Implement hydrostatic forces

Implement hydrostatic forces

Source/SeaOfCrooks/Private/Components/BuoyancyComponent.cpp

@@ -22,16 +22,16 @@ UBuoyancyComponent::UBuoyancyComponent()
 	// ...
 }
 
-
 // Called when the game starts
 void UBuoyancyComponent::BeginPlay()
 {
 	Super::BeginPlay();
 
-	// ...
 	UStaticMeshComponent* MeshComp = Cast<UStaticMeshComponent>(GetOwner()->GetRootComponent());
 	VolumeMesh = MeshComp->GetStaticMesh();
 	
+	VolumeAsPrimComp = Cast<UPrimitiveComponent>(MeshComp);
+	
 	SubmergedTriangles = TArray<FTriangleData>();
 	SubmergedTriangles.SetNum(GetNumTriangles(), false);
 }
@@ -46,7 +46,7 @@ void UBuoyancyComponent::TickComponent(float DeltaTime, ELevelTick TickType, FAc
 	
 	// determine height of vertices above or below surface of water
 	ASOCGameState* State = Cast<ASOCGameState>(GetWorld()->GetGameState());
-	AOcean* Ocean = nullptr;
+	Ocean = nullptr;
 	if(State)
 	{
 		Ocean = State->GetOcean();
@@ -70,11 +70,10 @@ void UBuoyancyComponent::TickComponent(float DeltaTime, ELevelTick TickType, FAc
 
 			if(V1.Depth < 0.0f || V2.Depth < 0.0f || V3.Depth < 0.0f)
 			{
-				FTriangleData temp(V1, V2, V3);
+				FTriangleData temp(V1, V2, V3, Ocean->GetOceanHeight());
 				Triangles.Add(temp);
-				FVector Center = (V1.Position + V2.Position + V3.Position) / 3.0f;
 				if(DebugBuoyancy)
-			        DrawDebugSphere(GetWorld(), Center, 5.0f, 12, FColor::Yellow, false, 0.0f, 0, 1.0f);
+			        DrawDebugSphere(GetWorld(), temp.Center, 5.0f, 12, FColor::Yellow, false, 0.0f, 0, 1.0f);
 			}
 		}
 
@@ -84,18 +83,33 @@ void UBuoyancyComponent::TickComponent(float DeltaTime, ELevelTick TickType, FAc
 		{
 			FString DebugMsg = FString::Printf(TEXT("Num Submerged Triangles: %d\nNum Generated Triangles: %d"),
              Triangles.Num(), SubmergedTriangles.Num());
-			GEngine->AddOnScreenDebugMessage(-1, 0.0f, FColor::Cyan, DebugMsg);
+			GEngine->AddOnScreenDebugMessage(-1, -1.0f, FColor::Cyan, DebugMsg);
 
 			for (auto Triangle : SubmergedTriangles)
 			{
-				DrawDebugSphere(GetWorld(), Triangle.Highest.Position, 2.0f, 12, FColor::Red,
+				DrawDebugSphere(GetWorld(), Triangle.V3.GlobalPosition, 2.0f, 12, FColor::Red,
 					false, 0.0f, 0, 1.0f);
-				DrawDebugSphere(GetWorld(), Triangle.Middle.Position, 2.0f, 12, FColor::Red,
+				DrawDebugSphere(GetWorld(), Triangle.V2.GlobalPosition, 2.0f, 12, FColor::Red,
 					false, 0.0f, 0, 1.0f);
-				DrawDebugSphere(GetWorld(), Triangle.Lowest.Position, 2.0f, 12, FColor::Red,
+				DrawDebugSphere(GetWorld(), Triangle.V1.GlobalPosition, 2.0f, 12, FColor::Red,
 					false, 0.0f, 0, 1.0f);
 			}
 		}
+
+		if(VolumeAsPrimComp)
+		{
+			for (auto Triangle : SubmergedTriangles)
+			{
+				float rhoInKgCm3 = 0.001025f;
+				// F = -p*g*Hcenter*normal
+				FVector Force = -rhoInKgCm3 * GetWorld()->GetGravityZ() * Triangle.DistanceToSurface * Triangle.Area * Triangle.Normal;
+				FVector VerticalForce(0.0f, 0.0f, Force.Z);
+				VolumeAsPrimComp->AddForceAtLocation(VerticalForce, Triangle.Center);
+			}
+		}
+		
+		FString DebugMsg = FString::Printf(TEXT("Velocity.Z: %s"), *FString::SanitizeFloat(VolumeAsPrimComp->GetPhysicsLinearVelocity().Z));
+		GEngine->AddOnScreenDebugMessage(-1, -1.0f, FColor::Magenta, DebugMsg);
 	}
 }
 
@@ -133,7 +147,7 @@ TArray<FVertexData> UBuoyancyComponent::GetVertexPositions()
 				// convert asset space vertex position to world space
 				FVector WorldSpaceVertexPos = GetOwner()->GetActorLocation() + GetOwner()->GetTransform().TransformVector(VertexBuffer->VertexPosition(idx));
 				FVertexData temp;
-				temp.Position = WorldSpaceVertexPos;
+				temp.GlobalPosition = WorldSpaceVertexPos;
 				VertexPositions.Add(temp);
 			}
 		}
@@ -175,12 +189,21 @@ void UBuoyancyComponent::ProcessTriangles(TArray<FTriangleData>& Triangles)
 		}
 		else if (NumSubmergedVertices == 2)
 		{
-			FVector H = Triangle.Highest.Position;
-			FVector M = Triangle.Middle.Position;
-			FVector L = Triangle.Lowest.Position;
-			float hH = Triangle.Highest.Depth;
-			float hM = Triangle.Middle.Depth;
-			float hL = Triangle.Lowest.Depth;
+			FVertexData V1 = Triangle.V1;
+			FVertexData V2 = Triangle.V2;
+			FVertexData V3 = Triangle.V3;
+			TArray<FVertexData> Vertices = {V1, V2, V3};
+			Vertices.Sort();
+			V1 = Vertices[0];
+			V2 = Vertices[1];
+			V3 = Vertices[2];
+			
+			FVector H = V3.GlobalPosition;
+			FVector M = V2.GlobalPosition;
+			FVector L = V1.GlobalPosition;
+			float hH = V3.Depth;
+			float hM = V2.Depth;
+			float hL = V1.Depth;
 			
 			FVector MH = H - M;
 			float tM = -hL/(hH - hL);
@@ -192,17 +215,26 @@ void UBuoyancyComponent::ProcessTriangles(TArray<FTriangleData>& Triangles)
 			FVector LIL = tL * LH;
 			FVector IL = LIL + L;
  
-			SubmergedTriangles.Add(FTriangleData(IM, IL, L));
-			SubmergedTriangles.Add(FTriangleData(M, IM, L));
+			SubmergedTriangles.Add(FTriangleData(L, IL, IM, Ocean->GetOceanHeight()));
+			SubmergedTriangles.Add(FTriangleData(M, L, IM, Ocean->GetOceanHeight()));
 		}
 		else if (NumSubmergedVertices == 1)
 		{
-			FVector H = Triangle.Highest.Position;
-			FVector M = Triangle.Middle.Position;
-			FVector L = Triangle.Lowest.Position;
-			float hH = Triangle.Highest.Depth;
-			float hM = Triangle.Middle.Depth;
-			float hL = Triangle.Lowest.Depth;
+			FVertexData V1 = Triangle.V1;
+			FVertexData V2 = Triangle.V2;
+			FVertexData V3 = Triangle.V3;
+			TArray<FVertexData> Vertices = {V1, V2, V3};
+			Vertices.Sort();
+			V1 = Vertices[0];
+			V2 = Vertices[1];
+			V3 = Vertices[2];
+			
+			FVector H = V3.GlobalPosition;
+			FVector M = V2.GlobalPosition;
+			FVector L = V1.GlobalPosition;
+			float hH = V3.Depth;
+			float hM = V2.Depth;
+			float hL = V1.Depth;
 
 			FVector LM = M - L;
 			float tM = -hL/(hM - hL);
@@ -214,7 +246,7 @@ void UBuoyancyComponent::ProcessTriangles(TArray<FTriangleData>& Triangles)
 			FVector LJH = tH * LH;
 			FVector JH = LJH + L;
 
-			SubmergedTriangles.Add(FTriangleData(JH, JM, L));
+			SubmergedTriangles.Add(FTriangleData(L, JH, JM, Ocean->GetOceanHeight()));
 		}
 	}
 }

Source/SeaOfCrooks/Private/ShipBase.cpp

@@ -11,6 +11,13 @@ AShipBase::AShipBase()
 
 	ShipMesh = CreateDefaultSubobject<UStaticMeshComponent>(TEXT("ShipMesh"));
 	ShipMesh->SetupAttachment(RootComponent);
+	UPrimitiveComponent* ShipMeshAsPrim = Cast<UPrimitiveComponent>(ShipMesh);
+	if(ShipMeshAsPrim)
+	{
+		ShipMeshAsPrim->SetSimulatePhysics(true);
+		ShipMeshAsPrim->SetMassOverrideInKg(NAME_None, 800.0f, true);
+		ShipMeshAsPrim->SetLinearDamping(0.05f);
+	}
 
 	BuoyancyComp = CreateDefaultSubobject<UBuoyancyComponent>(TEXT("BuoyancyComponent"));
 }

Source/SeaOfCrooks/Public/Components/BuoyancyComponent.h

@@ -4,14 +4,17 @@
 
 #include "CoreMinimal.h"
 #include "Components/ActorComponent.h"
+#include "Game/SOCGameState.h"
+
 #include "BuoyancyComponent.generated.h"
 
-USTRUCT()
+USTRUCT(BlueprintType)
 struct FVertexData
 {
 	GENERATED_BODY()
 
-	FVector Position;
+	FVector GlobalPosition;
+	
 	// depth of the vertex above the surface of the water
 	// negative value means the vertex is submerged
 	float Depth;
@@ -22,19 +25,19 @@ struct FVertexData
 
 	FVertexData(FVector Position)
 	{
-		this->Position = Position;
+		this->GlobalPosition = Position;
 		Depth = 0.0f;
 	}
 
 	FVertexData(FVector Position, float Depth)
 	{
-		this->Position = Position;
+		this->GlobalPosition = Position;
 		this->Depth = Depth;
 	}
 	
 	void CalculateDepth(float SurfaceHeight)
 	{
-		Depth = Position.Z - SurfaceHeight;
+		Depth = GlobalPosition.Z - SurfaceHeight;
 	}
 
 	bool operator< (const FVertexData& rhs) const
@@ -43,38 +46,61 @@ struct FVertexData
 	}
 };
 
-USTRUCT()
+USTRUCT(BlueprintType)
 struct FTriangleData
 {
 	GENERATED_BODY()
 	
-	FVertexData Highest;
-	FVertexData Middle;
-	FVertexData Lowest;
+	FVertexData V1; // lowest
+	FVertexData V2; // middle
+	FVertexData V3; // highest
+
+	FVector Center;
+	
+	float DistanceToSurface;
+
+	FVector Normal;
+
+	float Area;
 	
 	FTriangleData() {}
 	
-	FTriangleData(FVertexData V1, FVertexData V2, FVertexData V3)
+	FTriangleData(const FVertexData V1, const FVertexData V2, const FVertexData V3, float OceanHeight)
 	{
-		TArray<FVertexData> Vertices = {V1, V2, V3};
-		Vertices.Sort();
-		Lowest = Vertices[0];
-		Middle = Vertices[1];
-		Highest = Vertices[2];
+		this->V1 = V1;
+		this->V2 = V2;
+		this->V3 = V3;
+
+		Center = (V1.GlobalPosition + V2.GlobalPosition + V3.GlobalPosition) / 3.0f;
+
+		DistanceToSurface = FMath::Abs(OceanHeight - Center.Z);
+		
+		Normal = FVector::CrossProduct(V2.GlobalPosition - V1.GlobalPosition, V3.GlobalPosition - V1.GlobalPosition);
+		Normal.Normalize();
+
+		// Heron's formula
+		float V12 = FVector::Distance(V1.GlobalPosition, V2.GlobalPosition);
+		float V23 = FVector::Distance(V2.GlobalPosition, V3.GlobalPosition);
+		float V13 = FVector::Distance(V1.GlobalPosition, V3.GlobalPosition);
+
+		// Half Triangle Perimeter
+		float S = (V12 + V23 + V13) / 2.0f;
+		
+		Area = FMath::Sqrt(S * (S - V12) * (S - V23) * (S - V13));
 	}
 	
-	int32 GetNumSubmergedVertices()
+	int32 GetNumSubmergedVertices() const
 	{
 		int32 result = 0;
-		if(Highest.Depth < 0.0f)
+		if(V3.Depth < 0.0f)
 		{
 			result++;
 		}
-		if(Middle.Depth < 0.0f)
+		if(V2.Depth < 0.0f)
 		{
 			result++;
 		}
-		if(Lowest.Depth < 0.0f)
+		if(V1.Depth < 0.0f)
 		{
 			result++;
 		}
@@ -95,9 +121,11 @@ protected:
 	UPROPERTY(BlueprintReadOnly)
 	UStaticMesh* VolumeMesh;
 
-	UPROPERTY()
+	UPROPERTY(BlueprintReadOnly)
 	TArray<FTriangleData> SubmergedTriangles;
 
+	AOcean* Ocean;
+	
 	// Called when the game starts
 	virtual void BeginPlay() override;
 
@@ -106,6 +134,8 @@ public:
 	virtual void TickComponent(float DeltaTime, ELevelTick TickType, FActorComponentTickFunction* ThisTickFunction) override;
 
 private:
+	UPrimitiveComponent* VolumeAsPrimComp;
+	
 	int32 GetNumTriangles();
 	
 	TArray<FVertexData> GetVertexPositions();

Source/SeaOfCrooks/SeaOfCrooks.Build.cs

@@ -8,7 +8,7 @@ public class SeaOfCrooks : ModuleRules
 	{
 		PCHUsage = PCHUsageMode.UseExplicitOrSharedPCHs;
 	
-		PublicDependencyModuleNames.AddRange(new string[] { "Core", "CoreUObject", "Engine", "InputCore", "RenderCore", "RHI" });
+		PublicDependencyModuleNames.AddRange(new string[] { "Core", "CoreUObject", "Engine", "InputCore", "ProceduralMeshComponent", "RenderCore", "RHI" });
 
 		PrivateDependencyModuleNames.AddRange(new string[] {  });