Flip perspective-origin declarations

[elchininet]

At the moment, perspective-origin is not flipped. As this declaration has a similar syntax as transform-origin, it is easy to include it in the current transform origin processor. The tests have been copied from the transform-origin ones, removing the cases that are not compatible with perspective-origin syntax.

[MohammadYounes]

@elchininet Apologies for the late response, I was very overloaded lately.

I don't think perspective-origin is something that should be auto flipped, it should be left to the author to decide to flip or not.

Using MDN sample, This is what you get with and without flipping perspective-origin:

The samples do not reflect a real world scenario though! Do you happen to have a real use-case I can apply this on ?

[elchininet]

Hi @MohammadYounes,

Do not worry, this is not something urgent ;)

You are right, I didn't think on an element with multiple faces like the example on MDN. My use case was simpler, a regular 2D transformation and I noticed that rotateY transformations and perspective-origin were not flipped, so I did it manually. It was something like this:

LTR: https://jsfiddle.net/elchininet/zunkwt82/
RTL: https://jsfiddle.net/elchininet/awodq0vn/

I also was preparing a merge request for rotateY, but now, thinking in these kinds of cases, forcing it by default could be conflictive too and it should be left to the author to decide if flip it or not.

What do you think about these properties? Do you think that it could be provided by a configuration parameter, or do you think that these cases should not be covered at all?

[elchininet]

I discovered something, the examples on the MDN were also using rotateY, if those parameters are also flipped this is the result:

[MohammadYounes]

@elchininet The last one you shared is a more accurate

I believe this requires thorough investigation to ensure correct output when auto flipping transforms.

[elchininet]

I agree @MohammadYounes, my CSSs files are not good enough because they only have easy 2D transformations, this should be tested with complex transformations. To make this test easier, do you want me to push also the rotateY change in this merge request?

[MohammadYounes]

@elchininet I'm not sure at the moment, Looking at the code, rotateY was explicitly excluded. We need to double check what should/shouldn't be auto flipped