Collisions tell the game engine where a player can and cannot go. Without a collision mesh, the player could walk through walls or fall straight through the ground. Also, since we provide \features like jetpacks, you might want to limit the area your player could fly around.
Unreal can generate two types of collision, simple and complex collision shapes.
Simple Collision is primitives like cubes, spheres, capsules, and convex hulls. Complex Collision is the tri-mesh of a given object. By default, Unreal Engine creates both simple and complex shapes, then, based on what the user wants (complex query versus simple query), the physics solver will use the corresponding shape for scene queries and collision tests.
The auto-generated simple collision sometimes cannot meet all your detailed needs. And complex collision is often too heavy performance-wise. Creating a Custom Collision is the best solution for the times that we cannot use the auto-generated simple collision.
Follow this explanation by Unreal to create Custom Collision:
We also recommend you use Blocking Volumes, particularly in the case of walls, ceilings and floors in structures. This can cause scenes to operate more predictably, and can also improve performance by reducing the cost of physics simulation.
If you use blocking volumes in your scene, please create a sublevel named ‘Your Level Name_Collision’ and put them there. Remember to set the streaming method to be ‘Always Loaded’.
If you want a mesh to cut the teleporter ray without teleporting on it, you can block the teleport channel and add the NoTeleport or no teleport tag to the actor or on the component itself.