(Based on the fact that contact always takes place half-way between the point of aim and the centre of the object ball as viewed through the centre of the cue ball).
Aim at edge of ball. Ball takes a line drawn through it from ½ inch inside edge.
Aim ½ inch inside edge. Bail takes a line drawn through it from ¾ inch inside edge.
Aim ½ inch outside edge. Ball takes a line drawn through it from ¼ inch inside edge.
(The above are the three principal aims and contacts in billiards).
Aim ¼ inch inside edge. Ball takes a line drawn through it from 5/8 inch inside edge.
Aim ¾ inch inside edge. Ball takes a line drawn through it from 7/8 inch inside edge.
Aim ¼ inch outside edge. Ball takes a line drawn through it from 3/8 inch inside edge.
Aim ¾ inch outside edge. Ball takes a line drawn through it from 1/8 inch inside edge.
Aim 1 inch outside edge. Ball takes a line drawn through it from its edge, or almost a right angle.