Application design for specific points on image

Question

Hi guys I am starting a simple hobby app in Unity, its a 2D app, which have some alphabets like A,B,C..Z (images) . There ll be specific paths where user touch one by one to complete drawing the alphabet, like image below. Now I have some solutions for it in my mind:

1. Make a grid of small boxes/planes with colliders on complete alphabet character, and enable some of its planes, like in image the "red" line ll have small planes behind it with colliders enabled (planes with colliders on "yellow" and "blue" line ll be disabled) "red" plane colliders are triggered with some texture when user clicks/touches on that plane wo show some color on touch point. Thats how complete alphabets can be done with one grid.
2. Create mesh colliders for every alphabet in 3dsMax or any other modeling tool and enable them one by one. For e.g first enable "red" line collider then "yellow", then "blue". But this ll require to make collider for every curve and changing design ll require re work.
3. Picking specific pixel set on the image, e.g to first pick red area pixels, if user touching on these pixels then true else false.

I would like if some can have a better solution of it ? may be any optimized way, may be some variation of custom colliders, bounds, line renderes, curves etc.

Answer 1

Why not create a path under the alphabet that you can use as the drawing guide?

I don't know much about meshes, colliders or 3D models, but in Cocoa Touch or Core Graphics you could create a UIBezierPath of CGPath which and lay it underneath the image (whether you want it visible or not) and you could track the user's touch and drag along the path.

This would also allow you to easily create segments, lines and curves along the path in the order you wish them to be enabled/highlighted/shown. You could further overlay a colour on the path as the user is dragging over it. You could also bundle the paths inside the application with the images if you want.

Creating models in 3dsmax as well as the colliders and meshes seem like a waste of energy, but that's just my $0.02.