// Copyright UShaderLab. All Rights Reserved.
//
// Atmosphere / sky-light intrinsics.

#include "ShaderLabIntrinsics.h"

#include "Materials/MaterialExpressionAtmosphericLightColor.h"
#include "Materials/MaterialExpressionAtmosphericLightVector.h"
#include "Materials/MaterialExpressionSkyAtmosphereLightDirection.h"

void RegisterAtmosphereIntrinsics(FShaderLabIntrinsicRegistry& Registry)
{
	using namespace ShaderLabIntrinsic_Private;
	using EFreq = EShaderLabIntrinsicFrequency;

	AddSimple(Registry, TEXT("AtmosphericLightVector"), EFreq::Any, TEXT("float3"), [](UMaterial& M) { return MakeSimple<UMaterialExpressionAtmosphericLightVector>(M); });
	AddSimple(Registry, TEXT("AtmosphericLightColor"), EFreq::Any, TEXT("float3"), [](UMaterial& M) { return MakeSimple<UMaterialExpressionAtmosphericLightColor>(M); });

	// SkyAtmosphereLightDirection(LightIndex) — const int selects the atmosphere light.
	{
		FShaderLabIntrinsicDesc Desc;
		Desc.Name = FName(TEXT("SkyAtmosphereLightDirection"));
		Desc.ReturnType = TEXT("float3");
		Desc.Params = { { TEXT("int"), TEXT("LightIndex"), TEXT("0") } };
		Desc.MakeNode = [](UMaterial& M, const TArray<FString>& Args, FString&) -> UMaterialExpression*
		{
			UMaterialExpressionSkyAtmosphereLightDirection* E = NewObject<UMaterialExpressionSkyAtmosphereLightDirection>(&M);
			if (Args.Num() >= 1) { E->LightIndex = FCString::Atoi(*Args[0]); }
			M.GetExpressionCollection().AddExpression(E);
			return E;
		};
		Registry.Register(MoveTemp(Desc));
	}
}