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NAME
SoVRMLBackground -
The SoVRMLBackground class is used for specifying a viewer panorama.
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/SoVRMLBackground.h>
Inherits SoNode.
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.
SoVRMLBackground (void)
virtual void GLRender (SoGLRenderAction *action)
Static Public Member Functions
static SoType getClassTypeId (void)
static void initClass (void)
Public Attributes
SoMFColor groundColor
SoMFFloat groundAngle
SoMFColor skyColor
SoMFFloat skyAngle
SoMFString backUrl
SoMFString bottomUrl
SoMFString frontUrl
SoMFString leftUrl
SoMFString rightUrl
SoMFString topUrl
Protected Member Functions
virtual const SoFieldData * getFieldData (void) const
virtual SbBool readInstance (SoInput *in, unsigned short flags)
virtual ~SoVRMLBackground ()
Static Protected Member Functions
static const SoFieldData ** getFieldDataPtr (void)
Protected Attributes
SoSFBool set_bind
SoSFBool isBound
Additional Inherited Members
Detailed Description
The SoVRMLBackground class is used for specifying a viewer panorama.
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:
Background {
eventIn SFBool set_bind
exposedField MFFloat groundAngle [] # [0,pi/2]
exposedField MFColor groundColor [] # [0,1]
exposedField MFString backUrl []
exposedField MFString bottomUrl []
exposedField MFString frontUrl []
exposedField MFString leftUrl []
exposedField MFString rightUrl []
exposedField MFString topUrl []
exposedField MFFloat skyAngle [] # [0,pi]
exposedField MFColor skyColor 0 0 0 # [0,1]
eventOut SFBool isBound
}
The Background node is used to specify a colour backdrop that simulates ground and sky, as
well as a background texture, or panorama, that is placed behind all geometry in the scene
and in front of the ground and sky. Background nodes are specified in the local coordinate
system and are affected by the accumulated rotation of their ancestors as described below.
Background nodes are bindable nodes as described in 4.6.10, Bindable children nodes
(http://www.web3d.org/x3d/specifications/vrml/ISO-
IEC-14772-VRML97/part1/concepts.html#4.6.10). There exists a Background stack, in which
the top-most Background on the stack is the currently active Background. To move a
Background to the top of the stack, a TRUE value is sent to the set_bind eventIn. Once
active, the Background is then bound to the browsers view. A FALSE value sent to set_bind
removes the Background from the stack and unbinds it from the browser's view. More detail
on the bind stack is described in 4.6.10, Bindable children nodes
(http://www.web3d.org/x3d/specifications/vrml/ISO-
IEC-14772-VRML97/part1/concepts.html#4.6.10).
The backdrop is conceptually a partial sphere (the ground) enclosed inside of a full
sphere (the sky) in the local coordinate system with the viewer placed at the centre of
the spheres. Both spheres have infinite radius and each is painted with concentric circles
of interpolated colour perpendicular to the local Y-axis of the sphere. The Background
node is subject to the accumulated rotations of its ancestors' transformations. Scaling
and translation transformations are ignored. The sky sphere is always slightly farther
away from the viewer than the ground partial sphere causing the ground to appear in front
of the sky where they overlap. The skyColor field specifies the colour of the sky at
various angles on the sky sphere. The first value of the skyColor field specifies the
colour of the sky at 0.0 radians representing the zenith (i.e., straight up from the
viewer). The skyAngle field specifies the angles from the zenith in which concentric
circles of colour appear. The zenith of the sphere is implicitly defined to be 0.0
radians, the natural horizon is at pi/2 radians, and the nadir (i.e., straight down from
the viewer) is at pi radians. skyAngle is restricted to non-decreasing values in the range
[0.0, pi]. There shall be one more skyColor value than there are skyAngle values. The
first colour value is the colour at the zenith, which is not specified in the skyAngle
field. If the last skyAngle is less than pi, then the colour band between the last
skyAngle and the nadir is clamped to the last skyColor. The sky colour is linearly
interpolated between the specified skyColor values.
The groundColor field specifies the colour of the ground at the various angles on the
ground partial sphere. The first value of the groundColor field specifies the colour of
the ground at 0.0 radians representing the nadir (i.e., straight down from the user). The
groundAngle field specifies the angles from the nadir that the concentric circles of
colour appear. The nadir of the sphere is implicitly defined at 0.0 radians. groundAngle
is restricted to non-decreasing values in the range [0.0, pi/2]. There shall be one more
groundColor value than there are groundAngle values. The first colour value is for the
nadir which is not specified in the groundAngle field. If the last groundAngle is less
than pi/2, the region between the last groundAngle and the equator is non-existant. The
ground colour is linearly interpolated between the specified groundColor values.
The backUrl, bottomUrl, frontUrl, leftUrl, rightUrl, and topUrl fields specify a set of
images that define a background panorama between the ground/sky backdrop and the scene's
geometry. The panorama consists of six images, each of which is mapped onto a face of an
infinitely large cube contained within the backdrop spheres and centred in the local
coordinate system. The images are applied individually to each face of the cube. On the
front, back, right, and left faces of the cube, when viewed from the origin looking down
the negative Z-axis with the Y-axis as the view up direction, each image is mapped onto
the corresponding face with the same orientation as if the image were displayed normally
in 2D (backUrl to back face, frontUrl to front face, leftUrl to left face, and rightUrl to
right face). On the top face of the cube, when viewed from the origin looking along the
+Y-axis with the +Z-axis as the view up direction, the topUrl image is mapped onto the
face with the same orientation as if the image were displayed normally in 2D. On the
bottom face of the box, when viewed from the origin along the negative Y-axis with the
negative Z-axis as the view up direction, the bottomUrl image is mapped onto the face with
the same orientation as if the image were displayed normally in 2D.
Figure 6.1
Figure 6.1 illustrates the Background node backdrop and background textures. Alpha values
in the panorama images (i.e., two or four component images) specify that the panorama is
semi-transparent or transparent in regions, allowing the groundColor and skyColor to be
visible. See 4.6.11, Texture maps, for a general description of texture maps. Often, the
bottomUrl and topUrl images will not be specified, to allow sky and ground to show. The
other four images may depict surrounding mountains or other distant scenery. Browsers
shall support the JPEG (see 2.[JPEG]) and PNG (see 2.[PNG]) image file formats, and in
addition, may support any other image format (e.g., CGM) that can be rendered into a 2D
image. Support for the GIF (see E.[GIF]) format is recommended (including transparency).
More detail on the url fields can be found in 4.5, VRML and the World Wide Web
(http://www.web3d.org/x3d/specifications/vrml/ISO-
IEC-14772-VRML97/part1/concepts.html#4.5).
Constructor & Destructor Documentation
SoVRMLBackground::SoVRMLBackground (void)
Constructor.
SoVRMLBackground::~SoVRMLBackground () [protected], [virtual]
Destructor.
Member Function Documentation
SoType SoVRMLBackground::getClassTypeId (void) [static]
SoMFFloat SoVRMLBackground::groundAngle
The ground angles where different colors should be used.
SoMFColor SoVRMLBackground::groundColor
The color for each groundAngle.
SoMFFloat SoVRMLBackground::skyAngle
The sky angles where different colors should be used.
SoMFColor SoVRMLBackground::skyColor
The color for each skyAngle.
SoMFString SoVRMLBackground::backUrl
URL for the background image.
SoMFString SoVRMLBackground::bottomUrl
URL for the bottom image.
SoMFString SoVRMLBackground::frontUrl
URL for the front image.
SoMFString SoVRMLBackground::leftUrl
URL for the left image.
SoMFString SoVRMLBackground::rightUrl
URL for the right image.
SoMFString SoVRMLBackground::topUrl
URL for the top image.
SoSFBool SoVRMLBackground::set_bind An eventIn which is triggered when the node is bound.
SoSFBool SoVRMLBackground::isBound An eventOut that is sent after the node has been
bound/unbound.
SoType SoVRMLBackground::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.
Implements SoBase.
const SoFieldData * SoVRMLBackground::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 SoFieldContainer.
void SoVRMLBackground::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 SoNode.
SbBool SoVRMLBackground::readInstance (SoInput *in, unsigned shortflags) [protected],
[virtual]
This method is mainly intended for internal use during file import operations.
It reads a definition of an instance from the input stream in. The input stream state
points to the start of a serialized / persistant representation of an instance of this
class type.
TRUE or FALSE is returned, depending on if the instantiation and configuration of the new
object of this class type went ok or not. The import process should be robust and handle
corrupted input streams by returning FALSE.
flags is used internally during binary import when reading user extension nodes, group
nodes or engines.
Reimplemented from SoNode.
Author
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