UE4 collision

brief introduction ： In the scene , Collisions exist all the time , Sometimes we need to collide , Sometimes we don't need to collide , Want to close the collision , Illusion provides a collision mechanism . It can solve the collision problem well .

One 、 View collisions

Two 、 Delete and add collisions

3、 ... and 、 Introduction to collision attributes

Four 、 How collision events and collision responses work

5、 ... and 、 Custom collision

Next, we start to analyze the illusory collision mechanism ：

1. View collisions ： Click on the model, click on collsion

2. Delete and add collisions

Automatic collision generation is generally not recommended （ Not quite the collision we want ）

3. Introduction to collision attributes

 

4. Collision events

Before understanding the collision event , We need to understand the meaning of blocking and overlapping .

stop ： It refers to two objects with collision. As long as they touch, they will block , however , You need to enable   Simulate the generation of hit Events （Simulation Generates Hit Events）  To perform   Event hit , This function is in the blueprint 、 Destructables Actor、 Trigger, etc .

overlap ： Two objects containing collisions overlap , Overlapping events will occur .

So how do you set that Hit Events and Overlap event

Reference list ：

 Hit event ：

 

One parameter is set as follows

 

Overlap event ：

If disabled   Generate overlapping events （Generate Overlap Events）, Whatever the purpose , overlap   and   Ignore   The effect is exactly the same . In this case , The sphere is set to overlap or ignore ： Make sure Generate Overlap Events It's on . As long as one of the two colliding objects overlaps, an overlapping event will be generated （Generate Overlap Events）.

 

 5. Collision response

  Collision preset ：

Default （Default）	Use the settings that have been applied to static mesh bodies in the static mesh body editor .
Customize ...（Custom...）	Set all custom collision settings for this instance .
NoCollision	No collision .
BlockAll	Block all by default Actor Of WorldStatic object . All new custom channels will use their own default responses .
OverlapAll	By default, with all Actor Overlapping WorldStatic object . All new custom channels will use their own default responses .
BlockAllDynamic	Block all by default Actor Of WorldDynamic object . All new custom channels will use their own default responses .
OverlapAllDynamic	By default, with all Actor Overlapping WorldDynamic object . All new custom channels will use their own default responses .
IngoreOnlyPawn	Ignore Pawn And vehicle WorldDynamic object . All other channels will be set to default .
OverlapOnlyPawn	And Pawn、 The camera and vehicle overlap WorldDynamic object . All other channels will be set to default .
Pawn	Pawn object . It can be used for any operable role or AI Capsule of .
Spectator	Ignore Division WorldStatic All other than Actor Of Pawn object .
CharacterMesh	For character mesh body Pawn object . All other channels will be set to default .
PhysicsActor	simulation Actor.
Destructible	Destructables Actor.
InvisibleWall	Invisible WorldStatic object .
InvisibleWallDynamic	Invisible WorldDynamic object .
Trigger	For triggers WorldDynamic object . All other channels will be set to default .
Ragdoll	Simulate skeleton mesh body components . All other channels will be set to default .
Vehicle	Blocking vehicle （Vehicle）、WorldStatic and WorldDynamic Vehicle object . All other channels will be set to default .

  Collision enabled ：

attribute	explain
No collision （No Collision）	This shape will not have any representation in the physics engine . Not available for spatial queries （ Ray casting 、Sweep、 overlap ） Or simulation （ rigid body 、 constraint ）. This setting provides the best performance , Especially for moving objects .
query only （Query Only）	This shape can only be used for spatial queries （ Ray casting 、Sweep And overlap ）. Not available for simulation （ rigid body 、 constraint ）. For character motion and objects that do not need physical simulation , This setting is very useful . Some performance improvements can be achieved by reducing the data in the physical simulation tree .
Just physics （Physics Only）	This shape can only be used for physical simulation （ rigid body 、 constraint ）. Not available for spatial queries （ Ray casting 、Sweep、 overlap ）. For the simulated secondary motion on the character that does not need to be detected by bone , This setting is very useful . Some performance improvements can be achieved by reducing the data in the query tree .
Enable collision （Collision Enabled）	This shape can be used for spatial query （ Ray casting 、Sweep、 overlap ） And simulation （ rigid body 、 constraint ）.

Collision type ：

attribute	explain
WorldStatic	Apply to any that does not move Actor. Static mesh body Actor Yes, the type may be "WorldStatic" Of Actor A good example of .
WorldDynamic	WorldDynamic Used for moving under the influence of animation or code Actor type ; kinematics . The elevator and door are WorldDynamic Actor Typical example .
Pawn	The type of any entity controlled by the player should be Pawn. The player role is " object type （Object Type）" Should be "Pawn" Of Actor Typical example .
PhysicsBody	Any movement due to physical simulation Actor.
Vehicle （Vehicle）	This is the default type of vehicle .
Destructables （Destructible）	This is the default type of destructible mesh .

Collision response ：

The tracking response is used to track （ Ray casting ）, For example, blueprint node   Trace by channel （Line Trace by Channel）.

attribute	explain
Visibility （Visibility）	Generic visibility test channel .
The camera （Camera）	It is usually used to track an object from a camera .

Object response ：

attribute	explain
WorldStatic	When and WorldStatic When interacting with physical form object types , How should this physical form react .
WorldDynamic	When and WorldDynamic When interacting with physical form object types , How should this physical form react .
Pawn	When and Pawn When interacting with physical form object types , How should this physical form react .
PhysicsBody	When and PhysicsBody When interacting with physical form object types , How should this physical form react .
Vehicle （Vehicle）	When and " Vehicle （Vehicle）" When interacting with physical form object types , How should this physical form react .
Destructables （Destructible）	When and " Destructables （Destructible）" When interacting with physical form object types , How should this physical form react .

6. Custom collision type

Open project settings ->Collsion-> Add detection

summary ： Collision needs to be selected according to the actual situation , Different scenes choose different collision . 

Reference material ： Illusory official https://docs.unrealengine.com/5.0/zh-CN/collision-response-reference-in-unreal-engine/