Detect Surface Angle

Official Documentation: docs.unrealengine.com.

Description

Detect the Surface: get important data for example the angle to decide if it's climable or not.

tip

Useful to detect if a Wall would be steep enough to be Climbable.

Line Trace

First we need something to detect the Mesh/Object, so we'll use a LineTrace for that.

YourCharacter.cpp

// In this example we'll implement the LineTrace inside the Tick
// but you can move the Code wherever you want.
void AYourCharacter::Tick(float Deltatime)
{
  Super::Tick(Deltatime);

  // Define the parameters for the LineTrace
  FHitResult Hit; // Stores the Hit-Result from the first blocking hit
  // Getting the Forward Vector, where the Actor is currently facing
  // and multipling it by 1000 units along the axis to define the End Point
  FVector Forward = GetActorLocation()->GetForwardVector() * 1000.f; 
  // Get the Actors Location which will be our Starting point for the Trace
  FVector Start = GetActorLocation();
  FVector End = Start + Forward; // Combine both to have the full LineTrace
  FCollisionQueryParams CollisionParams; // define the collision
  CollisionParams.AddIgnoredActor(this); // add Actors to ignore, in this case this Actor
  // if you want to ignore more Actors, just add the Line above again
  // and add a different Actor Type inside the parantheses e.g: AddIgnoredActor(SomeActor::StaticClass())

  if (Controller != nullptr) //check if the Controller is not null
    // Call the LineTrace Function and provide the parameters we just defined
    GetWorld()->LineTraceSingleByChannel(Hit, Start, End, ECC_Visibility, CollisionParams);
    // To vizualize the LineTrace in-game, lets also draw a DebugLine:
    DrawDebugLine(GetWorld(), Start, End, Hit.bBlockingHit ? FColor::Blue : FColor::Red, false, 5.0f, 1.0f, 10.0f);

    // Check if ImpactNormal and your Characters GetActorUpVector() are not null
    if (Hit.ImpactNormal && GetActorUpVector())
    {
      float DotProduct = FVector::DotProduct(Hit.ImpactNormal, GetActorUpVector());

      if (FMath::Abs(DotProduct) < ClimbableAngleThreshold)
      {
        // Wall is climbable.
        // if DotProduct is above 0, then its angled and if its 1 then the surface is vertical
      }
    }
    else
    {
      // if nothing got hit, you can do something here 
      // or just Log that nothing got got
      UE_LOG(LogTemp, Log, TEXT("Nothing got got"));
    }
}

This was an example on how to detect surface angles with normals in Unreal Engine C++.