[Interest] Replacement for Qt4 QMatrix4x4?

Matthew Woehlke mwoehlke.floss at gmail.com
Fri Feb 22 17:19:03 CET 2019

On 22/02/2019 01.30, Thiago Macieira wrote:
> On Thursday, 21 February 2019 13:47:05 PST Matthew Woehlke wrote:
>> (Uh...why? I am not particularly amused by the loss of precision, nor
>> the extremely subtle incompatibility.)
> Changed in commit 51d40d7e9bdfc63c5109aef5b732aa2ba10f985a:
> http://code.qt.io/cgit/qt/qtbase.git/commit/?
> id=51d40d7e9bdfc63c5109aef5b732aa2ba10f985a
> One of the two reasons the commit message says was to avoid the surprise in 
> that it used float in embedded platforms (read: ARM).

...but if that's the case, I could argue that QPointF and friends also
all should have been changed for the same reason. IMHO it made sense
that all of these used "the platform-specific 'fast' floating point
type". But...

> That rationale is no 
> longer applicable, as we changed qreal to be double in all platforms about one 
> year later: http://code.qt.io/cgit/qt/qtbase.git/commit/?
> id=d8bf317546bcfab0b6b50375218429fa9d470705

...I guess this is no longer applicable. (Maybe for Qt6, all qreal
should just become double to avoid confusion?)

> I think we need to reconsider the storage type for Qt 6. Added to 
> https://bugreports.qt.io/browse/QTBUG-62425

Thanks. I would be in favor of making these types double again.


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