Command line access

Both Flax Engine and built game (Flax executable) support various input command line arguments. Using this feature can help with games development and can be involved in testing various scenarios.

It’s very common technique to build games on the separate machines or even in the cloud. For example, Jenkins server can be used to invoke Flax Game Cooker to build game for a QA team so it will be ready right in the morning to test it.

Here is an example command that will build the game project in the Output folder for the Windows platform:

FlaxEditor.exe -project "<project-path>" -headless -mute -null -std -build "Development.Windows 64bit"

To run Flax via Windows Command Prompt (cmd.exe) with logs use start /w ... as follows:

start /w FlaxEditor.exe -std -project "<project-path>"

To run Flax via Windows PowerShell with logs use Start-Process -Wait ... as follows:

Start-Process -Wait FlaxEditor.exe -Args "-std -project `"<project-path>`""

It will also send the log (including C# API Debug.Log) to the standard process output so in case of issues they can be easily detected. What is, even more, the editor may start without a window (headless mode) and perform some additional actions like clearing cooker cache or project cache. Of course, all those things can be made manually by using Flax Editor C# API and Editor Plugins (see here).

Options

Command	Description
-windowed	Starts the game in windowed mode (even if default built game setting was fullscreen).
-fullscreen	Starts the game in fullscreen mode (even if default built game setting was windowed).
-vsync	Forces to enable vertical synchronization when presenting the frame on screen.
-novsync	Forces to disable vertical synchronization when presenting the frame on screen.
-nolog	Disables output log file.
-std	Redirects log to the standard process output (std).
-debug ip:port	Sets the Mono debugger address and port (or just port) used for the remote debugging. The default Mono debugger IP=127.0.0.1, Port=41000+(process_id%1000). Can be just port number to use localhost.
-debugwait	Instructs Mono debugger to wait for client attach for 5 seconds. Can be used to debug initialization code when a standalone game starts.
-headless	Starts without windows, used by CL. Can be also used in cooked game on desktop platforms.
-lowdpi	Disables High DPI awareness support.
-vulkan	Forces to use Vulkan rendering backend (if available).
-d3d12	Forces to use DirectX 12 rendering backend (if available).
-d3d11	Forces to use DirectX 11 rendering backend (if available).
-d3d10	Forces to use DirectX 10 rendering backend (if available).
-null	Forces to use Null rendering backend. Graphics rendering will be disabled but other game systems will work normally. Highly recommended to use for headless server builds for multiplayer games.
-nvidia	Hints to use NVIDIA GPU (if available).
-amd	Hints to use AMD GPU (if available).
-intel	Hints to use Intel GPU (if available).
-monolog	Enables advanced debugging for Mono runtime. Can be used to debug problems with managed scripting runtime. Produces lots of logs.
-mute	Disables audio playback and uses Null Audio Backend.

Editor-only options

Command	Description
-project	Startup project path. It must be specified to start the editor.
-new	Generates the project files inside the specified project folder or uses current workspace folder.
-play	Starts the play-mode in Editor after startup. Can open a certain level if provided with asset id (eg. -play SCENE_ASSET_ID).
-genProjectFiles	Generates the scripts project files and exits.
-skipcompile	Skips the scripts compilation on editor startup, useful when launching engine from IDE.
-shaderdebug	Enables debugging data generation for shaders and disables shader compiler optimizations.
-shaderprofile	Enables debugging data generation for shaders but leaves shader compiler optimizations active for performance profiling.
-clearCache	Clears the project cache before starting the editor.
-clearCooker	Clears the project Game Cooker cache before starting the editor.
-build preset.target	Starts the game building after editor launch and closes editor after building end. You can specify the single present name to build all its targets or specify both the present name and target name (separated by a dot). You can use braces if your preset/target name contains space characters.