Truncation and round off
nicolas cellier
ncellier at ifrance.com
Sun Feb 5 14:18:33 UTC 2006
> I'd like to add that this incompleteness is part of a
> problem morphic has in displaying graphics. See:
>
> http://bugs.impara.de/view.php?id=2453
>
> Summary 0002453:
> [Bugs] What is the extent of a truncated rectangle?
>
> The basic problem was that truncation and rounding did
> not mix well with rectangles. Particularly when
> rectangels were mixing with rendering Transformation
> morphs.
>
> Part of the solution would be to have more choices
> particular ceiling and floor options for rectangles
> (an by extention Points.) I was headed in that
> direction as I attempted fixes to the errors. If a
> set of vocabularies exist that would also make squeak
> more compatable with other smalltalks and we have all
> the necessary permissions to include them. Then I say
> squeak could use them. The sooner the better.
>
> Yours in service, -- Jerome Peace
>
I perfectly understand that you need to round the rectangle toward interior or
exterior.
Base VW is not better than Squeak, both have trivial st-80 implementation
that will also round topLeft and bottomRight to nearest.
I think you'll have to invent the messages or look elsewhere.
Putting a constraint like:
aRectangle truncated extent = aRectangle extent truncated
whatever the coordinate transform is does not sound easy: maths say it is
simply impossible even without a rotation (unless rectangle sides are 3*n and
4*n).
But I do not see why you need to do rounding in intermediate steps.
Isn't rounding deferred until rendering and intermediate coordinates kept
Fraction or Float ?
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