[Blindmath] Understanding how to draw 3D objects

[Andrew Stacey]

On Fri, Mar 23, 2012 at 08:01:00PM -0000, Michael Whapples wrote:
> Thank you Andrew, that clears up a few things for me. So from what
> you say it sounds like shading should be used if one feels
> additional time is worth spending on the diagram, which may be
> influenced by who will be viewing it (IE. if they are familiar with
> the shape) and also for what purpose the diagram is being drawn (IE.
> if it was an important report being submitted for publication then
> its probably more important than a diagram going to colleagues just
> to communicate an idea).

Yes, though I'd put a seminar above something being submitted for publication
(on one article I was asked by the journal to effectively downgrade my
diagrams).

> Out of interest what is the tool you are using to convert from the
> TeX source to SVG?

TikZ/PGF can output SVG if given the right options.  It tends to be quite
verbose SVG.  There's a python script that can condense it considerably which
I sometimes use if the SVG is intended for public consumption.

> As for my original question, sorry if it was a bit confusing, I
> meant the comment on the wikibook torus to illustrate that when I
> have a diagram I can work out what 3D object it shows (even if I may
> be reconstructing the image from the TeX commands). I think the bit
> where I said about actually working out what commands I would use
> when drawing was a bit hidden away in all the other stuff I said at
> that point.

No worries.  I was pretty sure I wouldn't have anything sensible to say on the
real question so probably didn't read the original too closely.

> As I said in a different message, is there a set of "design
> patterns" for what elements to use to represent certain 3D shapes?

Not that I know of, which is why I tend to create this sort of thing from
scratch by working out a parametrisation of the surface and then sampling at
intervals.  Almost certainly not a very efficient method.

Andrew