On Fri, Jun 6, 2014 at 2:34 PM, Dirk Schulze <dschu...@adobe.com> wrote:

>
> On Jun 6, 2014, at 11:22 PM, Rik Cabanier <caban...@gmail.com> wrote:
>
> >
> > The issue is not that "isIdentity()" is confusing. The problem is that
> you
> > shouldn't make decisions based on it. From earlier in the thread:
> >
> > The isIdentity() method has the same issue as was described about is2D()
> > above: as matrices get computed, they are going to jump unpredicably
> > between being exactly identity and not. People using isIdentity() to jump
> > between code paths are going to get unexpected jumps between code paths
> > i.e. typically performance cliffs, or worse if they start asserting that
> a
> > matrix should or should not be exactly identity. For that reason, I would
> > remove the isIdentity method.
>
> And as real world examples show (browser implementations, graphic
> libraries and even game engines). This is not really an issue in practice.
>

It *is* an issue. Check all the cases in WebKit where you're checking for
"almost" identity.
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