RTS engine

Repository: https://codeberg.org/langurmonkey/rts-engine

This is an RTS engine project on which I work very occasionally. It is a testing sandbox and does not have much focus. Maybe it’ll grow into a proper game in the future, who knows. Nobody cares. I started playing around with the idea as a time killer some years ago, kicking off the development with a fast version of the A* path-finding algorithm backed not by a grid (as usual) but by a quad-tree. Quad-trees make path-finding super-fast because of their hierarchical division of space and their adaptive partition sizes. Even though I used visibility graphs to store the navigable nodes from one given point, quad-trees are also fast for checking the properties/elements of a position’s surroundings, for child nodes are always spatially contained in parent nodes. However, the tree re-balancing operation is too costly, so I ended up implementing a regular grid based approach, which is the one in use today. A* is also quite fast in a regular grid.

Once I got this path-finding on a quad-tree thing up and running, It was time to implement the movement of my entities. I dove a bit into the topic and stumbled upon Craig Reynolds steering behaviours. They turned out to be an excellent method of implementing movement, but they come with caveats. I found these steering behaviours very powerful at producing organic-like movements that do not look forced at all. However, they are usually hard to implement and need A LOT of tweaking to really get them rolling. If you are interested in the topic you can check out Reynolds’ original paper or have a look at the book “Programming game AI by example” by Mat Buckland.

It looks like Libgdx itself provides nowadays an alternative implementation of steering behaviours, which is probably nicer than mine, but mine was first, so I got that going for me.

I wrote a blog post about this project.

Current features

• Shiny, shitty 2D graphics.
• The model is fully 3D, though.
• Real time selection and movement of units and groups.
• Unit life bars.
• Fog of war comes in two flavors: tile-based (bad) and mesh-based (awesome).
• Own implementation of steering behaviours that work (with a lot of tweaking).
• Zoom and pan freely.
• Tiled tile map integration.
• Quad-tree and regular grid implementations for spatial awareness.
• Some basic graphical and lighting effects.
• Ashley ECS as entity component system.
• Pretty fast, above 500 FPS on decent hardware. Around 130 FPS on 7th gen Intel laptop graphics.
• Theoretically, Android support.

Running

In order to run the RTS engine on the desktop, first clone the repository:

git clone https://codeberg.org/langurmonkey/rts-engine.git
cd rts-engine

Then, just run the following command:

$ gradlew desktop:run

Video

Here a video demonstrating a few of the features available as of now.

Licensing

This software is distributed under the MIT license.