member Functions inherited from SoGroup
static SoType getClassTypeId ()
 Returns the type identifier for this class.
 
- Static Public Member Functions inherited from SoNode
static SoType getClassTypeId ()
 Returns the type identifier for this class.
 
static SoNodegetByName (const SbName &name)
 A node's name can be set using SoBase::setName().
 
static int getByName (const SbName &name, SoNodeList &list)
 A node's name can be set using SoBase::setName().
 
- Static Public Member Functions inherited from SoFieldContainer
static SoType getClassTypeId ()
 Returns the type of this class.
 
- Static Public Member Functions inherited from SoBase
static SoType getClassTypeId ()
 Returns type identifier for this class.
 
- Static Public Member Functions inherited from SoTypedObject
static SoType getClassTypeId ()
 Returns the type identifier for this class.
 

Public Attributes

SoSFNode scene
 Scene to intersect with plane.
 
SoSFPlane plane
 Plane to intersect with.
 
SoSFBool polygon
 Specifies whether to compute a capping polygon (default false).
 
SoSFBool automatic
 Specifies whether to recompute the intersection automatically or not (default true).
 
SoSFFloat tolerance
 Tolerance for testing if vertices are equal.
 
- Public Attributes inherited from SoSeparator
SoSFEnum boundingBoxCaching
 Whether to cache during bounding box traversal.
 
SoSFEnum renderCulling
 Whether to cull during rendering traversal.
 
SoSFEnum pickCulling
 Whether to cull during picking traversal.
 
SoSFEnum fastEditing
 Specifies the fast edit mode of the separator node.
 
SoSFInt32 renderUnitId
 Used during the ScaleViz depth compositing process, this field specifies which render unit (OIRU) will render the sub scene graph below this separator.
 
SoDEPRECATED SoSFEnum renderCaching
 Whether to cache during rendering traversal.
 
- Public Attributes inherited from SoGroup
SoSFBool boundingBoxIgnoring
 Whether to ignore this node during bounding box traversal.
 

Additional Inherited Members

- Public Types inherited from SoSeparator
enum  CacheEnabled {
  OFF ,
  ON ,
  AUTO
}
 Possible values for caching. More...
 
enum  FastEditing {
  DISABLE = 0x01 ,
  KEEP_ZBUFFER = 0x02 ,
  CLEAR_ZBUFFER = 0x03
}
 Fast editing policy enumeration values. More...
 

Detailed Description

VSG extension (Preview feature) [Medical] Class for computing the intersection of geometry with a plane.

This class computes and (optionally) renders the intersection of the geometry in the specified scene graph with the specified plane. In curve mode it computes a set of line segments corresponding to the intersection. In polygon mode it computes a set of polygon boundaries that can be used as a "cap" for clipped geometry. The intent is that the specified scene graph is one shape. In fact it can be any scene graph, but the result is always a single polygon with multiple boundaries (if necessary). The computed vertices (and indices in polygon mode) can be accessed using the getShape() method. The curve or polygon may be exported to a file like any other Open Inventor geometry using SoWriteAction, SoSTLWriteAction, etc.

Curve mode:
By default we compute and render the curve(s) defined by the intersection of the scene geometry and the plane. This is fast and works reliably for any Open Inventor geometry that produces triangles when an SoCallbackAction is applied (almost all Open Inventor geometry nodes). The appearance of the intersection curve can be controlled like any Open Inventor geometry using SoMaterial, SoDrawStyle, etc. nodes. The application may need to use an SoPolygonOffset node to "push" the scene geometry behind the intersection curve (polygon offset does not affect the intersection curve because it is a line set). Curve mode is useful to see where a clip plane intersects the geometry. Because it is much faster than polygon mode it is useful as a preview of where the polygons will be generated (if possible).

Polygon mode:
When the polygon field is set to true, the node converts the intersection curves to polygon boundaries. All the boundaries are stored in an SoIndexedFaceSet node and an SoShapeHints node is created with the 'windingType' field set to ODD_TYPE. All boundaries have counterclockwise vertex ordering and the face normal vector is the opposite of the current plane normal vector (because for a clip plane the plane normal points toward the unclipped half space which is effectively toward the interior of the shape). The appearance of the polygon can be controlled like any Open Inventor geometry using SoMaterial, etc. nodes. There are cases where polygons cannot be constructed, for example if the geometry is self-intersecting.

The coordinates of the intersection boundaries can be accessed using the getShape() method. This is an SoLineSet in curve mode and an SoIndexedFaceSet in polygon mode. In either case the coordinates are in the shape's attached SoVertexProperty node. Note that in curve mode the line segments are in random order and do not form a connected polyline. This allows the intersection geometry to be computed in minimum time and does not (visually) effect rendering. If you need the boundary(s) as a connected polyline for some purpose, use the polygon mode. Note that in polygon mode there are redundant vertices in the vertex list because it still contains all the line segments. To follow the boundaries in connection order use the coordinate indices in the SoIndexedFaceSet node.

Notes:

  • Multiple boundaries in polygon mode.
    Currently does not test if whether multiple boundaries are "holes" or "islands". Rendering should be correct in either case, but eventually some optimization could be done if all boundaries are disjoint.
  • Memory.
    Memory allocated for vertices and indices is re-used on each recomputation and is not freed until the node is destroyed. This is best for performance. Eventually there should be a method to force memory to be freed.

Limitations:

  • Valid geometry.
    For polygon mode to work correctly, the geometry must obey the same rules as a valid STL geometry. In particular the geometry must form a closed solid and must not be self-intersecting. All the intersection boundaries must be closed and must not intersect any other boundary.
    However in curve mode, there are no limitations. For example, the node can be used to render the intersection of a surface with a plane.
  • Triangulation of the polygon.
    This node simply computes the intersection boundary(s). For rendering it relies on Open Inventor to convert the polygon to triangles. In many cases the resulting triangles have a poor (large) aspect ratio.
  • Floating point precision.
    Curve mode should work reasonably well with any geometry and any coordinates. However constructing polygon boundaries is very sensitive to floating point precision problems. If the results are not good, try adjusting the tolerance value.
  • Redundant coordinates.
    In polygon mode the SoVertexProperty node contains all the coordinates computed for the intersection line segments. The SoIndexedFaceSet node only indexes a subset of these vertices (typically about half). Not removing the unused vertices saves time and has no effect on rendering. To get only the coordinates that are actually used, extract vertices based on the index values in the SoIndexedFaceSet node. Eventually could be an option.
  • Performamce.
    This is currently a "brute force" implementation and performance could be better.

FILE FORMAT/DEFAULT

SEE ALSO

InventorMedical, SoClipPlane, SoClipPlaneManip, SoSTLWriteAction

Definition at line 142 of file PlaneGeometryIntersection.h.

Constructor & Destructor Documentation

◆ PlaneGeometryIntersection()

PlaneGeometryIntersection::PlaneGeometryIntersection ( )

Constructor.

Member Function Documentation

◆ exitClass()

static void PlaneGeometryIntersection::exitClass ( )
static

Finish using class (called automatically by InventorMedical::finish()).

◆ getClassTypeId()

static SoType PlaneGeometryIntersection::getClassTypeId ( )
static

Returns the type identifier for this class.


◆ getShape()

const SoShape * PlaneGeometryIntersection::getShape ( ) const

Get the shape node that contains the computed vertices and indices.

Returns null if no shape has been computed yet. In curve mode this is an SoLineSet. In polygon mode this is an SoIndexedFaceSet. In both cases the vertices are in the shape node's attached SoVertexProperty node's 'vertex' field.

The application must not modify these nodes.

◆ getTypeId()

virtual SoType PlaneGeometryIntersection::getTypeId ( ) const
virtual

Returns the type identifier for this specific instance.

Reimplemented from SoSeparator.

◆ initClass()

static void PlaneGeometryIntersection::initClass ( )
static

Initialize class (called automatically by InventorMedical::init()).

◆ recompute()

int PlaneGeometryIntersection::recompute ( )

Recompute the intersection.

Recomputes the intersection boundary(s) based on the current scene and plane. Normally used when the automatic field is set to false. Useful when the goal is simply to compute the intersection. Also useful if recomputation is too slow. For example, to defer recomputation until the user has finished moving the clip plane.

Returns 0 if successful. Any other value means that an error occured during the computation and the geometry may not be valid.

Member Data Documentation

◆ automatic

SoSFBool PlaneGeometryIntersection::automatic

Specifies whether to recompute the intersection automatically or not (default true).

If true, the intersection (curve or polygon depending on the polygon field) will be re-computed automatically when the scene or the plane changes. If false, the intersection will only be re-computed when the recompute method is called.

Definition at line 167 of file PlaneGeometryIntersection.h.

◆ plane

SoSFPlane PlaneGeometryIntersection::plane

Plane to intersect with.

Default is (1,0,0) at 0 (same as SoClipPlane). Typically this field is connected from the clipping node's 'plane' field.

Definition at line 155 of file PlaneGeometryIntersection.h.

◆ polygon

SoSFBool PlaneGeometryIntersection::polygon

Specifies whether to compute a capping polygon (default false).

If true, compute a capping polygon. If false, compute only the intersection curve.

Definition at line 160 of file PlaneGeometryIntersection.h.

◆ scene

SoSFNode PlaneGeometryIntersection::scene

Scene to intersect with plane.

Default is none.

Definition at line 149 of file PlaneGeometryIntersection.h.

◆ tolerance

SoSFFloat PlaneGeometryIntersection::tolerance

Tolerance for testing if vertices are equal.

Default is 1e-6. This tolerance is used for calculation of triangle intersections with the plane.

Definition at line 173 of file PlaneGeometryIntersection.h.


The documentation for this class was generated from the following file: