第一次提交

Plugins/GMS/Source/GenericMovementSystem/Public/Utility/GMS_Math.h

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+// Copyright 2025 https://yuewu.dev/en  All Rights Reserved.
+
+#pragma once
+
+#include "Kismet/BlueprintFunctionLibrary.h"
+#include "GMS_Math.generated.h"
+
+UCLASS(Meta = (BlueprintThreadSafe))
+class GENERICMOVEMENTSYSTEM_API UGMS_Math : public UBlueprintFunctionLibrary
+{
+	GENERATED_BODY()
+
+public:
+	static constexpr auto Ln2{0.6931471805599453f}; // FMath::Loge(2.0f).
+
+public:
+	UFUNCTION(BlueprintCallable, BlueprintPure, Category = "GMS|Math Utility", Meta = (ReturnDisplayName = "Value"))
+	static float Clamp01(float Value);
+
+	UFUNCTION(BlueprintCallable, BlueprintPure, Category = "GMS|Math Utility", Meta = (ReturnDisplayName = "Value"))
+	static float LerpClamped(float From, float To, float Ratio);
+
+	//Output the frame-rate stable alpha used for smoothly lerp current to target.
+	UFUNCTION(BlueprintCallable, BlueprintPure, Category = "GMS|Math Utility", Meta = (ReturnDisplayName = "Alpha"))
+	static float DamperExactAlpha(float DeltaTime, float HalfLife);
+
+	// HalfLife is the time it takes for the distance to the target to be reduced by half.
+	template <typename ValueType>
+	static ValueType DamperExact(const ValueType& Current, const ValueType& Target, float DeltaTime, float HalfLife);
+};
+
+inline float UGMS_Math::Clamp01(const float Value)
+{
+	return Value > 0.0f
+		       ? Value < 1.0f
+			         ? Value
+			         : 1.0f
+		       : 0.0f;
+}
+
+inline float UGMS_Math::LerpClamped(const float From, const float To, const float Ratio)
+{
+	return From + (To - From) * Clamp01(Ratio);
+}
+
+inline float UGMS_Math::DamperExactAlpha(const float DeltaTime, const float HalfLife)
+{
+	// https://theorangeduck.com/page/spring-roll-call#exactdamper
+
+	return 1.0f - FMath::InvExpApprox(Ln2 / (HalfLife + UE_SMALL_NUMBER) * DeltaTime);
+}
+
+template <typename ValueType>
+ValueType UGMS_Math::DamperExact(const ValueType& Current, const ValueType& Target, const float DeltaTime, const float HalfLife)
+{
+	return FMath::Lerp(Current, Target, DamperExactAlpha(DeltaTime, HalfLife));
+}