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  • Colliders are a component that allows

  • the game object they're attached to

  • to react to other colliders

  • provided that one of the game objects

  • has a rigidbody component attached.

  • Colliders come in various shapes and types,

  • and are denoted in the scene view

  • by a green outline.

  • They can have the following primitive shapes:

  • a sphere, a capsule and a box.

  • For more complex shapes you have two options

  • You can either combine several of these

  • primitive shapes together by applying

  • primitive colliders to different objects.

  • in our hierarchy.

  • For example this workbench

  • has a number of objects which simply

  • serve to make up it's different colliders

  • for various areas.

  • The other option is to use a mesh collider,

  • which will fit the exact shape of the

  • mesh that you specify.

  • The workbench on the right has no hierarchy

  • but instead uses a mesh collider.

  • The reason not to use a mesh collider

  • is that it will fit the exact shape

  • of the mesh that you specify. So if you

  • only specify the mesh of your detailed model

  • then it may be providing too detailed

  • a collision mesh and effecting performance.

  • This is the reason why it's often better

  • to make a compound setup instead.

  • However it should be noted that a third

  • option for creating collision geometry

  • is to use a separate, simpler set of

  • geometry and still use a mesh collider.

  • In this example we have this complex

  • robot arm asset.

  • It's a very detailed mesh

  • but we don't want a mesh as complex

  • as this for the collisions.

  • So what we've done is built

  • a secondary set of geometry which we've

  • then applied to a series of mesh colliders.

  • For example this part of the claw is more

  • detailed than the collision mesh

  • that we've created for it.

  • And this has been done in two separate

  • FBX files -The original artwork and

  • a simplified set of geometry.

  • We've then gone through each one,

  • applied a mesh collider and dragged

  • these meshes over as the

  • collision meshes to use.

  • This means that we get the kind of accuracy

  • that we need in terms of collision

  • without the performance overhead.

  • When collisions occur in the game engine

  • one collider strikes another and an event

  • called OnCollisionEnter is called.

  • In this scene our 'prop samoflange' object

  • has a sphere collider component and a rigidbody component.

  • The rigidbody provides mass and gravity.

  • When I play the game, one falls down

  • and strikes the other.

  • The power cube has a box collider attached to it.

  • Also attached to our falling object

  • is this script.

  • This script checks for three collision events.

  • OnCollisionEnter, OnCollisionStay

  • and OnCollisionExit.

  • When each of these occurs it writes

  • to the console using Debug.Log.

  • It will register when Enter is called,

  • when Stay is occurring

  • and when Exit is called.

  • So if we look at our console you can see

  • that Enter is called, Stay has occurred

  • for a while and then Exit is called.

  • If we pause the game and play we can look

  • at this example slowly.

  • As I step through the frames

  • when the collision occurs you can see

  • that Enter is called, so OnCollisionEnter

  • has just occurred.

  • As I continue OnCollisionStay is occurring.

  • You can see on the right here that it's

  • happening several times because these

  • two colliders are still in contact.

  • As we continue to step through

  • eventually OnCollisionExit is called

  • when the two colliders are no longer

  • in contact.

  • Note that for an OnCollision message to

  • to be sent, one of the two objects colliding

  • must have a rigidbody component.

Colliders are a component that allows

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B2 UK mesh collider collision component geometry detailed

Colliders - Unity Official Tutorials

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    朱瑛 posted on 2014/05/02
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