[mapserver-dev] Need mapfile for AGG and Transparent overlay

[Stephen Woodbridge]

Thomas,

I think this is mostly directed at you. I have been using your sample 
OSM mapfile and it is really great - Thanks for putting this together.

It raises an issue that I think needs to be dealt with, but maybe I'm 
missing some feature that is already implemented.

My use case is that I need a single mapfile that I can use for 
antialiased rendering like your file above, but I also need to generate 
transparent overlay images of just the road network by selecting just 
those layers or group. For example, in Openlayers, I need to have google 
like controls for [map][hybrid][etc] where the [map] view is like above 
and the hybrid view is satellite imagery as an OL layer and transparent 
road network overlay in OL.

So it would be nice if we can use a single mapfile to do both.

In OL, I would set the overlay layer to be:
   imagetype: 'png',
   transparency: 'on',
   antialias: 'off',
   ...

or whatever and then the mapfile would be interpreted correctly for 
generating a non-antialiased transparent image.

Questions:

1. Can this be done now? or do I need to build a separate mapfile for 
these two tasks?

2. Does this sound like a reasonable goal? Achievable in 6.0?

3. There were some posts that hinted that you might be trying to 
obsolete the gd rendering code, which I do not have a problem with. How 
would this impact this issue?

I hope this all makes sense.

Thanks,
   -Steve W