SbViewVolume: The sbviewvolume class is a viewing volume in 3d space. this class contains the necessary information for storing a view volume. it has methods for projection of primitives into the 3d volume from 2d points in the projection plane or vice versa, doing camera transforms, view volume transforms, etc.

SYNOPSIS

Public Types

enum ProjectionType { ORTHOGRAPHIC = 0, PERSPECTIVE = 1 }

Public Member Functions

SbViewVolume (void)

~SbViewVolume (void)

void getMatrices (SbMatrix &affine, SbMatrix &proj) const

SbMatrix getMatrix (void) const

SbMatrix getCameraSpaceMatrix (void) 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

SbPlane getPlane (const float distFromEye) const

SbVec3f getSightPoint (const float distFromEye) const

SbVec3f getPlanePoint (const 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

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 nearval, float farval)

void perspective (float fovy, float aspect, float nearval, float farval)

void frustum (float left, float right, float bottom, float top, float nearval, float farval)

void rotateCamera (const SbRotation &q)

void translateCamera (const SbVec3f &v)

SbVec3f zVector (void) const

SbViewVolume zNarrow (float nearval, float farval) const

void scale (float factor)

void scaleWidth (float ratio)

void scaleHeight (float ratio)

ProjectionType getProjectionType (void) const

const SbVec3f & getProjectionPoint (void) const

const SbVec3f & getProjectionDirection (void) const

float getNearDist (void) const

float getWidth (void) const

float getHeight (void) const

float getDepth (void) const

void print (FILE *fp) const

void getViewVolumePlanes (SbPlane planes[6]) const

void transform (const SbMatrix &matrix)

SbVec3f getViewUp (void) const

SbBool intersect (const SbVec3f &p) const

SbBool intersect (const SbVec3f &p0, const SbVec3f &p1, SbVec3f &closestpoint) const

SbBool intersect (const SbBox3f &box) const

SbBox3f intersectionBox (const SbBox3f &box) const

SbBool outsideTest (const SbPlane &p, const SbVec3f &bmin, const SbVec3f &bmax) const

const SbDPViewVolume & getDPViewVolume (void) const

Public Attributes

ProjectionType type

SbVec3f projPoint

SbVec3f projDir

float nearDist

float nearToFar

SbVec3f llf

SbVec3f lrf

SbVec3f ulf

Detailed Description

The SbViewVolume class is a viewing volume in 3D space.

This class contains the necessary information for storing a view volume. It has methods for projection of primitives into the 3D volume from 2D points in the projection plane or vice versa, doing camera transforms, view volume transforms, etc.

See also:

SbViewportRegion

Member Enumeration Documentation

enum \fBSbViewVolume::ProjectionType\fP

An SbViewVolume instance can represent either an orthogonal projection volume or a perspective projection volume.

See also:

ortho(), perspective(), getProjectionType().

Enumerator

ORTHOGRAPHIC: Orthographic projection.
PERSPECTIVE: Perspective projection.

Constructor & Destructor Documentation

SbViewVolume::SbViewVolume (void)

Constructor. Note that the SbViewVolume instance will be uninitialized until you explicitly call ortho() or perspective().

See also:

ortho(), perspective().

SbViewVolume::~SbViewVolume (void)

Destructor.

Member Function Documentation

void SbViewVolume::getMatrices (\fBSbMatrix\fP &affine, \fBSbMatrix\fP &proj) const

Returns the view volume's affine matrix and projection matrix.

See also:

getMatrix(), getCameraSpaceMatrix()

\fBSbMatrix\fP SbViewVolume::getMatrix (void) const

Returns the combined affine and projection matrix.

See also:

getMatrices(), getCameraSpaceMatrix()

\fBSbMatrix\fP SbViewVolume::getCameraSpaceMatrix (void) const

Returns a matrix which will translate the view volume camera back to origo, and rotate the camera so it'll point along the negative z axis.

Note that the matrix will not include the rotation necessary to make the camera up vector point along the positive y axis (i.e. camera roll is not accounted for).

See also:

getMatrices(), getMatrix()

void SbViewVolume::projectPointToLine (const \fBSbVec2f\fP &pt, \fBSbLine\fP &line) const

Project the given 2D point from the projection plane into a 3D line.

pt coordinates should be normalized to be within [0, 1].

void SbViewVolume::projectPointToLine (const \fBSbVec2f\fP &pt, \fBSbVec3f\fP &line0, \fBSbVec3f\fP &line1) const

Project the given 2D point from the projection plane into two points defining a 3D line. The first point, line0, will be the corresponding point for the projection on the near plane, while line1 will be the line endpoint, lying in the far plane.

void SbViewVolume::projectToScreen (const \fBSbVec3f\fP &src, \fBSbVec3f\fP &dst) const

Project the src point to a normalized set of screen coordinates in the projection plane and place the result in dst.

It is safe to let src and be the same SbVec3f instance.

The z-coordinate of dst is monotonically increasing for points closer to the far plane. Note however that this is not a linear relationship, the dst z-coordinate is calculated as follows:

Orthogonal view: DSTz = (-2 * SRCz - far - near) / (far - near), Perspective view: DSTz = (-SRCz * (far - near) - 2*far*near) / (far - near)

The returned coordinates (dst) are normalized to be in range [0, 1].

\fBSbPlane\fP SbViewVolume::getPlane (const floatdistFromEye) const

Returns an SbPlane instance which has a normal vector in the opposite direction of which the camera is pointing. This means the plane will be parallel to the near and far clipping planes.

See also:

getSightPoint()

\fBSbVec3f\fP SbViewVolume::getSightPoint (const floatdistFromEye) const

Returns the point on the center line-of-sight from the camera position with the given distance.

See also:

getPlane()

\fBSbVec3f\fP SbViewVolume::getPlanePoint (const floatdistFromEye, const \fBSbVec2f\fP &normPoint) const

Return the 3D point which projects to normPoint and lies on the plane perpendicular to the camera direction and distFromEye distance away from the camera position.

normPoint should be given in normalized coordinates, where the visible render canvas is covered by the range [0.0, 1.0].

\fBSbRotation\fP SbViewVolume::getAlignRotation (SbBoolrightangleonly = \fCFALSE\fP) const

Returns a rotation that aligns an object so that its positive x-axis is to the right and its positive y-axis is up in the view volume.

If rightangleonly is TRUE, it will create a rotation that aligns the x and y-axis with the closest orthogonal axes to right and up.

float SbViewVolume::getWorldToScreenScale (const \fBSbVec3f\fP &worldCenter, floatnormRadius) const

Given a sphere with center in worldCenter and an initial radius of 1.0, return the scale factor needed to make this sphere have a normRadius radius when projected onto the near clipping plane.

\fBSbVec2f\fP SbViewVolume::projectBox (const \fBSbBox3f\fP &box) const

Projects the given box onto the projection plane and returns the normalized screen space it occupies.

\fBSbViewVolume\fP SbViewVolume::narrow (floatleft, floatbottom, floatright, floattop) const

Returns a narrowed version of the view volume which is within the given [0, 1] normalized coordinates. The coordinates are taken to be corner points of a normalized 'view window' on the near clipping plane. I.e.:

SbViewVolume view;
view.ortho(0, 100, 0, 100, 0.1, 1000);
view = view.narrow(0.25, 0.5, 0.75, 1.0);

..will give a view volume with corner points <25, 75> and <50, 100>.

See also:

scale(), scaleWidth(), scaleHeight()

\fBSbViewVolume\fP SbViewVolume::narrow (const \fBSbBox3f\fP &box) const

Returns a narrowed version of the view volume which is within the given [0, 1] normalized coordinates. The box x and y coordinates are taken to be corner points of a normalized 'view window' on the near clipping plane. The box z coordinates are used to adjust the near and far clipping planes, and should be relative to the current clipping planes. A value of 1.0 is at the current near plane. A value of 0.0 is at the current far plane.

void SbViewVolume::ortho (floatleft, floatright, floatbottom, floattop, floatnearval, floatfarval)

Set up the view volume as a rectangular box for orthographic parallel projections.

The line of sight will be along the negative z axis, through the center of the plane defined by the point

[(right+left)/2, (top+bottom)/2, 0]

See also:

perspective().

void SbViewVolume::perspective (floatfovy, floataspect, floatnearval, floatfarval)

Set up the view volume for perspective projections. The line of sight will be through origo along the negative z axis.

See also:

ortho().

void SbViewVolume::frustum (floatleft, floatright, floatbottom, floattop, floatnearval, floatfarval)

Set up the frustum for perspective projection. This is an alternative to perspective() that lets you specify any kind of view volumes (e.g. off center volumes). It has the same arguments and functionality as the corresponding OpenGL glFrustum() function.

This function is an extension for Coin, and it is not available in the original SGI Open Inventor v2.1 API.

Since:

Coin 2.0

See also:

perspective()

void SbViewVolume::rotateCamera (const \fBSbRotation\fP &q)

Rotate the direction which the camera is pointing in.

See also:

translateCamera().

void SbViewVolume::translateCamera (const \fBSbVec3f\fP &v)

Translate the camera position of the view volume.

See also:

rotateCamera().

\fBSbVec3f\fP SbViewVolume::zVector (void) const

Return the vector pointing from the center of the view volume towards the camera. This is just the vector pointing in the opposite direction of getProjectionDirection().

See also:

getProjectionDirection().

\fBSbViewVolume\fP SbViewVolume::zNarrow (floatnearval, floatfarval) const

Return a copy SbViewVolume with narrowed depth by supplying parameters for new near and far clipping planes.

nearval and should be relative to the current clipping planes. A value of 1.0 is at the current near plane. A value of 0.0 is at the current far plane.

See also:

zVector().

void SbViewVolume::scale (floatfactor)

Scale width and height of viewing frustum by the given ratio around the projection plane center axis.

See also:

scaleWidth(), scaleHeight().

void SbViewVolume::scaleWidth (floatratio)

Scale width of viewing frustum by the given ratio around the vertical center axis in the projection plane.

See also:

scale(), scaleHeight().

void SbViewVolume::scaleHeight (floatratio)

Scale height of viewing frustum by the given ratio around the horizontal center axis in the projection plane.

See also:

scale(), scaleWidth().

\fBSbViewVolume::ProjectionType\fP SbViewVolume::getProjectionType (void) const

Return current view volume projection type, which can be either ORTHOGRAPHIC or PERSPECTIVE.

See also:

SbViewVolume::ProjectionType

const \fBSbVec3f\fP & SbViewVolume::getProjectionPoint (void) const

Returns the projection point, i.e. the camera position.

const \fBSbVec3f\fP & SbViewVolume::getProjectionDirection (void) const

Returns the direction of projection, i.e. the direction the camera is pointing.

See also:

getNearDist().

float SbViewVolume::getNearDist (void) const

Returns distance from projection plane to near clipping plane.

See also:

getProjectionDirection().

float SbViewVolume::getWidth (void) const

Returns width of viewing frustum in the projection plane.

See also:

getHeight(), getDepth().

float SbViewVolume::getHeight (void) const

Returns height of viewing frustum in the projection plane.

See also:

getWidth(), getDepth().

float SbViewVolume::getDepth (void) const

Returns depth of viewing frustum, i.e. the distance from the near clipping plane to the far clipping plane.

See also:

getWidth(), getHeight().

void SbViewVolume::print (FILE *fp) const

Dump the state of this object to the file stream. Only works in debug version of library, method does nothing in an optimized compile.

void SbViewVolume::getViewVolumePlanes (\fBSbPlane\fPplanes[6]) const

Returns the six planes defining the view volume in the following order: left, bottom, right, top, near, far. Plane normals are directed into the view volume.

This method is an extension for Coin, and is not available in the original Open Inventor.

void SbViewVolume::transform (const \fBSbMatrix\fP &matrix)

Transform the viewing volume by matrix.

\fBSbVec3f\fP SbViewVolume::getViewUp (void) const

Returns the view up vector for this view volume. It's a vector which is perpendicular to the projection direction, and parallel and oriented in the same direction as the vector from the lower left corner to the upper left corner of the near plane.

SbBool SbViewVolume::intersect (const \fBSbVec3f\fP &p) const

Returns TRUE if p is inside the view volume.

Since:

Coin 2.3

SbBool SbViewVolume::intersect (const \fBSbVec3f\fP &p0, const \fBSbVec3f\fP &p1, \fBSbVec3f\fP &closestpoint) const

Returns TRUE if the line segment p0, p1 may intersect volume. Be aware that it's not 100% certain that the line segment intersects the volume even if this function returns TRUE.

closestpoint is set to the closest point on the line to the center ray of the view volume.

Since:

Coin 2.3

SbBool SbViewVolume::intersect (const \fBSbBox3f\fP &box) const

Returns TRUE if box may be inside the view volume.

Since:

Coin 2.3

\fBSbBox3f\fP SbViewVolume::intersectionBox (const \fBSbBox3f\fP &box) const

Calculates the bbox of the intersection between bbox and the view volume.

Since:

Coin 4.0

SbBool SbViewVolume::outsideTest (const \fBSbPlane\fP &p, const \fBSbVec3f\fP &bmin, const \fBSbVec3f\fP &bmax) const

Returns TRUE if all eight corner points in bmin, bmax is outside p.