STALKER: Clear Sky Tweak Guide

[Page 9] Advanced Tweaking (Pt.3)

Command Line Switches

There are a range of additional commands you can execute when first launching Clear Sky called Command Line Switches. These 'switches' are commands which are passed on to the game's main executable file xrEngine.exe, telling the engine to do certain things as the game launches. To use a command line switch, go to your STALKER: Clear Sky launch icon, right-click on it and select Properties. Then in the Target box, one space after the last character, insert the switch(es) you wish to use, each separated by one blank space. For example:

"C:\Program Files\Deep Silver\S.T.A.L.K.E.R. - Clear Sky\bin\xrEngine.exe" -noprefetch -noshadows

The switches -noprefetch and -noshadows used above prevent prefetching of data and also disable all non-Sun shadows in the game engine. These would otherwise not be possible to do using the in-game settings. You can disable them at any time simply by removing the relevant switch from the launch icon, or creating a second launch icon without the switches and using that to launch the game whenever you don't wish to enable a certain switch.

Click to enlarge

Importantly: Some switches have no discernable impact, or simply cause the game to crash while loading. Furthermore some switches which were present in Shadow of Chernobyl are no longer present in Clear Sky, most notably -nointro and -dsound. Suggested usage instructions for the most useful switches are spread throughout this guide.

The full list of Command Line Switches for Clear Sky is provided below in alphabetical order.





-center_screen - Centers the game window when running in windowed mode.




-demomode [ ]




-file_activity - Records file activity in the console during the game.



-gpu_nopure - Switches the GPU state from Pure Hardware to simply Hardware mode.

-gpu_ref - Switches the GPU state to Reference mode.

-gpu_sw - Switches the GPU state to Software Renderer.




-load [savegame] - Loads specified saved game on startup.

-ltx [filename.ltx] - Loads and executes specified filename.ltx configuration file.

-mblur - Allows the r2_mblur command to function correctly if used.








-nodistort - Removes distortion effects, e.g heat haze around fires and warping near anomalies.


-nolog - Disables logging.


-noprefetch - Disables prefetching. Games load faster, in-game stuttering may increase or drop.

-noshadows - Disables shadows from dynamic light sources (excluding the Sun). May improve FPS.

-nosound - Disables all sound in the game.

-overlay [directory path] - Forces a different directory for saved games/profiles/config file.


-psp - Enables third person view mode, but has bugs.

-r2 - Forces the game to start with Full Dynamic Lighting DX9 Renderer.

-r2a - Forces the game to start with Objects Dynamic Lighting DX9 Renderer.

-r4xx - Forces the game to start with Static Lighting DX8 Renderer.


-sjitter - Enables Shadow Jittering to soften shadow edges.







The above switches set the Shadow Map size, which affects all shadow quality, similar to the in-game Shadows Quality setting. Here you can specify even higher quality shadow map resolutions (i.e. smap2048, smap3072 and smap4096) which improve image quality but reduce FPS.

-ss_tga - Forces all in-game screenshots to be taken in both .JPG and high quality .TGA format.

-start [ ]











Once again, if you have definite knowledge of what a switch does (please, no guesses), and it is something which would be quite useful to most people, then please Email Me with the details and I will update this list accordingly so everyone can benefit.

The next page brings the guide to a conclusion with a range of useful tips.