A Macintosh application that supports RenderMan, MacRenderMan is a rendering language developed by Pixar. RenderMan is a language, as well as the name of products sold by Pixar that support that language.
While capable of generating high-quality renderings, MacRenderMan is a surprisingly difficult product to use. It acts like a print driver, requiring that you select and control the renderer using the Chooser, which makes it difficult to set up and run. And at the time it was released it did not run well in 8 megabytes, the most common memory size.
RenderMan is a rendering language much like PostScript is a page description language. The scenes and models must first be written to the RenderMan file format RIB (RenderMan Interface Bytestream). These files are then turned into photographic quality images by the MacRenderMan renderer. Users can also write their own custom shaders. But because RenderMan is a complicated language to learn, and because few third-party applications were adapted to use RenderMan, few users were able to make use of the full power of the product.
Pixar released two end-user products, Typestry and ShowPlace, but these are fairly limited tools. Certainly, neither application could be used to create the kind of animation that Pixar creates for its clients and movies. It’s surprising that a company as well known for animation and rendering quality never released a powerful animation tool. Pixar no longer officially supports any of its Macintosh products.
Some third-party 3D tools, including Silicon Beach's Super 3D and Macromedia's Macromind Three-D did support MacRenderMan as an optional renderer. As an option, they had their own rendering engine, but also supported MacRenderMan.