[gl2ps] Re: problem with hidden surfaces

[Denis Roegel]

On Sat, Mar 05, 2005 at 09:48:44AM -0800, Christophe Geuzaine wrote:

> - With GL2PS_BSP_SORT, the issue seems to be that GL2PS actually
> traverses the tree in reverse compared to the ordering in the z-buffer.
> With the following patch (that simply reverses the traversal) the output
> is correct:

Thanks, it seems to work.

> > I have also run into other problems and I will write about
> > them later. I have both problems of parts sometimes not appearing
> > (for instance some faces of a standard icosahedron not colored,
> > when the others are), and problems with text. I haven't been
> > able to control the position of TeX text, even with the
> > GL2PS_TEXT options. Do you have a working example?
> 
> I don't see any problems with the text produced by your example except
> that you have to set the last argument of gl2psBeginPage to the output
> file name ("tmp"), otherwise the \includegraphics command in the LaTeX
> file will fail.

I am sorry, I think I was confused by the perspective.
That is, I had in my mind that the labels would be positioned
with respect to the point, but it is the point which
is positioned with respect to the label. I mean, I find it
more natural to write:

  "text" top left of point (x,y)

but with GL2PS one has to write

  point (x,y) at bottom right of "text"

Concerning LaTeX labels, there should be a way to output LaTeX
code which memorizes the current position, that is, it should
memorize the coordinates in \put(28,79) in some variable.
Then, later, the user can use appropriate macros with these
labels. An example would be drawing a nice arrow between two
points (for axes, for instance). The OpenGL code could output
two labels, one for the beginning and one for the end of the
arrow. And the LaTeX code supplied by the user would draw this arrow.

On GL2PS' side, the only necessary thing would be to output a label
such as \savecurrentposition{pos1}, so GL2PS wouldn't even need 
to be changed. I'll probably work on that at some point, 
as I'd like to have it.

Thanks,

Denis