Addd new computeLocalToWorld(NodePath) etc methods.

include/osg/Transform

@@ -19,6 +19,27 @@
 
 namespace osg {
 
+
+
+/** compute the matrix which transforms objects in local coords to world coords,
+  * by accumulating the Transform local to world matrices along the specified node path.*/
+extern SG_EXPORT Matrix computeLocalToWorld(NodePath& nodePath);
+
+/** compute the matrix which transforms objects in world coords to local coords,
+  * by accumulating the Transform world to local matrices along the specified node path.*/
+extern SG_EXPORT Matrix computeWorldToLocal(NodePath& nodePath);
+
+/** compute the matrix which transforms objects in local coords to world coords,
+  * by accumulating the Transform local to world matrices along the specified node path 
+  * the supplied initialial camera modelview .*/
+extern SG_EXPORT Matrix computeLocalToEye(const Matrix& modelview, NodePath& nodePath);
+
+/** compute the matrix which transforms objects in world coords to local coords,
+  * by accumulating the Transform world to local matrices along the specified node path 
+  * the inverse of the supplied initialial camera modelview.*/
+extern SG_EXPORT Matrix computeEyeToLocal(const Matrix& modelview, NodePath& nodePath);
+
+
 /** A Transform is a group node for which all children are transformed by
   * a 4x4 matrix.  It is often used for positioning objects within a scene,
   * producing trackball functionality or for animation.

src/osg/Transform.cpp

@@ -14,6 +14,93 @@
 
 using namespace osg;
 
+class TransformVisitor : public NodeVisitor
+{
+    public:
+    
+        enum CoordMode
+        {
+            WORLD_TO_LOCAL,
+            LOCAL_TO_WORLD
+        };
+        
+
+        CoordMode       _coordMode;
+        Matrix&         _matrix;
+
+        TransformVisitor(Matrix& matrix,CoordMode coordMode):
+            NodeVisitor(),
+            _coordMode(coordMode),
+            _matrix(matrix)
+            {}
+
+        virtual void apply(Transform& transform)
+        {
+            if (_coordMode==LOCAL_TO_WORLD)
+            {
+                transform.getLocalToWorldMatrix(_matrix,this);
+            }
+            else // worldToLocal
+            {
+                transform.getWorldToLocalMatrix(_matrix,this);
+            }
+        }
+        
+        void accumulate(NodePath& nodePath)
+        {
+            for(NodePath::iterator itr=nodePath.begin();
+                itr!=nodePath.end();
+                ++itr)
+            {
+                (*itr)->accept(*this);
+            }
+        }
+    
+};
+
+Matrix osg::computeLocalToWorld(NodePath& nodePath)
+{
+    Matrix matrix;
+    TransformVisitor tv(matrix,TransformVisitor::LOCAL_TO_WORLD);
+    tv.accumulate(nodePath);
+    return matrix;
+}
+
+Matrix osg::computeWorldToLocal(NodePath& nodePath)
+{
+    osg::Matrix matrix;
+    TransformVisitor tv(matrix,TransformVisitor::WORLD_TO_LOCAL);
+    tv.accumulate(nodePath);
+    return matrix;
+}
+
+Matrix osg::computeLocalToEye(const Matrix& modelview,NodePath& nodePath)
+{
+    Matrix matrix(modelview);
+    TransformVisitor tv(matrix,TransformVisitor::LOCAL_TO_WORLD);
+    tv.accumulate(nodePath);
+    return matrix;
+}
+
+Matrix osg::computeEyeToLocal(const Matrix& modelview,NodePath& nodePath)
+{
+    Matrix matrix;
+    matrix.invert(modelview);
+    TransformVisitor tv(matrix,TransformVisitor::WORLD_TO_LOCAL);
+    tv.accumulate(nodePath);
+    return matrix;
+}
+
+
+
+
+
+
+
+
+
+
+
 Transform::Transform()
 {
     _referenceFrame = RELATIVE_TO_PARENTS;