Unreal Engine Movement Systems: Physics vs. Scripted

Why Movement Systems Matter

Many developers struggle with two extremes:

• “I must use only CMC!” → Ends up with janky animations.
• “Scripting is too complex!” → Misses cinematic polish.

The truth? Most games use a hybrid approach. Here’s how to do it right.

1. Physics-Driven Movement (Default CMC)

Unreal’s Character Movement Component (CMC) handles gravity, slopes, and collisions automatically.

// Enable default walking mode
Character->GetCharacterMovement()->SetMovementMode(EMovementMode::MOVE_Walking);

When to Use

• Multiplayer shooters (Fortnite)
• Open-world survival (ARK: Survival Evolved)

Pros & Cons

Pros	Cons
Quick setup	Clunky animations
Dynamic interactions	Physics glitches

2. Scripted Movement (Splines/Detectors)

// Switch to custom movement mode
Character->GetMovementComponent()->SetMovementMode(EMovementMode::MOVE_Custom);

Best For

• Climbing systems (Uncharted)
• Quick-time events (God of War)

Pros & Cons

• Cinematic control
• Time-consuming setup

3. Hybrid Systems: Best of Both Worlds

Example workflow for climbing:

// 1. Detect climbable surface
if (HasValidClimbPoint())
{
  // 2. Switch to scripted mode
  SetMovementMode(MOVE_Custom);
  // 3. Play climb animation
  PlayAnimMontage(ClimbMontage);
}

4. Syncing Animations & Abilities

Use these tools to avoid chaos:

Tools Table

Tool	Purpose
Motion Warping	Snap characters to ledges
Anim Notifies	Trigger events mid-animation

// Using Anim Notify in C++
void UClimbAnimNotify::Notify(USkeletalMeshComponent* MeshComp)
{
  if (Actor = MeshComp->GetOwner())
  {
    Actor->StartClimb(); // Trigger climb logic
  }
}

5. Building a Custom Movement Component

For advanced control, create a custom movement component. Ideal for:

• Unique mechanics (e.g., wall-running, grappling hooks)
• Mixed movement modes (e.g., flying + climbing)

Step 1: Create the Component

// Header (.h)
UCLASS()
class UCustomMovementComponent : public UCharacterMovementComponent
{
  GENERATED_BODY()
  
public:
  // Define custom movement modes
  virtual void PhysCustom(float deltaTime, int32 Iterations) override;
};

Step 2: Add Custom Movement Logic

// Source (.cpp)
void UCustomMovementComponent::PhysCustom(float deltaTime, int32 Iterations)
{
  // Example: Climbing logic
  if (IsClimbing())
  {
    Velocity = ClimbDirection * ClimbSpeed;
    MoveUpdatedComponent(Velocity * deltaTime, UpdatedComponent->GetComponentRotation(), true);
  }
}

Step 3: Assign to Character

 

1. In your Character class header:

   UPROPERTY(VisibleAnywhere)
   UCustomMovementComponent* CustomMovement;

2. In the constructor:

   CustomMovement = CreateDefaultSubobject(TEXT("CustomMovement"));

Step 4: Switch Modes

// Enter climbing mode
CustomMovement->SetMovementMode(EMovementMode::MOVE_Custom);

When to Go Custom

Scenario	Solution
Unique movement (e.g., spider-man swinging)	Full custom component
Minor tweaks (e.g., double jump)	Extend CMC, don’t reinvent

Quick Guide

• Shooters: 90% CMC + 10% Scripted
• Cinematic Games: 30% CMC + 70% Scripted

Conclusion

Don’t fear hybrid systems! Even AAA games like Assassin’s Creed mix physics and scripting. Start simple, use Unreal’s tools, and iterate.

Need Help?

• Study the Lyra Starter Game (Unreal 5 sample project).
• Use Motion Warping plugin for smooth transitions.