Can we define entry/exit animation function in much the same way to ordinary animation functions?

[bglgwyng]

I'd like to define layout animations with shared values and write animation functions in the following style.

const entering = (values: EntryAnimationsValues): LayoutAnimation => {
  'worklet';
  t.value = withTiming(1, { duration: 300 }); // ignore where `t` comes from for now

  return {
    animations: {
      originX: interpolate(t.value, [0, 1], [0, values.targetOriginX]),
      originY: interpolate(t.value, [0, 1], [0, values.targetOriginY]),
    },
    initialValues: {
      originX: 0,
      originY: 0,
    },
  };
};

I know that the same behavior can be done without using t like,

const entering = (values: EntryAnimationsValues): LayoutAnimation => {
  'worklet';
  return {
    animations: {
      originX: withTiming(values.targetOriginX, { duration: 300 }),
      originY: withTiming(values.targetOriginY, { duration: 300 }),
    },
    initialValues: {
      originX: 0,
      originY: 0,
    },
  };
};

I think that when the animation gets more complicated, the style of the former will describe it better and sometimes it's even impossible to write in the style of the latter.
However, I found that the former just didn't work! And the properties in animations didn't behave like the ordinary animated style properties. We can't use derived values for it, like

animations: {
  originX: withTiming(values.targetOriginX, { duration: 300 }) + 100,
  originY: interpolate(withTiming(1, { duration: 300 }), [0, 1], [0, values.targetOriginY]),
}

The addition of 100 and the usage of interpolate makes is not work. Only simple animation values like withTiming(...) work as I observed.

Also, there's another problem with defining the shared value t. I tried makeMutable inside the worklet like,

const entering = (values: EntryAnimationsValues): LayoutAnimation => {
  'worklet';
  const t = makeMutable(0):
  t.value = withTiming(1, { duration: 300 });
  // ...

and I found that makeMutable is not callable inside a worklet. Do we have other options other than calling useSharedValue multiple times to use entering multiple times?

I'm worried that I totally misunderstood the concept of entry/exit animation functions. I would be really grateful if someone give a nice explanation of it.