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Cleanup: EEVEE: remove unused code block and simplify computations

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This commit is contained in:
Weizhen Huang
2024-10-09 12:40:33 +02:00
committed by Clément Foucault
parent 5df1afad1d
commit 3db43b6705
1 changed files with 14 additions and 41 deletions
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55
source/blender/draw/engines/eevee_next/shaders/eevee_bxdf_microfacet_lib.glsl
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@@ -174,23 +174,17 @@ BsdfEval bxdf_ggx_eval(vec3 N, vec3 L, vec3 V, float alpha, float eta, const boo
}
vec3 H = do_reflection ? L + V : eta * L + V;
/* Ensure `H` is on the same hemisphere as `V`. */
H = (do_reflection || eta < 1.0) ? H : -H;
float inv_len_H = safe_rcp(length(H));
H *= inv_len_H;
float NH = max(dot(N, H), 1e-8);
float VH = saturate(dot(V, H));
float LH = saturate(dot(do_reflection ? L : -L, H));
float a2 = square(alpha);
float G_V = bxdf_ggx_smith_G1(NV, a2);
float G_L = bxdf_ggx_smith_G1(NL, a2);
float NH = max(dot(N, H), 1e-8);
float D = bxdf_ggx_D(NH, a2);
mat3 tangent_to_world = from_up_axis(N);
vec3 Vt = V * tangent_to_world;
vec3 Lt = L * tangent_to_world;
BsdfEval eval;
if (do_reflection) {
/**
@@ -199,48 +193,27 @@ BsdfEval bxdf_ggx_eval(vec3 N, vec3 L, vec3 V, float alpha, float eta, const boo
* https://gpuopen.com/download/publications/Bounded_VNDF_Sampling_for_Smith-GGX_Reflections.pdf
* Listing 2.
*/
float s2 = square(1.0 + length(Vt.xy));
float len_ai_sqr = length_squared(alpha * Vt.xy);
float t = sqrt(len_ai_sqr + square(Vt.z));
if (Vt.z >= 0.0) {
float k = (1.0 - a2) * s2 / (s2 + a2 * square(Vt.z));
eval.pdf = D / (2.0 * (k * Vt.z + t));
float NV2 = square(NV);
float s2 = square(1.0 + sqrt(1.0 - NV2));
float len_ai_sqr = a2 * (1.0 - NV2);
float t = sqrt(len_ai_sqr + NV2);
if (NV >= 0.0) {
float k = (1.0 - a2) * s2 / (s2 + a2 * NV2);
eval.pdf = D / (2.0 * (k * NV + t));
}
else {
eval.pdf = D * (t - Vt.z) / (2.0 * len_ai_sqr);
eval.pdf = D * (t - NV) / (2.0 * len_ai_sqr);
}
#if 0 /* Should work without going into tangent space. But is currently wrong. */
float sin_theta = sqrt(1.0 - square(NV));
if (VH >= 0.0) {
float Vh_norm = length(vec2(sin_theta, NV));
float s2 = square(1.0 + sin_theta);
float k = (1.0 - a2) * s2 / (s2 + a2 * square(NV));
eval.pdf = D / (2.0 * (k * VH + Vh_norm));
}
else {
float len_Vt_alpha_sqr = square(alpha * sin_theta);
float t = sqrt(len_Vt_alpha_sqr + square(VH));
eval.pdf = D * (t - VH) / (2.0 * len_Vt_alpha_sqr);
}
#endif
/* TODO: But also unused for now. */
eval.throughput = 1.0;
}
else {
vec3 Vh = normalize(vec3(alpha * Vt.xy, Vt.z));
float G1_V = 2.0 * Vh.z / (1.0 + Vh.z);
float VH = saturate(dot(V, H));
float LH = saturate(dot(-L, H));
float Ht2 = square(-eta * LH + VH);
eval.pdf = (D * G1_V * abs(VH * LH) * square(eta)) / (NV * Ht2);
#if 0 /* Should work without going into tangent space. But is currently wrong. */
float Ht2 = square(eta * LH + VH);
eval.pdf = D * G_V * abs(VH * LH) * square(eta) / (NV * Ht2);
#endif
/* `btdf * NL = abs(VH * LH) * ior^2 * D * G(V) * G(L) / (Ht2 * NV * NL) * NL`. */
eval.throughput = (D * G_V * G_L * VH * LH * square(eta * inv_len_H)) / NV;
eval.pdf = (D * G_V * VH * LH * square(eta * inv_len_H)) / NV;
eval.throughput = eval.pdf * G_L;
}
return eval;
}