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Cycles: Multi-scale Principled Hair Huang Model #116094

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Weizhen Huang merged 4 commits from weizhen/blender:hair-nearfield into main 2024-02-22 18:18:24 +01:00
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1 changed files with 5 additions and 5 deletions
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10
intern/cycles/kernel/closure/bsdf_principled_hair_huang.h
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@ -188,8 +188,8 @@ ccl_device int bsdf_hair_huang_setup(ccl_private ShaderData *sd,
/* Compute local frame. The Y axis is aligned with the curve tangent; the X axis is perpendicular
to the ray direction for circular cross-sections, or aligned with the major axis for elliptical
cross-sections. */
const float3 Y = safe_normalize(sd->dPdu);
const float3 X = safe_normalize(cross(Y, sd->wi));
bsdf->extra->Y = safe_normalize(sd->dPdu);
const float3 X = safe_normalize(cross(sd->dPdu, sd->wi));
/* h from -1..0..1 means the rays goes from grazing the hair, to hitting it at the center, to
* grazing the other edge. This is the cosine of the angle between `sd->N` and `X`. */
@ -199,6 +199,8 @@ ccl_device int bsdf_hair_huang_setup(ccl_private ShaderData *sd,
kernel_assert(isfinite_safe(bsdf->h));
if (bsdf->aspect_ratio != 1.0f && (sd->type & PRIMITIVE_CURVE)) {
/* Adjust `bsdf->N` to be orthogonal to `sd->dPdu`. */
bsdf->N = safe_normalize(cross(sd->dPdu, safe_normalize(cross(bsdf->N, sd->dPdu))));
/* Align local frame with the curve normal. */
if (bsdf->aspect_ratio > 1.0f) {
/* Switch major and minor axis. */
@ -214,14 +216,12 @@ ccl_device int bsdf_hair_huang_setup(ccl_private ShaderData *sd,
/* Fill extra closure. */
if (is_zero(bsdf->N) || !isfinite_safe(bsdf->N)) {
bsdf->extra->Y = Y;
/* Construct arbitrary local coordinate system. The implementation should ensure smooth
* transition along the hair shaft. */
make_orthonormals(Y, &bsdf->extra->Z, &bsdf->N);
make_orthonormals(bsdf->extra->Y, &bsdf->extra->Z, &bsdf->N);
}
else {
bsdf->extra->Z = safe_normalize(cross(bsdf->N, sd->dPdu));
bsdf->extra->Y = safe_normalize(cross(bsdf->extra->Z, bsdf->N));
}
const float3 I = make_float3(