Spurred by this article, explaining that mental mill has been acquired by NVidia, i came to check out the products by mental images.
For instance, there is mental mill, currently in beta, and thus freely distributed:
“mental mill® enables artists and other professionals to develop, test and maintain shaders and complex shader graphs for hardware and software rendering through an intuitive graphical user interface with real-time visual feedback - without the need for programming skills. Software companies can incorporate parts or all of mental mill in the form of software libraries into their own digital content creation and design products. Shaders are automatically generated in the MetaSL™ language and can be modified easily. mental images designed MetaSL to encompass the expressive power of all current and future shading languages and shading language standards. Complex cooperating shader graphs can be encapsulated into Phenomena.
mental mill supports CgFX, HLSL, and GLSL, as well as C++ for mental ray and RealityServer. Back-end plug-ins for other targets such as special purpose processors and other software renderers can be developed by third parties using the mental mill API. ”
Note that mental images has already technology in NVidias FXComposer 2, a similar application to mental mill, which was recently updated (11/17/2007).