Create 'Tippex' for a drawn line.

Hello - hear me out, it sounds odd. I have a 2d physics game for IOS, where the player draws lines (made up of ink splats):

[2205-screen+shot+2012-07-27+at+17.16.50.png|2205]

these ink splats have a script which creates a sort of continuous collider, made of many box colliders, so a ‘ball’ rolls smoothly down them. Now after having a few people test my game the general feedback is that rather than restarting a level if you mess up these lines, add in an eraser, i thought, since its a pen, a ‘tippex’ type liquid corrector is better. So, i already have vectrosity and decided to use it. I have the white line in place and you switch between pen and ‘tippex’ easily, and i have layered it so it sees and removes the inks and colliders when over it, but it misses a few, due to the speed of update. I then put it in to fixed update so it raycasts more, but it still misses a couple. So i need to know, is there a better way to check if the touch position hits one of these colliders - ie not using raycasts, as fixed update isnt fast enough. And if not, any ideas how to go about upping the framerate? ive optimised the game already, rigorously, so im a bit stuck.

Tippex line :

[2206-screen+shot+2012-07-27+at+17.24.33.png|2206]

(basic test line, need to smooth it etc)

PS. sorry about the essay, but i know its better to have too much detail than too little.

So you won’t fix it by using a different frame rate - there’s always going to be a case where it misses. It sounds to me line you need to ray cast from the previous position of the line in the last Update to the current position making sure that such a line would intersect the plane on which the ink spots exist. You might also cast a sphere rather than a line to make sure that the width of the tippex brush is simulated.