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more pgraph refinements

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This commit is contained in:
David Rose 2002-03-21 00:45:03 +00:00
parent d210511b8b
commit 3559ab5380
1 changed files with 30 additions and 21 deletions
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51
panda/src/pgraph/pandaNode.cxx
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@ -32,29 +32,33 @@ TypeHandle PandaNode::_type_handle;
// NodePaths are kept consistent as we attach and detach nodes. We
// must enforce the following rules:
//
// 1) Each NodePath (i.e. chain of NodePathComponents) represents a
// complete unbroken chain from a PandaNode to the root of the graph.
// 1) Each NodePath (i.e. chain of NodePathComponents) represents a
// complete unbroken chain from a PandaNode to the root of the
// graph.
//
// 2) Each NodePathComponent chain is unique. There are no two
// different NodePathComponents that reference the same path to the
// root.
// 2) Each NodePathComponent chain is unique. There are no two
// different NodePathComponents that reference the same path to the
// root.
//
// 3) If a PandaNode with no parents is attached to a new parent, all
// NodePaths that previously indicated this node as the root of graph
// must now be updated to include the complete chain to the new root.
// The following rules all follow from rules (1) and (2):
//
// 4) If a PandaNode with other parents is attached to a new parent,
// any previously existing NodePaths are not affected.
// 3) If a PandaNode with no parents is attached to a new parent,
// all NodePaths that previously indicated this node as the root of
// graph must now be updated to include the complete chain to the
// new root.
//
// 5) If a PandaNode is disconnected from its parent, and it has no
// other parents, all NodePaths that previously passed through this
// node to the old parent must now be updated to indicate this node is
// now the root.
// 4) If a PandaNode with other parents is attached to a new parent,
// any previously existing NodePaths are not affected.
//
// 6) If a PandaNode is disconnected from its parent, and it has at
// least one other parent, all NodePaths that previously passed
// through this node to the old parent must now be updated to pass
// through one of the other parents instead.
// 5) If a PandaNode is disconnected from its parent, and it has no
// other parents, all NodePaths that previously passed through this
// node to the old parent must now be updated to indicate this node
// is now the root.
//
// 6) If a PandaNode is disconnected from its parent, and it has at
// least one other parent, all NodePaths that previously passed
// through this node to the old parent must now be updated to pass
// through one of the other parents instead.
//
// Rules (5) and (6) can especially complicate things because they
// introduce the possibility that two formerly distinct NodePaths are
@ -89,7 +93,7 @@ TypeHandle PandaNode::_type_handle;
// The NodePath support interface functions are strictly called from
// within the NodePath class, and are used to implement
// NodePath::reparent_to() and NodePath::remove_node(), etc. The
// fundamental interface, on the other hand, is designed to be called
// fundamental interface, on the other hand, is intended to be called
// directly by the user.
//
// The fundamental interface has a slightly lower overhead because it
@ -1354,8 +1358,13 @@ detach(qpNodePathComponent *child) {
nassertv(child != (qpNodePathComponent *)NULL);
nassertv(!child->is_top_node());
PandaNode *child_node = child->get_node();
PandaNode *parent_node = child->get_next()->get_node();
PT(PandaNode) child_node = child->get_node();
PT(PandaNode) parent_node = child->get_next()->get_node();
// We should actually have a parent-child relationship, since this
// came from a qpNodePathComponent that ought to know about this
// sort of thing.
nassertv(child_node->find_parent(parent_node) >= 0);
// Break the qpNodePathComponent connection.
child->set_top_node();