Wasn't it Pander who wrote:
>
>
>This is a feature request to have functionality in povray (or an external
>tool employing porvay) to generate a HTML map that contains areas that are
>masks for object contours. This would look like:

An alternative strategy to explore would be to generate a transparent
PNG mask to capture map clicks.

Use the +ua option to create a PNG file that is completely transparent
where no ray hits the target. Use a 2D image processing application to
reduce the opacity of the visible region from 100% to 1%. This results
in an image which is invisible to the user but visible to the browser's
click handler.

Place the transparent image on top of the normal image (remembering to
use AlphaImageLoader if the browser is MSIE with version less than 7),
but make only the transparent image clickable. When the user clicks on a
pixel where the mask is 100% transparent, the click falls through and
the onclick action is not performed. When the user clicks on a pixel
which has 1% opacity, the click is captured and the onclick function is
performed.

I don't know how browser independent this technique is.

-- 
Mike Williams
Gentleman of Leisure

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