Re: [AGG] SpanGenerators

[Maxim S. <mcs...@ya...>]

> What I am suggesting is to allow for some kind of integration of the
> compound rasterizer with other AGG pieces (e.g. other span rasterizers,
> scan-bool clipping, etc). 
> 
> For example, since compound rasterizer generates scanlines, it may be a good
> idea to wrap the compound rasterizer in a new SpanGenerator? Then the
> compound rasterizer could be used to fill spans generated using
> rasterizer_aa, rasterizer_aa_solid, or 'scan-bool' shapes (e.g. by caching
> the current scanline to fill all the spans generated by the span generator,
> then moving to the next scanline, etc). This way it would be possible to use
> compound rasterizer together with other rasterizers, clippers,
> SpanGenerators, etc. 

Yes, that's an interesting idea, I'll think about it. Inside the
render_scanlines_compound_layered() there's a color span generated, but the
eventual scanline is implicitly OR'ed, so that it always constists of a single
span from the leftmost to the rightmost boundaries of the shape. But if you
wrap it up with a span generator you will need a mechanism of regular
rasterization (rasterizer_scanline_aa) that will work independently (work over
it, so to speak). 

In fact, the compound rasterizer now simulates the "UNION" boolean operation,
and we had the possibility to simulate the other operations, this SpanGenerator
functionality would simply duplicate the scanline boolean. 

McSeem



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