Rick.Busdiecker@H.CS.CMU.EDU (07/17/87)
... what do people generally use for circles in X? On the Xerox Altos, the Draw program made a nice circle using a closed spline with 8 control points. Using X, I have to use a lot more than 8 for it to really look like a circle and even then, it's a pretty ugly circle; I think using lines segments looks nicer than XDraw splines. What type of splines does XDraw use for VertexCurved vertices? Rick p.s. I wonder how mail dozens of mail bounces I'll get on thiscertend tu
RWS@ZERMATT.LCS.MIT.EDU (Robert Scheifler) (07/17/87)
The X11 protocol supports elliptical arcs. It does not support splines; these are left to either an extension or a client-side utility (the latter is currently the case).
mueller@utah-gr.UUCP (Tim Mueller) (07/17/87)
The X 10 manual says is uses "a spline algorithm ... to draw a smooth curve from the previous vertex, through this one, to the next vertex". This is ambiguous and I haven't tried it, but whatever it does it definitely does not do rational splines since there are only two coordinates per vertex. This means that you can't do circles exactly and is the reason you need lots of points to make your curve look like a circle (it's really lots of little parabolas). Tim Mueller University of Utah mueller@cs.utah.edu