ue-physics-collision

Name: ue-physics-collision
Author: quodsoler

548installs39forks

How to install ue-physics-collision?

quodsoler/unreal-engine-skills/ue-physics-collision

$npx -y skills add quodsoler/unreal-engine-skills --skill ue-physics-collision

Installs into the current project.

Summary

Use when implementing collision detection, trace queries, physics simulation, or physical interactions in Unreal Engine. Triggers on: 'collision', 'trace', 'LineTrace', 'line trace', 'overlap', 'physics', 'hit result', 'sweep', 'collision channel', 'physics body', 'Chaos', 'raytr

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SKILL.md

1	# UE Physics & Collision
2
3	You are an expert in Unreal Engine's physics and collision systems, including collision channels, trace queries, collision events, physics bodies, and the Chaos physics engine.
4
5	---
6
7	## Step 1: Read Project Context
8
9	Read `.agents/ue-project-context.md` to confirm:
10	- UE version (Chaos is the default physics backend from UE 5.0; PhysX was deprecated)
11	- Which modules need `"PhysicsCore"` and `"Engine"` in their `Build.cs`
12	- Whether the project uses skeletal meshes with physics assets, or primarily static mesh collision
13	- Dedicated server targets (affects whether physics simulation should run server-side)
14
15	---
16
17	## Step 2: Identify the Need
18
19	Ask which area applies if not stated:
20	1. Collision setup — channels, profiles, responses on components
21	2. Trace queries — line traces, sweeps, overlap queries for gameplay logic
22	3. Collision events — OnComponentHit, OnBeginOverlap, OnEndOverlap delegates
23	4. Physics simulation — rigid body sim, forces, impulses, damping, constraints
24	5. Physical materials — friction, restitution, surface type detection
25
26	---
27
28	## Collision Channels & Profiles
29
30	### ECollisionChannel — built-in channels
31
32	```cpp
33	ECC_WorldStatic, ECC_WorldDynamic, ECC_Pawn, ECC_PhysicsBody,
34	ECC_Vehicle, ECC_Destructible // object channels (what an object IS)
35	ECC_Visibility, ECC_Camera // trace channels (used for queries)
36	// Custom: ECC_GameTraceChannel1..ECC_GameTraceChannel18
37	```
38
39	Responses: `ECR_Ignore` / `ECR_Overlap` (events, no block) / `ECR_Block` (physical block + events).
40
41	Built-in profiles: `BlockAll`, `BlockAllDynamic`, `OverlapAll`, `OverlapAllDynamic`, `Pawn`, `PhysicsActor`, `NoCollision`.
42
43	### Setting Collision in C++
44
45	```cpp
46	MyMesh->SetCollisionProfileName(TEXT("BlockAll")); // preferred — sets all at once
47	MyMesh->SetCollisionEnabled(ECollisionEnabled::QueryAndPhysics);
48	// ECollisionEnabled: NoCollision \| QueryOnly \| PhysicsOnly \| QueryAndPhysics
49	MyMesh->SetCollisionObjectType(ECC_PhysicsBody);
50	MyMesh->SetCollisionResponseToAllChannels(ECR_Block);
51	MyMesh->SetCollisionResponseToChannel(ECC_Pawn, ECR_Overlap);
52	MyMesh->SetCollisionResponseToChannel(ECC_Camera, ECR_Ignore);
53	```
54
55	### Object Type Channels vs Trace Channels
56
57	Object type channels describe what an actor IS (Pawn, WorldDynamic, Vehicle). Every component has exactly one object type. Trace channels are used for queries — they define what a trace is LOOKING FOR (Visibility, Camera, Weapon). This distinction determines which query function to use: `ByObjectType` matches the target's object type channel; `ByChannel` uses the querier's trace channel and checks responses. Most gameplay traces use trace channels (`ECC_Visibility`, custom `Weapon`); overlap queries for "find all pawns" use object type (`ECC_Pawn`).
58
59	### Custom Channels — DefaultEngine.ini
60
61	```ini
62	[/Script/Engine.CollisionProfile]
63	+DefaultChannelResponses=(Channel=ECC_GameTraceChannel1,DefaultResponse=ECR_Block,bTraceType=True,bStaticObject=False,Name="Weapon")
64	+DefaultChannelResponses=(Channel=ECC_GameTraceChannel2,DefaultResponse=ECR_Block,bTraceType=False,bStaticObject=False,Name="Interactable")
65	+Profiles=(Name="Interactable",CollisionEnabled=QueryAndPhysics,ObjectTypeName="Interactable",CustomResponses=((Channel="Weapon",Response=ECR_Ignore),(Channel="Visibility",Response=ECR_Block)))
66	```
67
68	`bTraceType=True` = trace channel; `bTraceType=False` = object type channel. They use separate query functions.
69
70	See `references/collision-channel-setup.md` for full profile examples.
71
72	---
73
74	## Trace Queries
75
76	### FCollisionQueryParams
77
78	```cpp
79	FCollisionQueryParams Params;
80	Params.TraceTag = TEXT("WeaponTrace"); // for profiling/debug
81	Params.bTraceComplex = false; // false=simple hull (fast); true=per-poly (expensive)
82	Params.bReturnPhysicalMaterial = true; // populates Hit.PhysMaterial
83	Params.bReturnFaceIndex = false; // expensive, only when needed
84	Params.AddIgnoredActor(this);
85	Params.AddIgnoredComponent(MyComp);
86	```
87
88	### World-Level Trace Functions (C++) — from `WorldCollision.h` via `UWorld`
89
90	```cpp
91	FHitResult Hit;
92	// By trace channel
93	GetWorld()->LineTraceSingleByChannel(Hit, Start, End, ECC_Visibility, Params);
94	GetWorld()->LineTraceMultiByChannel(Hits, Start, End, ECC_Visibility, Params);
95	// By object type
96	FCollisionObjectQueryParams ObjParams(ECC_PhysicsBody);
97	ObjParams.AddObjectTypesToQuery(ECC_WorldDynamic);
98	GetWorld()->LineTraceSingleByObjectType(Hit, Start, End, ObjParams, Params);
99	// By profile
100	GetWorld()->LineT

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ue-physics-collision

548installs39forks

View on GitHub

How to install ue-physics-collision?

quodsoler/unreal-engine-skills/ue-physics-collision

$npx -y skills add quodsoler/unreal-engine-skills --skill ue-physics-collision

Installs into the current project.

Summary

Files · 1

View on GitHub

SKILL.md

1	# UE Physics & Collision
2
3	You are an expert in Unreal Engine's physics and collision systems, including collision channels, trace queries, collision events, physics bodies, and the Chaos physics engine.
4
5	---
6
7	## Step 1: Read Project Context
8
9	Read `.agents/ue-project-context.md` to confirm:
10	- UE version (Chaos is the default physics backend from UE 5.0; PhysX was deprecated)
11	- Which modules need `"PhysicsCore"` and `"Engine"` in their `Build.cs`
12	- Whether the project uses skeletal meshes with physics assets, or primarily static mesh collision
13	- Dedicated server targets (affects whether physics simulation should run server-side)
14
15	---
16
17	## Step 2: Identify the Need
18
19	Ask which area applies if not stated:
20	1. Collision setup — channels, profiles, responses on components
21	2. Trace queries — line traces, sweeps, overlap queries for gameplay logic
22	3. Collision events — OnComponentHit, OnBeginOverlap, OnEndOverlap delegates
23	4. Physics simulation — rigid body sim, forces, impulses, damping, constraints
24	5. Physical materials — friction, restitution, surface type detection
25
26	---
27
28	## Collision Channels & Profiles
29
30	### ECollisionChannel — built-in channels
31
32	```cpp
33	ECC_WorldStatic, ECC_WorldDynamic, ECC_Pawn, ECC_PhysicsBody,
34	ECC_Vehicle, ECC_Destructible // object channels (what an object IS)
35	ECC_Visibility, ECC_Camera // trace channels (used for queries)
36	// Custom: ECC_GameTraceChannel1..ECC_GameTraceChannel18
37	```
38
39	Responses: `ECR_Ignore` / `ECR_Overlap` (events, no block) / `ECR_Block` (physical block + events).
40
41	Built-in profiles: `BlockAll`, `BlockAllDynamic`, `OverlapAll`, `OverlapAllDynamic`, `Pawn`, `PhysicsActor`, `NoCollision`.
42
43	### Setting Collision in C++
44
45	```cpp
46	MyMesh->SetCollisionProfileName(TEXT("BlockAll")); // preferred — sets all at once
47	MyMesh->SetCollisionEnabled(ECollisionEnabled::QueryAndPhysics);
48	// ECollisionEnabled: NoCollision \| QueryOnly \| PhysicsOnly \| QueryAndPhysics
49	MyMesh->SetCollisionObjectType(ECC_PhysicsBody);
50	MyMesh->SetCollisionResponseToAllChannels(ECR_Block);
51	MyMesh->SetCollisionResponseToChannel(ECC_Pawn, ECR_Overlap);
52	MyMesh->SetCollisionResponseToChannel(ECC_Camera, ECR_Ignore);
53	```
54
55	### Object Type Channels vs Trace Channels
56
57	Object type channels describe what an actor IS (Pawn, WorldDynamic, Vehicle). Every component has exactly one object type. Trace channels are used for queries — they define what a trace is LOOKING FOR (Visibility, Camera, Weapon). This distinction determines which query function to use: `ByObjectType` matches the target's object type channel; `ByChannel` uses the querier's trace channel and checks responses. Most gameplay traces use trace channels (`ECC_Visibility`, custom `Weapon`); overlap queries for "find all pawns" use object type (`ECC_Pawn`).
58
59	### Custom Channels — DefaultEngine.ini
60
61	```ini
62	[/Script/Engine.CollisionProfile]
63	+DefaultChannelResponses=(Channel=ECC_GameTraceChannel1,DefaultResponse=ECR_Block,bTraceType=True,bStaticObject=False,Name="Weapon")
64	+DefaultChannelResponses=(Channel=ECC_GameTraceChannel2,DefaultResponse=ECR_Block,bTraceType=False,bStaticObject=False,Name="Interactable")
65	+Profiles=(Name="Interactable",CollisionEnabled=QueryAndPhysics,ObjectTypeName="Interactable",CustomResponses=((Channel="Weapon",Response=ECR_Ignore),(Channel="Visibility",Response=ECR_Block)))
66	```
67
68	`bTraceType=True` = trace channel; `bTraceType=False` = object type channel. They use separate query functions.
69
70	See `references/collision-channel-setup.md` for full profile examples.
71
72	---
73
74	## Trace Queries
75
76	### FCollisionQueryParams
77
78	```cpp
79	FCollisionQueryParams Params;
80	Params.TraceTag = TEXT("WeaponTrace"); // for profiling/debug
81	Params.bTraceComplex = false; // false=simple hull (fast); true=per-poly (expensive)
82	Params.bReturnPhysicalMaterial = true; // populates Hit.PhysMaterial
83	Params.bReturnFaceIndex = false; // expensive, only when needed
84	Params.AddIgnoredActor(this);
85	Params.AddIgnoredComponent(MyComp);
86	```
87
88	### World-Level Trace Functions (C++) — from `WorldCollision.h` via `UWorld`
89
90	```cpp
91	FHitResult Hit;
92	// By trace channel
93	GetWorld()->LineTraceSingleByChannel(Hit, Start, End, ECC_Visibility, Params);
94	GetWorld()->LineTraceMultiByChannel(Hits, Start, End, ECC_Visibility, Params);
95	// By object type
96	FCollisionObjectQueryParams ObjParams(ECC_PhysicsBody);
97	ObjParams.AddObjectTypesToQuery(ECC_WorldDynamic);
98	GetWorld()->LineTraceSingleByObjectType(Hit, Start, End, ObjParams, Params);
99	// By profile
100	GetWorld()->LineT

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