Class SoRayPickAction


  • public class SoRayPickAction
    extends SoPickAction
    Intersects objects with a ray cast into scene. This class performs picking by casting a ray into a scene and performing intersection tests with each object. The ray is extended to be a frustum a pyramid or a rectangular prism, a cone or a cylinder, depending on the camera type and client inputs (refer to setRay and enableConicPickVolume) for intersection with points and lines. Each intersection is returned as an SoPickedPoint instance.

    The picking ray can be specified as either a ray from the camera location through a particular viewport pixel, or as a world-space ray. Calling any of the setPoint, setNormalizedPoint, or setRadius methods tells the action to compute the picking ray from a viewport pixel. In this case, a camera node must be encountered during traversal of the scene graph in order to determine the location of the ray in world space.

    Callers can request the action to compute all intersections along the ray (sorted closest to farthest) by setting the pickAll flag to true. By default, the action computes only the closest intersection. In either case, the intersections are returned in an SoPickedPointList. Each intersection can be examined by accessing the appropriate SoPickedPoint in the list. The SoPickedPoint object provides methods to get the path (SoPath) to the picked geometry in the scene graph, the intersection point in 3D space and other info.

    The SoPickedPoint object can also return one of the subclasses of SoDetail, which contains more information about the picked geometry. For example, if a polygonal geometry node like SoIndexedFaceSet was picked, an SoFaceDetail object is returned which provides methods to get the index of the face in the primitive, the vertices of the face and so on. For vertex based geometry each vertex can then be queried as an SoPointDetail.
    Note: Texture coordinates for the picked point are not computed by default (to save time). If you need this information, use enableTexCoordsGeneration(). Or set the environment variable OIV_PICK_GENERATE_ALL_PROPERTIES. You can also disable computing the normal vector for the picked if you do not need this information. See enableNormalsGeneration().

    In the default mode, Inventor computes the intersection of the pick ray with geometry nodes (face, line, point, volume, mesh, etc). In this case SoPickedPoint.getPoint() returns the coordinate of the intersection and SoPickedPoint.getDetail() typically returns an SoDetail class specific to the picked geometry. Since Open Inventor 9.0, SoRayPickAction also supports a POINT_PICKING mode (see PickingMode). In this mode, Inventor finds all the vertices inside the pick radius. This is only supported for SoBufferedShape and classes derived from SoIndexedShape. This mode can be much faster because, for example, it does not need to check for intersection with all the triangles of an SoIndexedFaceSet.

    Applications can use the SoPickStyle node to control if and how geometry can be picked. For example application might want to specify that annotation geometry, e.g. a legend, is not pickable. It can also specify that geometry should be picked using its bounding box rather than exact geometry. This may be more efficient for text strings when it is not necessary to know which character in the string was picked.

    The application can get platform independent input events, e.g. mouse button press, as SoEvent objects using the SoEventCallback node. In the callback function the application can create an SoRayPickAction and apply it to the scene graph. Note however that the application can also simply call the node's getPickedPoint() method. In this case Open Inventor automatically applies a pick action to the scene graph and returns the result, so the application does not need to use SoRayPickAction directly. Creating and using an SoRayPickAction explicitly does allow more options to be set. In this case the application will normally call setPoint with the position obtained from the event object. If using system events directly, remember that Open Inventor expects Y pixel values to start from zero at the bottom of the window.

    The SoSelection node provides an even higher level way to manage selecting and de-selecting objects in the scene. This node automatically applies a pick action and maintains a list of currently selected objects (paths). Using SoSelection the application does not need to use SoRayPickAction directly. The SoExtSelection node provides more complex picking algorithms. For example it allows the user to select objects using a "rubberband" rectangle or a freeform shape (lasso). Open Inventor provides special render actions that can automatically highlight objects selected using an SoSelection or SoExtSelection node. See SoBoxHighlightRenderAction, SoHaloHighlightRenderAction and SoLineHighlightRenderAction.

    Picking algorithm on vertex shapes

    Open Inventor implements two different picking algorithms : the GPU picking algorithm and the CPU picking algorithm.

    The GPU picking algorithm is very efficient when the shapes have millions of polygons. It is used when :

    • The shape is compatible with GPU picking.
      Note: For now, this is limited to MeshVizXLM surface shapes with structured faces of 8 or fewer edges.
      For example, MoMeshSkin or MoMeshSlab, if the underlying mesh is structured.
    • The MeshVizXLM shape has a MoDrawStyle with the flags displayFaces and displayEdges set to true.
    • The picking mode is DEFAULT, see setPickingMode().
    • The pick all is false, see setPickAll().
    • The picked shape is not in an SoRenderToTarget.

    The CPU picking algorithm is used when the previous conditions are not met. In this case, it does true geometric picking in 3D coordinates, so there are no limits the number of objects that can be picked. Geometric picking means that precise intersections with the geometry are computed. It also means that picking works for any type of primitive, including polygonal geometry, meshes and volumes (VolumeViz). The picking volume can be projected through the scene using orthogonal or perspective projection. See setRay for details. The shape of the picking volume can be rectangular (prism if orthogonal, frustum if perspective) or conic (cylinder if orthogonal, cone if perspective). See enableConicPickVolume().

    It is possible to mix GPU picking compatible and incompatible shapes in the same scenegraph, GPU picking will be automatically used for compatible shapes and CPU picking will be used for the others.

    CPU picking optimization

    Pick traversals are optimized using hierarchical bounding boxes cached at the SoSeparator (and a few other) grouping nodes. If the pick ray does not intersect the bounding box then the pick action will not traverse the children of that separator. When optimizing for picking the application should consider first how quickly can Open Inventor find the geometry that should be picked. Organizing the scene graph spatially to take advantage of the bounding box optimization can help with this. Second the application should consider how long will it take to find the face that should be picked. For a very large surface this can be significant. Enabling triangle culling, splitting large surfaces into smaller pieces or using proxy geometry may be helpful.

    Traversing the camera node:

    Note that when using SoRayPickAction with pixel coordinates (setPoint()) the pick action must traverse a camera node in order to unproject the coordinate back into 3D space. If the application explicitly creates its own camera, this is usually not a problem because the camera is in the application scene graph. However if the application allows the viewer to automatically create a camera then the camera is in the viewer's scene graph above the application scene graph. Calling the viewer's getSceneGraph() method returns the application scene graph, not the complete viewer scene graph. To ensure that the traversed scene graph contains a camera, call the viewer's getSceneManager() method, then call the scene manager's getSceneGraph method. Alternatively, in an event callback call the event action's getPickRoot() method.

    Picking SoVolumeRender nodes:

    Since Open Inventor 8.6, the SoVolumeRender node (by default) uses the GPU to compute the picked voxel during an SoRayPickAction. For this to work, the SoRayPickAction must have its scene manager initialised using the method SoAction.setSceneManager(). SoHandleEventAction does this automatically, so it is not necessary for the application to take any action when using (for example) an SoEventCallback node and calling the getPickedPoint() method. However if the application creates its own SoRayPickAction then it should set the scene manager. If no scene manager is specified, a warning message is issued and software picking is done. If necessary, using the GPU for volume picking may be disabled by setting the environment variable IVVR_GPU_PICKING to 0 (see SoPreferences).

    Hidden references:

    SoRayPickAction creates one or more SoPath objects when applied to the scene graph. The SoPath object references each node in the path. This reference will prevent the node and its associated memory from being reclaimed for as long as the SoPath object exists. These SoPath objects are stored internally in the action and exist until the action object itself is reclaimed or reset (see clearApplyResult()). Shapes that redefine the rayPick method:

    In order to make this action work properly with respect to the picked path stored in the picked point list, any shape that redefines the rayPick method must either call the method SoRayPickAction.setObjectSpace() or the method SoShape.computeObjectSpaceRay() in its rayPick method before calling the addIntersection() methods. See the chapter "Creating a node - Creating a Shape Node - Picking" in the Inventor Toolmaker Volume 1.

    Sets: SoPickRayElement, SoViewportRegionElement

    EXAMPLE

    Do picking using an SoEventCallback node.
    Note: In this case, you could do picking by simply calling the SoHandleEventAction's getPickedPoint() method, which applies an SoRayPickAction internally. However it may be necessary to use SoRayPickAction directly in order to set specific options.

     class mouseBtnCB extends SoEventCallbackCB {
         @Override
         public void invoke( SoEventCallback node ) {
             SoMouseButtonEvent evt = (SoMouseButtonEvent)node.getEvent();
             // If button 1 was pressed
             if (SoMouseButtonEvent.isButtonPressEvent( evt, SoMouseButtonEvent.Buttons.BUTTON1 ))
             {
                 SoHandleEventAction action = node.getAction();
                 SoRayPickAction rayPick = new SoRayPickAction( action.getViewportRegion() );
                 rayPick.setPoint( evt.getPosition() );
                 rayPick.setRadius( 10 ); // Optional: Use larger pick radius
                 rayPick.apply( action.getPickRoot() );
                 SoPickedPoint pickedPt = rayPick.getPickedPoint();
                 if (pickedPt != null) {
                     SoPath pickedPath = pickedPt.getPath();
                     SoNode pickedNode = pickedPath.full.getTail();
                 }
             }
        }
     }

    See Also:
    SoPickedPoint SoPickedPointList, SoPickStyle
    • Constructor Detail

      • SoRayPickAction

        public SoRayPickAction​(SbViewportRegion viewportRegion)
        Constructor takes viewport region to use for picking. Even though the picking operation may not involve a window per se, some nodes need this information to determine their size and placement.
    • Method Detail

      • setRay

        public void setRay​(SbVec3f start,
                           SbVec3f direction)
        Calls setRay(start, direction, (float)-1.0, (float)-1.0).
      • intersect

        public boolean intersect​(SbBox3f box)
        Calls intersect(box, true).
      • getPickedPoint

        public SoPickedPoint getPickedPoint()
        Calls getPickedPoint((int)0).
      • setRay

        public void setRay​(SbVec3f start,
                           SbVec3f direction,
                           float nearDistance)
        Calls setRay(start, direction, nearDistance, (float)-1.0).
      • setRay

        public void setRay​(float fovy,
                           SbVec3f start,
                           SbVec3f direction)
        Calls setRay(fovy, start, direction, (float)-1.0, (float)-1.0).
      • setRay

        public void setRay​(float fovy,
                           SbVec3f start,
                           SbVec3f direction,
                           float nearDistance)
        Calls setRay(fovy, start, direction, nearDistance, (float)-1.0).
      • intersect

        public boolean intersect​(SbXfBox3f box)
        Calls intersect(box, true).
      • enableTexCoordsGeneration

        public void enableTexCoordsGeneration​(boolean enable)
        Enables generation of texture coordinates for picked points. Default is false for performance (unless environment variable OIV_PICK_GENERATE_ALL_PROPERTIES envvar is set to true).
      • isPickAll

        public boolean isPickAll()
        Returns whether the action will return all objects intersected or just the closest one.
      • setRay

        public void setRay​(float fovy,
                           SbVec3f start,
                           SbVec3f direction,
                           float nearDistance,
                           float farDistance)
        Sets a world-space ray along which to pick in the the same way as the other version of setRay(), but allows you to set a view angle value. The ray is defined as a world space starting point and direction vector. The direction vector will be normalized automatically. The last two arguments specify optional near and far plane clipping during the pick operation. These values are distances from the start point along the direction vector, similar to nearDistance and farDistance in SoCamera. A negative distance (such as the default values) means disable clipping to that plane.

        If fovy is non-zero, perspective ray-picking is used. This means the pick volume is a frustum intersecting the plane passing through the point specified as start argument and having normal vector specified by the direction argument and whose base is a square having edges of length setRadius * 2 or else a circle of radius setRadius if enableConicPickVolume is set to true.

        NOTE: You can use this method or the setPoint / setNormalizedPoint Whichever method you call last is the one that takes effect.

      • setPickAll

        public void setPickAll​(boolean flag)
        Sets whether the action will return all objects intersected or just the closest one. Default is false (only closest intersection).
      • clearPickedPointList

        @Deprecated
        public void clearPickedPointList()
        Deprecated.
        As of Open Inventor 9600. Use clearApplyResult() method
        Clears the picked point list. The picked point list is automatically cleared when the action is destroyed or re-applied. However it may be useful to clear the list explicitly in order to remove references to picked node(s).

        Warning Deprecated since Open Inventor 9600. Use clearApplyResult() method

      • getPickedPoint

        public SoPickedPoint getPickedPoint​(int index)
        Returns the indexed picked point from the list. Returns NULL if index is larger than the number of picked points.
      • enableRadiusForTriangles

        public void enableRadiusForTriangles​(boolean flag)
        Enable radius for triangle-based shape. If true, the radius of the ray specified by setRadius is taken in account when checking for a ray intersection with triangle-based shapes (e.g., SoCylinder). Otherwise, the pick radius for these shapes is 1 pixel regardless of the specified pick radius. Default is false for performance.
      • getPickedPointList

        public java.util.Vector<SoPickedPoint> getPickedPointList()
        Returns list of picked points. This results in a copy of the picked point list and a copy of every SoPickedPoint object in the list.
      • isRadiusEnableForTriangles

        public boolean isRadiusEnableForTriangles()
        Returns whether the pick radius specified by setRadius is taken into account for picking on triangle-based shapes.
      • setPoint

        public void setPoint​(SbVec2s viewportPoint)
        Sets the viewport point through which the ray passes, starting at the camera position. Viewport coordinates range from (0,0) at the lower left to (width-1,height-1) at the upper right. Default is (0,0).

        NOTE: You can use this method or setNormalizedPoint or setRay. Whichever method you call last is the one that takes effect.

      • setPoint

        public void setPoint​(SbVec2f viewportPoint)
        Float version of setPoint. It can be used when a desktop is magnified on a wall of screens using ScaleViz with a tracker device calibrated for this wall.

        NOTE: You can use this method or setNormalizedPoint or setRay. Whichever method you call last is the one that takes effect.

      • setObjectSpace

        public void setObjectSpace()
      • setPickingMode

        public void setPickingMode​(SoRayPickAction.PickingModes pickingMode)
        Sets the picking mode. . Default value is PickingMode.DEFAULT
      • getPoint

        public SbVec2s getPoint()
        Gets the viewport point in pixels (returns the last value passed to setPoint).
      • setRadius

        public void setRadius​(float radius)
        Sets the radius around the point. The radius is defined in pixels when defining a ray using the setPoint or setNormalizedPoint method, and is defined in world coordinates, when the ray is defined using the setRay method. By default, for the setPoint and setNormalizedPoint method the radius is 5 pixels.

        By default, the radius is not taken into account for triangle based shapes, only for points and lines. To enable this use the enableRadiusForTriangles method. When radius is taken into account, the ray is extended in 3D space. For perspectivecameras, the ray is extended to be a cone. For orthographic cameras, the ray is extended to be a cylinder.

        Specifying a radius of 0 may give better performance. In particular, some shapes like MoMeshSkin implement a fast GPU picking algorithm that can only be used when radius is 0.

      • getRadius

        public float getRadius()
        Gets the radius (in pixels) around the point.
      • setRay

        public void setRay​(SbVec3f start,
                           SbVec3f direction,
                           float nearDistance,
                           float farDistance)
        Sets a world-space ray along which to pick. The ray is defined as a world space starting point and direction vector. The direction vector will be normalized automatically. The last two arguments specify optional near and far plane clipping during the pick operation. These values are distances from the start point along the direction vector, similar to nearDistance and farDistance in SoCamera. A negative distance (such as the default values) means disable clipping to that plane.

        The ray-picking is orthogonal. This means the pick volume is a rectangular prism with a square base having edges of length setRadius * 2 or else a cylinder having radius setRadius if enableConicPickVolume is set to true.

        NOTE: You can use this method or the setPoint / setNormalizedPoint Whichever method you call last is the one that takes effect.

      • getPointFloat

        public SbVec2f getPointFloat()
        Float version of getPoint(). It can be used when a desktop is magnified on a wall of screens using ScaleViz with a tracker device calibrated for this wall.
      • setNormalizedPoint

        public void setNormalizedPoint​(SbVec2f normPoint)
        Sets the viewport point in normalized coordinates, which range from (0,0) at the lower left to (1,1) at the upper right. NOTE: You can use this method or setPoint or setRay. Whichever method you call last is the one that takes effect.
      • getNormalizedPoint

        public SbVec2f getNormalizedPoint()
        Gets the viewport point in normalized coordinates 0..1. A point is inside the viewport if its coordinates are in the range [0, 1].

        If no point has been set or the setRay method was called instead of setXXXPoint, this method returns an undefined coordinate (NaN, NaN).

      • intersect

        public boolean intersect​(SbBox3f box,
                                 boolean useFullViewVolume)
        Bounding box: just return whether the ray intersects it. If useFullViewVolume is true, it intersects the picking view volume with the box. Otherwise, it uses just the picking ray, which is faster.
      • getPickedPointsListLength

        public int getPickedPointsListLength()
      • intersect

        public boolean intersect​(SbXfBox3f box,
                                 boolean useFullViewVolume)
        Bounding box: just return whether the ray intersects it. If useFullViewVolume is true, it intersects the picking view volume with the box. Otherwise, it uses just the picking ray, which is faster.
      • setObjectSpace

        public void setObjectSpace​(SbMatrix matrix)
      • intersect

        public boolean intersect​(SbVec3f point)
      • getLine

        public SbLine getLine()
      • isBetweenPlanes

        public boolean isBetweenPlanes​(SbVec3f intersection)
      • addIntersection

        public SoPickedPoint addIntersection​(SbVec3f objectSpacePoint)
        Adds an SoPickedPoint instance representing the given object space point to the current list and returns it. If pickAll is true, this inserts the instance in correct sorted order. If it is false, it replaces the one instance in the list only if the new one is closer; if the new one is farther away, no instance is created and NULL is returned, meaning that no more work has to be done to set up the SoPickedPoint.
      • getUnsortedPickedPoint

        public SoPickedPoint getUnsortedPickedPoint​(int i)
      • enableConicPickVolume

        public void enableConicPickVolume​(boolean flag)
        Controls the pick volume shape for picking with setRay(). The default is false, meaning that the picking volume is a rectangular shape, either a prism or a frustum (depending on which version of setRay was called). When enableConicPickVolume is true the picking volume is a conic shape, either a cylinder or a cone (depending on which version of setRay was called).

        Setting enableConicPickVolume to true ensures that the entities picked using setRay() will be the same as picking using an equivalent call to setPoint(), but this mode is slightly more costly than frustum picking.

      • isConicPickVolume

        public boolean isConicPickVolume()
        Returns true if the picking volume is a conic shape (not a frustum).
      • setStereoMode

        public static void setStereoMode​(SoCamera.StereoModes stereoMode)
        Tells ray pick action in which view the pick occurs. When stereo mode is active, user can choose between left, right, or normal view to perform the action. Only applicable when stereo is active. Default is LEFT_VIEW.
      • enableNormalsGeneration

        public void enableNormalsGeneration​(boolean enable)
        Enables generation of normal vectors for picked points. Default is true.
      • isTexCoordsGenerationEnabled

        public boolean isTexCoordsGenerationEnabled()
        Returns whether texture coordinate generation is enabled for picked points. See enableTexCoordsGeneration().
      • isNormalsGenerationEnabled

        public boolean isNormalsGenerationEnabled()
        Returns whether generation of normal vectors is enabled for picked points. See enableNormalsGeneration().
      • enableElement

        public static void enableElement​(java.lang.Class<? extends Inventor> t,
                                         int stkIndex)
      • computeWorldSpaceRay

        public void computeWorldSpaceRay()
      • hasWorldSpaceRay

        public boolean hasWorldSpaceRay()
      • getStereoMode

        public static SoCamera.StereoModes getStereoMode()
        Returns the view used to perform pick when stereo is active.
      • enableTriangleCulling

        public static void enableTriangleCulling​(boolean flag)
        Enables culling of triangles relative to the ray frustum. Enabling culling improves performance for shapes containing a large number of triangles. Default is false.
      • isTriangleCulling

        public static boolean isTriangleCulling()
        Returns whether triangle culling is enabled.