# SbViewVolume.3iv man page

SbViewVolume ā 3D viewing volume class

## Inherits from

SbViewVolume

## Synopsis

**#include <Inventor/SbLinear.h>**

**enum ProjectionType {**

**SbViewVolume::ORTHOGRAPHIC** Orthographic projection

**SbViewVolume::PERSPECTIVE** Perspective projection**}**

Methods from class SbViewVolume:

**SbViewVolume()**

**~SbViewVolume()**

**void 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**

**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**

**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 near, float far)**

**void perspective(float fovy, float aspect, float near, float far)**

**void rotateCamera(const SbRotation &q)**

**void translateCamera(const SbVec3f &v)**

**SbVec3f zVector() const**

**SbViewVolume zNarrow(float near, float far) const**

**void scale(float factor)**

**void scaleWidth(float ratio)**

**void scaleHeight(float ratio)**

**ProjectionType getProjectionType() const**

**const SbVec3f & getProjectionPoint() const**

**const SbVec3f & getProjectionDirection() const**

**float getNearDist() const**

**float getWidth() const**

**float getHeight() const**

**float getDepth() const**

## Description

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.

## Methods

**SbViewVolume()**

**~SbViewVolume()**

Constructor and destructor.

**void 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.

**SbMatrix getMatrix() const**

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

**SbMatrix 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.

**void projectPointToLine(const SbVec2f &pt, SbLine &line) const**

**void projectPointToLine(const SbVec2f &pt, SbVec3f &line0, SbVec3f &line1) const**

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

**void projectToScreen(const SbVec3f &src, SbVec3f &dst) const**

Maps the 3D point in world coordinates to a 2D point in normalized screen coordinates (0 <= x,y,z <= 1). The z-screen coordinate represents the homogenized z coordinate which goes (nonlinearly) from 0 at the near clipping plane to 1 at the far clipping plane.

**SbPlane 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 getSightPoint(float distFromEye) const**

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

**SbVec3f getPlanePoint(float distFromEye, const SbVec2f &normPoint) const**

Returns the projection of a given point in normalized screen coordinates (see **projectToScreen()**) onto the plane parallel to the near plane that is at **distFromEye** units from the eye.

**SbRotation 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 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.

**SbVec2f 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.

**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.

**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.

**void ortho(float left, float right, float bottom, float top, float near, float far)**

Sets up an orthographic view volume with the given sides. The parameters are the same as for the OpenGL **glOrtho()** routine.

**void perspective(float fovy, float aspect, float near, float far)**

Sets up a perspective view volume with the given field of view and aspect ratio. The parameters are the same as for the OpenGL **gluPerspective()** routine, except that the field of view angle is specified in radians.

**void 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 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.

**SbVec3f 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.

**SbViewVolume zNarrow(float near, float far) 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.

**void scale(float factor)**

Scales width and height of view volume by given factor.

**void scaleWidth(float ratio)**

**void scaleHeight(float ratio)**

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

**ProjectionType getProjectionType() const**

**const SbVec3f & getProjectionPoint() const**

**const SbVec3f & getProjectionDirection() const**

Returns projection information.

**float getNearDist() const**

Returns distance from projection point to near plane.

**float getWidth() const**

**float getHeight() const**

**float getDepth() const**

Returns bounds of viewing frustum.

## See Also

**SbVec3f, SbVec2f, SbBox3f, SbMatrix, SbRotation**