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 18:14:09 EDT (-0400)
  Re: PointWriter: New app for making spline-based shapes easily  
From: Nevado
Date: 13 Sep 2014 14:20:01
Message: <web.54148a159ace5296dce1a360@news.povray.org>
> Hi Christian,
> Thanks for putting this together - it looks like a useful tool and a nice
> complement to existing utilities.

Glad to hear it.

> 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.

stores them in an array (where one dimension also keeps track of subprisms or
subpolys). The screen points are not translated into POV-Ray scene language

write them as different shapes, if you want.

> 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.)

be other warnings.

cubic prism you must close it before writing.

> 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.

You may have a point. That would be easy to change.

> Maybe it was just me, but it seemed sometimes that a point was inserted a bit
> off from where I actually clicked.

off by pressing 0, and then you can put your points anywhere.

> It appears that once I close a prism, I can begin drawing a new one.

the next. This is all explained in the PointWriterHelp.txt file.)

> How do I select(?) / move / edit the previous one?

When you click close enough to a point, it will be recognized as the one you
want to edit and turn green. It will then be replaced by the next point you
If you click too far from any point, a new point will simply be added to the

> 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
> behaviour?
> Can I INSERT points into an existing spline?

No, you can move any single point anywhere and delete them from the last point
backward, but not insert new points (except at the end, of course).

> =============================================
> 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.

You cannot rotate the shape on screen, but you can move it left, right, up or
down in the grid at any time (in jumps of 0.25 units) by using the F1,F2,F3 and
F4 keys. You can actually move it all the way out of the screen to get more
drawing space, and it will still be there, ready to be moved back in.

> 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
> easily.

Well, you can center the Y and/or X-axis and so choose between origin at screen
center, center bottom, center left or bottom left. And then you can move your
shape anywhere in relation to the origin with the F1-F4 keys as described above,
so you can basically get what you want.

> 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.

always insert previously saved work as background or reference for drawing new

> 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,
> z>"
> [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
> dimensions...
> =================================
> 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
> lines!

Good to hear - and thanks for the feedback!

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