[racket] image.ss: can one make a rotation-invariant middle?

From: Robby Findler (robby at eecs.northwestern.edu)
Date: Sun Feb 6 08:33:56 EST 2011

(I see you answered this and I just missed the message before sending
mine. Sorry for the noise.)


On Sun, Feb 6, 2011 at 7:26 AM, Robby Findler
<robby at eecs.northwestern.edu> wrote:
> I've pushed a change that makes place-image/align not insist on the
> second image argument having a pinhole. That was too much checking.
> Does that help?
> Robby
> On Sat, Feb 5, 2011 at 9:05 PM, Yaron Minsky <yminsky at gmail.com> wrote:
>> In playing around with image.ss, I've run into the following problem: the
>> center of an image does not appear to be rotation invariant.  Thus, if you
>> use place-image/align in order to place a triangle, say, that you then
>> rotate continuously, you will see the triangle wobble as its effective
>> center moves around.
>> Is there any way around this?  I tried using pinholes, but pinholes seem to
>> require that all images involved have pinholes, which is not quite what I'm
>> going for.  What I really want to do is to declare a stable center for an
>> image, but I can't quite figure out how to do that.
>> y
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