// Copyright Epic Games, Inc. All Rights Reserved.
#pragma once

#define DefineStatelessDistributionSampler(HLSLTYPE, NAMETYPE) \
	struct FStatelessDistributionSampler##NAMETYPE \
	{ \
		void Init(uint RandomSeedOffset, FNiagaraStatelessBuiltDistributionType InBuildDistribution) \
		{ \
			BuildDistribution = InBuildDistribution; \
			RandomOffset = 0.0f; \
			if ( FNiagaraStatelessBuiltDistribution::IsRandom(BuildDistribution) != 0) \
			{ \
				RandomOffset = Random##NAMETYPE##(RandomSeedOffset); \
			} \
		} \
		\
		bool IsValid() { return FNiagaraStatelessBuiltDistribution::IsValid(BuildDistribution); } \
		\
		HLSLTYPE GetValue(float Time) \
		{ \
			const uint DataOffset = FNiagaraStatelessBuiltDistribution::GetDataOffset(BuildDistribution); \
			if (FNiagaraStatelessBuiltDistribution::IsBinding(BuildDistribution)) \
			{ \
				return GetParameterBuffer##NAMETYPE##(DataOffset, 0); \
			} \
			else if (FNiagaraStatelessBuiltDistribution::IsRandom(BuildDistribution)) \
			{ \
				const HLSLTYPE Value0 = GetStatic##NAMETYPE##(DataOffset, 0); \
				const HLSLTYPE Value1 = GetStatic##NAMETYPE##(DataOffset, 1); \
				return StatelessLerp(Value0, Value1, RandomOffset, FNiagaraStatelessBuiltDistribution::IsUniform(BuildDistribution)); \
			} \
			else \
			{ \
				const float Offset = FNiagaraStatelessBuiltDistribution::ConvertTimeToLookup(BuildDistribution, Time); \
				const HLSLTYPE Value0 = GetStatic##NAMETYPE##(DataOffset, floor(Offset)); \
				const HLSLTYPE Value1 = GetStatic##NAMETYPE##(DataOffset, ceil(Offset)); \
				return lerp(Value0, Value1, frac(Offset)); \
			} \
		} \
		\
		FNiagaraStatelessBuiltDistributionType		BuildDistribution; \
		HLSLTYPE									RandomOffset; \
	}

DefineStatelessDistributionSampler(float,  Float);
DefineStatelessDistributionSampler(float2, Float2);
DefineStatelessDistributionSampler(float3, Float3);
DefineStatelessDistributionSampler(float4, Float4);

#undef DefineStatelessDistributionSampler