On 12/19/23 03:32, Kenneth wrote:
> It's interesting that you should mention this topic.*Many*  years ago (2009), I
> had a 'discussion' in the newsgroups with long-time user Warp

Thanks for the pointer. I read through it. I'll say my up front concern 
isn't really the averaging(a,b,c) when it comes into play, but rather 
that with relatively simple test cases for the cutaway_textures I found 
bugs and instability in behavior depending on the kind of inputs given 
to the intersection{} and difference{} blocks. Maybe the 'bug' mentioned 
in that 2009 thread compared to v3.6 didn't get fixed - or didn't get 
fixed completely?

(a) - Relative to the specific averaged texture discussion in that 
thread, the yuqk fork introduced a list_object{} pattern for pretty much 
the situation discussed. It allows the user to specify a list of objects 
for a patterned / *_map texture in a last one wins order. In other 
words, the user selects which texture wins in overlapping regions.

(b) - The averaging method provides a way to generate a texture when 
there are object overlaps, but the result is clunky I think; as in not 
being actually useful except to provide 'some' texture result indicating 
overlapping regions. In what I've seen so far you get bits that are 
averaged and bits not, depending on overlaps. If all we are after is 
some special effect - like image transitions in an animation or 
something - the set up could be useful.

(c) - I still haven't unrolled completely how the averaging gets done in 
our code. What concerns me some is the inside tests. These are sometimes 
very expensive. Even fast ones will be costly if there are huge numbers 
of shapes in the input CSG objects to the intersection / difference 
(really a modified intersection).

Anyhow, see the image and yuqk scene file(d) for the list_object{} 
pattern approach as a cutaway_textures alternative - one also with 
limitations.

(d) - I played very briefly with cutaway_textures in this file too and 
it seemed like the behavior was different yet again (ignored sometimes 
where not previous...?), but I didn't dig into it.

Bill P.

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