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Surfaceflags or something of that sort?

Development Discussion C++ Gameplay Programming
#1

Hello.

I’m pretty new to UE4 (I’m about a month in at the moment) and I’d like to ask if there are any kind of surfaceflags or something of that sort?
By surfaceflags, I mean some kind of indicator which tells you if you are on solid ground, on slippery ice or any other kind of surface. Or would I have to build this in on my own and if so; what would be a good approach?

Best Regards

#2

Take a look at the ShooterGame example, specifically Source/ShooterGame/Effects/ShooterImpactEffect.cpp. There you will see the game code has mapped some #defines in ShooterTypes.h to various values in the EPhysicalSurface enum. You can give these enums names (like ice) in Projects Settings under Engine > Physics > Physical Surfaces. Once you do that, you can create Physic Material Assets which you can assign these surface types to.

Engine/EngineTypes.h:



/** Types of surfaces in the game. */
UENUM(BlueprintType)
enum EPhysicalSurface
{
    SurfaceType_Default UMETA(DisplayName="Default"),
    SurfaceType1 UMETA(Hidden),
    SurfaceType2 UMETA(Hidden),
    SurfaceType3 UMETA(Hidden),
    ...

ShooterTypes.h



#define SHOOTER_SURFACE_Default        SurfaceType_Default
#define SHOOTER_SURFACE_Concrete    SurfaceType1
#define SHOOTER_SURFACE_Dirt        SurfaceType2
#define SHOOTER_SURFACE_Water        SurfaceType3
#define SHOOTER_SURFACE_Metal        SurfaceType4
#define SHOOTER_SURFACE_Wood        SurfaceType5
#define SHOOTER_SURFACE_Grass        SurfaceType6
#define SHOOTER_SURFACE_Glass        SurfaceType7
#define SHOOTER_SURFACE_Flesh        SurfaceType8

Looking up the surface type in ShooterImpactEffect.cpp:



void AShooterImpactEffect::PostInitializeComponents()
{
    Super::PostInitializeComponents();

    UPhysicalMaterial* HitPhysMat = SurfaceHit.PhysMaterial.Get();
    EPhysicalSurface HitSurfaceType = UPhysicalMaterial::DetermineSurfaceType(HitPhysMat);

    // show particles
    UParticleSystem* ImpactFX = GetImpactFX(HitSurfaceType);
    if (ImpactFX)
    {
        UGameplayStatics::SpawnEmitterAtLocation(this, ImpactFX, GetActorLocation(), GetActorRotation());
    }
    ...

Surfaces.PNG
Surfaces.PNG828×623 70.5 KB

Physics-Material.jpg
Physics-Material.jpg652×570 62.8 KB

#3

Great information, thank you!

What I was looking for was more of the physical altering surfaces though; like when you’re walking on ice you’re sliding et.c. Are any of these dynamics built into the engine?

#4

The Physical Material (the last image above) has settings related to friction.

#5

Again, thank you.

If I was to force my character to slide on any surface, how would be best to go about it? I’ve tried setting the Friction to 0 but that doesn’t do it for me.

#6

I’m not sure. Assuming you are using UCharacterMovementComponent, then maybe look at SetWalkableFloorAngle, CurrentFloor, and GroundFriction. GroundFriction, in particular, has the following note that sounds like what you’re trying to achieve:

#7

I made it work by setting all friction variables to 0 when entering the “slide field”, thank you very much!