RE: convert graphics

*To*: mathgroup at smc.vnet.net*Subject*: [mg30630] RE: [mg30602] convert graphics*From*: "David Park" <djmp at earthlink.net>*Date*: Fri, 31 Aug 2001 19:58:06 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

Borut, What you want is the Graphics3D directive EdgeForm. EdgeForm[] suppresses the drawing of the polygon edge lines in an object. The problem is how to sneak that directive into the plotting statement. I will do some examples with a parametrization of a sphere. If you look up ParametricPlot3D in Help, you will see that there is a third form where "color specifications" can be added as a fourth item in the parametrization. This is misleading. You can, in fact, put any Graphics3D directives there, or a list of them. WRI should really change that particular Help message. So, the following will plot the sphere without the polygon edges. ParametricPlot3D[{Cos[t]Cos[s], Sin[t]Cos[s], Sin[s], EdgeForm[]}, {s, -Pi/2, Pi/2}, {t, 0, 2 Pi}]; Still, this is to my mind a somewhat awkward method of doing it, and is a result of Mathematica's inside out graphics paradigm. Suppose that you have already written a parametrization for your surface. sphere[s_, t_] := {Cos[t]Cos[s], Sin[t]Cos[s], Sin[s]}; Then, to sneak in the plotting directives you have to write a second parametrization: sphere2[s_, t_] := Join[sphere[s, t], {EdgeForm[]}] ParametricPlot3D[Evaluate[sphere2[s, t]], {s, -Pi/2, Pi/2}, {t, 0, 2 Pi}]; The natural way would be to specify graphics directives first and then plot the items that use the directives. This can be done with the Show statement, but is also awkward. Show[Graphics3D[{EdgeForm[], First[ParametricPlot3D[ Evaluate[sphere[s, t]], {s, -Pi/2, Pi/2}, {t, 0, 2 Pi}, DisplayFunction -> Identity]]}]]; My DrawingCube package provides a more direct method for doing this. Needs["Graphics`DrawingCube`"] Needs["Graphics`ParametricDrawing3D`"] Show[Graphics3D[ {EdgeForm[], ParametricDraw3D[ Evaluate[sphere[s, t]], {s, -Pi/2, Pi/2}, {t, 0, 2 Pi}]}]]; Finally, there is a very nice package done by Allan Hayes and Hartmuth Wolf called Smooth3D. Allan posted it on MathGroup a few months ago. It allows a surface to be plotted with a fine "mesh" so that it will be smooth, but with much more widely spaced coordinate lines, so that they don't dominate the surface. Quite often that is the reason people want to eliminate the edges. David Park djmp at earthlink.net http://home.earthlink.net/~djmp/ > From: Borut L [mailto:borut at email.si] To: mathgroup at smc.vnet.net > > Hi, > > > I have a ParametricPlot3D object (Graphic3D object), which I would like to > have no mesh-lines. The option for Sufrace Graphics (Mesh -> > False) is what > I would like. But I can't convert the first to the later. Is > there a way to > convert it or is there alternative to disable mesh in Graphics3D object? > > > Thank you, > > Borut Levart > > >