Re: Bug associated with Graphics3D???

*To*: mathgroup at smc.vnet.net*Subject*: [mg105237] Re: [mg105210] Bug associated with Graphics3D???*From*: Syd Geraghty <sydgeraghty at me.com>*Date*: Wed, 25 Nov 2009 02:32:57 -0500 (EST)*References*: <200911241050.FAA00829@smc.vnet.net>

Wow Lou, That was a very interesting artifact of Show[]. The key is to be found in the Possible Issues documentation for Show[]. Show uses the options from the first graphic: So you first have to reverse the order of the shown functions!!!! Show[Pla[x], Bloid], x] ...... that fixes the 5.1 issue !! Do[Print[Show[Pla[x], Bloid], x], {x, 5.05, 5.15, 0.025}]; works fine! Cheers .... Syd Syd Geraghty B.Sc, M.Sc. sydgeraghty at mac.com Mathematica 7.0.1.0 for Mac OS X x86 (64 - bit) (12th September 2009) MacOS X V 10.6.1 Snow Leopard MacBook Pro 2.33 GHz Intel Core 2 Duo 2GB RAM On Nov 24, 2009, at 5:50 AM, Louis Talman wrote: > Can anyone explain why the disk that corresponds to x = 5.1 (see the > last line of the code below) isn't red---like the others? > > ------------------------- > > Rho[Psi_] = 2/(1 - Cos[Psi]); > > Para = ParametricPlot3D[ > Rho[Psi] {Cos[Psi], Sin[Psi] Cos[Theta], Sin[Psi] Sin[Theta]}, > {Psi, Pi/3, Pi}, {Theta, 0, 2 Pi}, > PlotStyle -> {Specularity[0.9], Opacity[0.3]}, Mesh -> None, > Axes -> None, PlotRange -> {{-1.3, 6.7}, {-3.5, 3.5}, {-3.5, > 3.5}}]; > > Focus = Graphics3D[{PointSize[0.015], Point[{0, 0, 0}]}]; > > Bloid = Show[Para, Focus]; > > Pla[x_] := ParametricPlot3D[ > x Sec[Psi] { Cos[Psi], Sin[Psi] Cos[Theta], Sin[Psi] Sin[Theta]}, > {Theta, 0, 2 Pi}, {Psi, 0, ArcTan[(2 Sqrt[3])/x]}, Mesh -> None, > Axes -> None, PlotStyle -> {Red, Opacity[0.6]}]; > > Do[Print[Show[Bloid, Pla[x]]], {x, 4.8, 5.4, 0.1}]; > > --------------------------- > > It also happens when x = 3.5, but for no other values of x generated > by {x, 3.0, 6.5, 0.1}. > > > --Lou Talman > Department of Mathematical and Computer Sciences > Metropolitan State College of Denver > > <http://clem.mscd.edu/%7Etalmanl> > > >

**References**:**Bug associated with Graphics3D???***From:*Louis Talman <talmanl@gmail.com>