Beyond the act of drawing, the Cocktail Napkin aims to support intelligent design critiquing, retrieval of relevant items from a case library, and simulation. Therefore, the Napkin attempts to recognize and interpret the elements and configurations of drawings. Figure 1 shows the Cocktail Napkin drawing board and its associated sketchbook. Napkin Drawing Board and Sketchbook. We delay recognition of ambiguous glyphs and use context and role in larger configurations to later resolve ambiguity.
End users define recognizers by example.
End users program recognizers for higher-level configurations by drawing examples. The Napkin identifies elements and spatial relations, and constructs a function to recognize instances of the configuration. Users may also provide a picture to replace a recognized configuration of elements, in effect programming a graphical rewrite rule. The Cocktail Napkin provides semi-transparent trace overlays to simulate tracing paper designers use to copy and combine drawings. The Napkin can search the sketchbook for drawings similar to a given query.