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, 7 insertions, 6 deletions

diff --git a/src/removeoverlap/remove_rectangle_overlap.cpp b/src/libvpsc/remove_rectangle_overlap.cpp
index 9fbef647b..6f6ace03a 100755..100644
--- a/src/removeoverlap/remove_rectangle_overlap.cpp
+++ b/src/libvpsc/remove_rectangle_overlap.cpp
@@ -40,18 +40,19 @@ double Rectangle::yBorder=0;
  *    too much in the first pass.
  */
 void removeRectangleOverlap(unsigned n, Rectangle *rs[], double xBorder, double yBorder) {
+	assert(0 <= n);
 	try {
 	// The extra gap avoids numerical imprecision problems
 	Rectangle::setXBorder(xBorder+EXTRA_GAP);
 	Rectangle::setYBorder(yBorder+EXTRA_GAP);
 	Variable **vs=new Variable*[n];
-	for(unsigned int i=0;i<n;i++) {
+	for(int i=0;i<n;i++) {
 		vs[i]=new Variable(i,0,1);
 	}
 	Constraint **cs;
 	double *oldX = new double[n];
 	int m=generateXConstraints(n,rs,vs,cs,true);
-	for(unsigned int i=0;i<n;i++) {
+	for(int i=0;i<n;i++) {
 		oldX[i]=vs[i]->desiredPosition;
 	}
 	VPSC vpsc_x(n,vs,m,cs);
@@ -61,7 +62,7 @@ void removeRectangleOverlap(unsigned n, Rectangle *rs[], double xBorder, double
 	f.close();
 #endif
 	vpsc_x.solve();
-	for(unsigned int i=0;i<n;i++) {
+	for(int i=0;i<n;i++) {
 		rs[i]->moveCentreX(vs[i]->position());
 	}
 	for(int i = 0; i < m; ++i) {
@@ -79,7 +80,7 @@ void removeRectangleOverlap(unsigned n, Rectangle *rs[], double xBorder, double
 	f.close();
 #endif
 	vpsc_y.solve();
-	for(unsigned int i=0;i<n;i++) {
+	for(int i=0;i<n;i++) {
 		rs[i]->moveCentreY(vs[i]->position());
 		rs[i]->moveCentreX(oldX[i]);
 	}
@@ -101,14 +102,14 @@ void removeRectangleOverlap(unsigned n, Rectangle *rs[], double xBorder, double
 		delete cs[i];
 	}
 	delete [] cs;
-	for(unsigned int i=0;i<n;i++) {
+	for(int i=0;i<n;i++) {
 		rs[i]->moveCentreX(vs[i]->position());
 		delete vs[i];
 	}
 	delete [] vs;
 	} catch (char const *str) {
 		std::cerr<<str<<std::endl;
-		for(unsigned int i=0;i<n;i++) {
+		for(int i=0;i<n;i++) {
 			std::cerr << *rs[i]<<std::endl;
 		}
 	}