Can a typeface be designed to have characters depend on previous characters within a typed word?

Question

I am embarking on a project to design my own font for a personal project that will resemble my handwriting. I have read a few good guides to get a broad view of what it will take for me to achieve this, this one was a particularly good one I found.

I cannot seem to find anywhere that suggests it is possible to do what I’d like; can a letter within a font be made to have different appearances depending on which letters precede it?

My aim would be to make the letters connect as they do in my hand writing but to do that I do change their shape as I write to connect to each other based on what letter I have written before another. Can a font be programmed to have each letter adapt based on the previously typed one?

Answer 1

Yes you can do it. You do it through an OpenType feature called Contextual Alternates (calt).

Sample code:

feature calt { 
    lookup calt1 { 
       sub a' b  by a.ss01 ; 
       } calt1; 
    }

Basically, you tell the font: substitute a+b with a.ss01 + b

This is a good overview of OpenType substitution features.

Answer 2

Yes, this can be done. There are several intelligent font standards, namely AAT, Graphite, and OpenType, that allow to do this. The latter seems to be the succeeding one.

Here is an example that I created using such techniques. Note how the letter s is rendered differently based on the preceding and following letter:

How exactly you best achieve your goal depends on your specifics, but you almost certainly want to work with lookup classes and contextual forms.