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// This files include various function uses to evaluate lights
// To use deferred directional shadow with cascaded shadow map,
// it is required to define USE_DEFERRED_DIRECTIONAL_SHADOWS before including this files
//-----------------------------------------------------------------------------
// Directional Light evaluation helper
//-----------------------------------------------------------------------------
float3 EvaluateCookie_Directional(LightLoopContext lightLoopContext, DirectionalLightData lightData,
float3 lightToSample)
{
// Translate and rotate 'positionWS' into the light space.
// 'lightData.right' and 'lightData.up' are pre-scaled on CPU.
float3x3 lightToWorld = float3x3(lightData.right, lightData.up, lightData.forward);
float3 positionLS = mul(lightToSample, transpose(lightToWorld));
// Perform orthographic projection.
float2 positionCS = positionLS.xy;
// Remap the texture coordinates from [-1, 1]^2 to [0, 1]^2.
float2 positionNDC = positionCS * 0.5 + 0.5;
// We let the sampler handle clamping to border.
return SampleCookie2D(lightLoopContext, positionNDC, lightData.cookieIndex, lightData.tileCookie);
}
// None of the outputs are premultiplied.
// Note: When doing transmission we always have only one shadow sample to do: Either front or back. We use NdotL to know on which side we are
void EvaluateLight_Directional(LightLoopContext lightLoopContext, PositionInputs posInput,
DirectionalLightData lightData, BuiltinData builtinData,
float3 N, float3 L,
out float3 color, out float attenuation)
{
float3 positionWS = posInput.positionWS;
float shadow = 1.0;
float shadowMask = 1.0;
color = lightData.color;
attenuation = 1.0; // Note: no volumetric attenuation along shadow rays for directional lights
UNITY_BRANCH if (lightData.cookieIndex >= 0)
{
float3 lightToSample = positionWS - lightData.positionRWS;
float3 cookie = EvaluateCookie_Directional(lightLoopContext, lightData, lightToSample);
color *= cookie;
}
#ifdef SHADOWS_SHADOWMASK
// shadowMaskSelector.x is -1 if there is no shadow mask
// Note that we override shadow value (in case we don't have any dynamic shadow)
shadow = shadowMask = (lightData.shadowMaskSelector.x >= 0.0) ? dot(BUILTIN_DATA_SHADOW_MASK, lightData.shadowMaskSelector) : 1.0;
#endif
// We test NdotL >= 0.0 to not sample the shadow map if it is not required.
UNITY_BRANCH if (lightData.shadowIndex >= 0 && (dot(N, L) >= 0.0))
{
#ifdef USE_DEFERRED_DIRECTIONAL_SHADOWS
shadow = LOAD_TEXTURE2D(_DeferredShadowTexture, posInput.positionSS).x;
#else
shadow = GetDirectionalShadowAttenuation(lightLoopContext.shadowContext, positionWS, N, lightData.shadowIndex, L, posInput.positionSS);
#endif
#ifdef SHADOWS_SHADOWMASK
// TODO: Optimize this code! Currently it is a bit like brute force to get the last transistion and fade to shadow mask, but there is
// certainly more efficient to do
// We reuse the transition from the cascade system to fade between shadow mask at max distance
uint payloadOffset;
real fade;
int cascadeCount;
int shadowSplitIndex = EvalShadow_GetSplitIndex(lightLoopContext.shadowContext, lightData.shadowIndex, positionWS, payloadOffset, fade, cascadeCount);
// we have a fade caclulation for each cascade but we must lerp with shadow mask only for the last one
// if shadowSplitIndex is -1 it mean we are outside cascade and should return 1.0 to use shadowmask: saturate(-shadowSplitIndex) return 0 for >= 0 and 1 for -1
fade = ((shadowSplitIndex + 1) == cascadeCount) ? fade : saturate(-shadowSplitIndex);
// In the transition code (both dithering and blend) we use shadow = lerp( shadow, 1.0, fade ) for last transition
// mean if we expend the code we have (shadow * (1 - fade) + fade). Here to make transition with shadow mask
// we will remove fade and add fade * shadowMask which mean we do a lerp with shadow mask
shadow = shadow - fade + fade * shadowMask;
// See comment in EvaluateBSDF_Punctual
shadow = lightData.nonLightmappedOnly ? min(shadowMask, shadow) : shadow;
// Note: There is no shadowDimmer when there is no shadow mask
#endif
// Transparent have no contact shadow information
#ifndef _SURFACE_TYPE_TRANSPARENT
shadow = min(shadow, GetContactShadow(lightLoopContext, lightData.contactShadowIndex));
#endif
}
attenuation *= shadow;
}
//-----------------------------------------------------------------------------
// Punctual Light evaluation helper
//-----------------------------------------------------------------------------
// Return L vector for punctual light (normalize surface to light), lightToSample (light to surface non normalize) and distances {d, d^2, 1/d, d_proj}
void GetPunctualLightVectors(float3 positionWS, LightData lightData, out float3 L, out float3 lightToSample, out float4 distances)
{
lightToSample = positionWS - lightData.positionRWS;
int lightType = lightData.lightType;
distances.w = dot(lightToSample, lightData.forward);
if (lightType == GPULIGHTTYPE_PROJECTOR_BOX)
{
L = -lightData.forward;
distances.xyz = 1; // No distance or angle attenuation
}
else
{
float3 unL = -lightToSample;
float distSq = dot(unL, unL);
float distRcp = rsqrt(distSq);
float dist = distSq * distRcp;
L = unL * distRcp;
distances.xyz = float3(dist, distSq, distRcp);
}
}
float4 EvaluateCookie_Punctual(LightLoopContext lightLoopContext, LightData lightData,
float3 lightToSample)
{
int lightType = lightData.lightType;
// Translate and rotate 'positionWS' into the light space.
// 'lightData.right' and 'lightData.up' are pre-scaled on CPU.
float3x3 lightToWorld = float3x3(lightData.right, lightData.up, lightData.forward);
float3 positionLS = mul(lightToSample, transpose(lightToWorld));
float4 cookie;
UNITY_BRANCH if (lightType == GPULIGHTTYPE_POINT)
{
cookie.rgb = SampleCookieCube(lightLoopContext, positionLS, lightData.cookieIndex);
cookie.a = 1;
}
else
{
// Perform orthographic or perspective projection.
float perspectiveZ = (lightType != GPULIGHTTYPE_PROJECTOR_BOX) ? positionLS.z : 1.0;
float2 positionCS = positionLS.xy / perspectiveZ;
bool isInBounds = Max3(abs(positionCS.x), abs(positionCS.y), 1.0 - positionLS.z) <= 1.0;
// Remap the texture coordinates from [-1, 1]^2 to [0, 1]^2.
float2 positionNDC = positionCS * 0.5 + 0.5;
// Manually clamp to border (black).
cookie.rgb = SampleCookie2D(lightLoopContext, positionNDC, lightData.cookieIndex, false);
cookie.a = isInBounds ? 1 : 0;
}
return cookie;
}
// None of the outputs are premultiplied.
// distances = {d, d^2, 1/d, d_proj}, where d_proj = dot(lightToSample, lightData.forward).
// Note: When doing transmission we always have only one shadow sample to do: Either front or back. We use NdotL to know on which side we are
void EvaluateLight_Punctual(LightLoopContext lightLoopContext, PositionInputs posInput,
LightData lightData, BuiltinData builtinData,
float3 N, float3 L, float3 lightToSample, float4 distances,
out float3 color, out float attenuation)
{
float3 positionWS = posInput.positionWS;
float shadow = 1.0;
float shadowMask = 1.0;
color = lightData.color;
attenuation = SmoothPunctualLightAttenuation(distances, lightData.rangeAttenuationScale, lightData.rangeAttenuationBias,
lightData.angleScale, lightData.angleOffset);
// TODO: sample the extinction from the density V-buffer.
float distVol = (lightData.lightType == GPULIGHTTYPE_PROJECTOR_BOX) ? distances.w : distances.x;
attenuation *= TransmittanceHomogeneousMedium(_GlobalExtinction, distVol);
// Projector lights always have cookies, so we can perform clipping inside the if().
UNITY_BRANCH if (lightData.cookieIndex >= 0)
{
float4 cookie = EvaluateCookie_Punctual(lightLoopContext, lightData, lightToSample);
color *= cookie.rgb;
attenuation *= cookie.a;
}
#ifdef SHADOWS_SHADOWMASK
// shadowMaskSelector.x is -1 if there is no shadow mask
// Note that we override shadow value (in case we don't have any dynamic shadow)
shadow = shadowMask = (lightData.shadowMaskSelector.x >= 0.0) ? dot(BUILTIN_DATA_SHADOW_MASK, lightData.shadowMaskSelector) : 1.0;
#endif
// We test NdotL >= 0.0 to not sample the shadow map if it is not required.
UNITY_BRANCH if (lightData.shadowIndex >= 0 && (dot(N, L) >= 0.0))
{
// TODO: make projector lights cast shadows.
// Note:the case of NdotL < 0 can appear with isThinModeTransmission, in this case we need to flip the shadow bias
shadow = GetPunctualShadowAttenuation(lightLoopContext.shadowContext, positionWS, N, lightData.shadowIndex, L, distances.x, posInput.positionSS);
#ifdef SHADOWS_SHADOWMASK
// Note: Legacy Unity have two shadow mask mode. ShadowMask (ShadowMask contain static objects shadow and ShadowMap contain only dynamic objects shadow, final result is the minimun of both value)
// and ShadowMask_Distance (ShadowMask contain static objects shadow and ShadowMap contain everything and is blend with ShadowMask based on distance (Global distance setup in QualitySettigns)).
// HDRenderPipeline change this behavior. Only ShadowMask mode is supported but we support both blend with distance AND minimun of both value. Distance is control by light.
// The following code do this.
// The min handle the case of having only dynamic objects in the ShadowMap
// The second case for blend with distance is handled with ShadowDimmer. ShadowDimmer is define manually and by shadowDistance by light.
// With distance, ShadowDimmer become one and only the ShadowMask appear, we get the blend with distance behavior.
shadow = lightData.nonLightmappedOnly ? min(shadowMask, shadow) : shadow;
shadow = lerp(shadowMask, shadow, lightData.shadowDimmer);
#else
shadow = lerp(1.0, shadow, lightData.shadowDimmer);
#endif
// Transparent have no contact shadow information
#ifndef _SURFACE_TYPE_TRANSPARENT
shadow = min(shadow, GetContactShadow(lightLoopContext, lightData.contactShadowIndex));
#endif
}
attenuation *= shadow;
}
// Environment map share function
#include "Reflection/VolumeProjection.hlsl"
void EvaluateLight_EnvIntersection(float3 positionWS, float3 normalWS, EnvLightData lightData, int influenceShapeType, inout float3 R, inout float weight)
{
// Guideline for reflection volume: In HDRenderPipeline we separate the projection volume (the proxy of the scene) from the influence volume (what pixel on the screen is affected)
// However we add the constrain that the shape of the projection and influence volume is the same (i.e if we have a sphere shape projection volume, we have a shape influence).
// It allow to have more coherence for the dynamic if in shader code.
// Users can also chose to not have any projection, in this case we use the property minProjectionDistance to minimize code change. minProjectionDistance is set to huge number
// that simulate effect of no shape projection
float3x3 worldToIS = WorldToInfluenceSpace(lightData); // IS: Influence space
float3 positionIS = WorldToInfluencePosition(lightData, worldToIS, positionWS);
float3 dirIS = mul(R, worldToIS);
float3x3 worldToPS = WorldToProxySpace(lightData); // PS: Proxy space
float3 positionPS = WorldToProxyPosition(lightData, worldToPS, positionWS);
float3 dirPS = mul(R, worldToPS);
float projectionDistance = 0;
// Process the projection
// In Unity the cubemaps are capture with the localToWorld transform of the component.
// This mean that location and orientation matter. So after intersection of proxy volume we need to convert back to world.
if (influenceShapeType == ENVSHAPETYPE_SPHERE)
{
projectionDistance = IntersectSphereProxy(lightData, dirPS, positionPS);
// We can reuse dist calculate in LS directly in WS as there is no scaling. Also the offset is already include in lightData.capturePositionRWS
R = (positionWS + projectionDistance * R) - lightData.capturePositionRWS;
weight = InfluenceSphereWeight(lightData, normalWS, positionWS, positionIS, dirIS);
}
else if (influenceShapeType == ENVSHAPETYPE_BOX)
{
projectionDistance = IntersectBoxProxy(lightData, dirPS, positionPS);
// No need to normalize for fetching cubemap
// We can reuse dist calculate in LS directly in WS as there is no scaling. Also the offset is already include in lightData.capturePositionRWS
R = (positionWS + projectionDistance * R) - lightData.capturePositionRWS;
weight = InfluenceBoxWeight(lightData, normalWS, positionWS, positionIS, dirIS);
}
// Smooth weighting
weight = Smoothstep01(weight);
weight *= lightData.weight;
}
// ----------------------------------------------------------------------------
// Helper functions to use Transmission with a material
// ----------------------------------------------------------------------------
// For EvaluateTransmission.hlsl file it is required to define a BRDF for the transmission. Defining USE_DIFFUSE_LAMBERT_BRDF use Lambert, otherwise it use Disneydiffuse
#ifdef MATERIAL_INCLUDE_TRANSMISSION
// This function return transmittance to provide to EvaluateTransmission
float3 PreEvaluatePunctualLightTransmission(LightLoopContext lightLoopContext, PositionInputs posInput, float distFrontFaceToLight,
float NdotL, float3 L, BSDFData bsdfData,
inout float3 normalWS, inout LightData lightData)
{
float3 transmittance = bsdfData.transmittance;
// if NdotL is positive, we do one fetch on front face done by EvaluateLight_XXX. Just regular lighting
// If NdotL is negative, we have two cases:
// - Thin mode: Reuse the front face fetch as shadow for back face - flip the normal for the bias (and the NdotL test) and disable contact shadow
// - Mixed mode: Do a fetch on back face to retrieve the thickness. The thickness will provide a shadow attenuation (with distance travelled there is less transmission).
// (Note: EvaluateLight_Punctual discard the fetch if NdotL < 0)
if (NdotL < 0 && lightData.shadowIndex >= 0)
{
if (HasFlag(bsdfData.materialFeatures, MATERIAL_FEATURE_FLAGS_TRANSMISSION_MODE_THIN_THICKNESS))
{
normalWS = -normalWS; // Flip normal for shadow bias
lightData.contactShadowIndex = -1; // Disable shadow contact
}
else // MATERIAL_FEATURE_FLAGS_TRANSMISSION_MODE_MIXED_THICKNESS
{
// Recompute transmittance using the thickness value computed from the shadow map.
// Compute the distance from the light to the back face of the object along the light direction.
float distBackFaceToLight = GetPunctualShadowClosestDistance( lightLoopContext.shadowContext, s_linear_clamp_sampler,
posInput.positionWS, lightData.shadowIndex, L, lightData.positionRWS);
// Our subsurface scattering models use the semi-infinite planar slab assumption.
// Therefore, we need to find the thickness along the normal.
float thicknessInUnits = (distFrontFaceToLight - distBackFaceToLight) * -NdotL;
float thicknessInMeters = thicknessInUnits * _WorldScales[bsdfData.diffusionProfile].x;
float thicknessInMillimeters = thicknessInMeters * MILLIMETERS_PER_METER;
#if SHADEROPTIONS_USE_DISNEY_SSS
// We need to make sure it's not less than the baked thickness to minimize light leaking.
float thicknessDelta = max(0, thicknessInMillimeters - bsdfData.thickness);
float3 S = _ShapeParams[bsdfData.diffusionProfile].rgb;
// Approximate the decrease of transmittance by e^(-1/3 * dt * S).
#if 0
float3 expOneThird = exp(((-1.0 / 3.0) * thicknessDelta) * S);
#else
// Help the compiler.
float k = (-1.0 / 3.0) * LOG2_E;
float3 p = (k * thicknessDelta) * S;
float3 expOneThird = exp2(p);
#endif
transmittance *= expOneThird;
#else // SHADEROPTIONS_USE_DISNEY_SSS
// We need to make sure it's not less than the baked thickness to minimize light leaking.
thicknessInMillimeters = max(thicknessInMillimeters, bsdfData.thickness);
transmittance = ComputeTransmittanceJimenez(_HalfRcpVariancesAndWeights[bsdfData.diffusionProfile][0].rgb,
_HalfRcpVariancesAndWeights[bsdfData.diffusionProfile][0].a,
_HalfRcpVariancesAndWeights[bsdfData.diffusionProfile][1].rgb,
_HalfRcpVariancesAndWeights[bsdfData.diffusionProfile][1].a,
_TransmissionTintsAndFresnel0[bsdfData.diffusionProfile].rgb,
thicknessInMillimeters);
#endif // SHADEROPTIONS_USE_DISNEY_SSS
// Note: we do not modify the distance to the light, or the light angle for the back face.
// This is a performance-saving optimization which makes sense as long as the thickness is small.
}
transmittance = lerp( bsdfData.transmittance, transmittance, lightData.shadowDimmer);
}
return transmittance;
}
// This function return transmittance to provide to EvaluateTransmission
float3 PreEvaluateDirectionalLightTransmission(float NdotL, DirectionalLightData lightData, BSDFData bsdfData, inout float3 normalWS, inout int contactShadowIndex)
{
if (NdotL < 0 && lightData.shadowIndex >= 0)
{
if (HasFlag(bsdfData.materialFeatures, MATERIAL_FEATURE_FLAGS_TRANSMISSION_MODE_THIN_THICKNESS))
{
normalWS = -normalWS; // Flip normal for shadow bias
contactShadowIndex = -1; // Disable shadow contact
}
}
return bsdfData.transmittance;
}
#define TRANSMISSION_WRAP_ANGLE (PI/12) // 15 degrees
#define TRANSMISSION_WRAP_LIGHT cos(PI/2 - TRANSMISSION_WRAP_ANGLE)
// Currently, we only model diffuse transmission. Specular transmission is not yet supported.
// Transmitted lighting is computed as follows:
// - we assume that the object is a thick plane (slab);
// - we reverse the front-facing normal for the back of the object;
// - we assume that the incoming radiance is constant along the entire back surface;
// - we apply BSDF-specific diffuse transmission to transmit the light subsurface and back;
// - we integrate the diffuse reflectance profile w.r.t. the radius (while also accounting
// for the thickness) to compute the transmittance;
// - we multiply the transmitted radiance by the transmittance.
// transmittance come from the call to PreEvaluateLightTransmission
// attenuation come from the call to EvaluateLight_Punctual
float3 EvaluateTransmission(BSDFData bsdfData, float3 transmittance, float NdotL, float NdotV, float LdotV, float attenuation)
{
// Apply wrapped lighting to better handle thin objects at grazing angles.
float wrappedNdotL = ComputeWrappedDiffuseLighting(-NdotL, TRANSMISSION_WRAP_LIGHT);
// Apply BSDF-specific diffuse transmission to attenuation. See also: [SSS-NOTE-TRSM]
// We don't multiply by 'bsdfData.diffuseColor' here. It's done only once in PostEvaluateBSDF().
#ifdef USE_DIFFUSE_LAMBERT_BRDF
attenuation *= Lambert();
#else
attenuation *= DisneyDiffuse(NdotV, max(0, -NdotL), LdotV, bsdfData.perceptualRoughness);
#endif
float intensity = attenuation * wrappedNdotL;
return intensity * transmittance;
}
#endif // #ifdef MATERIAL_INCLUDE_TRANSMISSION