the game object they're attached to

它可以讓所依附的遊戲物件 對其它碰撞體產生碰撞行為

to react to other colliders

而那些遊戲物件必須有剛體(Rigidbody)元件

provided that one of the game objects

碰撞體有不同的形狀與類別

has a rigidbody component attached.

在場景視圖內它們會以綠色外框形狀顯示

Colliders come in various shapes and types,

它們有這些主要的形狀 球形, 柱形和方形

and are denoted in the scene view

如果需要更複雜的形狀有兩個方法

by a green outline.

你可以用多個幾何物件 將它們的碰撞體放入不同的物件

They can have the following primitive shapes:

最後在階層裡結合成為新的碰撞結構

a sphere, a capsule and a box.

舉例來說, 這個工作檯由許多不同的 碰撞體放在各部位組成一個碰撞結構

For more complex shapes you have two options

另外一個方式是使用網格碰撞體

You can either combine several of these

網格碰撞體會和網格的形狀相同

primitive shapes together by applying

右邊的這個工作檯並沒有碰撞體 因為它使用了網格碰撞體

primitive colliders to different objects.

我們不建議使用網格碰撞體 因為網格碰撞體是依照網格形狀所產生

in our hierarchy.

所以可能會造成太複雜的碰撞結構 進而影響遊戲的效能

For example this workbench

這也是為甚麼通常 我們會使用組合式碰撞體的原因

has a number of objects which simply

此外還有第三種方式 來產生幾何形狀碰撞體

serve to make up it's different colliders

先簡化物件的模型 然後將模型製作成網格碰撞體即可

for various areas.

在這個範例裡我們所用的是 一個複雜的機器手臂

The other option is to use a mesh collider,

它擁有很複雜的網格 但我們並不希望它的網格碰撞體如此複雜

which will fit the exact shape of the

所以我們建立了第二組簡化的網格模型 然後用這些簡化的模型製作網格碰撞體

mesh that you specify.

像是這個機器爪的網格 比我們為它產生的網格碰撞體還要複雜

The workbench on the right has no hierarchy

這是用兩個FBX檔來完成

but instead uses a mesh collider.

一個是原始的機器手臂 和簡化過的幾何模型

The reason not to use a mesh collider

然後我們在每一個子物件裡 都加入了網格碰撞體

is that it will fit the exact shape

然後將簡化過的幾何模型 拖曳到對應的網格碰撞體的網格(Mesh)

of the mesh that you specify. So if you

這樣一來，我們就可以達到碰撞的需求 同時也避免效能的問題

only specify the mesh of your detailed model

當碰撞在遊戲引擎裡發生時 碰撞體會呼叫OnCollisionEnter事件

then it may be providing too detailed

在這個場景我們的球體物件 附有一個球形碰撞體和剛體

a collision mesh and effecting performance.

剛體有重量(Mass)和重力(Gravity)屬性

This is the reason why it's often better

當我播放時, 球體物件會掉落 並碰到其他物件

to make a compound setup instead.

我們的方體物件附有一個方形碰撞體

However it should be noted that a third

而在掉落的球體上我們加入了這個程式腳本

option for creating collision geometry

這個程式腳本進行了三個碰撞事件的檢查

is to use a separate, simpler set of

碰撞進入(OnCollisionEnter)

geometry and still use a mesh collider.

碰撞持續(OnCollisionStay)

In this example we have this complex

和碰撞結束(OnCollisionExit)

robot arm asset.

當這些事件被呼叫時我用Debug.Log語法 在控制台(Console)寫入資訊

It's a very detailed mesh

提示進入、停留和離開的訊息

but we don't want a mesh as complex

所以當我們檢視控制台內容時

as this for the collisions.

你會先看到碰撞進入 接下來碰撞持續了一陣子, 最後碰撞結束

So what we've done is built

如果我們將遊戲暫停 我們可以詳細的檢視這個範例

a secondary set of geometry which we've

當我單步執行每一幀

then applied to a series of mesh colliders.

你可以看到當碰撞開始時 控制台顯示了碰撞進入的訊息

For example this part of the claw is more

代表OnCollisionEnter事件剛被呼叫

detailed than the collision mesh

當我繼續後換OnCollisionStay被呼叫

that we've created for it.

控制台顯示了碰撞持續的訊息 因為兩個碰撞體還保持在碰撞的階段

And this has been done in two separate

直到兩個碰撞體不再有碰撞行為 OnCollisionExit事件就會被呼叫

FBX files -The original artwork and

要注意的是，如果要觸發碰撞(OnCollision) 兩個碰撞的物件之中一個必須有剛體元件

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.