Vaclav Cermak schrieb:
> 
> Hello,
> 
> My idea is to create some "masked_polygon", or to add a "mask" into the 
> polygon and use this mask when determing, if some ray hits the polygon. 
> When the ray hits completely transparent part of the polygon, consider 
> it as "no hit" and return hits only with full opaque or semi-transparent 
> parts. Something like
> 
> #declare BitmapPig = pigment {
>   image_map {png "something.png"}
> }
> 
> polygon {
>   5, <0, 0>, <1, 0>, <1, 1>, <0, 1>, <0, 0>
>   mask {BitmapPig}
>   pigment {BitmapPig}
> }
> 
> This will remove the neccesasrity of high max_trace_level and I think, 
> that it can be faster, than shooting new ray from every hitted, but 
> completely transparent part of polygons.
> 
> What do you think about this?

Not the answer, but you might consider bounding boxes (see "bounded_by" 
pov-help 3.4.9.2), if your bitmap doesn't vary much. So you can clip 
parts of the polygons that are always transparent. But you have to 
declare a nice bounding-shape...


KK

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