Re: Problem/bug with ends of thick lines in graphics

*To*: mathgroup at smc.vnet.net*Subject*: [mg88472] Re: Problem/bug with ends of thick lines in graphics*From*: David Reiss <dbreiss at gmail.com>*Date*: Tue, 6 May 2008 06:40:40 -0400 (EDT)*References*: <fvhe27$3t8$1@smc.vnet.net> <fvmmuc$8gt$1@smc.vnet.net>

Good try Jens! Alas it creates a series of points that create a jagged outer boundary where the disks of the points undulate. But an approach like this may work for the end points. I have communicated with the folks at WRI about this and the bug is known. --David On May 5, 6:18 am, Jens-Peer Kuska <ku... at informatik.uni-leipzig.de> wrote: > Hi, > > Plot[x, {x, 1/3, 3/4}, PlotRange -> {{0, 1}, {0, 1}}, > PlotStyle -> {AbsoluteThickness[20]}] /. > Line[pnts_] :> {AbsolutePointSize[20], Point[pnts]} > > may help in this case. But AFAIK Mathematica has no directive > to set the line ends. > > Regards > Jens > > David Reiss wrote: > > In a quick search of things I haven't found a mention of the following > > simple graphics issue and I'm checking in with the group to see if > > there is a memory of its mention and if there is a simple fix (and > > which is not a complicated hack) that I've not been able to come up > > with. > > > Consider the following graph: > > > Plot[x, {x, 1/3, 3/4}, PlotRange -> {{0, 1}, {0, 1}}, > > PlotStyle -> {AbsoluteThickness[20]}] > > > When you plot it you will see that the line's ends are not > > rectangular, whereas you would certainly want them to be so. (An > > alternative would be to have them be rounded, for example, but the > > question will remain the same whatever your preference is.) Rather > > they appear as polygonal in a way inconsistent with the line itself. > > > One assums that this is an artifact of how the line is rendered based > > on the individual line segments, and that that segmental rendering has > > to do something with how a segment relates to the segments on either > > side of it. The lack of a segment beyond the end segment presumably > > runes the algorithm for rendering in a way that leads to this > > appearance. > > > I have two related questions here. The first is how, if at all > > possible, to fix this in a general way through some specific options > > settings for the graphics function. > > > The second is how, when exporting this graphic as, say, a PDF, to make > > it behave properly. > > > There was a trick in pre version-6 Mathematica that would involve > > adding an explicit postscript command to the PlotStyle option. Though= > > this would not (I think) correct the screen appearance of the graphic, > > it would properly fix it when the graphic was exported to PDF or EPS. > > Here is an example of how it was done: > > > Plot[x, {x, 1/3, 3/4}, PlotRange -> {{0, 1}, {0, 1}}, > > PlotStyle -> {{ PostScript["0 setlinecap"],AbsoluteThickness[20]}}] > > > This, however, no longer works in Mathematica 6+ presumably because of > > the new way that graphics rendering is handled. > > > Does anyone have any solutions to either or both of these issues? > > > Thanks! > > > --David