[Development] matrix math help needed - https://bugreports.qt.io/browse/QTBUG-84441

Edward Welbourne edward.welbourne at qt.io
Tue May 26 18:17:05 CEST 2020

Thiago Macieira (26 May 2020 18:06) wrote:
> Neither QMatrix nor QTransform have seen any change since the Qt 5.0
> repository import that was related to the underlying math. Only licensing
> and C++ updates.
> The task https://bugreports.qt.io/browse/QTBUG-84441 is claiming there's
> some wrong math or at least unexpected behaviour. Can someone who
> understands these classes take a look?

I'll comment.
It's down to the confusing nature of what the order of operations is.
(Matrix multiplication isn't commutative.)
I'll try to work out whether QMatrix / QTransform are consistent about it ...


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