Class SbViewVolume


  • public class SbViewVolume
    extends Inventor
    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
    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      boolean equals​(SbViewVolume v, float tolerance)
      Equality comparison within given tolerance.
      SbRotation getAlignRotation()
      Calls getAlignRotation(false).
      SbRotation getAlignRotation​(boolean rightAngleOnly)
      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.
      float getBalanceAdjustment()
      Queries the parallax balance.
      SbMatrix getCameraSpaceMatrix()
      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 getDepth()
      Returns depth of viewing frustum.
      float getHeight()
      Returns height of viewing frustum.
      SbViewVolume.Matrices getMatrices()
      Returns two matrices corresponding to the view volume.
      SbMatrix getMatrix()
      Like the method above, but returns the affine and projection parts together in one matrix (i.e., affine.multRight(proj) ).
      float getNearDist()
      Returns distance from projection point to near plane.
      SbPlane getPlane​(float distFromEye)
      Returns a plane parallel to the near (or far) plane of the view volume at a given distance from the projection point (eye).
      SbVec3f getPlanePoint​(float distFromEye, SbVec2f normPoint)
      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.
      SbBox3f getProjectedBbox​(SbBox3f box)
      Projects the given 3D bounding box onto the near plane and returns it (in normalized screen coordinates).
      SbBox3f getProjectedBbox​(SbMatrix affineProj, SbBox3f box)
      Same as getProjectedBbox but takes a matrix (containing affine and projection parts) to use instead of the one returned by getMatrix.
      SbVec3f getProjectionDirection()
      Returns projection direction.
      SbVec3f getProjectionPoint()
      Returns projection point.
      SbViewVolume.ProjectionTypes getProjectionType()
      Returns projection type.
      SbVec3f getSightPoint​(float distFromEye)
      Returns the point along the line of sight at the given distance from the projection point (eye).
      float getStereoAdjustment()
      Queries the stereo offset.
      SbViewVolume.StereoModes getStereoMode()
      Queries the stereo mode.
      float getWidth()
      Returns width of viewing frustum.
      float getWorldToScreenScale​(SbVec3f worldCenter, float normRadius)
      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.
      boolean isBalanceNearFraction()
      Returns true if the stereo balance adjustement is defined as a fraction of the camera near distance.
      boolean isStereoAbsoluteAdjustments()
      Returns true if the stereo adjustments are absolute.
      SbViewVolume narrow​(float left, float bottom, float right, float top)
      Given a view volume, narrows the view to the given sub-rectangle of the near plane.
      SbViewVolume narrow​(SbBox3f box)
      Narrows a view volume by the given box.
      void ortho​(float left, float right, float bottom, float top, float nearPlane, float farPlane)
      Sets up an orthographic view volume with the given sides.
      void perspective​(float fovy, float aspect, float nearPlane, float farPlane)
      Sets up a perspective view volume with the given field of view and aspect ratio.
      SbVec2f projectBox​(SbBox3f box)
      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.
      SbVec3f projectFromScreen​(SbVec3f src)
      Maps a 3D point in normalized screen coordinates (0 <= x,y,z <= 1) to a 3D world point.
      SbLine projectPointToLine​(SbVec2f pt)
      Maps a 2D point (in 0 <= x,y <= 1) to a 3D line.
      SbVec3f projectToScreen​(SbVec3f src)
      Maps a 3D point in world coordinates to a 2D point in normalized screen coordinates (0 <= x,y,z <= 1).
      void rotateCamera​(SbRotation q)
      Rotate the camera view direction.
      void scale​(float factor)
      Scales width and height of view volume by given factor.
      void 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 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 setBalanceAdjustment​(float adjustment)
      Calls setBalanceAdjustment(adjustment, (boolean)false).
      void setBalanceAdjustment​(float adjustment, boolean nearFrac)
      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.
      void setStereoAbsoluteAdjustments​(boolean absolute)
      Specifies if stereo adjustments are absolute.
      void setStereoAdjustment​(float adjustment)
      Sets the stereo offset (the distance of each eye from the camera position).
      void setStereoMode​(SbViewVolume.StereoModes mode)
      Sets the stereo mode.
      void setValue​(SbViewVolume copyFrom)  
      static SbViewVolume[] toArray​(long nativeArray, long length)  
      void translateCamera​(SbVec3f v)
      Translate the camera viewpoint.
      SbViewVolume zNarrow​(float nearPlane, float farPlane)
      Returns a narrowed view volume which contains as tightly as possible the given interval on the z axis (in eye space).
      SbVec3f zVector()
      Returns the positive z axis in eye space.
      • Methods inherited from class java.lang.Object

        equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
    • Constructor Detail

      • SbViewVolume

        public SbViewVolume​(SbViewVolume copyFrom)
      • SbViewVolume

        public SbViewVolume()
        Default constructor. The view volume is not initialized.
    • Method Detail

      • getAlignRotation

        public SbRotation getAlignRotation()
        Calls getAlignRotation(false).
      • setBalanceAdjustment

        public void setBalanceAdjustment​(float adjustment)
        Calls setBalanceAdjustment(adjustment, (boolean)false).
      • equals

        public boolean equals​(SbViewVolume v,
                              float tolerance)
        Equality comparison within given tolerance.
      • getMatrices

        public SbViewVolume.Matrices getMatrices()
        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.

      • setValue

        public void setValue​(SbViewVolume copyFrom)
      • narrow

        public SbViewVolume narrow​(float left,
                                   float bottom,
                                   float right,
                                   float top)
        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.
      • toArray

        public static SbViewVolume[] toArray​(long nativeArray,
                                             long length)
      • narrow

        public SbViewVolume narrow​(SbBox3f box)
        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.
      • getProjectedBbox

        public SbBox3f getProjectedBbox​(SbMatrix affineProj,
                                        SbBox3f box)
        Same as getProjectedBbox but takes a matrix (containing affine and projection parts) to use instead of the one returned by getMatrix.
      • getProjectedBbox

        public SbBox3f getProjectedBbox​(SbBox3f box)
        Projects the given 3D bounding box onto the near plane and returns it (in normalized screen coordinates).
      • getPlane

        public SbPlane getPlane​(float distFromEye)
        Returns a plane parallel to the near (or far) plane of the view volume at a given distance from the projection point (eye).
      • getNearDist

        public float getNearDist()
        Returns distance from projection point to near plane.
      • zVector

        public SbVec3f zVector()
        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.
      • getProjectionDirection

        public SbVec3f getProjectionDirection()
        Returns projection direction.
      • getWorldToScreenScale

        public float getWorldToScreenScale​(SbVec3f worldCenter,
                                           float normRadius)
        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.
      • getHeight

        public float getHeight()
        Returns height of viewing frustum.
      • translateCamera

        public void translateCamera​(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.
      • getWidth

        public float getWidth()
        Returns width of viewing frustum.
      • projectFromScreen

        public SbVec3f projectFromScreen​(SbVec3f src)
        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().

      • scaleWidth

        public void 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.
      • getPlanePoint

        public SbVec3f getPlanePoint​(float distFromEye,
                                     SbVec2f normPoint)
        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().)
      • scale

        public void scale​(float factor)
        Scales width and height of view volume by given factor.
      • getAlignRotation

        public SbRotation getAlignRotation​(boolean rightAngleOnly)
        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.
      • scaleHeight

        public void 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.
      • getSightPoint

        public SbVec3f getSightPoint​(float distFromEye)
        Returns the point along the line of sight at the given distance from the projection point (eye).
      • getProjectionPoint

        public SbVec3f getProjectionPoint()
        Returns projection point.
      • zNarrow

        public SbViewVolume zNarrow​(float nearPlane,
                                    float farPlane)
        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.
      • getBalanceAdjustment

        public float getBalanceAdjustment()
        Queries the parallax balance.
      • perspective

        public void 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.
      • setBalanceAdjustment

        public void setBalanceAdjustment​(float adjustment,
                                         boolean nearFrac)
        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.

      • getCameraSpaceMatrix

        public SbMatrix getCameraSpaceMatrix()
        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.
      • isBalanceNearFraction

        public boolean isBalanceNearFraction()
        Returns true if the stereo balance adjustement is defined as a fraction of the camera near distance.
      • ortho

        public void 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.
      • getMatrix

        public SbMatrix getMatrix()
        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.multiply(0.5f); dst.plus(new SbVec3f(0.5f,0.5f,0.5f));
      • setStereoAbsoluteAdjustments

        public void setStereoAbsoluteAdjustments​(boolean absolute)
        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.
      • isStereoAbsoluteAdjustments

        public boolean isStereoAbsoluteAdjustments()
        Returns true if the stereo adjustments are absolute.
      • getDepth

        public float getDepth()
        Returns depth of viewing frustum.
      • projectToScreen

        public SbVec3f projectToScreen​(SbVec3f src)
        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.multiply(0.5f); dst.plus(new SbVec3f(0.5f,0.5f,0.5f));

      • rotateCamera

        public void rotateCamera​(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.
      • getStereoAdjustment

        public float getStereoAdjustment()
        Queries the stereo offset.
      • projectBox

        public SbVec2f projectBox​(SbBox3f box)
        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.
      • setStereoAdjustment

        public void setStereoAdjustment​(float adjustment)
        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.
      • projectPointToLine

        public SbLine projectPointToLine​(SbVec2f pt)
        Maps a 2D point (in 0 <= x,y <= 1) to a 3D line.