US Patent 7123265 Method and apparatus for adding real-time primitives

A method of adding primitives in real time to a model to produce a non-photorealistic rendering (NPR) of a model includes storing attribute data for each one of the primitives. A ring buffer is provided, having at least one stage, for each vertex of the model which is to have a primitive. Within each ring buffer, data is stored representative of a direction of each one of the primitives. Information is retrieved from the ring buffer by using a pointer, wherein the pointer is incremented and iterated over each stage of the ring buffer.