Area Collision (File Format)

The format for area collision stores the collision geometry for levels, and can be found in the MREA format. Most of it is shared with the DCLN format, but there are a few parts that are exclusive to MREA.

Collision Octree
The collision octree is a node tree that allows an actor to quickly locate any triangles it might be colliding with without needing to check every triangle in the mesh. The type of the root node of the tree is determined by the Octree Root Node Type value in the header, but it's usually a branch node.

Branch Node
A branch node has eight child nodes. Each child occupies one octant of the branch's bounding box.

Leaf Node
A leaf node marks the end of a tree branch. It contains a list of triangles that an object in this leaf could be colliding with.