How to create custom ttf font?

Question

Fonts

I am interested in the process of creating a font with the following properties:
1) when the Y character code is entered, O is displayed on the screen
2) when the Y character code is entered, a vertical stick is displayed on the screen
3) when the Y and Y character codes are consecutive, Y is displayed on the screen
How to create such a font?

Answer 1

in order to "create" a font from an existing one, you need to find a TTF editing program and use it to change the glyph table as you need.
but I don’t remember about ligatures (replacing 2 characters with 1 glyph) in TTF. not sure.
>> to understand how such fonts are created.
if "roughly" - TTF font is a set of glyphs (vector pictures) and a table of correspondence between characters and glyphs.