Important notes:
First:
Expert-Modus on!
In order to change the settings of the shader, open file "ogse_config.h" inside the folder "gamedate/shaders/r2" with your text editor.
By editing this file you can have massive influence to the graphics of the game - you can alter it carefully to fit your PC-System best.
To get rid of some options just place "//" in front of the specific #define.
To turn on some options just delete the "//" in front of the specific #define.
For fine adjustment, just edit the specific value.
Save. Done.
If you do not feel comfortable by editing the file - just ignore it.