Hi Tom, Since the poppler PDF library made some big strides GNU-PDF has been pretty dead (despite the occasional objection of some devs).
Perhaps you can accomplish what you want using a CAD program like Free-CAD (http://www.freecadweb.org). I also have some VRML tools which I had built to help create pretty models of electronic components; you can abuse some of the tools to create other things of course. In fact there's a 'wire' tool which allows you to specify a path and a polygon to sweep along the path. The only problem I see with the wire tool (and I'm too lazy to fix it) is that the polygon is not rotated to compensate for torsion along the path - this doesn't matter for a circle since no one will notice, but if you coiled a triangular or rectangular wire it looks ugly. You can get the tools (and see an example of the wire tool) from http://kicad3dmodels.sourceforge.net - Cirilo On Thu, Jul 18, 2013 at 9:11 PM, Thomas Veatch <[email protected]> wrote: > Hi, > > I'm Tom Veatch, unemployed furniture maker, plumber, software developer, > contemplating working on a program to build graphical scenes out of > abstract descriptions thereof and converting them to a visible/printable > output form such as PDF. I spent the last day learning about PDF and this > last two hours reading everything at gnupdf.org. It seems the project is > inactive for a couple of years since the Contact pages' developers' links > are broken as is the flyspray link with a lot of debug noise on it. I can > understand that the project could be perhaps depressingly ambitious since > PDF 1.7 is so enormous itself. I wanted to do two things in this email, > one to encourage the developers, and two to offer a simple user story which > might be an attractive development target or test case. > > So congratulations on working on this project; I do think it will help the > world. Not only is PDF everywhere but its capabilities are expanding > greatly, and a PDF viewer could function as a multimedia display system, a > powerpoint display, a lecture presentation form, an internet UI, many > things that it isn't presently much doing, but that PDF 1.7 includes the > possibilities for. I am rooting for you! > > The user story I have is like this. Consider creating a 3D wire frame > model of something, then making a PDF view of it. So I'd like to build a > software model of an object, say something rather like a PDF path object in > a 3D object coordinate space, being a set of 1 or more subpaths, each > subpath being a sequence of one or more straight-line or cubic-bezier curve > segments. It could constitude a mesh-like model of the outlines of some > physical object, for example. Then I'd like to place that object within a > world coordinate system at some location. Then I'd like to establish a > camera coordinate system with location and orientation thereof, and with > some window in its view, and finally I'd like to transform the object path > segments from object coordinates into their positions in the camera > coordinate system, then determine if they are clipped out or in to the > viewing window, and then draw them in 2D PDF graphics. Fiinally, prepend > and append the PDF header, xref table, etc.,etc., thereby generating an > actual PDF file representing a displayable view of my object. I wasn't > really thinking about sketchup PDF writing, but you could think of it that > way if you wanted to. > > So shouldn't that be a nice simple example, a tutorial even, for using > GNUpdf library code to generate PDF files from the object description? I > thought so. > > But I didn't find graphics commands in the GNUpdf library functions, nor a > tutorial of what a GNUpdf program might look like and how it would go about > creating a path ("0 0 100 100 re" in a PDF file, how would that be > generated by GNUpdf library functions? On the other hand it seems to me > that that would be a nice baseline simple case of how to use such a library > to do stuff people might be interested in. So I thought I'd offer it to > you as a thought experiment. > > If you have suggestions or ideas for me please let me know. > > Meanwhile I think I'm going to be writing code that generates PDF myself, > just for this project of mine. It doesn't have to do everything, but I > hope it will do something! > > Again I am glad you folks are there and I wish you all success in this > project. > > Regards, > > Tom Veatch > PS Check out http://tomveatch.com/pffs which might be inspiring on the > point of how to get projects paid for... > >
