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sebastienlagardesebastienlagarde
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Merge pull request #18 from EvgeniiG/master
Implement LTC linear light shading for GGX and Disney Diffuse
2 parents aa8db43 + 69f926f commit a433ed1

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17 files changed

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‎Assets/ScriptableRenderLoop/HDRenderLoop/Lighting/SinglePass/SinglePassLoop.hlsl‎

Lines changed: 10 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -41,8 +41,16 @@ void LightLoop( float3 V, float3 positionWS, PreLightData prelightData, BSDFData
4141
{
4242
float3 localDiffuseLighting, localSpecularLighting;
4343

44-
EvaluateBSDF_Area(context, V, positionWS, prelightData, _AreaLightList[i], bsdfData,
45-
localDiffuseLighting, localSpecularLighting);
44+
if (_AreaLightList[i].lightType == GPULIGHTTYPE_LINE)
45+
{
46+
EvaluateBSDF_Line(context, V, positionWS, prelightData, _AreaLightList[i], bsdfData,
47+
localDiffuseLighting, localSpecularLighting);
48+
}
49+
else
50+
{
51+
EvaluateBSDF_Area(context, V, positionWS, prelightData, _AreaLightList[i], bsdfData,
52+
localDiffuseLighting, localSpecularLighting);
53+
}
4654

4755
diffuseLighting += localDiffuseLighting;
4856
specularLighting += localSpecularLighting;

‎Assets/ScriptableRenderLoop/HDRenderLoop/Material/Lit/Lit.hlsl‎

Lines changed: 197 additions & 198 deletions
Large diffs are not rendered by default.

‎Assets/ScriptableRenderLoop/ShaderLibrary/AreaLighting.hlsl‎

Lines changed: 76 additions & 20 deletions
Original file line numberDiff line numberDiff line change
@@ -163,48 +163,104 @@ float PolygonRadiance(float4x3 L, bool twoSided)
163163
return twoSided ? abs(sum) : max(sum, 0.0);
164164
}
165165

166-
float LTCEvaluate(float4x3 L, float3 V, float3 N, float NdotV, bool twoSided, float3x3 minV)
166+
// For polygonal lights.
167+
float LTCEvaluate(float4x3 L, float3 V, float3 N, float NdotV, bool twoSided, float3x3 invM)
167168
{
168169
// Construct local orthonormal basis around N, aligned with N
169170
// TODO: it could be stored in PreLightData. All LTC lights compute it more than once!
171+
// Also consider using 'bsdfData.tangentWS', 'bsdfData.bitangentWS', 'bsdfData.normalWS'.
170172
float3x3 basis;
171173
basis[0] = normalize(V - N * NdotV);
172174
basis[1] = normalize(cross(N, basis[0]));
173175
basis[2] = N;
174176

175177
// rotate area light in local basis
176-
minV = mul(transpose(basis), minV);
177-
L = mul(L, minV);
178+
invM = mul(transpose(basis), invM);
179+
L = mul(L, invM);
178180

179181
// Polygon radiance in transformed configuration - specular
180182
return PolygonRadiance(L, twoSided);
181183
}
182184

183-
float LineFpo(float rcpD, float rcpDL, float l)
185+
float LineFpo(float tLDDL, float lrcpD, float rcpD)
184186
{
185-
// Compute: l / d / (d * d + l * l) + 1.0 / (d * d) * atan(l / d).
186-
return l * rcpDL + rcpD * rcpD * atan(l * rcpD);
187+
// Compute: ((l / d) / (d * d + l * l)) + (1.0 / (d * d)) * atan(l / d).
188+
return tLDDL + sq(rcpD) * atan(lrcpD);
187189
}
188190

189-
float LineFwt(float sqL, float rcpDL)
191+
float LineFwt(float tLDDL, float l)
190192
{
191-
// Compute: l * l / d / (d * d + l * l).
192-
return sqL * rcpDL;
193+
// Compute: l * ((l / d) / (d * d + l * l)).
194+
return l * tLDDL;
193195
}
194196

195197
// Computes the integral of the clamped cosine over the line segment.
196-
// 'dist' is the shortest distance to the line. 'l1' and 'l2' define the integration interval.
197-
float LineIrradiance(float l1, float l2, float dist, float pointZ, float tangentZ)
198+
// 'l1' and 'l2' define the integration interval.
199+
// 'tangent' is the line's tangent direction.
200+
// 'normal' is the direction orthogonal to the tangent. It is the shortest vector between
201+
// the shaded point and the line, pointing away from the shaded point.
202+
float LineIrradiance(float l1, float l2, float3 normal, float3 tangent)
198203
{
199-
float sqD = dist * dist;
200-
float sqL1 = l1 * l1;
201-
float sqL2 = l2 * l2;
202-
float rcpD = rcp(dist);
203-
float rcpDL1 = rcpD * rcp(sqD + sqL1);
204-
float rcpDL2 = rcpD * rcp(sqD + sqL2);
205-
float intP0 = LineFpo(rcpD, rcpDL2, l2) - LineFpo(rcpD, rcpDL1, l1);
206-
float intWt = LineFwt(sqL2, rcpDL2) - LineFwt(sqL1, rcpDL1);
207-
return intP0 * pointZ + intWt * tangentZ;
204+
float d = length(normal);
205+
float l1rcpD = l1 * rcp(d);
206+
float l2rcpD = l2 * rcp(d);
207+
float tLDDL1 = l1rcpD * rcp(sq(d) + sq(l1));
208+
float tLDDL2 = l2rcpD * rcp(sq(d) + sq(l2));
209+
float intWt = LineFwt(tLDDL2, l2) - LineFwt(tLDDL1, l1);
210+
float intP0 = LineFpo(tLDDL2, l2rcpD, rcp(d)) - LineFpo(tLDDL1, l1rcpD, rcp(d));
211+
return intP0 * normal.z + intWt * tangent.z;
212+
}
213+
214+
// For line lights.
215+
float LTCEvaluate(float3 P1, float3 P2, float3 B, float3x3 invM)
216+
{
217+
// Inverse-transform the endpoints and the binormal.
218+
P1 = mul(P1, invM);
219+
P2 = mul(P2, invM);
220+
B = mul(B, invM);
221+
222+
// Terminate the algorithm if both points are below the horizon.
223+
if (P1.z <= 0.0 && P2.z <= 0.0) return 0.0;
224+
225+
if (P2.z <= 0.0)
226+
{
227+
// Convention: 'P2' is above the horizon.
228+
swap(P1, P2);
229+
}
230+
231+
// Recompute the length and the tangent in the new coordinate system.
232+
float len = length(P2 - P1);
233+
float3 T = normalize(P2 - P1);
234+
235+
// Clip the part of the light below the horizon.
236+
if (P1.z <= 0.0)
237+
{
238+
// P = P1 + t * T; P.z == 0.
239+
float t = -P1.z / T.z;
240+
P1 = float3(P1.xy + t * T.xy, 0.0);
241+
242+
// Set the length of the visible part of the light.
243+
len -= t;
244+
}
245+
246+
// Compute the normal direction to the line, s.t. it is the shortest vector
247+
// between the shaded point and the line, pointing away from the shaded point.
248+
// Can be interpreted as a point on the line, since the shaded point is at the origin.
249+
float proj = dot(P1, T);
250+
float3 P0 = P1 - proj * T;
251+
252+
// Compute the parameterization: distances from 'P1' and 'P2' to 'P0'.
253+
float l1 = proj;
254+
float l2 = l1 + len;
255+
256+
// Integrate the clamped cosine over the line segment.
257+
float irradiance = LineIrradiance(l1, l2, P0, T);
258+
259+
// Compute the width factor. We take the absolute value because the points may be swapped.
260+
float width = abs(dot(B, normalize(cross(T, P1))));
261+
262+
// Guard against numerical precision issues.
263+
return max(INV_PI * width * irradiance, 0.0);
208264
}
209265

210266
#endif // UNITY_AREA_LIGHTING_INCLUDED

‎Assets/ScriptableRenderLoop/ShaderLibrary/Common.hlsl‎

Lines changed: 7 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -128,6 +128,11 @@ float4 Max3(float4 a, float4 b, float4 c)
128128
}
129129
#endif // INTRINSIC_MINMAX3
130130

131+
float sq(float x)
132+
{
133+
return x * x;
134+
}
135+
131136
void swap(inout float a, inout float b)
132137
{
133138
float t = a; a = b; b = t;
@@ -211,7 +216,8 @@ void GetCubeFaceID(float3 dir, out int faceIndex)
211216
#define HALF_PI 1.57079632679
212217
#define INV_HALF_PI 0.636619772367
213218

214-
#define FLT_EPSILON 1.192092896e-07f // smallest such that 1.0 + FLT_EPSILON != 1.0
219+
#define FLT_EPSILON 1.192092896e-07 // Smallest positive number, such that 1.0 + FLT_EPSILON != 1.0
220+
#define FLT_MAX 3.402823466e+38 // Maximum representable floating-point number
215221

216222
#define MERGE_NAME(X, Y) X##Y
217223

‎Assets/ScriptableRenderLoop/ShaderLibrary/CommonLighting.hlsl‎

Lines changed: 17 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -59,6 +59,23 @@ float GetAngleAttenuation(float3 L, float3 lightDir, float lightAngleScale, floa
5959
return attenuation;
6060
}
6161

62+
// Applies SmoothDistanceAttenuation() after stretching the fade-out sphere of the given radius
63+
// into an ellipsoid with the specified aspect ratio and the longest axis.
64+
float GetEllipsoidalDistanceAttenuation(float3 unL, float invSqrAttenuationRadius,
65+
float3 axis, float invAspectRatio)
66+
{
67+
// Project the unnormalized light vector onto the expansion axis.
68+
float projL = dot(unL, axis);
69+
70+
// We want 'unL' to shrink along 'axis' by the aspect ratio. Therefore, we compute
71+
// the difference between the length of the original projection and the shrunk one.
72+
// It is equivalent to the expansion of the fade-out sphere into an ellipsoid.
73+
float scale = projL - projL * invAspectRatio;
74+
unL -= scale * axis;
75+
76+
return SmoothDistanceAttenuation(dot(unL, unL), invSqrAttenuationRadius);
77+
}
78+
6279
//-----------------------------------------------------------------------------
6380
// IES Helper
6481
//-----------------------------------------------------------------------------

‎Assets/TestScenes/HDTest/Material/HDRenderLoopMaterials/GGX Test/GGX_D_a00_s00.mat‎

Lines changed: 162 additions & 0 deletions
Original file line numberDiff line numberDiff line change
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‎Assets/TestScenes/HDTest/Material/HDRenderLoopMaterials/GGX Test/GGX_D_a00_s00.mat.meta‎

Lines changed: 8 additions & 0 deletions
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