Previously graph layout was done using the Kamada-Kawai layout algorithm

implemented in Boost.  I am replacing this with a custom implementation of
a constrained stress-majorization algorithm.

The stress-majorization algorithm is more robust and has better convergence
characteristics than Kamada-Kawai, and also simple constraints can be placed
on node position (for example, to enforce downward-pointing edges, non-overlap constraints, or cluster constraints).

Another big advantage is that we no longer need Boost.

I've tested the basic functionality, but I have yet to properly handle
disconnected graphs or to properly scale the resulting layout.

This commit also includes significant refactoring... the quadratic program solver - libvpsc (Variable Placement with Separation Constraints) has been moved to src/libvpsc and the actual graph layout algorithm is in libcola.

(bzr r1394)

1 files changed, 15 insertions, 0 deletions

diff --git a/src/libvpsc/variable.cpp b/src/libvpsc/variable.cpp
new file mode 100644
index 000000000..1890f788e
--- /dev/null
+++ b/src/libvpsc/variable.cpp
@@ -0,0 +1,15 @@
+/**
+ *
+ * Authors:
+ *   Tim Dwyer <tgdwyer@gmail.com>
+ *
+ * Copyright (C) 2005 Authors
+ *
+ * Released under GNU LGPL.  Read the file 'COPYING' for more information.
+ */
+#include "variable.h"
+std::ostream& operator <<(std::ostream &os, const Variable &v) {
+	os << "(" << v.id << "=" << v.position() << ")";
+	return os;
+}
+