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This is a SpatialOS project which serves as an example of building workers using the C API.
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SpatialOS C example project


This project contains workers written in both C and C#, so therefore it depends on the following:

  1. The C example workers use CMake as their build system. On Windows, Visual Studio 2015 or above needs to be installed.
  2. The C# worker depends on Mono, as specified in the C# worker SDK requirements.

Quick start

Build the project and start it with the default launch configuration:

spatial worker build --target windows
spatial local launch

(Replacing windows with macos on macOS, or linux on Linux).

This will launch SpatialOS locally with a single C# "physics" worker that updates the position of a single entity. You can then connect either one of the two C client workers (one implemented using "direct" serialization, the other implemented using "vtable" serialization). These workers can be launched with the following commands:

  • Client (direct): spatial local worker launch client_direct local
  • Client (vtable): spatial local worker launch client_vtable local


This project is used to showcase the C API and how it can be used to implement a simple client worker which visualizes the state of a single entity whose position is updated by a "physics" worker. As serialization in the C API can be implemented in two different ways, we provide two implementations of the same worker in workers/c_client_direct and workers/c_client_vtable. Either one of these can be used as a basis for further experimentation, and the client worker that's not being used can easily be deleted without breaking any other functionality.

When a client worker connects, it sends a command to the C# worker (on the sample.Login component). The C# worker then modifies the entity's write ACLs to delegate component 1001 (sample.ClientData) to the client, using the CallerWorkerAttributes field of the CommandRequestOp. This causes the entity to be checked out by the client worker, and the client worker will begin to receive component updates for position changes. The physics worker will also begin to send a simple command to the client every few seconds.


The snapshot exists in both text and binary format in the snapshots folder. There is no script to generate the snapshot as the snapshot was written by hand in the text format, but it's possible to make simple changes to the text format and regenerate the binary snapshot from it. To update the binary snapshot after making a change, run the following command:

spatial project history snapshot convert --input-format=text --input=snapshots/default.txt --output-format=binary --output=snapshots/default.snapshot
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