Recast

Recast is state of the art navigation mesh construction toolset for games.

• It is automatic, which means that you can throw any level geometry at it and you will get a robust mesh out.
• It is fast which means swift turnaround times for level designers.
• It is open source so it comes with full source and you can customize it to your hearts content.

The latest version can be found on GitHub.

The Recast process starts with constructing a voxel mold from level geometry and then casting a navigation mesh over it. The process consists of three steps, building the voxel mold, partitioning the mold into simple regions, and peeling off the regions as simple polygons.

1. The voxel mold is built from the input triangle mesh by rasterizing the triangles into a multi-layer heightfield. Some simple filters are then applied to the mold to prune out locations where the character would not be able to move.
2. The walkable areas described by the mold are divided into simple overlayed 2D regions. The resulting regions have only one non-overlapping contour, which simplifies the final step of the process tremendously.
3. The navigation polygons are peeled off from the regions by first tracing the boundaries and then simplifying them. The resulting polygons are finally converted to convex polygons which makes them perfect for pathfinding and spatial reasoning about the level.

Detour

Recast is accompanied by Detour, a path-finding and spatial reasoning toolkit. You can use any navigation mesh with Detour, but of course the data generated by Recast fits perfectly.

Detour offers a simple static navigation mesh that is suitable for many simple cases, as well as a tiled navigation mesh that allows you to add and remove pieces of the mesh. The tiled mesh allows you to create systems where you stream new navigation data in and out as the player progresses the level, or regenerate tiles as the world changes.

Recast Demo

You can find a comprehensive demo project in the RecastDemo folder. It is a kitchen sink demo containing all the functionality of the library. If you are new to Recast & Detour, check out Sample_SoloMesh.cpp to get started with building navmeshes and NavMeshTesterTool.cpp to see how Detour can be used to find paths.

Building RecastDemo

RecastDemo uses premake4 to build platform specific projects, now is good time to install it if you don't have it already. To build RecastDemo, in your favourite terminal navigate into the RecastDemo folder, then:

• OS X: premake4 xcode4
• Windows: premake4 vs2010
• Linux: premake4 gmake

See the premake4 documentation for full list of supported build file types. The projects will be created in the RecastDemo/Build folder. After you have compiled the project, the RecastDemo executable will be located in RecastDemo/Bin folder.

Integrating With Your Own Project

It is recommended to add the source directories DebugUtils, Detour, DetourCrowd, DetourTileCache, and Recast into your own project depending on which parts of the project you need. For example your level building tool could include DebugUtils, Recast, and Detour, and your game runtime could just include Detour.

Discuss

• Discuss Recast and Detour: Recast Navigation Group
• Development Blog: Digesting Duck

License

Recast Navigation is licensed under the ZLib license.