How can I split up a large model into an octree codewise?

Question

For collision detection, I am attempting to split up a large model into an octree.

If we take this black thing thing to be the ship (104,000 vertices):

Then I would like to split up the faces

I could easily split them up, but the problem is one of location. For example, if we take the bottom left chunk, how can I know that the projectile (in this case, a cannonball) is at that specific chunk?

And also how can I define the areas of the chunks in the first place? And for that matter, I need them to rotate with the ship as well!

I'm hopelessly lost as of how to do this, and so I'm hoping someone can help me out.

Answer 1

first you transform the cannon ball into the coordinate space of the ship.

Then you act as if you want to add the ball's model to the octree and step down through the nodes. If the ball straddles a boundary line then go through both sides.

Once you get into a leaf not then there is the bucket with faces to test with.