POV-Ray : Newsgroups : povray.general : Request for Comments: Quadratic Bezier Splines : Re: Request for Comments: Quadratic Bezier Splines Server Time
1 Aug 2021 22:58:15 EDT (-0400)
  Re: Request for Comments: Quadratic Bezier Splines  
From: Leroy
Date: 6 Jun 2021 18:35:00
Message: <web.60bd4c5084e2d21b7a6f5201f712fc00@news.povray.org>
clipka <ano### [at] anonymousorg> wrote:
> Hi folks,
>
> the `prism` primitive currently supports, among others, cubic Bezier
> spline outlines.
>
> For certain technical reasons, I may need to add support for _quadratic_
> Bezier splines at the render engine level as well, but it would be a
> waste to not expose them to the scene description language (and, while
> I'm at it, possibly also extend `lathe` accordingly).
>
> An open question is, what keyword should be used for this type of spline?
>
>
> For the records:
>
> - Quadratic Bezier splines are a flavor of quadratic splines, aka 2nd
> order polynomial splines.
>
> - Quadratic splines are also occasionally referred to as "conic splines"
> or "conic arcs", for reasons I'm not entirely sure of.
>
> - `bezier_spline` is the current moniker for cubic Bezier splines.
>
> - `quadratic_spline` is already in use for some quirky flavor of
> quadratic spline that, in my mind, doesn't even deserve to live, but has
> a long-standing tradition of existing under this moniker and therefore
> isn't going anywhere in POV-Ray v3.x.
>
>
> Here are some ideas:
>
> - `quadratic_bezier_spline`, being the most accurate term.
>
> - `conic_bezier_spline`, being a bit shorter.
>
> - `conic_spline`, being yet shorter.
>
> - `bezier2_spline`, the "2" referring to the polynomial order.
>
>
> Personally, I'm somewhat unhappy with the very first for being rather
> verbose, and the third for being prone to confusion with both
> `cubic_spline` and `conic_sweep`, the latter being also used in `prism`.
> I'm also not quite happy with the second one, because it's still
> somewhat lengthy, and I think it isn't the most accurate of terms.
>
>

 I like the last one 'bezier2_spline'
To tell the truth I had to look up the quadratic bezier spline, to see how it
worked. I have looked at pov sorce code to help my prism/polygon program match
pov prisms better.
 After reading about the quadratic bezier spline I was wondering why it wasn't
already a part of prisms. It seems a logic step up from the other splines
leading to the qubic bezier spline. But having said that, Now it seems a step
back. I rarely use any thing but the cubic to make prisms.

Have Fun!


Post a reply to this message

Copyright 2003-2021 Persistence of Vision Raytracer Pty. Ltd.