hidden line removal and gnuplot

[Ben Abbott]

I've attempted to simplify the hidden line removal for the gnuplot backend. The 
changeset is attached.

Looking at the demo fro ezmeshc, the changeset works as I'd expected.

        demo ezmeshc
        grid on
        print -dpdfwrite ezmeshc.pdf

Looking at the demo for ezsurfc, the contour plot is properly hidden behind the 
surface plot. However, the plot box and grid lines are not.

        demo ezsurfc
        grid on
        print -dpdfwrite ezsurfc.pdf

PDFs for each plot are attached.

Does anyone understand what is happening?

My tip is ...

        changeset:   11426:c503ccbe5033
        tag:         tip
        user:        Ben Abbott  <address@hidden>
        date:        Thu Dec 30 17:32:59 2010 -0500
        summary:     Place contour for meshc/surfc at zlim(1)

Since the results prior to this changeset did not hide the contour or grid 
lines for the ezmeshc demo, the attached changeset is an improvement over the 
tip, but it would be preferred to resolve all the problems.

Ben

changeset.patch
Description: Binary data

ezmeshc.pdf
Description: Adobe PDF document

ezsurfc.pdf
Description: Adobe PDF document