Re: [PyX-devel] Another geometry version

[Andre W. <wo...@us...>]

Hi,

On 27.07.04, Magnus Lie Hetland wrote:
> So, here is a version which uses André's linear equation stuff
> (although I've switched to numarray -- it's what I use; and numarray
> 1.0 is out now, so... Hooray for that :).

Hey, isn't that something for try-import-except? No isinstance
available ... ;-)

> So, presto, we've got a bidirectional thingy. Note that the angle in
> the transform is still a constant, though. As André pointed out, if
> the angle is to be a variable, we'd end up getting equations with
> sin() and cos(), and that's not exactly pleasant.

Well, I have to look at MetaPost at some point. Don't we really want
to create a transformation by setting 3 2d input and output points?
This is a linear problem.

How is it in MetaPost? Is it allowed to define write P = t*p where the
points P and p are not defined as well as t is not defined? What does
MetaPost with such an equation? Does it store it for later evaluation
(for example until p and P becomes known)? And what about having
several transformations: P = t2*t1*p? And what about restricting a
transformation to a rotation, for example? I should take a look at
MetaPost/MetaFont at some point.


André

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