257 lines
12 KiB
Plaintext
257 lines
12 KiB
Plaintext
//C++ header - Open Scene Graph - Copyright (C) 1998-2002 Robert Osfield
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//Distributed under the terms of the GNU Library General Public License (LGPL)
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//as published by the Free Software Foundation.
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#ifndef OSG_NODEVISITOR
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#define OSG_NODEVISITOR 1
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#include <osg/Node>
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#include <osg/Matrix>
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#include <osg/FrameStamp>
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namespace osg {
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class Geode;
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class Billboard;
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class LightSource;
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class ClipNode;
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class Group;
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class Transform;
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class DOFTransform;
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class MatrixTransform;
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class PositionAttitudeTransform;
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class Projection;
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class LOD;
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class Switch;
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class Impostor;
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class ClearNode;
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class OccluderNode;
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class Sequence;
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/** Visitor for type safe operations on osg::Node's.
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Based on GOF's Visitor pattern. The NodeVisitor
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is useful for developing type safe operations to nodes
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in the scene graph (as per Visitor pattern), and adds to this
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support for optional scene graph traversal to allow
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operations to be applied to whole scenes at once. The Visitor
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pattern uses a technique of double dispatch as a mechanism to
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called the appropriate apply(..) method of the NodeVisitor. To
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use this feature one must use the Node::accept(NodeVisitor) which
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is extended in each Node subclass, rather than the NodeVisitor
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apply directly. So use root->accept(myVisitor); instead of
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myVisitor.apply(*root). The later method will bypass the double
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dispatch and the appropriate NodeVisitor::apply(..) method will
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not be called. */
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class SG_EXPORT NodeVisitor : public Referenced
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{
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public:
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enum TraversalMode
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{
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TRAVERSE_NONE,
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TRAVERSE_PARENTS,
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TRAVERSE_ALL_CHILDREN,
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TRAVERSE_ACTIVE_CHILDREN,
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TRAVERSE_VISITOR
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};
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enum VisitorType
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{
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NODE_VISITOR = 0,
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APP_VISITOR,
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COLLECT_OCCLUDER_VISITOR,
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CULL_VISITOR
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};
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NodeVisitor(TraversalMode tm=TRAVERSE_NONE);
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NodeVisitor(VisitorType type,TraversalMode tm=TRAVERSE_NONE);
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virtual ~NodeVisitor();
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/** Method to call to reset visitor. Useful for your visitor accumulates
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state during a traversal, and you plan to reuse the visitor.
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To flush that state for the next traversal than call reset() prior
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to each traversal.*/
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virtual void reset() {}
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/** Set the VisitorType, used to distingush different visitors during
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* traversal of the scene, typically used in the Node::traverse() method
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* to select which behaviour to use for different types of traversal/visitors.*/
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inline void setVisitorType(VisitorType type) { _visitorType = type; }
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/** Get the VisitorType.*/
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inline VisitorType getVisitorType() const { return _visitorType; }
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/** Set the traversal number. Typically used to denote the frame count.*/
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inline void setTraversalNumber(int fn) { _traversalNumber = fn; }
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/** Get the traversal number. Typically used to denote the frame count.*/
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inline int getTraversalNumber() const { return _traversalNumber; }
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/** Set the FrameStamp that this traversal is assoicated with.*/
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inline void setFrameStamp(FrameStamp* fs) { _frameStamp = fs; }
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/** Get the FrameStamp that this traversal is assoicated with.*/
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inline const FrameStamp* getFrameStamp() const { return _frameStamp.get(); }
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/** Set the TraversalMask of this NodeVisitor.
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* The TraversalMask is used by the NodeVisitor::validNodeMask() method
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* to determine whether to operate on a node and its subgraph.
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* validNodeMask() is called automaticaly in the Node::accept() method before
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* any call to NodeVisitor::apply(), apply() is only ever called if validNodeMask
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* returns true. Note, if NodeVisitor::_traversalMask is 0 then all operations
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* will be swithced off for all nodes. Whereas setting both _traversalMask and
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* _nodeMaskOverride to 0xffffffff will allow a visitor to work on all nodes
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* regardless of their own Node::_nodeMask state.*/
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inline void setTraversalMask(Node::NodeMask mask) { _traversalMask = mask; }
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/** Get the TraversalMask.*/
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inline Node::NodeMask getTraversalMask() const { return _traversalMask; }
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/** Set the NodeMaskOverride mask.
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* Used in validNodeMask() to determine whether to operate on a node or its
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* subgraph, by OR'ing NodeVisitor::_nodeMaskOverride with the Node's own Node::_nodeMask.
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* Typically used to force on nodes which may have
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* been switched off by their own Node::_nodeMask.*/
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inline void setNodeMaskOverride(Node::NodeMask mask) { _nodeMaskOverride = mask; }
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/** Get the NodeMaskOverride mask.*/
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inline Node::NodeMask getNodeMaskOverride() const { return _nodeMaskOverride; }
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/** Method to called by Node and its subclass' Node::accept() method, if the result is true
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* to be used to cull operations of nodes and their subgraphs.
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* Return true if the result of a bit wise and of the NodeVisitor::_traversalMask
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* with the bit or between NodeVistor::_nodeMaskOverride and the Node::_nodeMask.
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* default values for _traversalMask is 0xffffffff, _nodeMaskOverride is 0x0,
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* and osg::Node::_nodeMask is 0xffffffff. */
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inline bool validNodeMask(const osg::Node& node) const
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{
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return (getTraversalMask() & (getNodeMaskOverride() | node.getNodeMask()))!=0;
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}
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/** Set the traversal mode for Node::traverse() to use when
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deciding which children of a node to traverse. If a
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NodeVisitor has been attached via setTraverseVisitor()
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and the new mode is not TRAVERSE_VISITOR then the attached
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visitor is detached. Default mode is TRAVERSE_NONE.*/
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void setTraversalMode(const TraversalMode mode);
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/** Get the traversal mode.*/
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inline TraversalMode getTraversalMode() const { return _traversalMode; }
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/** Set a visitor to handle traversal.
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Overrides the traverse mode setting it to TRAVERSAL_VISITOR.*/
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void setTraversalVisitor(NodeVisitor* nv);
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/** Get the traversal visitor, returns NULL if none is attached.*/
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inline NodeVisitor* getTraversalVisitor() { return _traversalVisitor.get(); }
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/** Method for handling traversal of a nodes.
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If you intend to use the visitor for actively traversing
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the scene graph then make sure the accept() methods call
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this method unless they handle traversal directly.*/
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inline void traverse(Node& node)
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{
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if (_traversalVisitor.valid()) node.accept(*_traversalVisitor);
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else if (_traversalMode==TRAVERSE_PARENTS) node.ascend(*this);
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else if (_traversalMode!=TRAVERSE_NONE) node.traverse(*this);
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}
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/** Method called by osg::Node::accept() method before
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* a call the NodeVisitor::apply(..). The back of the list will,
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* therefore, be the current node being visited inside the apply(..),
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* and the rest of the list will be the parental sequence of nodes
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* from the top most node applied down the graph to the current node.
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* Note, the user does not typically call pushNodeOnPath() as it
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* will be called automatically by the Node::accept() method.*/
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inline void pushOntoNodePath(Node* node) { _nodePath.push_back(node); }
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/** Method callby osg::Node::accept() method after
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* a call the NodeVisitor::apply(..).
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* Note, the user does not typically call pushNodeOnPath() as it
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* will be called automatically by the Node::accept() method.*/
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inline void popFromNodePath() { _nodePath.pop_back(); }
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/** Get the non const NodePath from the top most node applied down
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* to the current Node being visited.*/
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NodePath& getNodePath() { return _nodePath; }
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/** Get the const NodePath from the top most node applied down
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* to the current Node being visited.*/
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const NodePath& getNodePath() const { return _nodePath; }
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/** Get the Local To World Matrix from the NodePath for specified Transform::Mode, and u.*/
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virtual bool getLocalToWorldMatrix(Matrix& matrix, Node* node);
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/** Get the World To Local Matrix from the NodePath for specified Transform::Mode.*/
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virtual bool getWorldToLocalMatrix(Matrix& matrix, Node* node);
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/** Get the distance from a point to the eye point, distance value in local coordinate system.
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* Note, not all NodeVisitor implement this method, it is mainly cull visitors which will implement.
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* If the getDistianceFromEyePoint(pos) is not implmented than a default value of 0.0 is returned.*/
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virtual float getDistanceToEyePoint(const Vec3& /*pos*/, bool /*useLODBias*/) const { return 0.0f; }
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/** Get the distance of a point from the eye point, distance value in the eye coordinate system.
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* Note, not all NodeVisitor implement this method, it is mainly cull visitors which will implement.
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* If the getDistianceFromEyePoint(pos) is not implmented than a default value of 0.0 is returned.*/
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virtual float getDistanceFromEyePoint(const Vec3& /*pos*/, bool /*useLODBias*/) const { return 0.0f; }
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virtual void apply(Node& node) { traverse(node);}
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virtual void apply(Geode& node) { apply((Node&)node); }
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virtual void apply(Billboard& node) { apply((Geode&)node); }
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virtual void apply(Group& node) { apply((Node&)node); }
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virtual void apply(Projection& node) { apply((Group&)node); }
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virtual void apply(ClipNode& node) { apply((Group&)node); }
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virtual void apply(LightSource& node) { apply((Group&)node); }
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virtual void apply(Transform& node) { apply((Group&)node); }
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virtual void apply(DOFTransform& node) { apply((Transform&)node); }
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virtual void apply(MatrixTransform& node) { apply((Transform&)node); }
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virtual void apply(PositionAttitudeTransform& node) { apply((Transform&)node); }
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virtual void apply(Switch& node) { apply((Group&)node); }
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virtual void apply(Sequence& node) { apply((Switch&)node); }
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virtual void apply(LOD& node) { apply((Group&)node); }
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virtual void apply(Impostor& node) { apply((LOD&)node); }
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virtual void apply(ClearNode& node) { apply((Group&)node); }
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virtual void apply(OccluderNode& node) { apply((Group&)node); }
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protected:
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VisitorType _visitorType;
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int _traversalNumber;
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ref_ptr<FrameStamp> _frameStamp;
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ref_ptr<NodeVisitor> _traversalVisitor;
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TraversalMode _traversalMode;
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Node::NodeMask _traversalMask;
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Node::NodeMask _nodeMaskOverride;
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NodePath _nodePath;
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};
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/** Convenience functor for assisting visiting of arrays of osg::Node's.*/
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struct NodeAcceptOp
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{
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NodeVisitor& _nv;
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NodeAcceptOp(NodeVisitor& nv):_nv(nv) {}
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void operator () (Node* node) { node->accept(_nv); }
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void operator () (ref_ptr<Node> node) { node->accept(_nv); }
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};
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}
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#endif
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