//A was pressed so set a variable or do something
gCurrentPatternNumber = 0;
...
//B was pressed so set a variable or do something
gCurrentPatternNumber = 1;
...
//C was pressed so set a variable or do something
gCurrentPatternNumber = 2;
...
//C was pressed so set a variable or do something
gCurrentPatternNumber = 3;
And un comment out the
gPatterns[gCurrentPatternNumber]();