SoText2(3) The SoText2 class is a node type for visualizing 2D text aligned with the camera plane.


#include <Inventor/nodes/SoText2.h>

Inherits SoShape.

Public Types

enum Justification { LEFT = 1, RIGHT, CENTER }

Public Member Functions

virtual SoType getTypeId (void) const

SoText2 (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

SoMFString string

SoSFFloat spacing

SoSFEnum justification

Protected Member Functions

virtual const SoFieldData * getFieldData (void) const

virtual ~SoText2 ()

virtual void generatePrimitives (SoAction *action)

virtual void computeBBox (SoAction *action, SbBox3f &box, SbVec3f &center)

Static Protected Member Functions

static const SoFieldData ** getFieldDataPtr (void)

Detailed Description

The SoText2 class is a node type for visualizing 2D text aligned with the camera plane.

SoText2 text is not scaled according to the distance from the camera, and is not influenced by rotation or scaling as 3D primitives are. If these are properties that you want the text to have, you should instead use an SoText3 or SoAsciiText node.

Note that even though the size of the 2D text is not influenced by the distance from the camera, the text is still subject to the usual rules with regard to the depthbuffer, so it will be obscured by graphics laying in front of it.

The text will be positioned according to the current transformation. The x origin of the text is the first pixel of the leftmost character of the text. The y origin of the text is the baseline of the first line of text (the baseline being the imaginary line on which all upper case characters are standing).

The size of the fonts on screen is decided from the SoFont::size field of a preceding SoFont-node in the scene graph, which specifies the size in pixel dimensions. This value sets the approximate vertical dimension of the letters. The default value if no SoFont-nodes are used, is 10.

One important issue about rendering performance: since the positioning and rendering of an SoText2 node depends on the current viewport and camera, having SoText2 nodes in the scene graph will lead to a cache dependency on the previously encountered SoCamera-node. This can have severe influence on the rendering performance, since if the camera is above the SoText2's nearest parent SoSeparator, the SoSeparator will not be able to cache the geometry under it.

(Even worse rendering performance will be forced if the SoSeparator::renderCaching flag is explicitly set to ON, as the SoSeparator node will then continuously generate and destruct the same cache as the camera moves.)

SoText2 nodes are therefore best positioned under their own SoSeparator node, outside areas in the scene graph that otherwise contains static geometry.

Also note that SoText2 nodes cache the ids and positions of each glyph bitmap used to render string. This means that USE of a DEF'ed SoText2 node, with a different font, will be noticeably slower than using two separate SoText2 nodes, one for each font, since it will have to recalculate glyph bitmap ids and positions for each call to GLrender().

SoScale nodes can not be used to influence the dimensions of the rendering output of SoText2 nodes.


    Text2 {
        string ''
        spacing 1
        justification LEFT

See also:

SoFont, SoFontStyle, SoText3, SoAsciiText

Member Enumeration Documentation

enum SoText2::Justification

Enum contains the various options for how the horizontal text layout text should be done. Valid values are LEFT, RIGHT and CENTER.

Constructor & Destructor Documentation

SoText2::SoText2 (void)


SoText2::~SoText2 () [protected], [virtual]


Member Function Documentation

SoType SoText2::getClassTypeId (void) [static]

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

Reimplemented from SoShape.

SoType SoText2::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 SoShape.

const SoFieldData ** SoText2::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.

Reimplemented from SoShape.

const SoFieldData * SoText2::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 SoShape.

void SoText2::initClass (void) [static]

Sets up initialization for data common to all instances of this class, like submitting necessary information to the Coin type system.

Reimplemented from SoShape.

void SoText2::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 SoText2::rayPick (SoRayPickAction *action) [virtual]

Calculates picked point based on primitives generated by subclasses.

Reimplemented from SoShape.

void SoText2::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 SoText2::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 SoText2::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

SoMFString SoText2::string

The set of strings to render. Each string in the multiple value field will be rendered on it's own line.

The default value of the field is a single empty string.

SoSFFloat SoText2::spacing

Spacing between each consecutive vertical line. Default value is 1.0, which means that the space between the uppermost line of each rendered string will equal the vertical size of the highest character in the bitmap alphabet.

SoSFEnum SoText2::justification

Decides how the horizontal layout of the text strings is done.


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