[mapserver-dev] RFC113 Chainable Compositing Filters

[thomas bonfort]

All credit for those beautiful maps go to the http://sitn.ne.ch/ team,
I didn't have a play in them. I've cc'd Marc who might be able to
share more details as to what he was using exactly (note that those
maps predate the actual filter chaining implementation, and used a
hack present in 7.0 along with drawing the shaded layers twice).
For the water bodies, I suspect it can be done with:

COMPOSITE
 #first we render normal water color
END
COMPOSITE
 COMPFILTER "whiten()"
 COMPFILTER "blur(5)"
 COMPOP "soft-light"
 OPACITY 50
END
CLASS
 STYLE
  COLOR water-color
 END
END

At present filters are not supported on labels (unless they don't go
through the labelcache). They could be supported in the longer run if
we explicitely had a "labelcache" layer that we could draw into and
that we could therefore plug into the compositing chain.

regards,
thomas

On 2 October 2015 at 18:18, Lime, Steve D (MNIT) <Steve.Lime at state.mn.us> wrote:
> Beautiful maps... How'd you do the inside shading on the water bodies? Can these be applied to labels? --Steve
>
> -----Original Message-----
> From: mapserver-dev-bounces at lists.osgeo.org [mailto:mapserver-dev-bounces at lists.osgeo.org] On Behalf Of thomas bonfort
> Sent: Friday, October 02, 2015 4:36 AM
> To: MapServer Dev Mailing List <mapserver-dev at lists.osgeo.org>; MapserverList OSGEO <mapserver-users at lists.osgeo.org>
> Subject: [mapserver-dev] RFC113 Chainable Compositing Filters
>
> Hi All,
>
> I have finished implementing the chainable compositing filters that
> were architectured along with RFC113, and the code has been committed
> to the master branch. The aim of the development is essentially to
> enable soft shadow and blurring effects, although other usages can
> exist or could be added in the future.
> To obtain a soft shadow effect that can be seen for example around the
> buildings on http://sitn.ne.ch/production/wsgi/mobile/?theme=mobile_default&baselayer_ref=plan_ville&map_x=554942.49763489&map_y=200242.9936142&map_zoom=6&tree_layers=
> you can use
>
> LAYER
>  NAME "buildings"
>  TYPE POLYGON
>  COMPOSITE
>   #create the shadow/blur effect by translating a blurred version of the layer
>   COMPFILTER "grayscale()"
>   COMPFILTER "translate(5,5)"
>   COMPFILTER "blur(4)"
>   OPACITY 50
>  END
>  COMPOSITE
>   #and render the buildings themselves
>   OPACITY 100
>  END
>  CLASS
>   STYLE
>     COLOR 128 128 128
>     OUTLINECOLOR 0 0 0
>     WIDTH 1
>    END
>   END
> END
>
> The currently available filters are:
> - "blur(integer)"
> - "translate(integer,integer)"
> - "grayscale()"
> - "blacken()"
> - "whiten()"
>
> I'll add some documentation and autotests next week.
>
> best regards,
> Thomas
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