SoVRMLExtrusion(3) Coin SoVRMLExtrusion(3)

SoVRMLExtrusion - The SoVRMLExtrusion class is a a geometry node for extruding a cross section along a spine.

#include <Inventor/VRMLnodes/SoVRMLExtrusion.h>

Inherits SoVRMLGeometry.


virtual SoType getTypeId (void) const
SoVRMLExtrusion (void)
virtual void GLRender (SoGLRenderAction *action)
virtual void getPrimitiveCount (SoGetPrimitiveCountAction *action)
virtual void computeBBox (SoAction *action, SbBox3f &bbox, SbVec3f &center)

Public Member Functions inherited from SoVRMLGeometry
virtual void search (SoSearchAction *action)
virtual void copyContents (const SoFieldContainer *from, SbBool copyConn)

Public Member Functions inherited from SoShape
virtual SbBool affectsState (void) const
virtual void getBoundingBox (SoGetBoundingBoxAction *action)
virtual void rayPick (SoRayPickAction *action)
virtual void callback (SoCallbackAction *action)
const SoBoundingBoxCache * getBoundingBoxCache (void) const

Public Member Functions inherited from SoNode
void setOverride (const SbBool state)
SbBool isOverride (void) const
void setNodeType (const NodeType type)
NodeType getNodeType (void) const
virtual SoNode * copy (SbBool copyconnections=FALSE) const
virtual void doAction (SoAction *action)
virtual void GLRenderBelowPath (SoGLRenderAction *action)
virtual void GLRenderInPath (SoGLRenderAction *action)
virtual void GLRenderOffPath (SoGLRenderAction *action)
virtual void getMatrix (SoGetMatrixAction *action)
virtual void handleEvent (SoHandleEventAction *action)
virtual void pick (SoPickAction *action)
virtual void write (SoWriteAction *action)
virtual void audioRender (SoAudioRenderAction *action)
virtual void grabEventsSetup (void)
virtual void grabEventsCleanup (void)
virtual void startNotify (void)
SbUniqueId getNodeId (void) const
virtual void writeInstance (SoOutput *out)
virtual SoNode * addToCopyDict (void) const
virtual SoFieldContainer * copyThroughConnection (void) const

Public Member Functions inherited from SoFieldContainer
void setToDefaults (void)
SbBool hasDefaultValues (void) const
SbBool fieldsAreEqual (const SoFieldContainer *container) const
void copyFieldValues (const SoFieldContainer *container, SbBool copyconnections=FALSE)
SbBool set (const char *const fielddata)
void get (SbString &fielddata)
virtual int getFields (SoFieldList &l) const
virtual int getAllFields (SoFieldList &l) const
virtual SoField * getField (const SbName &name) const
virtual SoField * getEventIn (const SbName &name) const
virtual SoField * getEventOut (const SbName &name) const
SbBool getFieldName (const SoField *const field, SbName &name) const
SbBool enableNotify (const SbBool flag)
SbBool isNotifyEnabled (void) const
SbBool set (const char *fielddata, SoInput *input)
void get (SbString &fielddata, SoOutput *out)
virtual SbBool validateNewFieldValue (SoField *field, void *newval)
virtual void addWriteReference (SoOutput *out, SbBool isfromfield=FALSE)
SbBool getIsBuiltIn (void) const
virtual void getFieldsMemorySize (size_t &managed, size_t &unmanaged) const
void setUserData (void *userdata) const
void * getUserData (void) const

Public Member Functions inherited from SoBase
void ref (void) const
void unref (void) const
void unrefNoDelete (void) const
int32_t getRefCount (void) const
void touch (void)
SbBool isOfType (SoType type) const
Returns TRUE if the type of this object is either of the same type or inherited from type. virtual SbName getName (void) const
virtual void setName (const SbName &newname)
void addAuditor (void *const auditor, const SoNotRec::Type type)
void removeAuditor (void *const auditor, const SoNotRec::Type type)
const SoAuditorList & getAuditors (void) const
SbBool shouldWrite (void)
void assertAlive (void) const


static SoType getClassTypeId (void)
static void initClass (void)

Static Public Member Functions inherited from SoVRMLGeometry
static SoType getClassTypeId (void)
static void initClass (void)

Static Public Member Functions inherited from SoShape
static SoType getClassTypeId (void)
static void initClass (void)
Sets up initialization for data common to all instances of this class, like submitting necessary information to the Coin type system. static void getScreenSize (SoState *const state, const SbBox3f &boundingbox, SbVec2s &rectsize)
static float getDecimatedComplexity (SoState *state, float complexity)

Static Public Member Functions inherited from SoNode
static uint32_t getCompatibilityTypes (const SoType &nodetype)
static SoType getClassTypeId (void)
static SoNode * getByName (const SbName &name)
static int getByName (const SbName &name, SoNodeList &l)
static void initClass (void)
Sets up initialization for data common to all instances of this class, like submitting necessary information to the Coin type system. static void initClasses (void)
static SbUniqueId getNextNodeId (void)
static int getActionMethodIndex (const SoType type)
static void getBoundingBoxS (SoAction *action, SoNode *node)
static void GLRenderS (SoAction *action, SoNode *node)
static void callbackS (SoAction *action, SoNode *node)
static void getMatrixS (SoAction *action, SoNode *node)
static void handleEventS (SoAction *action, SoNode *node)
static void pickS (SoAction *action, SoNode *node)
static void rayPickS (SoAction *action, SoNode *node)
static void searchS (SoAction *action, SoNode *node)
static void writeS (SoAction *action, SoNode *node)
static void audioRenderS (SoAction *action, SoNode *node)
static void getPrimitiveCountS (SoAction *action, SoNode *node)

Static Public Member Functions inherited from SoFieldContainer
static void initClass (void)
Sets up initialization for data common to all instances of this class, like submitting necessary information to the Coin type system. static SoType getClassTypeId (void)
This static method returns the SoType object associated with objects of this class. static void cleanupClass (void)
static void initCopyDict (void)
static void addCopy (const SoFieldContainer *orig, const SoFieldContainer *copy)
static SoFieldContainer * checkCopy (const SoFieldContainer *orig)
static SoFieldContainer * findCopy (const SoFieldContainer *orig, const SbBool copyconnections)
static void copyDone (void)

Static Public Member Functions inherited from SoBase
static void initClass (void)
Sets up initialization for data common to all instances of this class, like submitting necessary information to the Coin type system. static SoType getClassTypeId (void)
This static method returns the SoType object associated with objects of this class. static void addName (SoBase *const base, const char *const name)
static void removeName (SoBase *const base, const char *const name)
static void incrementCurrentWriteCounter (void)
static void decrementCurrentWriteCounter (void)
static SoBase * getNamedBase (const SbName &name, SoType type)
static int getNamedBases (const SbName &name, SoBaseList &baselist, SoType type)
static SbBool read (SoInput *input, SoBase *&base, SoType expectedtype)
static void setInstancePrefix (const SbString &c)
static void setTraceRefs (SbBool trace)
static SbBool getTraceRefs (void)
static SbBool connectRoute (SoInput *input, const SbName &fromnodename, const SbName &fromfieldname, const SbName &tonodename, const SbName &tofieldname)
static SbBool readRoute (SoInput *input)


SoSFBool beginCap
SoSFBool ccw
SoSFBool convex
SoSFFloat creaseAngle
SoMFVec2f crossSection
SoSFBool endCap
SoMFRotation orientation
SoMFVec2f scale
SoSFBool solid
SoMFVec3f spine

Public Attributes inherited from SoBase


virtual const SoFieldData * getFieldData (void) const
virtual ~SoVRMLExtrusion ()
virtual void notify (SoNotList *list)
virtual void generatePrimitives (SoAction *action)
virtual SoDetail * createTriangleDetail (SoRayPickAction *action, const SoPrimitiveVertex *v1, const SoPrimitiveVertex *v2, const SoPrimitiveVertex *v3, SoPickedPoint *pp)

Protected Member Functions inherited from SoVRMLGeometry
SoVRMLGeometry (void)
virtual ~SoVRMLGeometry ()
void setupShapeHints (SoState *state, const SbBool ccw, const SbBool solid)
virtual SbBool shouldGLRender (SoGLRenderAction *action)
virtual SoChildList * getChildren (void) const

Protected Member Functions inherited from SoShape
SoShape (void)
virtual ~SoShape ()
float getComplexityValue (SoAction *action)
void beginSolidShape (SoGLRenderAction *action)
void endSolidShape (SoGLRenderAction *action)
void GLRenderBoundingBox (SoGLRenderAction *action)
SbBool shouldPrimitiveCount (SoGetPrimitiveCountAction *action)
SbBool shouldRayPick (SoRayPickAction *const action)
void computeObjectSpaceRay (SoRayPickAction *const action)
void computeObjectSpaceRay (SoRayPickAction *const action, const SbMatrix &matrix)
virtual SoDetail * createLineSegmentDetail (SoRayPickAction *action, const SoPrimitiveVertex *v1, const SoPrimitiveVertex *v2, SoPickedPoint *pp)
virtual SoDetail * createPointDetail (SoRayPickAction *action, const SoPrimitiveVertex *v, SoPickedPoint *pp)
void invokeTriangleCallbacks (SoAction *const action, const SoPrimitiveVertex *const v1, const SoPrimitiveVertex *const v2, const SoPrimitiveVertex *const v3)
void invokeLineSegmentCallbacks (SoAction *const action, const SoPrimitiveVertex *const v1, const SoPrimitiveVertex *const v2)
void invokePointCallbacks (SoAction *const action, const SoPrimitiveVertex *const v)
void beginShape (SoAction *const action, const TriangleShape shapetype, SoDetail *const detail=NULL)
void shapeVertex (const SoPrimitiveVertex *const v)
void endShape (void)
void generateVertex (SoPrimitiveVertex *const pv, const SbVec3f &point, const SbBool useTexFunc, const SoMultiTextureCoordinateElement *const tce, const float s, const float t, const SbVec3f &normal)
void generateVertex (SoPrimitiveVertex *const pv, const SbVec3f &point, const SbBool useTexFunc, const SoMultiTextureCoordinateElement *const tce, const float s, const float t, const float r, const SbVec3f &normal)
SbBool startVertexArray (SoGLRenderAction *action, const SoCoordinateElement *coords, const SbVec3f *pervertexnormals, const SbBool texpervertex, const SbBool colorpervertex)
void finishVertexArray (SoGLRenderAction *action, const SbBool vbo, const SbBool normpervertex, const SbBool texpervertex, const SbBool colorpervertex)

Protected Member Functions inherited from SoNode
SoNode (void)
virtual ~SoNode ()
virtual SbBool readInstance (SoInput *in, unsigned short flags)

Protected Member Functions inherited from SoFieldContainer
SoFieldContainer (void)
virtual ~SoFieldContainer ()

Protected Member Functions inherited from SoBase
SoBase (void)
virtual ~SoBase ()
virtual void destroy (void)
SbBool hasMultipleWriteRefs (void) const
SbBool writeHeader (SoOutput *out, SbBool isgroup, SbBool isengine) const
void writeFooter (SoOutput *out) const
virtual const char * getFileFormatName (void) const
virtual SoNotRec createNotRec (void)


static const SoFieldData ** getFieldDataPtr (void)

Static Protected Member Functions inherited from SoVRMLGeometry
static const SoFieldData ** getFieldDataPtr (void)

Static Protected Member Functions inherited from SoShape
static const SoFieldData ** getFieldDataPtr (void)

Static Protected Member Functions inherited from SoNode
static const SoFieldData ** getFieldDataPtr (void)
static void setNextActionMethodIndex (int index)
static int getNextActionMethodIndex (void)
static void incNextActionMethodIndex (void)
static void setCompatibilityTypes (const SoType &nodetype, const uint32_t bitmask)

Static Protected Member Functions inherited from SoBase
static uint32_t getCurrentWriteCounter (void)
static void staticDataLock (void)
static void staticDataUnlock (void)

Public Types inherited from SoShape
enum TriangleShape { TRIANGLE_STRIP, TRIANGLE_FAN, TRIANGLES, POLYGON, QUADS, QUAD_STRIP, POINTS, LINES, LINE_STRIP }

Public Types inherited from SoNode
enum NodeType { INVENTOR = 0x0000, VRML1 = 0x0001, VRML2 = 0x0002, INVENTOR_1 = 0x0004, INVENTOR_2_0 = 0x0008, INVENTOR_2_1 = 0x0010, INVENTOR_2_5 = 0x0020, INVENTOR_2_6 = 0x0040, COIN_1_0 = 0x0080, COIN_2_0 = 0x0100, EXTENSION = 0x0200, COIN_2_2 = 0x0400, COIN_2_3 = 0x0800, COIN_2_4 = 0x1000, INVENTOR_5_0 = 0x2000, COIN_2_5 = 0x4000, COIN_3_0 = 0x8000, INVENTOR_6_0 = 0x10000, COIN_4_0 = 0x20000 }

Protected Types inherited from SoBase
enum BaseFlags { IS_ENGINE = 0x01, IS_GROUP = 0x02 }

Protected Attributes inherited from SoNode
SbUniqueId uniqueId

Protected Attributes inherited from SoFieldContainer
SbBool isBuiltIn

Static Protected Attributes inherited from SoNode
static SbUniqueId nextUniqueId = 1
static int nextActionMethodIndex = 0

The SoVRMLExtrusion class is a a geometry node for extruding a cross section along a spine.

The detailed class documentation is taken verbatim from the VRML97 standard (ISO/IEC 14772-1:1997). It is copyright The Web3D Consortium, and is used by permission of the Consortium:

Extrusion {
  eventIn MFVec2f    set_crossSection
  eventIn MFRotation set_orientation
  eventIn MFVec2f    set_scale
  eventIn MFVec3f    set_spine
  field   SFBool     beginCap         TRUE
  field   SFBool     ccw              TRUE
  field   SFBool     convex           TRUE
  field   SFFloat    creaseAngle      0                # [0,inf)
  field   MFVec2f    crossSection     [ 1 1, 1 -1, -1 -1, -1 1, 1  1 ]    # (-inf,inf)
  field   SFBool     endCap           TRUE
  field   MFRotation orientation      0 0 1 0          # [-1,1],(-inf,inf)
  field   MFVec2f    scale            1 1              # (0,inf)
  field   SFBool     solid            TRUE
  field   MFVec3f    spine            [ 0 0 0, 0 1 0 ] # (-inf,inf)
}

Introduction

The Extrusion node specifies geometric shapes based on a two dimensional cross-section extruded along a three dimensional spine in the local coordinate system. The cross-section can be scaled and rotated at each spine point to produce a wide variety of shapes. An Extrusion node is defined by:

•
a 2D crossSection piecewise linear curve (described as a series of connected vertices);
•
a 3D spine piecewise linear curve (also described as a series of connected vertices);
•
a list of 2D scale parameters;
•
a list of 3D orientation parameters.

Algorithmic description

Shapes are constructed as follows. The cross-section curve, which starts as a curve in the Y=0 plane, is first scaled about the origin by the first scale parameter (first value scales in X, second value scales in Z). It is then translated by the first spine point and oriented using the first orientation parameter (as explained later). The same procedure is followed to place a cross- section at the second spine point, using the second scale and orientation values. Corresponding vertices of the first and second cross-sections are then connected, forming a quadrilateral polygon between each pair of vertices. This same procedure is then repeated for the rest of the spine points, resulting in a surface extrusion along the spine.

The final orientation of each cross-section is computed by first orienting it relative to the spine segments on either side of point at which the cross-section is placed. This is known as the spine-aligned cross-section plane (SCP), and is designed to provide a smooth transition from one spine segment to the next (see Figure 6.6). The SCP is then rotated by the corresponding orientation value. This rotation is performed relative to the SCP. For example, to impart twist in the cross- section, a rotation about the Y-axis (0 1 0) would be used. Other orientations are valid and rotate the cross-section out of the SCP.


Figure 6.6

The SCP is computed by first computing its Y-axis and Z-axis, then taking the cross product of these to determine the X-axis. These three axes are then used to determine the rotation value needed to rotate the Y=0 plane to the SCP. This results in a plane that is the approximate tangent of the spine at each point, as shown in Figure 6.6. First the Y-axis is determined, as follows:

Let n be the number of spines and let i be the index variable satisfying 0 <= i < n:

•
For all points other than the first or last: The Y-axis for spine[i] is found by normalizing the vector defined by (spine[i+1]
•
spine[i-1]).
•
If the spine curve is closed: The SCP for the first and last points is the same and is found using (spine[1] - spine[n-2]) to compute the Y-axis.
•
If the spine curve is not closed: The Y-axis used for the first point is the vector from spine[0] to spine[1], and for the last it is the vector from spine[n-2] to spine[n-1].

The Z-axis is determined as follows:

•
For all points other than the first or last: Take the following cross-product:
Z = (spine[i+1] - spine[i]) × (spine[i-1] - spine[i])
•
If the spine curve is closed: The SCP for the first and last points is the same and is found by taking the following cross- product:
Z = (spine[1] - spine[0]) × (spine[n-2] - spine[0])
•
If the spine curve is not closed: The Z-axis used for the first spine point is the same as the Z-axis for spine[1]. The Z- axis used for the last spine point is the same as the Z-axis for spine[n-2].
•
After determining the Z-axis, its dot product with the Z-axis of the previous spine point is computed. If this value is negative, the Z-axis is flipped (multiplied by -1). In most cases, this prevents small changes in the spine segment angles from flipping the cross-section 180 degrees.

Once the Y- and Z-axes have been computed, the X-axis can be calculated as their cross-product.

Special Cases

If the number of scale or orientation values is greater than the number of spine points, the excess values are ignored. If they contain one value, it is applied at all spine points. The results are undefined if the number of scale or orientation values is greater than one but less than the number of spine points. The scale values shall be positive.

If the three points used in computing the Z-axis are collinear, the cross-product is zero so the value from the previous point is used instead. If the Z-axis of the first point is undefined (because the spine is not closed and the first two spine segments are collinear) then the Z-axis for the first spine point with a defined Z-axis is used.

If the entire spine is collinear, the SCP is computed by finding the rotation of a vector along the positive Y-axis (v1) to the vector formed by the spine points (v2). The Y=0 plane is then rotated by this value. If two points are coincident, they both have the same SCP. If each point has a different orientation value, then the surface is constructed by connecting edges of the cross-sections as normal. This is useful in creating revolved surfaces.

Note: combining coincident and non-coincident spine segments, as well as other combinations, can lead to interpenetrating surfaces which the extrusion algorithm makes no attempt to avoid.

Common Cases

The following common cases are among the effects which are supported by the Extrusion node:

•
Surfaces of revolution: If the cross-section is an approximation of a circle and the spine is straight, the Extrusion is equivalent to a surface of revolution, where the scale parameters define the size of the cross-section along the spine.
•
Uniform extrusions: If the scale is (1, 1) and the spine is straight, the cross-section is extruded uniformly without twisting or scaling along the spine. The result is a cylindrical shape with a uniform cross section.
•
Bend/twist/taper objects: These shapes are the result of using all fields. The spine curve bends the extruded shape defined by the cross-section, the orientation parameters (given as rotations about the Y-axis) twist it around the spine, and the scale parameters taper it (by scaling about the spine).

Other Fields

Extrusion has three parts: the sides, the beginCap (the surface at the initial end of the spine) and the endCap (the surface at the final end of the spine). The caps have an associated SFBool field that indicates whether each exists (TRUE) or doesn't exist (FALSE).

When the beginCap or endCap fields are specified as TRUE, planar cap surfaces will be generated regardless of whether the crossSection is a closed curve. If crossSection is not a closed curve, the caps are generated by adding a final point to crossSection that is equal to the initial point. An open surface can still have a cap, resulting (for a simple case) in a shape analogous to a soda can sliced in half vertically. These surfaces are generated even if spine is also a closed curve. If a field value is FALSE, the corresponding cap is not generated.

Texture coordinates are automatically generated by Extrusion nodes. Textures are mapped so that the coordinates range in the U direction from 0 to 1 along the crossSection curve (with 0 corresponding to the first point in crossSection and 1 to the last) and in the V direction from 0 to 1 along the spine curve (with 0 corresponding to the first listed spine point and 1 to the last). If either the endCap or beginCap exists, the crossSection curve is uniformly scaled and translated so that the larger dimension of the cross-section (X or Z) produces texture coordinates that range from 0.0 to 1.0. The beginCap and endCap textures' S and T directions correspond to the X and Z directions in which the crossSection coordinates are defined.

The browser shall automatically generate normals for the Extrusion node,using the creaseAngle field to determine if and how normals are smoothed across the surface. Normals for the caps are generated along the Y-axis of the SCP, with the ordering determined by viewing the cross-section from above (looking along the negative Y-axis of the SCP). By default, a beginCap with a counterclockwise ordering shall have a normal along the negative Y-axis. An endCap with a counterclockwise ordering shall have a normal along the positive Y-axis.

Each quadrilateral making up the sides of the extrusion are ordered from the bottom cross-section (the one at the earlier spine point) to the top. So, one quadrilateral has the points:

spine[0](crossSection[0], crossSection[1])
spine[1](crossSection[1], crossSection[0])

in that order. By default, normals for the sides are generated as described in 4.6.3, Shapes and geometry (http://www.web3d.org/documents/specifications/14772/V2.0/part1/concepts.html#4.6.3).

For instance, a circular crossSection with counterclockwise ordering and the default spine form a cylinder. With solid TRUE and ccw TRUE, the cylinder is visible from the outside. Changing ccw to FALSE makes it visible from the inside. The ccw, solid, convex, and creaseAngle fields are described in 4.6.3, Shapes and geometry (http://www.web3d.org/documents/specifications/14772/V2.0/part1/concepts.html#4.6.3).

Constructor.

Destructor.

SoType SoVRMLExtrusion::getClassTypeId (void ) [static]

This static method returns the SoType object associated with objects of this class.

SoType SoVRMLExtrusion::getTypeId (void ) const [virtual]

Returns the type identification of an object derived from a class inheriting SoBase. This is used for runtime type checking and 'downward' casting.

Reimplemented from SoVRMLGeometry.

const SoFieldData ** SoVRMLExtrusion::getFieldDataPtr (void ) [static], [protected]

This API member is considered internal to the library, as it is not likely to be of interest to the application programmer.


Returns the SoFieldData class which holds information about fields in this node.

const SoFieldData * SoVRMLExtrusion::getFieldData (void ) const [protected], [virtual]

Returns a pointer to the class-wide field data storage object for this instance. If no fields are present, returns NULL.

Reimplemented from SoVRMLGeometry.

Action method for the SoGLRenderAction.

This is called during rendering traversals. Nodes influencing the rendering state in any way or want to throw geometry primitives at OpenGL override this method.

Reimplemented from SoShape.

Action method for the SoGetPrimitiveCountAction.

Calculates the number of triangle, line segment and point primitives for the node and adds these to the counters of the action.

Nodes influencing how geometry nodes calculate their primitive count also override this method to change the relevant state variables.

Reimplemented from SoShape.

Implemented by SoShape subclasses to let the SoShape superclass know the exact size and weighted center point of the shape's bounding box.

The bounding box and center point should be calculated and returned in the local coordinate system.

The method implements action behavior for shape nodes for SoGetBoundingBoxAction. It is invoked from SoShape::getBoundingBox(). (Subclasses should not override SoNode::getBoundingBox().)

The box parameter sent in is guaranteed to be an empty box, while center is undefined upon function entry.

Implements SoShape.

Notifies all auditors for this instance when changes are made.

Reimplemented from SoVRMLGeometry.

The method implements action behavior for shape nodes for SoCallbackAction. It is invoked from SoShape::callback(). (Subclasses should not override SoNode::callback().)

The subclass implementations uses the convenience methods SoShape::beginShape(), SoShape::shapeVertex(), and SoShape::endShape(), with SoDetail instances, to pass the primitives making up the shape back to the caller.

Implements SoShape.

SoDetail * SoVRMLExtrusion::createTriangleDetail (SoRayPickAction * action, const SoPrimitiveVertex * v1, const SoPrimitiveVertex * v2, const SoPrimitiveVertex * v3, SoPickedPoint * pp) [protected], [virtual]

Will create triangle detail for a SoPickedPoint. This method will only be called internally, when generatePrimitives() is used for picking (SoShape::rayPick() is not overridden).

This method returns NULL in Open Inventor, and subclasses will need to override this method to create details for a SoPickedPoint.

This is not necessary with Coin. Of course, if you choose to override it, it will work in the same way as Open Inventor.

For this to work, you must supply a face or line detail when generating primitives. If you supply NULL for the detail argument in SoShape::beginShape(), you'll have to override this method.

Reimplemented from SoShape.

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Fri Sep 6 2024 15:32:06 Version 4.0.3