SbViewVolume Class Reference
[Basics]

3D viewing volume class. More...

#include <Inventor/SbViewVolume.h>

List of all members.

Public Types

enum  ProjectionType {
  ORTHOGRAPHIC,
  PERSPECTIVE
}
enum  StereoMode {
  MONOSCOPIC,
  LEFT_VIEW,
  RIGHT_VIEW
}

Public Member Functions

 SbViewVolume ()
 ~SbViewVolume ()
float getMatrices (SbMatrix &affine, SbMatrix &proj) const
SbMatrix getMatrix () const
SbMatrix getCameraSpaceMatrix () const
void projectPointToLine (const SbVec2f &pt, SbLine &line) const
void projectPointToLine (const SbVec2f &pt, SbVec3f &line0, SbVec3f &line1) const
void projectToScreen (const SbVec3f &src, SbVec3f &dst) const
void projectFromScreen (const SbVec3f &src, SbVec3f &dst) const
SbPlane getPlane (float distFromEye) const
SbVec3f getSightPoint (float distFromEye) const
SbVec3f getPlanePoint (float distFromEye, const SbVec2f &normPoint) const
SbRotation getAlignRotation (SbBool rightAngleOnly=FALSE) const
float getWorldToScreenScale (const SbVec3f &worldCenter, float normRadius) const
SbVec2f projectBox (const SbBox3f &box) const
SbBox3f getProjectedBbox (const SbBox3f &box) const
SbBox3f getProjectedBbox (const SbMatrix &affineProj, const SbBox3f &box) const
SbViewVolume narrow (float left, float bottom, float right, float top) const
SbViewVolume narrow (const SbBox3f &box) const
void ortho (float left, float right, float bottom, float top, float nearPlane, float farPlane)
void perspective (float fovy, float aspect, float nearPlane, float farPlane)
void rotateCamera (const SbRotation &q)
void translateCamera (const SbVec3f &v)
SbVec3f zVector () const
SbViewVolume zNarrow (float nearPlane, float farPlane) const
void scale (float factor)
void scaleWidth (float ratio)
void scaleHeight (float ratio)
ProjectionType getProjectionType () const
const SbVec3fgetProjectionPoint () const
const SbVec3fgetProjectionDirection () const
float getNearDist () const
float getWidth () const
float getHeight () const
float getDepth () const
void setStereoAbsoluteAdjustments (SbBool absolute)
SbBool isStereoAbsoluteAdjustments () const
void setStereoAdjustment (float adjustment)
float getStereoAdjustment () const
void setBalanceAdjustment (float adjustment, SbBool nearFrac=false)
float getBalanceAdjustment () const
SbBool isBalanceNearFraction () const
void setStereoMode (StereoMode mode)
StereoMode getStereoMode () const
SbBool equals (const SbViewVolume &v, float tolerance)

Detailed Description

3D viewing volume class.

Class used to represent a 3D viewing volume. This class is used to represent viewing frusta and picking volumes. For perspective projection, the view volume is a frustum. For orthographic (parallel) projection, the view volume is a rectangular prism.

The view volume used for rendering can be queried from an SoCamera node using its getViewVolume() method.

SEE ALSO

SbVec3f, SbVec2f, SbBox3f, SbMatrix, SbRotation, SoViewVolumeElement


Member Enumeration Documentation

Projection type.

Enumerator:
ORTHOGRAPHIC 

Orthographic projection.

PERSPECTIVE 

Perspective projection.

Stereo Modes.

Enumerator:
MONOSCOPIC 

Monoscopic (i.e., non-stereo) viewing.

LEFT_VIEW 

Left eye view.

RIGHT_VIEW 

Right eye view.


Constructor & Destructor Documentation

SbViewVolume::SbViewVolume (  ) 

Default constructor.

The view volume is not initialized.

SbViewVolume::~SbViewVolume (  )  [inline]

Destructor.


Member Function Documentation

SbBool SbViewVolume::equals ( const SbViewVolume v,
float  tolerance 
)

Equality comparison within given tolerance.

SbRotation SbViewVolume::getAlignRotation ( SbBool  rightAngleOnly = FALSE  )  const

Returns a rotation that would align a viewed object so that its positive x-axis (of its object space) is to the right in the view and its positive y-axis is up.

If rightAngleOnly is TRUE, it will come as close as it can to this goal by using only 90 degree rotations.

float SbViewVolume::getBalanceAdjustment (  )  const [inline]

Queries the parallax balance.

SbMatrix SbViewVolume::getCameraSpaceMatrix (  )  const

Returns a matrix that transforms the view volume into camera space: it translates the view volume so the viewpoint is at the origin, and rotates it so the view direction is along the negative z axis.

float SbViewVolume::getDepth (  )  const [inline]

Returns depth of viewing frustum.

float SbViewVolume::getHeight (  )  const [inline]

Returns height of viewing frustum.

float SbViewVolume::getMatrices ( SbMatrix affine,
SbMatrix proj 
) const

Returns two matrices corresponding to the view volume.

The first is a viewing matrix, which is guaranteed to be an affine transformation. The second is suitable for use as a projection matrix in OpenGL. The return value is the stereo offset for a camera.

Prior to release 2.6, the return value was a void, not a float.

SbMatrix SbViewVolume::getMatrix (  )  const

Like the method above, but returns the affine and projection parts together in one matrix (i.e., affine.multRight(proj) ).

Note that this matrix transforms world coordinates into normalized clip space, -1 to 1, not directly to normalized screen coordinates, 0 to 1. To convert the result to normalized screen coordinates: dst = dst * 0.5f + SbVec3f(0.5f,0.5f,0.5f);

float SbViewVolume::getNearDist (  )  const [inline]

Returns distance from projection point to near plane.

SbPlane SbViewVolume::getPlane ( float  distFromEye  )  const

Returns a plane parallel to the near (or far) plane of the view volume at a given distance from the projection point (eye).

SbVec3f SbViewVolume::getPlanePoint ( float  distFromEye,
const SbVec2f normPoint 
) const

Maps a 2D point in normalized screen coordinates (0 <= x,y <= 1) to a 3D world coordinates point on the plane parallel to the near plane that is at distFromEye units from the eye.

(See also projectFromScreen().)

SbBox3f SbViewVolume::getProjectedBbox ( const SbMatrix affineProj,
const SbBox3f box 
) const

Same as getProjectedBbox but takes a matrix (containing affine and projection parts) to use instead of the one returned by getMatrix.

SbBox3f SbViewVolume::getProjectedBbox ( const SbBox3f box  )  const

Projects the given 3D bounding box onto the near plane and returns it (in normalized screen coordinates).

const SbVec3f& SbViewVolume::getProjectionDirection (  )  const [inline]

Returns projection direction.

const SbVec3f& SbViewVolume::getProjectionPoint (  )  const [inline]

Returns projection point.

ProjectionType SbViewVolume::getProjectionType (  )  const [inline]

Returns projection type.

SbVec3f SbViewVolume::getSightPoint ( float  distFromEye  )  const

Returns the point along the line of sight at the given distance from the projection point (eye).

float SbViewVolume::getStereoAdjustment (  )  const [inline]

Queries the stereo offset.

StereoMode SbViewVolume::getStereoMode (  )  const [inline]

Queries the stereo mode.

float SbViewVolume::getWidth (  )  const [inline]

Returns width of viewing frustum.

float SbViewVolume::getWorldToScreenScale ( const SbVec3f worldCenter,
float  normRadius 
) const

Returns a scale factor that would scale a unit sphere centered at worldCenter so that it would appear to have the given radius in normalized screen coordinates when projected onto the near plane.

SbBool SbViewVolume::isBalanceNearFraction (  )  const [inline]

Returns TRUE if the stereo balance adjustement is defined as a fraction of the camera near distance.

SbBool SbViewVolume::isStereoAbsoluteAdjustments (  )  const [inline]

Returns TRUE if the stereo adjustments are absolute.

SbViewVolume SbViewVolume::narrow ( const SbBox3f box  )  const

Narrows a view volume by the given box.

The box must lie inside the unit cube, and the view will be shrunk according to the size of the box.

SbViewVolume SbViewVolume::narrow ( float  left,
float  bottom,
float  right,
float  top 
) const

Given a view volume, narrows the view to the given sub-rectangle of the near plane.

The coordinates of the rectangle are between 0 and 1, where (0,0) is the lower-left corner of the near plane and (1,1) is the upper-right corner.

void SbViewVolume::ortho ( float  left,
float  right,
float  bottom,
float  top,
float  nearPlane,
float  farPlane 
)

Sets up an orthographic view volume with the given sides.

The parameters are the same as for the OpenGL glOrtho() routine.

void SbViewVolume::perspective ( float  fovy,
float  aspect,
float  nearPlane,
float  farPlane 
)

Sets up a perspective view volume with the given field of view and aspect ratio.

The parameters are the same as for the OpenGLgluPerspective() routine, except that the field of view angle is specified in radians.

SbVec2f SbViewVolume::projectBox ( const SbBox3f box  )  const

Projects the given 3D bounding box onto the near plane and returns the size (in normalized screen coordinates) of the rectangular region that encloses it.

void SbViewVolume::projectFromScreen ( const SbVec3f src,
SbVec3f dst 
) const

Maps a 3D point in normalized screen coordinates (0 <= x,y,z <= 1) to a 3D world point.

The resulting Z coordinate represents the normalized distance at which the point would be back projected, ranging from 0 at the near clipping plane to 1 at the far clipping plane. This method is simply the inverse of projectToScreen(). See also getPlanePoint().

Note: This is a convenience function that calls the getMatrix() method and apply inverse() on it, then transforms the point. The getMatrix() and inverse() calls are somewhat expensive, so if you need to project a large number of points you should call the getMatrix() and inverse() methods just once and apply the matrix to each point using SbMatrix::multVecMatrix().

void SbViewVolume::projectPointToLine ( const SbVec2f pt,
SbVec3f line0,
SbVec3f line1 
) const

Maps a 2D point (in 0 <= x,y <= 1) to a 3D line.

void SbViewVolume::projectPointToLine ( const SbVec2f pt,
SbLine line 
) const

Maps a 2D point (in 0 <= x,y <= 1) to a 3D line.

void SbViewVolume::projectToScreen ( const SbVec3f src,
SbVec3f dst 
) const

Maps a 3D point in world coordinates to a 2D point in normalized screen coordinates (0 <= x,y,z <= 1).

The resulting Z screen coordinate represents the homogeneous Z coordinate which goes (nonlinearly) from 0 at the near clipping plane to 1 at the far clipping plane.

NOTE: This is a convenience function that calls the getMatrix() method, then transforms the point. The getMatrix() call is somewhat expensive, so if you need to project a large number of points you should call the getMatrix() method just once and apply the matrix to each point using SbMatrix::multVecMatrix().
However be aware that this matrix transforms world coordinates into normalized clip space, -1 to 1, not directly to normalized screen coordinates, 0 to 1. To convert the result to normalized screen coordinates: dst = dst * 0.5f + SbVec3f(0.5f,0.5f,0.5f);

void SbViewVolume::rotateCamera ( const SbRotation q  ) 

Rotate the camera view direction.

Note that this accomplishes the reverse of doing an OpenGL glRotate() command after defining a camera, which rotates the scene viewed by the camera.

void SbViewVolume::scale ( float  factor  ) 

Scales width and height of view volume by given factor.

void SbViewVolume::scaleHeight ( float  ratio  ) 

Scales view volume to be the given ratio of its current height, leaving the resulting view volume centered about the same point (in the near plane) as the current one.

void SbViewVolume::scaleWidth ( float  ratio  ) 

Scales view volume to be the given ratio of its current width, leaving the resulting view volume centered about the same point (in the near plane) as the current one.

void SbViewVolume::setBalanceAdjustment ( float  adjustment,
SbBool  nearFrac = false 
) [inline]

Sets the stereo balance (the position of the zero parallax plane) and specifies whether the balance value is defined as a fraction of the camera near distance.

Note: Since the projection matrix always depends on the camera's near plane, in some cases it may be necessary to detect changes to the camera near plane and adjust by setting a new stereo balance value. Open Inventor will make these adjustments automatically if the nearFrac parameter is set to TRUE. In this case the stereo balance value is defined as a fraction of the camera near distance.

Default balance is 1.0. The default can be set using the OIV_STEREO_BALANCE environment variable. Default nearFrac is FALSE. The default can be set using the OIV_STEREO_BALANCE_NEAR_FRAC environment variable.

void SbViewVolume::setStereoAbsoluteAdjustments ( SbBool  absolute  )  [inline]

Specifies if stereo adjustments are absolute.

FALSE by default.

The default non-absolute mode allows the stereo settings to be valid over a range of different view volume settings. If you chose absolute mode, you are responsible for modifying the stereo settings (if necessary) when the view volume changes.

When absolute mode is TRUE, stereo offset and balance for the right eye view are used as in the following pseudo-code:

 StereoCameraOffset = getStereoAdjustment();
 FrustumAsymmetry   = getBalanceAdjustment();

 glTranslated (-StereoCameraOffset, 0, 0);
 glFrustum (FrustumLeft + FrustumAsymmetry, FrustumRight + FrustumAsymmetry,
            FrustumBottom, FrustumTop, NearClipDistance, FarClipDistance);

The left eye view is symmetric.

When absolute mode is FALSE, stereo offset and balance for the right eye view are used as in the following pseudo-code:

Xrange is right minus left (i.e., first two arguments of glFrustum) and multiply that difference by the ratio of the distance to the desired plane of zero parallax to the near clipping plane distance.

 StereoCameraOffset   = Xrange * 0.035 * getStereoAdjustment();
 FrustumAsymmetry     = -StereoCameraOffset * getBalanceAdjustment();
 ZeroParallaxDistance = (NearClipDistance + FarClipDistance)/0.5;

 FrustumAsymmetry *= NearClipDistance / ZeroParallaxDistance;

 glTranslated (-StereoCameraOffset, 0, 0);
 glFrustum (FrustumLeft + FrustumAsymmetry, FrustumRight + FrustumAsymmetry,
            FrustumBottom, FrustumTop, NearClipDistance, FarClipDistance);

The left eye view is symmetric.

void SbViewVolume::setStereoAdjustment ( float  adjustment  )  [inline]

Sets the stereo offset (the distance of each eye from the camera position).

The right eye is moved plus offset and the left eye is moved minus offset. Default is 0.7. The default can be set using OIV_STEREO_OFFSET environment variable.

void SbViewVolume::setStereoMode ( StereoMode  mode  )  [inline]

Sets the stereo mode.

void SbViewVolume::translateCamera ( const SbVec3f v  ) 

Translate the camera viewpoint.

Note that this accomplishes the reverse of doing an OpenGL glTranslate() command after defining a camera, which translates the scene viewed by the camera.

SbViewVolume SbViewVolume::zNarrow ( float  nearPlane,
float  farPlane 
) const

Returns a narrowed view volume which contains as tightly as possible the given interval on the z axis (in eye space).

The returned view volume will never be larger than the current volume, however. near and far are given in terms of zVector(): this means that near > far must hold.

SbVec3f SbViewVolume::zVector (  )  const

Returns the positive z axis in eye space.

In this coordinate system, the z value of the near plane should be greater than the z value of the far plane.


The documentation for this class was generated from the following file:

Open Inventor Toolkit reference manual, generated on 16 Sep 2021
Copyright © Thermo Fisher Scientific All rights reserved.
http://www.openinventor.com/