Added a 0 check for the random position distribution, such that nodes can be placed at height 0.

src/de/tud/kom/p2psim/impl/topology/placement/RandomPositionDistribution.java

@@ -38,7 +38,15 @@ public class RandomPositionDistribution extends PositionDistribution {
 		Random r = Randoms.getRandom(RandomPositionDistribution.class);
 		double[] vec = new double[getDimensions()];
 		for (int i = 0; i < getDimensions(); i++) {
-			vec[i] = r.nextInt((int) getWorldDimensions().getEntry(i));
+			
+			int dim = (int) getWorldDimensions().getEntry(i);
+			
+			if(dim == 0) {
+				vec[i] = 0;
+			}
+			else {
+				vec[i] = r.nextInt(dim);
+			}
 		}
 		PositionVector position = new PositionVector(vec);
 		return position;