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The SoVRMLBackground node is used to specify a color 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. SoVRMLBackground nodes are specified in the local coordinate system and are affected by the accumulated rotation of their parents.

<font color="#0000FF">NOTE:</font> This class does not exist in Open Inventor 10.0 and later.

VRML97 SPECIFICATION

This section describes the expected behavior of the node in a conforming VRML97 browser application. In some cases, the application is responsible for implementing portions of the expected behavior. Open Inventor viewer classes and IVF classes implement some of the application behaviors.

This section may reference portions of the VRML97 specification that are not present in this help file. The complete VRML97 spec is available at http://www.web3d.org.

The SoVRMLBackground node is used to specify a color 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. SoVRMLBackground nodes are specified in the local coordinate system and are affected by the accumulated rotation of their parents (see below).

SoVRMLBackground nodes are bindable nodes (see "Concepts - Bindable Children Nodes"). There exists an SoVRMLBackground stack, in which the top-most SoVRMLBackground on the stack is the currently active SoVRMLBackground and thus applied to the view. To move an SoVRMLBackground to the top of the stack, a true value is sent to the set_bind eventIn. Once active, the SoVRMLBackground is then bound to the browsers view. A false value of set_bind , removes the SoVRMLBackground from the stack and unbinds it from the browser viewer. See "Concepts - Bindable Children Nodes" for more details on the the bind stack.

The ground and sky backdrop is conceptually a partial sphere (i.e., ground) enclosed inside of a full sphere (i.e., sky) in the local coordinate system, with the viewer placed at the center of the spheres. Both spheres have infinite radius (epsilon apart), and each is painted with concentric circles of interpolated color perpendicular to the local Y axis of the sphere. The SoVRMLBackground node is subject to the accumulated rotations of its parent transformations - scaling and translation transformations are ignored. The sky sphere is always slightly farther away from the viewer than the ground sphere - the ground appears in front of the sky in cases where they overlap.

The skyColor field specifies the color of the sky at the various angles on the sky sphere. The first value of the skyColor field specifies the color of the sky at 0.0 degrees, the north pole (i.e., straight up from the viewer). The skyAngle field specifies the angles from the north pole in which concentric circles of color appear - the north pole of the sphere is implicitly defined to be 0.0 degrees, the natural horizon at pi/2 radians, and the south pole is pi radians. skyAngle is restricted to increasing values in the range 0.0 to pi. There must be one more skyColor value than there are skyAngle values - the first color value is the color at the north pole, which is not specified in the skyAngle field. If the last skyAngle is less than pi, then the color band between the last skyAngle and the south pole is clamped to the last skyColor. The sky color is linearly interpolated between the specified skyColor values.

The groundColor field specifies the color of the ground at the various angles on the ground sphere. The first value of the groundColor field specifies the color of the ground at 0.0 degrees, the south pole (i.e., straight down). The groundAngle field specifies the angles from the south pole that the concentric circles of color appear - the south pole of the sphere is implicitly defined at 0.0 degrees. groundAngle is restricted to increasing values in the range 0.0 to pi. There must be one more groundColor values than there are groundAngle values - the first color value is for the south pole which is not specified in the groundAngle field. If the last groundAngle is less than pi (it usually is), then the region between the last groundAngle and the north pole is invisible. The ground color 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 world's geometry. The panorama consists of six images, each of which is mapped onto the faces of an infinitely large cube centered in the local coordinate system. The images are applied individually to each face of the cube; the entire image goes on each face. On the front, back, right, and left faces of the cube, when viewed from the inside with the Y-axis up, the texture is mapped onto each face with the same orientation as the if image was displayed normally in 2D. On the top face of the cube, when viewed from the inside looking up along the +Y axis with the +Z axis as the view up direction, the texture is mapped onto the face with the same orientation as the if image was displayed normally in 2D. On the bottom face of the box, when viewed from the inside down the -Y axis with the -Z axis as the view up direction, the texture is mapped onto the face with the same orientation as the if image was displayed normally in 2D.

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. One-component images are displayed in grayscale; two-component images are displayed in grayscale with alpha transparency; three-component images are displayed in full RGB color; four-component images are displayed in full RGB color with alpha transparency. 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 are required to support the JPEG and PNG image file formats, and in addition, may support any other image formats. Support for the GIF format (including transparent backgrounds) is recommended. See the section "Concepts - URLS and URNs" for details on the url fields.

Panorama images may be one-component (grayscale), two-component (grayscale plus alpha), three-component (full RGB color), or four-component (full RGB color plus alpha).

Ground colors, sky colors, and panoramic images do not translate with respect to the viewer, though they do rotate with respect to the viewer. That is, the viewer can never get any closer to the background, but can turn to examine all sides of the panorama cube, and can look up and down to see the concentric rings of ground and sky (if visible).

SoVRMLBackground is not affected by SoVRMLFog. Therefore, if an SoVRMLBackground is active (i.e bound) while an SoVRMLFog is active, then the SoVRMLBackground will be displayed with no fogging effects. It is the author's responsibility to set the SoVRMLBackground values to match the SoVRMLFog (e.g. ground colors fade to fog color with distance and panorama images tinted with fog color).

The first SoVRMLBackground node found during reading of the world is automatically bound (receives set_bind true) and is used as the initial background when the world is loaded.

FILE FORMAT/DEFAULT

VRMLBackground {

groundAngle	[]
groundColor	[]
backUrl	[]
bottomUrl	[]
frontUrl	[]
leftUrl	[]
rightUrl	[]
topUrl	[]
skyAngle	[]
skyColor	[ 0 0 0 ]
metadata	NULL

}

EVENTS

eventIn

SoSFBool	set_bind
SoMFFloat	set_groundAngle
SoMFColor	set_groundColor
SoMFFilePathString	set_backUrl
SoMFFilePathString	set_bottomUrl
SoMFFilePathString	set_frontUrl
SoMFFilePathString	set_leftUrl
SoMFFilePathString	set_rightUrl
SoMFFilePathString	set_topUrl
SoMFFloat	set_skyAngle
SoMFColor	set_skyColor
SoSFNode	set_metadata

eventOut

SoSFBool	isBound
SoSFTime	bindTime
SoMFFloat	groundAngle_changed
SoMFColor	groundColor_changed
SoMFFilePathString	backUrl_changed
SoMFFilePathString	bottomUrl_changed
SoMFFilePathString	frontUrl_changed
SoMFFilePathString	leftUrl_changed
SoMFFilePathString	rightUrl_changed
SoMFFilePathString	topUrl_changed
SoMFFloat	skyAngle_changed
SoMFColor	skyColor_changed
SoSFNode	metadata_changed

Obsoletesince Open Inventor 9500 The VRML API is no longer supported. See section http://oivdoc95.vsg3d.com/content/compatibility-notes-4#Deprecation of the Reference Manual.

Reference