Animated displacement and displacement offset

[SonyBoy]

It appears that when there is displacement connected but with displacement amount set to 0, the displacement offset attribute still has the effect of offsetting the surface from its original level by whatever value it has. Why is this? This is very unintuitive, and causing problems with animating displacement.

It would be intuitive for the displacement offset to simply be a multiplier for the displacement amount, so that when displacement amount is set to 0, the offset should also have zero effect.

As it is, to animate displacement from 0-1 also requires setting up animation on the displacement offset, which is really annoying and unnecessary.

[SonyBoy]

Actually I can see that there are situations where you might want independent control of these two attrs, but surely 0 displacement should mean exactly that -- it should have zero effect.

[hermit.crab]

The Displacement Amount doesn't "offset" the geometry by default, it displaces it depending on the texture and chosen value. The Displacement shift is like an overall multiplier for the displacement effect. If you wish to animate an object and keep its relative size, animate the Shift to be minus half of the displacement amount.

[SonyBoy]

My point is that with the displacement value set to 0, it would be intuitive to expect the displacement shift to have zero effect as well, regardless of any value it may be assigned, but that's not the case. Thus, when wanting to animate a displacement effect from a 0 base mesh level to fully displaced, it's also necessary to animate displacement shift value.

This can be done with an expression or a multiply divide node or any other means (in the case of a displacement of 1 the formula is "displacement shift = displacement * -0.5").

I guess it kind of makes sense.