Re: forming continuous "trail" with Locator
- To: mathgroup at smc.vnet.net
- Subject: [mg79919] Re: forming continuous "trail" with Locator
- From: markholtuk at googlemail.com
- Date: Thu, 9 Aug 2007 05:09:34 -0400 (EDT)
- References: <f96jsd$qh3$1@smc.vnet.net><f990nd$c0s$1@smc.vnet.net>
Aah, I see. Thanks Mariusz. So what I should have done is more like this then?: list = {}; Manipulate[AppendTo[list, pnt]; FinishDynamic[]; LocatorPane[Dynamic[pnt], Graphics[{{Gray, Disk[{32, 32}, 32]}, Dynamic[{Hue[0], Point /@ (DeleteCases[list, Null])}]}]], {pnt}] Mark On Aug 8, 10:14 am, Mariusz Jankowski <mjankow... at usm.maine.edu> wrote: > Mark, you made the first argument of Manipulate a list, the three > elements are AppendTo, LocatorPane, and FinishDynamic. You suppressed > the output of the first and the output of the third is Null - which is > exactly what you see in the Manipulate panel. > > Bye, Mariusz > > markhol... at googlemail.com wrote: > > Hi Murray, > > Does this do what you want?: > > > list = {}; > > Manipulate[{AppendTo[list, pnt]; > > LocatorPane[ > > Dynamic[pnt], {Graphics[{{Gray, Disk[{32, 32}, 32]}, > > Dynamic[{Hue[0], Point /@ DeleteCases[list, Null]}]}]}], > > FinishDynamic[]}, {pnt}] > > > - sorry about the Null next to the graphic - not sure why it's there! > > > To plot the trace afterwards: > > > ListPlot[DeleteCases[list, Null], Joined -> True, PlotRange -> All, > > AspectRatio -> Automatic] > > > On Aug 6, 8:50 am, Murray Eisenberg <mur... at math.umass.edu> wrote: > >> Is there some way in Mathematica 6 to use a Locator so as to create a > >> continuous-appearing "trail" after you click and then drag the cursor > >> around? > > >> Of course one could write code allowing addition of points through > >> successive clicks, and then one could try to click repeatedly on > >> successive points very near one another, but that could get very tedious. > > >> I mean the sort of thing one gets in drawing programs (and with the > >> Mathematica 6 2D Drawing Tools). > > >> -- > >> Murray Eisenberg mur... at math.umass.edu > >> Mathematics & Statistics Dept. > >> Lederle Graduate Research Tower phone 413 549-1020 (H) > >> University of Massachusetts 413 545-2859 (W) > >> 710 North Pleasant Street fax 413 545-1801 > >> Amherst, MA 01003-9305 > > > Best wishes, > > > Mark > > ___________________ > > Mark R. Holt, BA, PhD > > Cardiovascular Division and > > Randall Division of Cell and Molecular Biophysics > > New Hunt's House > > King's College London > > Guy's Hospital Campus > > LONDON, U.K., SE1 1UL > > Phone: +44 20 7848 6438 > > Fax: +44 20 7848 6435