In this tutorial you'll learn about the structure and philosophie in our main layout algorithm KLay Layered. It is based on an idea that became known as Sugiyama-style layout, where the task to layout a graph is split into multiple subsequent steps with the goal to emphasize direction, i.e. let as many edges point into the same direction as possible.

The Five Phases

explain

KLay Layered's Structure

class diagram?

Intermediate processor

Preliminaries

Installing Eclipse for Layout Development

Getting the Source Code

Additionally, we need to get our hands on the actual source code of KLay Layered. You can find it in the pragmatics repository in our Stash.

1. Clone the repository.
2. Import the de.cau.cs.kieler.klay.layered plugin into your workspace.

Assignment

The goal of this assignment is to write a very simple layering algorithm. As you learnt earlier, classically the layering phase expects the input graph to be acyclic. Here however, you will configure the layout algorithm to use a NullPhase for cycle breaking, layer the possibly cyclic graph in a fashion as you like, and use an intermediate processor to reverse edges (if required) such that subsequent phases are guaranteed to work with an acyclic graph.

A result might look like this: