this post was submitted on 24 Aug 2024
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2d trulesformations (lemmy.blahaj.zone)
submitted 3 weeks ago* (last edited 3 weeks ago) by [email protected] to c/[email protected]
 
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[–] [email protected] 10 points 3 weeks ago (4 children)

The scaled down rectangle should be narrower; it's not scaled in this diagram, it's squished.

(Yes I know you can 'scale' objects on one axis but that's usually not how it's taught on an introductory level. Standard scaling assumes object similarity, which is not present in the diagram's 'scaled' rectangle.)

[–] [email protected] 4 points 3 weeks ago

This is some quality pedantry.

[–] [email protected] 1 points 3 weeks ago* (last edited 3 weeks ago)

Ackchuawually, this example depicts a squish and a translation. A true scaling would have the scaling being done in place, resulting in an overlayed and smaller rectangle.

[–] [email protected] 1 points 3 weeks ago

Damnit, I wanted to say that

[–] [email protected] 0 points 3 weeks ago* (last edited 3 weeks ago) (2 children)

Scaling in 2D has 2 parameters, X and Y, in the example X was at 1 while Y was below 1. You are referring to a subset of scaling transformation where X = Y and the aspect ratio is kept.

[–] [email protected] 2 points 3 weeks ago

Yes, and introductory geometry courses teach students how to do uniform scaling far before they teach them axis-based because it's better illustrative of the concepts of similarity and congruence

[–] [email protected] 1 points 3 weeks ago* (last edited 3 weeks ago)

And what about the arrow?

It's pointing down diagonally, which - at least to me (and for pretty much any GUI I can think of) - indicates, that it should be affecting both axes.

Then again, that whole illustration isn't all that great to begin with. So who knows, what that arrow is supposed to signify...