POV-Ray : Newsgroups : povray.tools.general : vector direction turned into rotation angles : Re: vector direction turned into rotation angles Server Time
8 Feb 2023 07:45:04 EST (-0500)
  Re: vector direction turned into rotation angles  
From: Kenneth
Date: 6 Oct 2018 03:15:01
Message: <web.5bb86075555c34daa47873e10@news.povray.org>
"Bald Eagle" <cre### [at] netscapenet> wrote:

> Although I LOVE that you worked it out a priori:
> You know that there are macros and functions for this, right?
> http://www.povray.org/documentation/view/3.6.2/459/

Honestly, I would say that I understand maybe half of those things, from a
conceptual/3-D spatial viewpoint (my preferred or ONLY way of thinking about
math concepts.) Others like dot-products I have a really hard time visualizing.
And of the ones that I *do* understand, I'm just not sure how or when to use
some of them. THAT's quite frustrating-- to know that they are useful, but to
not know when to apply them.

That's really why I wanted to work out this angle-finder code from scratch (so
to speak); I could follow my own step-by-step construction, while using just
basic tools. Of course 'basic tools' is a relative concept-- I can tell that
you're WAY ahead of me in the maths department ;-) But I'm learning some
important things from your discussions.

From that docs page, I DO see some tools that I could have used...

VAngle(V1, V2), VAngleD(V1, V2)-- Compute the angle between two vectors.

VCos_Angle(V1, V2)-- Compute the cosine of the angle between two vectors.

[hey, where's VSin_Angle(V1 V2) ??]

VProject_Plane(V1, Axis)-- Project vector V1 onto the plane defined by Axis.
[Uh, then what? Does it return a length? A vector?]

.... but their actual operations still appear a bit mysterious to me. Maybe it's
the rather terse 'textbook' descriptions that give me a hard time, I dunno.

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