X-Received: by 10.70.128.78 with SMTP id nm14mr14850492pdb.8.1437757885233; Fri, 24 Jul 2015 10:11:25 -0700 (PDT) X-Received: by 10.182.138.9 with SMTP id qm9mr189677obb.34.1437757885169; Fri, 24 Jul 2015 10:11:25 -0700 (PDT) Path: csiph.com!optima2.xanadu-bbs.net!xanadu-bbs.net!usenet.blueworldhosting.com!feeder01.blueworldhosting.com!border2.nntp.dca1.giganews.com!nntp.giganews.com!pg9no3680868igb.0!news-out.google.com!a16ni27361ign.0!nntp.google.com!pg9no3680867igb.0!postnews.google.com!glegroupsg2000goo.googlegroups.com!not-for-mail Newsgroups: comp.graphics.apps.gnuplot Date: Fri, 24 Jul 2015 10:11:24 -0700 (PDT) In-Reply-To: Complaints-To: groups-abuse@google.com Injection-Info: glegroupsg2000goo.googlegroups.com; posting-host=148.202.75.4; posting-account=1vqSWgoAAABiG3xDGniOaMUa6N_-mQAE NNTP-Posting-Host: 148.202.75.4 References: <5cea66c0-f6e0-44d6-8f31-30b8de0c62b9@googlegroups.com> <62fd5eb6-784e-446b-a59e-6c7a60ee7f11@googlegroups.com> User-Agent: G2/1.0 MIME-Version: 1.0 Message-ID: <74660779-d4e9-46d0-b58b-07d288ed257b@googlegroups.com> Subject: Re: 3D mesh plotting with a fourth column of data for colouring pm3d From: Javiere Injection-Date: Fri, 24 Jul 2015 17:11:25 +0000 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Lines: 71 Xref: csiph.com comp.graphics.apps.gnuplot:2998 On Wednesday, July 22, 2015 at 1:55:40 PM UTC-5, Ethan A Merritt wrote: > javierevergarab@gmail.com wrote: >=20 > > On Wednesday, July 22, 2015 at 12:41:46 PM UTC-5, Javiere wrote: > >> Dear all. > >>=20 > >> My 3d mesh plotting is currently being colored using gnuplot pm3d. > >> However the pm3d colours should be related to a variable different fro= m > >> the z value. > >>=20 > >> It is indicated that (in addition to x,y,z) a fourth column of data > >> should be used for gnuplot to read RGB color information > >> (http://www.gnuplotting.org/manpage-gnuplot-4-6/#Q1-1-536). > >>=20 > >>=20 > >> Can anybody can let me know how to relate number values with colours? > >=20 > > It clear to me the command required to do the plotting: > > splot ... using 1:2:3:4 with pm3d lc rgb variable. > >=20 > > I do not know how to relate the 4th column values with RGB colours. >=20 > The 4th column in that case is interpreted as a 24-bit integer > with containing 8-bit color components (integers 0-255) > I.e.=20 >=20 > foo =3D (Red << 16) + (Green << 8) + (Blue) >=20 > Gnuplot can read hexadecimal numbers, so one possible format for > the 4th column is >=20 > 0xffffff # white > 0xff0000 # pure red > 0x7f007f # half intensity magenta >=20 > and so on. >=20 > >> I only recently started using gnuplot and am further constrained by th= e > >> fact that gnuplot site is temporarily offline > >> (http://gnuplot.sourceforge.net/demo/). >=20 > Older copy of relevant demo: >=20 > http://skuld.bmsc.washington.edu/~merritt/gnuplot/demo_canvas/heatmaps.= html >=20 > Ethan Ethan. I appreciate your help. I have been trying different options and managed to include 3d mesh colorin= g using a fourth columns including number values using. I am using commands= of the form "splot "data.txt" using 1:2:3:6 with lines lt 27" However I did not find hexadecimal colour representation useful to plot the= fading and blending effect of colours of a given palette as can be seen in= the demos you sent me. In fact, these graphs use formulas to produce numbe= rs to be translated into corresponding colours of the given palette. Therefore I decided to work with a fourth column containing number values != ? Worringly, if I try to include a black spot at a particular position on the= surface (which i need to do for signaling purposes), the whole surface acq= uires a colour that corresponds to an extreme of the palette in effect. I a= ssume this is not supported by gnuplot. Javiere