FX Composer empowers developers to create high performance shaders in an integrated development environment with unique real-time preview & optimization features. FX Composer was designed with the goal of making shader development and optimization easier for programmers while providing an intuitive GUI for artists customizing shaders for a particular scene. FX Composer comes with dozens of sample projects, performance tutorials, and more than 120 sample shaders. It supports all the standard features you would expect in an integrated development environment for high performance shaders:

NVIDIA: FX Composer 1.0