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## Re: [Texmacs-dev] Drawing mode feature request: Annotation of .eps graph

 From: Karl Hegbloom Subject: Re: [Texmacs-dev] Drawing mode feature request: Annotation of .eps graphics. Date: Tue, 08 Nov 2005 18:01:39 -0800

```On Tue, 2005-11-08 at 22:09 +0100, Henri Lesourd wrote:
> In practice, what I do is that I have a list, and then I
> implement the features one after the other (or sometimes
> I don't add such or such a feature, because i.e. I discover
> that I would need some other thing implemented first).

Another item for a sublist...  I'd like to show dimensions in some
constructions.  There's two ways to show them.  One is the dimension
lines as used in blueprints, where you draw line segments in line with
the end points of the item you are measuring, and then draw a line with
arrows on the ends that has a break in the center where the dimension is
written.  Another nice way to show it is to use a large {, as in the
\choice macro of TeXmacs, or like a large opened calipers.

For the 3-d constructions, perhaps a nice way to do a projection drawing
would be nice.  Have you ever learned to do one point or two point
projections?  It's where you tape down your sheet of paper, then pick
one or two points off to the upper right of your page, the distance they
are from your paper determines your viewing angle.  You then draw the
"going away from you" parts so that their lines always converge towards
those chosen points. The things you draw that you can see the left side
of have their lines converging toward the right dot, and the ones you
can see the right side of converge toward the left dot.  It can also be
done with a single point.  Think of a railroad track that extends from
where you are standing off across a very flat plain to the horizon.  It
appears to come to a point at the horizon.  If you are standing off to
one side of it, it converges also, but farther toward the right,
depending on where you are 'standing'...  If the two points are far
enough away, they converge into one.  So when your clipping box, the
page, shows only part of that track, you use two points.  If it shows
the horizon, you use one point at the horizon.

It probably works well enough for the simple kind of geometric diagram
required for schematic illustrations of physics problems, I think.

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