>From the user's perspective, I think simplest would be if "line" took a "fill" attribute subject to the constraint that the line ends where it begins, something pic can enforce. In that case, it would draw a solid polygon instead of a sequence of lines.
I once looked into the code to see if that would work. Unfortunately, in pic each segment (identified by "to") is independent, The most obvious fix would be to introduce a new kind of object, "polygon", with line-like syntax, but a new (variable-length) data structure, and an alternate way to record "to" phrases. In short, it was not as easy as I had imagined, and I was too lazy to follow up on the idea. Folks may be amused by how I actually fill polygons in pic. I break them up into boxes and right triangles. Each triangle is described as a filled box that spans the triangle's three corners. Then the PostScript is edited to delete the extra corner. Doug
