[Mapserver-users] Transparency and WMS

[Frank Warmerdam]

Matthew Perry wrote:
> Hello,
> 
> I've been trying to get mapserver to display a
> partially transparent shaded relief over a DRG. Both
> layers are WMS and display correctly individually. I
> have tried many combinations of image types and
> various mapfile settings but no luck. Am I
> understanding TRANSPARENCY correctly.. that it makes
> all pixels semi-transparent? Or does it make certain
> classes of pixels completely transparent? Is
> TRANSPARENCY set to work with WMS layers or just local
> images??

Matthew,

I see your problem.  You have setup your mapfile properly, but it seems
there is an "issue" internally in mapserver.  The msDrawLayer() function
is responsible for applying the layer level transparency (ie. TRANSPARENCY 50)
but for WMS, layers msDrawLayer() is not used ... instead msDrawMap() calls
msDrawWMSLayer() directly.  I am not exactly clear why it is that way, but
the result is any of the "generic" logic in msDrawLayer() is missed.

I would suggest you file a bug in bugzilla and hopefully one of the WMS
rascals will step forward to resolve the problem.  Ideally by actually
putting WMS layers through msDrawLayer() somehow.

Best regards,
-- 
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
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and watch the world go round - Rush    | Geospatial Programmer for Rent