Cannot give Parent Node attributes to Child Node

[GondorCallsForAid]

Cannot give Parent Node attributes to Child Node

[aarthificial]

You can read about how Motion Canvas uses JSX in this section of our docs but in general, your snippet is equivalent to something like this:

const t = [
  new Polygon({
    ref: tMain,
    // ...
    children: [
      new Rect({
        // ...
        fill: tMain().fill,
        // ...
      }),
    ],
  }),
];

Notice that for a new Polygon to be constructed, its children need to be constructed first, so when fill: tMain().fill is resolved, the polygon doesn't exists yet and so the tMain reference has not been assigned yet.

A really easy solution would be to just use a signal which is lazy and so it won't be called immediately:

const t =
<>	
  <Polygon
    ref={tMain}
    sides={8}
    y={-100}
    size={120}
    fill={'grey'}
    opacity={0}
  >
    <Rect
      ref={tBot}
      y={28+100}
      width={111}
      height={100}
      fill={() => tMain().fill}
      opacity={() => tMain().opacity}
    >
  </Polygon>
</>

[GondorCallsForAid]

Thank a lot, that resolved my issue :D
Also, motion canvas is really amazing so far, it makes everything so clean and convenient :D