Unity Game Optimization - Third Edition

The Collision Matrix

The physics engine features a Collision Matrix that defines which objects are allowed to collide with which other objects. Objects that do not fit this matrix are automatically ignored by the physics engine when the time comes to resolve bounding volume overlaps and collisions. This saves on physics processing during collision detection stages and allows the objects to move through one another without any collisions taking place.

The Collision Matrix can be accessed through Edit | Project Settings | (Physics / Physics2D) | Layer Collision Matrix.

The Collision Matrix system works through Unity's Layer system. The matrix represents every possible Layer-to-Layer combination that might be possible, and enabling a checkbox ...