// Copyright Epic Games, Inc. All Rights Reserved.
/*=============================================================================
IESLightProfiles.ush: Common shader code for IES light profiles
=============================================================================*/
#if (RAYHITGROUPSHADER || RAYGENSHADER || RAYMISSSHADER)
#define USE_IES_PROFILE 1
//#define USE_IES_STANDALONE_TEXTURE 1
#else
#ifndef USE_IES_PROFILE
#define USE_IES_PROFILE 0
#endif
#endif
#if SUPPORTS_INDEPENDENT_SAMPLERS
#define IESAtlasSampler View.SharedBilinearClampedSampler
#else
#define IESAtlasSampler View.IESAtlasSampler
#endif
//#if SUPPORTS_INDEPENDENT_SAMPLERS
//#define IESAtlasSampler View.SharedPointClampedSampler
//#else
//#define IESAtlasSampler View.IESAtlasSampler
//#endif
// Special case for IES texture preview, which require a standalone texture
#if defined(USE_IES_STANDALONE_TEXTURE) && USE_IES_STANDALONE_TEXTURE == 1
Texture2D IESTexture;
SamplerState IESTextureSampler;
#endif
// Apply IES light profile texture
float ComputeLightProfileMultiplier(float3 WorldPosition, float3 LightPosition, float3 LightDirection, float3 LightTangent, float InIESAtlasIndex)
{
float Out = 1.0f;
#if USE_IES_PROFILE && !VISUALIZE_LIGHT_CULLING
if (InIESAtlasIndex >= 0)
{
float3 LightBitangent = normalize( cross( LightTangent, LightDirection ) );
float4x4 LightTransform = float4x4( float4(LightDirection.xyz, 0), float4(LightBitangent.xyz, 0), float4(LightTangent.xyz, 0), float4(0, 0, 0, 1) );
float4x4 InvLightTransform = transpose(LightTransform);
float3 ToLight = normalize(LightPosition - WorldPosition);
float3 LocalToLight = mul(float4(ToLight.xyz, 0), InvLightTransform).xyz;
// -1..1
float DotProd = dot(ToLight, LightDirection);
// -PI..PI (this distortion could be put into the texture but not without quality loss or more memory)
float Angle = asin(DotProd);
// 0..1
float NormAngle = Angle / PI + 0.5f;
float TangentAngle = atan2( -LocalToLight.z, -LocalToLight.y ); // -Y represents 0/360 horizontal angle and we're rotating counter-clockwise
float NormTangentAngle = TangentAngle / (PI * 2.f) + 0.5f;
#if USE_IES_STANDALONE_TEXTURE
Out = Texture2DSampleLevel(IESTexture, IESTextureSampler, float2(NormAngle, NormTangentAngle), 0).r;
#else
Out = View.IESAtlasTexture.SampleLevel(IESAtlasSampler, float3(NormAngle, NormTangentAngle, InIESAtlasIndex) , 0);
#endif
}
#endif
return Out;
}
Hello, I ahve created a 2d ies light texture by myking changes in IESLoader.cpp. But i am not able to sample the texture using Texture2DSampleLevel. Can anyone please help me. Thanks.