How to render part of an object

Hi guys, i’m trying to make a dead tree change when the player gets closer to her. I know that i need to model 2 different trees, and my player need to have a sphere or box collider, but how to make the tree change and where change.15056-tree2.png

You can put extra foliage in as a separate object and switch the rendering on or off for that object as you need it. Some clever operations on a Texture2D could allow you to mix a ‘dead’ and ‘alive’ texture across some defined boundary.

I found the solution, thank you all.
You can see the solution of this problem here