change color of collided part of a line

Hello!!

I would like to be able to do something similar:



I am drawing a line with the mouse.
I'd like that only the segment of the line that collides changes colour. I'd prefer to avoid to create different lines to solve this issue but I have no experience with shaders. May someone help me?


Ps. Already tried:
- The classical
"line.startColor = Color.green;
line.endColor = Color.green;"
changes the colour of the entire line when the line collides with the cube, while I would like to change only the colour of the segment that is colliding.
- Also changing shader does not work since the new shader is applied to the entire line as well.