If you want to manually modify the shader's code, you can do that in the Quick Shader area.
Enable – Makes the Quick Shader's text area active. Once enabled, place the original code inside the text area. Alternatively, start writing in the blank area your own code. If you have already loaded a shader in the texture parameters, right-click on it and select Open in Quick Shader option.
Another way to do this is to activate the text area and drag and drop the .osl file in there. It will load the code instantly.
Right-clicking on the Quick Shader panel opens a context menu. You can Compile the code after doing changes or Compile and Reset Parameters, which affects the values of the parameters in the shader as well.
Once ready with editing, press the Compile button to refresh the UI. Modifications are updated in the UI and renderer after the successful code compilation. You can monitor the messages in the Compiler Output rollout during compilation.
|UI Text Box|
The shader file originally loaded in the material (if any) will not be affected in the compilation. You need to manually save your code.
OSL Include Paths
System Paths – Shows the System Paths defined with the V-Ray Environment variable VRAY_OSL_PATH_3DSMAX####_x64. This path cannot be changed from within 3ds Max, but only from your account's Environment Variables.