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, 0 insertions, 47 deletions

diff --git a/src/removeoverlap/constraint.cpp b/src/removeoverlap/constraint.cpp
deleted file mode 100644
index 7c200878b..000000000
--- a/src/removeoverlap/constraint.cpp
+++ /dev/null
@@ -1,47 +0,0 @@
-/**
- * \brief A constraint determines a minimum or exact spacing required between
- * two variables.
- *
- * Authors:
- *   Tim Dwyer <tgdwyer@gmail.com>
- *
- * Copyright (C) 2005 Authors
- *
- * Released under GNU LGPL.  Read the file 'COPYING' for more information.
- */
-
-#include "constraint.h"
-#include <cassert>
-Constraint::Constraint(Variable *left, Variable *right, double gap, bool equality)
-: left(left),
-  right(right),
-  gap(gap),
-  timeStamp(0),
-  active(false),
-  visited(false),
-  equality(equality)
-{
-	left->out.push_back(this);
-	right->in.push_back(this);
-}
-Constraint::~Constraint() {
-	Constraints::iterator i;
-	for(i=left->out.begin(); i!=left->out.end(); i++) {
-		if(*i==this) break;
-	}
-	left->out.erase(i);
-	for(i=right->in.begin(); i!=right->in.end(); i++) {
-		if(*i==this) break;
-	}
-	right->in.erase(i);
-}
-std::ostream& operator <<(std::ostream &os, const Constraint &c)
-{
-	if(&c==NULL) {
-		os<<"NULL";
-	} else {
-		const char *type=c.equality?"=":"<=";
-		os<<*c.left<<"+"<<c.gap<<type<<*c.right<<"("<<c.slack()<<")"<<(c.active?"-active":"");
-	}
-	return os;
-}