LocalToScene Transformation (related to Affine Transforms)

[Pavel Safrata]

Hi Alexander,

On 14.5.2012 11:21, Alexander Kouznetsov wrote:
> Hi Pavel,
>
> On 11.05.2012 13:33, Pavel Safrata wrote:
>>>
>>> Can't we just make Affine3D public instead? That way we'll provide 
>>> matrices calculation layer and all we need is to provide methods to 
>>> convert Affine3D to Affine and vice versa. Just an idea.
>>
>> This sounds like a bad idea to me. From user's point of view, 
>> Affine3D and Affine would be duplicates except that Affine's members 
>> are observable. What I think we should do is to port some of the 
>> Affine3D functionality to the Affine class (which sounds close to 
>> RT-17942).
> I don't see a really big difference here. Newly added class regardless 
> of its name would be "a duplicate" of Affine class. 

I'm not going to add any new class (except of an internal immutable 
implementation of Transform). The Affine class is already part of public 
API for a long time, so we should use it and not create any duplicates 
of it.

> Moreover if you're not going to port all of its methods there would 
> always be a feature requests to port the rest of them. 

We will consider all the feature requests and implement the reasonable 
ones. If we end up with something very close to Affine3D, we may then 
consider switching to the public classes internally.

> On the other hand the Affine class wouldn't be just a class that 
> members are observable but would be also a class that has no matrix 
> algebra methods and that is part of Transforms API. Affine3D is 
> clearly a different layer then.

The Affine class will have the matrix algebra methods. I don't think we 
should publish any other layer (our proposal tries to avoid that) - that 
would lead to more confusion and more work with converting matrices 
between the layers. Everything should work with the existing classes 
from the user's point of view.

Thanks,
Pavel

>
> Best regards,
> Alexander Kouznetsov
>
>