Multiple questions about the custom tool

I'm struggling to understand some things

1.What is the technical difference between Set up and Intermediate?

2. What is the difference between w/h, x/y, and ax/ay?

3. Is there a way of making custom mathematical expressions? I don't want to be just limited to the ones provided in the software. I think this may involve going through Fuse, but I have no idea how to start on that.

Thanks in advance if you could answer any of these questions.

Hi - main difference is that the setup expressions are calculated once per frame, and the intermediate expressions once per frame per pixel.

w/h - width and height of the image in pixels
x/y - coordinates of the pixel that's being processed (so, would not make any sense to use this in the setup expressions as that's not evaluated on a per pixel-basis)
ax/ay - reflect the image aspect. If you work with "square pixels" these will always be 1.

You can use a lot of standard math functions in expressions, check page 500 of the Fusion 9 tooling reference doc for further details.

Hope this helps

I haven't yet found a formula that I couldn't adapt to the Custom Tool. If you have specific questions, feel free to ask. In the meantime, I have a little primer on my blog here:
http://www.bryanray.name/wordpress/blac ... pressions/

You'll have to scroll about halfway down to the heading "Per-Pixel Expressions with the Custom Tool."