OSL Shaders

 

 

It is possible to create your own shaders using Open Shading Language. OSL shaders can be used to implement anything from simple texture patterns to full materials using closures. They can be placed in the plugin search path, and will then be automatically loaded like other types of shaders. Once loaded, they can be inspected, instantiated and linked in the same way as C++ shaders. The osl node provides an alternate way to load OSL shaders, which can be used to write shader code for a specific material. When setting the shader name or code, the parameters from the OSL shader automatically appear on the node to be set or linked.

A limitation is that only one output parameter is supported at the moment.

Limitations 

  • The shaders must have unique names. If the name conflicts with an existing shader, the OSL shader won't load. You should see a warning in the log in this case.
  • Multiple outputs are not supported at the moment.

More information about using OSL shaders can be found here.

An example .osl shader and .mtd file can be found here.

Installation 

Just like any other third-party shader libraries, OSL shaders placed in the shader search path are automatically registered as Arnold shader nodes. The OSL shader parameters are converted to Arnold parameters. Once loaded, they can be inspected, instantiated and linked in exactly the same way as C++ shaders.


You can render OSL shaders directly in MAXtoA. You must do the following: 

  • Create a folder where the OSL shader will reside. Setup the following Environment Variable (location of the .osl shaders):  

 ARNOLD_PLUGIN_PATH

  • Place the OSL shader (with .mtd metadata file) in the ARNOLD_PLUGIN_PATH folder and they will automatically be available as shader nodes. Arnold will automatically compile the .osl file and produce a dill (.oso) file.

 

OSL in 3ds Max 2019

In 3ds 2019, there is a new way of using OSL. Arnold will take advantage of this automatically. Simply use the OSL maps provided with 3ds max, or use the OSL editor built into the OSL map to write your own, or load up external OSL files. In this mode, the actual OSL sources are embedded into the Arnold scene and exported as text into .ass file, so there will be no dependency of external OSL files when rendering, and the limitations about shaders not having the same name are lifted. You could, in theory, have twenty totally different shaders named ‘Bob’ and it would still work (not that we recommend this).

See the 3ds Max documentation for more information about OSL. There is also a GitHub for OSL shader exchange which also contains developer documentation and more info a:t https://github.com/ADN-DevTech/3dsMax-OSL-Shaders ”

 

 

 

  • No labels