NAME¶

SoVRMLElevationGrid - The SoVRMLElevationGrid class is used to represent elevation grids. 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:

SYNOPSIS¶

#include <Inventor/VRMLnodes/SoVRMLElevationGrid.h> Inherits SoVRMLGeometry.

Public Member Functions¶

virtual SoType getTypeId (void) const Returns the type identification of an object derived from a class inheriting SoBase. This is used for run-time type checking and 'downward' casting. SoVRMLElevationGrid (void) virtual void GLRender (SoGLRenderAction *action) virtual void rayPick (SoRayPickAction *action) virtual void getPrimitiveCount (SoGetPrimitiveCountAction *action)

Static Public Member Functions¶

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

Public Attributes¶

SoSFBool ccw SoSFBool solid SoSFFloat creaseAngle SoSFInt32 zDimension SoSFInt32 xDimension SoSFFloat zSpacing SoSFFloat xSpacing SoMFFloat height SoSFNode texCoord SoSFNode normal SoSFNode color SoSFBool colorPerVertex SoSFBool normalPerVertex

Protected Member Functions¶

virtual const SoFieldData * getFieldData (void) const virtual ~SoVRMLElevationGrid (void) virtual void notify (SoNotList *list) virtual void generatePrimitives (SoAction *action) virtual void computeBBox (SoAction *action, SbBox3f &bbox, SbVec3f &center)

Static Protected Member Functions¶

static const SoFieldData ** getFieldDataPtr (void)

Additional Inherited Members¶

Detailed Description¶

The SoVRMLElevationGrid class is used to represent elevation grids. 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:

ElevationGrid {
  eventIn      MFFloat  set_height
  exposedField SFNode   color             NULL
  exposedField SFNode   normal            NULL
  exposedField SFNode   texCoord          NULL
  field        MFFloat  height            []      # (-inf,inf)
  field        SFBool   ccw               TRUE
  field        SFBool   colorPerVertex    TRUE
  field        SFFloat  creaseAngle       0       # [0,inf]
  field        SFBool   normalPerVertex   TRUE
  field        SFBool   solid             TRUE
  field        SFInt32  xDimension        0       # [0,inf)
  field        SFFloat  xSpacing          1.0     # (0,inf)
  field        SFInt32  zDimension        0       # [0,inf)
  field        SFFloat  zSpacing          1.0     # (0,inf)
}

The ElevationGrid node specifies a uniform rectangular grid of varying height in the Y=0 plane of the local coordinate system. The geometry is described by a scalar array of height values that specify the height of a surface above each point of the grid. The xDimension and zDimension fields indicate the number of elements of the grid height array in the X and Z directions. Both xDimension and zDimension shall be greater than or equal to zero. If either the xDimension or the zDimension is less than two, the ElevationGrid contains no quadrilaterals. The vertex locations for the rectangles are defined by the height field and the xSpacing and zSpacing fields:

•

The height field is an xDimension by zDimension array of scalar values representing the height above the grid for each vertex.

•

The xSpacing and zSpacing fields indicate the distance between vertices in the X and Z directions respectively, and shall be greater than zero.

Thus, the vertex corresponding to the point P[i, j] on the grid is placed at:

  P[i,j].x = xSpacing × i
  P[i,j].y = height[ i + j × xDimension]
  P[i,j].z = zSpacing × j     

  where 0 <= i < xDimension and 0 <= j < zDimension, and 
  P[0,0] is height[0] units above/below the origin of the local
  coordinate system

The set_height eventIn allows the height MFFloat field to be changed to support animated ElevationGrid nodes. The color field specifies per-vertex or per-quadrilateral colours for the ElevationGrid node depending on the value of colorPerVertex. If the color field is NULL, the ElevationGrid node is rendered with the overall attributes of the Shape node enclosing the ElevationGrid node (see 4.14, Lighting model). The colorPerVertex field determines whether colours specified in the color field are applied to each vertex or each quadrilateral of the ElevationGrid node. If colorPerVertex is FALSE and the color field is not NULL, the color field shall specify a Color node containing at least (xDimension-1)×(zDimension-1) colours; one for each quadrilateral, ordered as follows:

  QuadColor[i,j] = Color[ i + j × (xDimension-1)]

  where 0 <= i < xDimension-1 and 0 <= j < zDimension-1, and
  QuadColor[i,j] is the colour for the quadrilateral defined by
  height[i+j×xDimension], height[(i+1)+j×xDimension],
  height[(i+1)+(j+1)×xDimension] and height[i+(j+1)×xDimension] 

If colorPerVertex is TRUE and the color field is not NULL, the color field shall specify a Color node containing at least xDimension × zDimension colours, one for each vertex, ordered as follows:

  VertexColor[i,j] = Color[ i + j × xDimension] 

  where 0 <= i < xDimension and 0 <= j < zDimension, and 
  VertexColor[i,j] is the colour for the vertex defined by 
  height[i+j×xDimension] 

The normal field specifies per-vertex or per-quadrilateral normals for the ElevationGrid node. If the normal field is NULL, the browser shall automatically generate normals, using the creaseAngle field to determine if and how normals are smoothed across the surface (see 4.6.3.5, Crease angle field). The normalPerVertex field determines whether normals are applied to each vertex or each quadrilateral of the ElevationGrid node depending on the value of normalPerVertex. If normalPerVertex is FALSE and the normal node is not NULL, the normal field shall specify a Normal node containing at least (xDimension-1)×(zDimension-1) normals; one for each quadrilateral, ordered as follows:

  QuadNormal[i,j] = Normal[ i + j × (xDimension-1)] 

  where 0 <= i < xDimension-1 and 0 <= j < zDimension-1, and 
  QuadNormal[i,j] is the normal for the quadrilateral 
  defined by height[i+j×xDimension], height[(i+1)+j×xDimension], 
  height[(i+1)+(j+1)×xDimension] and height[i+(j+1)×xDimension] 

If normalPerVertex is TRUE and the normal field is not NULL, the normal field shall specify a Normal node containing at least xDimension × zDimension normals; one for each vertex, ordered as follows:

  VertexNormal[i,j] = Normal[ i + j × xDimension] 
  
  where 0 <= i < xDimension and 0 <= j < zDimension, and
  VertexNormal[i,j] is the normal for the vertex defined by
  height[i+j×xDimension] 

The texCoord field specifies per-vertex texture coordinates for the ElevationGrid node. If texCoord is NULL, default texture coordinates are applied to the geometry. The default texture coordinates range from (0,0) at the first vertex to (1,1) at the last vertex. The S texture coordinate is aligned with the positive X-axis, and the T texture coordinate with positive Z-axis. If texCoord is not NULL, it shall specify a TextureCoordinate node containing at least (xDimension)×(zDimension) texture coordinates; one for each vertex, ordered as follows:

  VertexTexCoord[i,j] = TextureCoordinate[ i + j × xDimension] 

  where 0 <= i < xDimension and 0 <= j < zDimension, and 
  VertexTexCoord[i,j] is the texture coordinate for the vertex 
  defined by height[i+j×xDimension] 

The ccw, solid, and creaseAngle fields are described in 4.6.3, Shapes and geometry. By default, the quadrilaterals are defined with a counterclockwise ordering. Hence, the Y-component of the normal is positive. Setting the ccw field to FALSE reverses the normal direction. Backface culling is enabled when the solid field is TRUE. See Figure 6.5 for a depiction of the ElevationGrid node.
Figure 6.5

Constructor & Destructor Documentation¶

SoVRMLElevationGrid::SoVRMLElevationGrid (void)¶

Constructor.

SoVRMLElevationGrid::~SoVRMLElevationGrid (void) [protected], [virtual]¶

Destructor.

Member Function Documentation¶

SoType SoVRMLElevationGrid::getTypeId (void) const [virtual]¶

Returns the type identification of an object derived from a class inheriting SoBase. This is used for run-time type checking and 'downward' casting. Usage example:

void foo(SoNode * node)
{
  if (node->getTypeId() == SoFile::getClassTypeId()) {
    SoFile * filenode = (SoFile *)node;  // safe downward cast, knows the type
  }
}

For application programmers wanting to extend the library with new nodes, engines, nodekits, draggers or others: this method needs to be overridden in all subclasses. This is typically done as part of setting up the full type system for extension classes, which is usually accomplished by using the pre-defined macros available through for instance Inventor/nodes/SoSubNode.h (SO_NODE_INIT_CLASS and SO_NODE_CONSTRUCTOR for node classes), Inventor/engines/SoSubEngine.h (for engine classes) and so on. For more information on writing Coin extensions, see the class documentation of the toplevel superclasses for the various class groups. Reimplemented from SoVRMLGeometry.

const SoFieldData * SoVRMLElevationGrid::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.

void SoVRMLElevationGrid::GLRender ( SoGLRenderAction *action) [virtual]¶

Action method for the SoGLRenderAction. This is called during rendering traversals. Nodes influencing the rendering state in any way or who wants to throw geometry primitives at OpenGL overrides this method. Reimplemented from SoShape.

void SoVRMLElevationGrid::rayPick ( SoRayPickAction *action) [virtual]¶

Calculates picked point based on primitives generated by subclasses. Reimplemented from SoShape.

void SoVRMLElevationGrid::getPrimitiveCount ( SoGetPrimitiveCountAction *action) [virtual]¶

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 calculates their primitive count also overrides this method to change the relevant state variables. Reimplemented from SoShape.

void SoVRMLElevationGrid::notify ( SoNotList *l) [protected], [virtual]¶

Notifies all auditors for this instance when changes are made. Reimplemented from SoVRMLGeometry.

void SoVRMLElevationGrid::generatePrimitives ( SoAction *action) [protected], [virtual]¶

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.

void SoVRMLElevationGrid::computeBBox ( SoAction *action, SbBox3f &box, SbVec3f &center) [protected], [virtual]¶

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.

Member Data Documentation¶

SoSFBool SoVRMLElevationGrid::ccw¶

Specifies whether generated triangles are counterclockwise. Default value is TRUE.

SoSFBool SoVRMLElevationGrid::solid¶

Specifies whether backface culling should be done. Default value is TRUE.

SoSFFloat SoVRMLElevationGrid::creaseAngle¶

Specifies the normal calculation crease angle.

SoSFInt32 SoVRMLElevationGrid::zDimension¶

Specifies the number of points in the z dimension.

SoSFInt32 SoVRMLElevationGrid::xDimension¶

Specifies the number of points in the x dimension.

SoSFFloat SoVRMLElevationGrid::zSpacing¶

Specifies the spacing between points in the z dimension. Default value is 1.0.

SoSFFloat SoVRMLElevationGrid::xSpacing¶

Specifies the spacing between points in the x dimension. Default value is 1.0.

SoMFFloat SoVRMLElevationGrid::height¶

Contains the array of height values.

SoSFNode SoVRMLElevationGrid::texCoord¶

Can contain an SoVRMLTextureCoordinate node containing one texture coordinate per grid point.

SoSFNode SoVRMLElevationGrid::normal¶

Can contain an SoVRMLTextureCoordinate node containing normals for the grid.

SoSFNode SoVRMLElevationGrid::color¶

Can contain an SoVRMLColor node containing grid colors.

SoSFBool SoVRMLElevationGrid::colorPerVertex¶

Specifies whether colors should be applied per vertex. Default value is TRUE.

SoSFBool SoVRMLElevationGrid::normalPerVertex¶

Specifies whether normals should be applied per vertex. Default value is TRUE.

Author¶

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