Re: Lost Line Directives in 3D Graphics
- To: mathgroup at smc.vnet.net
- Subject: [mg30169] Re: Lost Line Directives in 3D Graphics
- From: Tom Burton <tburton at cts.com>
- Date: Wed, 1 Aug 2001 02:19:24 -0400 (EDT)
- References: <9k2d95$2ds$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Hello, On Mon, 30 Jul 2001 01:29:09 +0000 (UTC), in comp.soft-sys.math.mathematica you wrote: >Dear MathGroup, > >Here is a case where it appears that Mathematica incorrectly renders the >postscript code for Graphics3D. I wonder if other people obtain the same >effect that I obtain. ... >The plot consists of a long thin black line, and a shorter thick red line on >top of it, with a three polygon cone at the end, but slightly detached from >the short line. The line directives for the short line are lost, so that it >also appears thin and black. ... I tried this with version 4.1.0 for Windows (11/2/2000) on Windows NT 4 service pack 6. I may be seeing the same thing you do, but I interpret it differently. The short line is not different in some frames; rather, it is entirely suppressed. When two lines coincide in a 3D graphic, the choice of which to display is undefined and therefore, I assume here, subject to the vagaries of numerical round-off accidents. So when I see that, sometimes the thick line is suppressed by the thin line and sometimes not, I am not surprised. As far as the presence or absense of the polygon is concerned, once I get into the realm of round-off accidents, all bets are off. I suggest that either you shorten the shorten the thin black line to keep it away from the thik red line. Tom Burton