showing lines of overlapping polygons

[Frank Warmerdam]

On Wed, 9 Feb 2005 07:26:06 -0500, Erwin v.d. Bij <ErwinVanderBij at cs.com> wrote:
> Hello,
>
> I want to see the lines of 2 or more polygons which do overlap. Polygons are in the same layer. Polygons are filled with a style. Currently, I see only all the lines of the polygon which is obvious on top. I've experienced with the TRANSPARANCY attribute, but that did not help. Do you have any ideas?

Erwin,

I am unaware of a way of rendering multiple polygons in the
same layer transparently on one another.  As you note the
layer level transparency doesn't work in this case.  It is
implemented by rendering the layer into a seperate bitmap
and then doing a transparent overlay of the whole rendered
layer onto the map-so-far.

I would really like to see us add an "alpha" component to
colors everywhere, so that any object could be rendered
with transparency.  There are a variety of issues with this
though (beyond just the work involved) including the fact
that it wouldn't work well in the common 8bit case.

Best regards,
--
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
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