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Ray Tracing with POV-Ray: 25 scenes in 25 days (2013)

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Re: Ray Tracing with POV-Ray: 25 scenes in 25 days (2013)

#111
post #109

Earlier quoted context omitted.

Yes, exactly, knowing they’ll be smoothed is a big difference, it leads to different choices. Looking at a smoothed surface during the modeling process is an even bigger difference than looking a mesh all the way through. Knowing how they’ll be smoothed is important. What about creases? What if you want a creased edge smoothed and it’s part of two separate mesh groups? You can subdivide polygons without smoothing the…

> What about creases? Creases are done by just making polygons/bevels/line loops close to the edge that needs to be sharpened. > What if you want a creased edge smoothed and it’s part of two separate mesh groups? Mesh groups don't have to mean their polygons don't share vertices and this is one of the reasons why - you need to be able to interpolate the attributes of the vertices, like normals. > You can subdivide po…

> No, I explained that nurbs require extra/different tools.

I’m sorry if you feel defensive. I was responding to your explicit inclusion of “other curved surface representations” besides NURBS here https://news.ycombinator.com/item?id=23043791 and here https://news.ycombinator.com/item?id=23044537

Really just pointing out that a subdivision surface is literally another curved surface representation, does have some conceptual differences from polygons, and can be ray traced without subdivision. Calling it polygons was confusing to me, but now that I understand what you mean, call it polygons if you want.

Re: Ray Tracing with POV-Ray: 25 scenes in 25 days (2013)

#112
post #61
post #57

Earlier quoted context omitted.

I didn't say it was impossible, I'm talking about why these other geometry types aren't typically used instead of polygons. I asked 'how do you trace rays against it' because to do it directly is not fast, yet you are left with all the problems I stated that you skipped over. Think about what it would take to directly trace lots of overlapping primitives. What you gain from tracing it directly is minimal and what you…

Look at the POV-Ray source code. It does it. Again, I am literally telling you how the software under discussion works. and you keep insisting it is not so. It's open source!

POV-Ray is not yet open source, although the remaining authors hope to be able to solve that problem soon. (Its license contains a field-of-use restriction.) Also, I don't think BubRoss was claiming that rendering CSG directly was impossible, just that it's a bad tradeoff.
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