Formula node mk3

[portnov]

Addressed problem description

Our current "Formula" node has a couple of problems:

• Inconvenient syntax with only variables being available "X" and "n[0]" .. "n[150]"
• weird code with Lenin and some other strange people being involved for some reason >_<

It is also not very convenient to use it to produce curves or surfaces, because you have to write something like "[sin(n[0]), cos(n[0]), 0]".

Solution description

Re-implement Formula node:

• Allow to write arbitrary Python expressions with arbitrary variable names, so that you can just write R*sin(phi). Use the same technique as in "mesh evaluate" node to manage input sockets.
• Add possibility to write not only single formula, but up to 4. So to generate an ellipse, you have to write A*cos(t) in one input box, B*sin(t) in another, and that's it, no brackets and so on. By default, show only one input box to save screen space for most cases.
• Support a flag to enclose each vector produced by several formulas into separate sub-list. It is usually required when you have more than one formula; it is usually not required if you have only one formula; but there may be other options.
• Support a flag to enclose the whole output into additional pair of brackets, which other nodes may want to see.

Preflight checklist

Put an x letter in each brackets when you're done this item:

• Code changes complete.
• Code documentation complete.
• Documentation for users complete (or not required, if user never sees these changes).
• Manual testing done.
• Unit-tests implemented.
• Migration from old node supported.
• Ready for merge.

[portnov]

[portnov]

[portnov]

[portnov]

[nortikin]

спасибо, Илья.