Visual Studio Code

1. Introduction

Visual Studio Code is a powerful, free and open-source, cross-platform text editor for programmers.

Below we describe how to configure it to be a perfect code editor for Pascal, and in particular for your Castle Game Engine projects. We’re proud to provide an LSP server that will make VS Code do intelligent code completion that works great with Pascal and automatically completes all Castle Game Engine API.

Visual Studio Code completing CGE code
The configuration described here also works with VSCodium, a version of VS Code built using 100% open-source code (without e.g. Microsoft telemetry).

2. Make Castle Game Engine invoke VS Code

Go to Castle Game Engine editor preferences, "Code Editor" tab, and select the "Visual Studio Code".

Configure VS Code in CGE Preferences

This will make CGE automatically open VS Code when you open Pascal file

  • by double-clicking Pascal unit from CGE editor "Files" panel,

  • by double-clicking a message in the "Output" window referencing some Pascal file,

  • using menu item "Code → Open Project in Code Editor",

  • and in all other cases when CGE wants to open Pascal file.

3. Pascal syntax highlighting

There are multiple VS Code extensions that provide Pascal code highlighting.

We recommend Pascal Language Basics. It’s available in the VS Code marketplace, so you can just search for it and install right inside the VS Code "Extensions" panel.


Searching extensions' marketplace for "Pascal" will yield a number of solid alternatives. They will likely work just as well for your Pascal and CGE editing, go ahead and try them. We just recommend choosing any "simple" extension that adds Pascal highlighting but doesn’t do code completion and parsing (because the LSP server will already take care of it).

For VS Codium users, the Pascal magic extension may be the easiest to install, as is available in the VS Codium (and VS Code too) extensions' marketplace.

4. Pascal code completion

We provide an LSP server that implements an intelligent code completion for Pascal and is aware of Castle Game Engine units and default syntax options (e.g. FPC ObjFpc mode).

Our LSP server is based on Philip Zander's LSP server which in turn relies on Lazarus CodeTools to do the code completion. So inside there is really a lot of work and testing from many people in the Pascal ecosystem to make it powerful.

To use it with VS Code:

  1. Install the Pascal Language Server Extension for Visual Studio Code. It’s easiest to do this by:

    • Downloading this VSIX file.

    • Use "Install from VSIX…​" menu item in VS Code to install it:

      Install from VSIX
    • Once done, you will see "Pascal Language Server" extension installed. Make sure it is enabled.

  2. Configure the extension, pointing it to your FPC, Lazarus, and pasls (our LSP server).

    VS Code Extension configuration
    • Open the extension settings.

    • Set Env: FPCDIR to point to the FPC source code. If you use FPC bundled with CGE, this should look like <cgepath>/tools/contrib/fpc/src/.

    • Set Env: FPCTARGET to your OS, like linux or win64.


      Use operating system names that match FPC and CGE. You can see valid OS names:

      • In CGE editor menu "Run → Platform (To Compile And Run) → …​".

      • If you execute on the command-line build tool as castle-engine --help. Look for possible arguments for the --os option.

      You can also leave it empty, our LSP will autodetect it.

    • Set Env: FPCTARGETCPU to your CPU, like x86_64.


      Use processor names that match FPC and CGE. You can see valid CPU names:

      • In CGE editor menu "Run → Platform (To Compile And Run) → …​".

      • If you execute on the command-line build tool as castle-engine --help. Look for possible arguments for the --cpu option.

      You can also leave it empty, our LSP will autodetect it.

    • Set Env: LAZARUSDIR to your Lazarus (source) directory. This is optional, fill it if you have Lazarus installed. It will enable to find LCL units and do the code completion for LCL components too.

    • Set Env: PP to your FPC executable. If you use FPC bundled with CGE, this should look like <cgepath>/tools/contrib/fpc/bin/fpc-cge. Add .exe extension on Windows. If you use regular FPC, this is a path to your regular FPC executable (fpc, fpc.exe,

    • Finally, set Executable to point to our LSP server, inside CGE bin subdirectory. This should look like <cgepath>/bin/pasls. Add .exe extension on Windows.

  1. Enjoy!

    • Open any Castle Game Engine project.

    • You can open it from Castle Game Engine editor (e.g. by "Code → Open Project in Code Editor" menu item).

    • Or you can open it from VS Code, using "File → Open Folder".

    • Place your cursor somewhere, hit Ctrl + Space and enjoy a proper code completion.

      VS Code Extension configuration
    • Right click on any Pascal item and use "Go To Definition", "Go To Declaration" or just Ctrl + click on it to move around. You can also peek at definition and declaration using "Peek → …​".

There are more VS Code extension settings, but most of them are not handled (and not necessary) for our LSP server, they are only handled by the alternative Ryan Joseph's Pascal LSP server.

If you have installed FPC yourself using fpcupdeluxe on Unix, remember to point Env: PP to the script (and not to the fpc binary) that should always be used to execute FPC managed by fpcupdeluxe on Unix.

In general, the Env: PP executable may be run by CodeTools, which may assume this FPC version "knows" standard RTL paths. That’s why it’s important to pass (in case of fpcupdeluxe) or fpc-cge (in case of FPC bundled with CGE) and not the "bare" fpc executable.

5. Running and debugging

It is easiest to just run from Castle Game Engine editor using F9 ("Run → Compile And Run").

If you really want to run and debug from VS Code:

  • CGE applications compiled in debug mode contain debug symbols compatible with GDB. Any debugger extension in VS Code based on GDB should work.

  • To build and run CGE applications without leaving VS Code, you can utilize our command-line build tool.

    • Set CASTLE_ENGINE_PATH environment variable to point to your CGE directory.

    • Extend the PATH environment variable to contain the bin subdirectory of your CGE directory.

    • Make sure that FPC is also on PATH, so that our build tool can find it.

    • Remember to restart all applications (like VS Code) that need to be aware of new environment variables' values.

    • Configure the VS Code tasks to build using castle-engine compile --mode=debug and run using castle-engine run.

6. More Information and Credits

7. Other text editors

The LSP server is fully useful with any text editor that supports LSP, not only VS Code.

7.1. Emacs

The short version is:

  • Install lsp-pascal, lsp-mode, company Emacs packages,

  • Configure it like this in your ~/.emacs:

    (require 'lsp-pascal)
    ;; choose LSP server binary
    (setq lsp-pascal-command "/home/michalis/sources/castle-engine/castle-engine/bin/pasls")
    ;; pass basic info to LSP server, all LSP Pascal servers above support these:
    (setq lsp-pascal-fpcdir "/home/michalis/cge/tools/contrib/fpc/src")
    (setq lsp-pascal-lazarusdir "/home/michalis/lazarus")
    (setq lsp-pascal-pp "/home/michalis/cge/tools/contrib/fpc/bin/fpc-cge")
    (setq lsp-pascal-fpctarget "linux")
    (setq lsp-pascal-fpctargetcpu "x86_64")

7.2. NeoVim

The LSP server can be used with NeoVim. See the client/nvim subdirectory of Philip Zander's repository.

8. Plans, TODOs

  • The big plan is to bundle CGE with VS Code at some point in 2023. If you just install (unpack) CGE you should have a ready setup with CGE + VS Code, and VS Code should automatically have Pascal syntax highlighting and code completion.

    Of course we will still make everything such that you don’t have to use this "bundled" VS Code and instead can use your existing VS Code installation, or really any other text editor / IDE, like Lazarus, Emacs, NeoVim etc.

  • The LSP server should require less (or even zero) configuration. All the parameters required now by LSP configuration are things that CGE editor knows, after all.

  • Can we have "Code Completion" (that happens in Lazarus when you Ctrl + Shift + C) that can automatically insert e.g. method declarations or complete property declarations?

  • Have a recommended and perfectly working approach to running and debugging. If you open a directory with CGE project (CastleEngineManifest.xml) then running and debugging it in VS Code should be just a keystroke (like F9) away. We should use CGE build tool with all parameters that CGE editor already knows.

    There is DAP (Debug Adapter Protocol) with similar goals as LSP, but for debuggers. Maybe someone will wrap Lazarus debugger (GDB with Pascal specific interpretations) in DAP?

To improve this documentation just edit the source of this page in AsciiDoctor (simple wiki-like syntax) and create a pull request to Castle Game Engine WWW (cge-www) repository.