Graphics Directives Lost In Certain Cases

*To*: mathgroup at smc.vnet.net*Subject*: [mg25622] Graphics Directives Lost In Certain Cases*From*: "David Park" <djmp at earthlink.net>*Date*: Mon, 16 Oct 2000 03:04:43 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

Dear MathGroup, I have come across a strange behavior of 3D graphics where graphics directives are lost in certain cases. It has to do with a 3D arrow routine I am working on, but here is the bare bones essence of the problem. The following plot gives a second thick blue line plotted on top half of the first thin black line. Show[Graphics3D[ {{Line[{{0, 0, 0}, {10, 10, 10}}]}, RGBColor[0, 0, 1], AbsoluteThickness[2], {Line[{{0, 0, 0}, {10, 10, 10}/2}]}}], AspectRatio -> Automatic, PlotRange -> All]; If I combine the second line with this polygon, the color and thickness directives are lost. Why? Show[Graphics3D[{{Line[{{0, 0, 0}, {10, 10, 10}}]}, RGBColor[0, 0, 1], AbsoluteThickness[2], {Line[{{0, 0, 0}, {10, 10, 10}/2}], {Polygon[{{5., 5., 5.}, {4., 4.306186217847897, 3.6938137821521027}, {3.6938137821521027, 4., 4.306186217847897}}]}}}], AspectRatio -> Automatic, PlotRange -> All]; But the directives are not lost if the second line is not right on top of the first line. Show[Graphics3D[{{Line[{{0, 0, 0}, {10, 10, 10}}]}, RGBColor[0, 0, 1], AbsoluteThickness[2], {Line[{{0, 0, 0}, {10, 10, 10.000001}/2}], {Polygon[{{5., 5., 5.}, {4., 4.306186217847897, 3.6938137821521027}, {3.6938137821521027, 4., 4.306186217847897}}]}}}], AspectRatio -> Automatic, PlotRange -> All]; Nor are the directives lost if a different polygon is used. Show[Graphics3D[{{Line[{{0, 0, 0}, {10, 10, 10}}]}, RGBColor[0, 0, 1], AbsoluteThickness[2], {Line[{{0, 0, 0}, {10, 10, 10}/2}], {Polygon[{{5., 5., 5.}, {4., 4.306186217847897, 3.6938137821521027}, {4., 3.6938137821521027, 4.306186217847897}}]}}}], AspectRatio -> Automatic, PlotRange -> All]; Needless to say, most of the time I lose the directives. Does anyone know the cause of this? David Park djmp at earthlink.net http://home.earthlink.net/~djmp/