The larger square shows the total area of the small virtual world. Each smaller square represents a microcell, an area of the world to be assigned to and updated by a single worker node. The worker nodes are shown by the three colours in the images below, which are each viewed from the central server. The simulation was run for a number of minutes, with cells being redistributed dynamically between nodes. Numbers at the bottom right indicate the number of minutes the system had been active for when the screenshot was captured.

This image shows the view from a worker node, each blue dot represents a single entity following a path. This node is completely under-loaded just so that the entities can be seen clearly, when thousands are processed it can be hard to pick out individuals.

This shows the use of varying microcell sizes. The use of different sizes didn’t actually make a difference to average load, maximum load or load disparity between worker nodes except when particularly small cells were used. This caused a great deal of load for the central server, a huge increase in the number of transfers required and as the images show prevent the world from being re-partitioned in a reasonable period of time.

Finally, this image shows the cell distribution between worker nodes when the number used was scaled to match the problem size. As the number of entities was increased and then decreased, the number of computers used was scaled similarly.

That’s all for now, I’ll do my best to go over some details when my laptop has been repaired.

Additionally, the framework now supports both hexagons and quads as cells. Hexagons have the advantage that only 3 cells meet at any corner, limiting the maximum number of nodes which might be involved should an event take place there. Here’s some images of the view from the server with the most basic (block) distribution of cells:

A major part of the project involves distributing microcells (fixed areas of the world) between a series of worker nodes both statically and dynamically. In order to test methods of achieving this, I created a small testbed application which simulates the task without networking. It is capable of using various methods to distribute cells, both at the start of the application and as it runs, both controlled by a central server and initiated by worker nodes and gives graphical and numerical feedback.

The images below were taken with a greatly reduced number of cells, and the work involved in processing each cell is artificial: there are no pathfinding characters yet. However hopefully it demonstrates to some extent how division of the world takes place, and allows me to easily test distribution methods before using them in the proper simulation.

Coloured by number of characters per cell.

Initial block distribution.

Random distribution for comparison.

Block distribution with dynamic passing after time.

As the actual application I am working on is written in C#, I used XNA to create the images here. As it is possible to render XNA frames to a windows form application with little difficulty, this is also the approach I will employ for visualising the complete project.