On 2013-11-17 10:58-0800 Alan W. Irwin wrote: > So the above tells you how to get alpha transparency information from > the Plplot library (the easy part), and also how to supply that > information appropriate to the format supplied by the device (easy > here, but in general more difficult than the first part). For > example, according to > http://en.wikipedia.org/wiki/Transparency_(graphic)#Transparency_in_PostScript > PostScript version 3 is the first version of that standard to supply > full alpha support.
Actually, I misread that information. There is no semitransparent colour support in basic PostScript itself. Instead, you must use the pdfmark extension. And reading further in pdfmark documentation, it looks like it is completely straightforward to specify a semi-transparent colour with one pdfmark operation. The impression I get from further reading is most PostScript viewers (such as the common gv PostScript viewer for Linux) support the pdfmark extension. So it appears likely that semitransparent alpha channel support for our ps device driver would be straightforward to implement and use. Of course, I have way too much already on my PLplot ToDo list so I am going to ignore this possibility myself, but if anybody else here is keen to implement alpha channel support for the ps device driver using a pdfmark command, please give it a go. Alan __________________________ Alan W. Irwin Astronomical research affiliation with Department of Physics and Astronomy, University of Victoria (astrowww.phys.uvic.ca). Programming affiliations with the FreeEOS equation-of-state implementation for stellar interiors (freeeos.sf.net); the Time Ephemerides project (timeephem.sf.net); PLplot scientific plotting software package (plplot.sf.net); the libLASi project (unifont.org/lasi); the Loads of Linux Links project (loll.sf.net); and the Linux Brochure Project (lbproject.sf.net). __________________________ Linux-powered Science __________________________ ------------------------------------------------------------------------------ DreamFactory - Open Source REST & JSON Services for HTML5 & Native Apps OAuth, Users, Roles, SQL, NoSQL, BLOB Storage and External API Access Free app hosting. Or install the open source package on any LAMP server. Sign up and see examples for AngularJS, jQuery, Sencha Touch and Native! http://pubads.g.doubleclick.net/gampad/clk?id=63469471&iu=/4140/ostg.clktrk _______________________________________________ Plplot-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/plplot-devel
