Added asGroup() and asTransform() methods to osg::Node to downcast nodes

to these types without requiring an expensive dynamic_cast<>.

Also added asGeometry() to osg::Drawable for the same reasons.

include/osg/Drawable

@@ -21,6 +21,7 @@ class Vec3;
 class Vec4;
 class UByte4;
 class Node;
+class Geometry;
 
 // this is define to alter the way display lists are compiled inside the
 // the draw method, it has been found that the NVidia drivers fail completely
@@ -49,6 +50,12 @@ class SG_EXPORT Drawable : public Object
         virtual const char* libraryName() const { return "osg"; }
         virtual const char* className() const { return "Drawable"; }
 
+        /** convert 'this' into a Geometry pointer if Drawable is a Geometry, otherwise return 0.
+          * Equivalent to dynamic_cast<Geometry*>(this).*/
+        virtual Geometry* asGeometry() { return 0; }
+        /** convert 'const this' into a const Geometry pointer if Drawable is a Geometry, otherwise return 0.
+          * Equivalent to dynamic_cast<const Geometry*>(this).*/
+        virtual const Geometry* asGeometry() const { return 0; }
 
         /** A vector of osg::Node pointers which is used to store the parent(s) of drawable.*/
         typedef std::vector<Node*> ParentList;

include/osg/Geometry

@@ -30,6 +30,9 @@ class SG_EXPORT Geometry : public Drawable
         virtual const char* libraryName() const { return "osg"; }
         virtual const char* className() const { return "Geometry"; }
 
+        virtual Geometry* asGeometry() { return this; }
+        virtual const Geometry* asGeometry() const { return this; }
+
         enum AttributeBinding
         {
             BIND_OFF=0,

include/osg/Group

@@ -27,6 +27,9 @@ class SG_EXPORT Group : public Node
 
         META_Node(osg, Group);
 
+        virtual Group* asGroup() { return this; }
+        virtual const Group* asGroup() const { return this; }
+
         virtual void traverse(NodeVisitor& nv);
 
         /** Add Node to Group.

include/osg/Node

@@ -17,6 +17,7 @@ namespace osg {
 
 class NodeVisitor;
 class Group;
+class Transform;
 
 /** META_Node macro define the standard clone, isSameKindAs, className
   * and accept methods.  Use when subclassing from Node to make it
@@ -60,6 +61,20 @@ class SG_EXPORT Node : public Object
         /** return the name of the node's class type.*/
         virtual const char* className() const { return "Node"; }
 
+        /** convert 'this' into a Group pointer if Node is a Group, otherwise return 0.
+          * Equivalent to dynamic_cast<Group*>(this).*/
+        virtual Group* asGroup() { return 0; }
+        /** convert 'const this' into a const Group pointer if Node is a Group, otherwise return 0.
+          * Equivalent to dynamic_cast<const Group*>(this).*/
+        virtual const Group* asGroup() const { return 0; }
+
+        /** convert 'this' into a Transform pointer if Node is a Transform, otherwise return 0.
+          * Equivalent to dynamic_cast<Transform*>(this).*/
+        virtual Transform* asTransform() { return 0; }
+        /** convert 'const this' into a const Transform pointer if Node is a Transform, otherwise return 0.
+          * Equivalent to dynamic_cast<const Transform*>(this).*/
+        virtual const Transform* asTransform() const { return 0; }
+
         /** Visitor Pattern : calls the apply method of a NodeVisitor with this node's type.*/
         virtual void accept(NodeVisitor& nv);
         /** Traverse upwards : calls parents' accept method with NodeVisitor.*/

include/osg/Transform

@@ -45,6 +45,9 @@ class SG_EXPORT Transform : public Group
 
         META_Node(osg, Transform);
 
+        virtual Transform* asTransform() { return this; }
+        virtual const Transform* asTransform() const { return this; }
+
         enum ReferenceFrame
         {
             RELATIVE_TO_PARENTS,

src/osg/Group.cpp

@@ -229,7 +229,7 @@ bool Group::computeBound() const
         itr!=_children.end();
         ++itr)
     {
-        const osg::Transform* transform = dynamic_cast<const osg::Transform*>(itr->get());
+        const osg::Transform* transform = (*itr)->asTransform();
         if (!transform || transform->getReferenceFrame()==osg::Transform::RELATIVE_TO_PARENTS)
         {
             bb.expandBy((*itr)->getBound());
@@ -244,7 +244,7 @@ bool Group::computeBound() const
         itr!=_children.end();
         ++itr)
     {
-        const osg::Transform* transform = dynamic_cast<const osg::Transform*>(itr->get());
+        const osg::Transform* transform = (*itr)->asTransform();
         if (!transform || transform->getReferenceFrame()==osg::Transform::RELATIVE_TO_PARENTS)
         {
             _bsphere.expandRadiusBy((*itr)->getBound());