[BUG] possible MatrixTransform2x3 bug?

Ned Konz ned at bike-nomad.com
Wed Aug 20 19:23:41 UTC 2003


On Wednesday 20 August 2003 12:15 pm, Ned Konz wrote:
> This one's got me baffled. I've got a Matrix2x3Plugin internally
> built, using the sources off SF and generated from a recent 3.6
> image.

[snip]

> m1 globalPointToLocal: 0 at 0 "print it =>" -99 at -99
> m1 globalPointToLocal: (0 at 0) asFloatPoint "print it =>" -99 at -99
>
> Hmm. The code falls back to "^(self invertPoint: aPoint) rounded"
> if the plugin is not present. And that works OK:
>
> m1 invertPoint: 0 at 0 "print it =>" -100.0 at -100.0
>
> (m1 invertPoint: 0 at 0) rounded "print it =>"  -100 at -100
>
> I've looked in the sources and in the C source, and I have verified
> that the return value is indeed getting rounded.

Figured it out: the assumption all over the Matrix2x3Plugin is that 
it's dealing with positive-valued points. It rounds by adding 0.5 and 
then truncating the value.

-- 
Ned Konz
http://bike-nomad.com
GPG key ID: BEEA7EFE



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