Path: csiph.com!fu-berlin.de!uni-berlin.de!news.dfncis.de!not-for-mail From: =?UTF-8?Q?Hans-Bernhard_Br=c3=b6ker?= Newsgroups: comp.graphics.apps.gnuplot Subject: Re: Strange Mobius strip in rendering a cylinder with pm3d Date: Wed, 29 Jun 2016 00:04:33 +0200 Lines: 21 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-Trace: news.dfncis.de rh7vjvynjtjmBOd+xlrtmwcm1nW4SUcZIXbg02oJfFOyvXTcfUsAz68kjk Cancel-Lock: sha1:93gpZvq5UVVIXeNrMgguKUBrq7I= User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.1.1 In-Reply-To: Xref: csiph.com comp.graphics.apps.gnuplot:3358 Am 28.06.2016 um 06:43 schrieb musiphil@bawi.org: > splot "data" using (3*cos($1)):(2*sin($1)):2:3 palette with pm3d notitle > > where "data" is generated by the following program (made up for illustrative purposes): [...] Just FTR, there's not really a need to use a datafile to get that effect: set parametric splot [h=0:1][phi=-pi:pi] cos(phi),sin(phi),h w pm3d And the root cause is quite simple: pm3d doesn't actually respect the screen z coordinate (i.e. front-to-back) by default. It draws the patches of colour in the same order they have in your input. And yes, that drawing order is quite wrong in a large fraction of possible orientations of this particular surface. The solution is to read "help pm3d" and find out about "depthorder".