1- In Substance Painter, the viewport rotation reacts differently depending on whether the user starts the alt-click-drag rotation input over the empty space around the model, or over the model itself (if the input for viewport rotation is started over the empty space, the model stays centered as previously framed ; if the input is started over the model itself, the view now rotates around this new point).
I can see that this behavior can be useful in some occasions, especially when working on small tertiary details (it is somewhat similar to the way the Zbrush navigation works, therefore I suppose that this where the request came from) but it can also be very distracting/irritating when working fast and on big areas of a model. There needs to be an option to disable this behavior, or a way to letting the user chose one or the other or both, as desired.
Following this, there is also a need for an option to frame the view to the cursor location on the model at any time, to still be able to zoom in on details. Basically "frame to cursor".
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2- Substance Painter needs an option to lock the skybox lighting direction to the camera angle. At the moment, if an object is lit sideways (which is almost always the case) it makes it is hard to see the details in the shadow side when texturing, forcing the user to constantly adjust the Env rotation value (this too is apparent in the above video).
This is a waste of time - imagine modeling in a 3d program and having to constantly adjust the lighting just to work around a model. This would be insane ... but this is exactly what is currently happening in SP
A good analogy to understand the issue is to think of the clarity of the lighting when working on pottery wheel. I hope this makes sense.