Unexpected behavior: Sin(time) seems to be "invisibly" remapped

Hi, there! This is a quick, and maybe pedantic question about the Sin and Time nodes in Unreal, but I’m experiencing some odd behavior that I’d like to better understand.

In this screen recording, I have a simple material set up with sin(time) going into the opacity channel (after being remapped from -1,1 to 0,1) – and the odd thing is, that produces an oscillation with a period of one second.

In my mind, the expected behavior would be a period of 2π, or 6.28 seconds, because the sin node receives an input in radians and the default period of a sin operation is 2π. Meanwhile, when I try to multiply the Time node output by 2π / PERIOD PARAMETER in the video (which is what I would think to do in order to create a cleanly parameterizable period), I get an oscillation with 2π oscillations per minute.

So, what’s going on here? Does the sin node somehow “know” that it’s receiving a time input and trigger some special remapping behavior? Is my time input just operating on a 2π-multiplied scale? This isn’t necessarily a blocker, but if there’s some predetermined behavior I’d like to know how it works and be able to work around it

Much thanks!
Brendan

This is definitely an intended behavior.

Hi, Deathrey! I agree that it totally seems intended, but my question is more with regard to the way that this is implemented – whether this happens only if the Time is directly hooked up to a Sin node or if Time → arbitrary node → Sin also works, whether there are other nodes that have custom behavior with Time input or sin output, and other things of that nature.

It’s obviously a nice convenience, but invisible behaviors like these can be dangerous if you don’t 100% understand them. Ultimately, I wish there was some documentation!