POV-Ray : Newsgroups : povray.binaries.utilities : PointWriter: New app for making spline-based shapes easily : Re: PointWriter: New app for making spline-based shapes easily Server Time
28 Mar 2023 16:20:43 EDT (-0400)
  Re: PointWriter: New app for making spline-based shapes easily  
From: Bald Eagle
Date: 13 Sep 2014 11:05:01
Message: <web.54145bfc9ace5295e7df57c0@news.povray.org>
"Nevado" <nomail@nomail> wrote:
> See povray.news-submissions for details

Hi Christian,
Thanks for putting this together - it looks like a useful tool and a nice
complement to existing utilities.

I've really only just started modeling objects using spline-based primitives, so
I may have "problems" that - aren't, or solutions for problems that don't exist.

I'm giving it a go now, and I'll just write out my observations and thoughts.

Running Windows XP on an Acer Aspire One with 2GB.

Issues and request for help:

The executable appears to be "always on top", and overrides my taskbar, so I
have to minimize it to switch between windows.

I tried making several cubic prisms, and I ran into some issues.
at first, I just clicked "close poly" because not enough coffee had been
absorbed yet.  This does not play well with Write Cubic Prism.
Perhaps you could add a bit of insight about what to do if I close a spline for
one purpose, and then reload it, but want to use it for another purpose.

When the SDL for the spline points is written, it might be helpful for keeping
track, editing, and debugging to add a few comments into the mix. (Prism not
closed, too few points, etc.)

prism {
cubic_spline 0, 1, 12345,
<A, B, C>, // Control Point
<D, E, F>, // First Point
<U, V, W>, // Last Point
<X, Y, Z>  // Control Point

[A trick I use sometimes to "highlight" certain values is to just enclose them
in parentheses:  <0, (3.14159), 1> - maybe that could be done in addition to /
in lieu of //comments.]

Red dots on a red spline are hard to see.
Maybe it was just me, but it seemed sometimes that a point was inserted a bit
off from where I actually clicked.

It appears that once I close a prism, I can begin drawing a new one.
How do I select(?) / move / edit the previous one?

Would it be possible to cycle a color value for the current object being drawn?
(1st prism red, 2nd green, 3rd blue, etc.)

When I tried to edit a prism, the points all disappeared!
I hit M to get rid of the background graphic I was tracing, and then I saw a
single green point - that's it.
When Writing an object, the background graphic disappears. Is that intended

Can I INSERT points into an existing spline?

Suggestions for additional features, food for thought:

Addition of exported SDL for sweep primitives?

I'd like to be able to translate, rotate, and align items after the fact.
Some things I thought might be useful would be:

The ability to select a point and then have a button that redefines all the
prism/lathe coordinates with the selected point at the origin.  Now since I know
the reference point, I can rotate, translate, and align things a lot more

Being able to insert reference points or whole CSG objects.
Since I'm drawing things "in cross section", it would be useful to be able to
insert points as references for later elaboration.

Suppose I wanted to make "part" and have a certain point line up with something
in a large SDL file.  It would be useful to be able to click/make a solo
floating point, which could just be exported as "#declare Ref_Point_1 = <x, y,
[Picture a connecting rod (O)---(O).  If I define one side as being at the
origin, then having another point defined as a reference would allow me to
trivially align some other origin-reference-point by translating to that
reference point.  "object {ConnectingRod translate <x, y, z>}"

If I wanted to subtract a hole at that point, it would be useful to define that
point as the ends of a cylinder going from y = -0.1 to 1.1.  That way it's big
enough to see in a union, or avoid coincident surfaces in a difference.

If I wanted a sphere there, I could use the reference point as its center, or
you could just export the sphere definition directly. I suppose a clever way to
insert a box would be useful as well, using the diagonal to define the


Thanks again for developing this utility, and I'll keep playing with it to see
how it works.  I especially like the background graphic, the "Work in Back"
feature, and the ability to draw perfectly straight vertical and horizontal

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