[Bf-blender-cvs] [0b7c007ad59] cycles-x: Cleanup: remove a bit more unused diffusion BSSRDF code
Brecht Van Lommel
noreply at git.blender.org
Tue Aug 17 19:52:40 CEST 2021
Commit: 0b7c007ad591e12033db9dd5475fdb1b50bec5cb
Author: Brecht Van Lommel
Date: Tue Aug 17 18:35:03 2021 +0200
Branches: cycles-x
https://developer.blender.org/rB0b7c007ad591e12033db9dd5475fdb1b50bec5cb
Cleanup: remove a bit more unused diffusion BSSRDF code
===================================================================
M intern/cycles/kernel/closure/bssrdf.h
===================================================================
diff --git a/intern/cycles/kernel/closure/bssrdf.h b/intern/cycles/kernel/closure/bssrdf.h
index ada661779ec..76f62845ea9 100644
--- a/intern/cycles/kernel/closure/bssrdf.h
+++ b/intern/cycles/kernel/closure/bssrdf.h
@@ -24,145 +24,19 @@ typedef ccl_addr_space struct Bssrdf {
float3 radius;
float3 albedo;
float roughness;
- float channels;
} Bssrdf;
static_assert(sizeof(ShaderClosure) >= sizeof(Bssrdf), "Bssrdf is too large!");
-/* Approximate Reflectance Profiles
- * http://graphics.pixar.com/library/ApproxBSSRDF/paper.pdf
- */
-
-/* This is a bit arbitrary, just need big enough radius so it matches
- * the mean free length, but still not too big so sampling is still
- * effective. Might need some further tweaks.
- */
-#define BURLEY_TRUNCATE 16.0f
-#define BURLEY_TRUNCATE_CDF 0.9963790093708328f // cdf(BURLEY_TRUNCATE)
-
-ccl_device_inline float bssrdf_burley_fitting(float A)
-{
- /* Diffuse surface transmission, equation (6). */
- return 1.9f - A + 3.5f * (A - 0.8f) * (A - 0.8f);
-}
-
-/* Scale mean free path length so it gives similar looking result
- * to Cubic and Gaussian models.
+/* Scale mean free path length so it gives similar looking result to older
+ * to Cubic, Gaussian and Burley models.
*/
ccl_device_inline float3 bssrdf_burley_compatible_mfp(float3 r)
{
return 0.25f * M_1_PI_F * r;
}
-ccl_device float bssrdf_burley_eval(const float d, float r)
-{
- const float Rm = BURLEY_TRUNCATE * d;
-
- if (r >= Rm)
- return 0.0f;
-
- /* Burley reflectance profile, equation (3).
- *
- * NOTES:
- * - Surface albedo is already included into sc->weight, no need to
- * multiply by this term here.
- * - This is normalized diffuse model, so the equation is multiplied
- * by 2*pi, which also matches cdf().
- */
- float exp_r_3_d = expf(-r / (3.0f * d));
- float exp_r_d = exp_r_3_d * exp_r_3_d * exp_r_3_d;
- return (exp_r_d + exp_r_3_d) / (4.0f * d);
-}
-
-ccl_device float bssrdf_burley_pdf(const float d, float r)
-{
- return bssrdf_burley_eval(d, r) * (1.0f / BURLEY_TRUNCATE_CDF);
-}
-
-/* Find the radius for desired CDF value.
- * Returns scaled radius, meaning the result is to be scaled up by d.
- * Since there's no closed form solution we do Newton-Raphson method to find it.
- */
-ccl_device_forceinline float bssrdf_burley_root_find(float xi)
-{
- const float tolerance = 1e-6f;
- const int max_iteration_count = 10;
- /* Do initial guess based on manual curve fitting, this allows us to reduce
- * number of iterations to maximum 4 across the [0..1] range. We keep maximum
- * number of iteration higher just to be sure we didn't miss root in some
- * corner case.
- */
- float r;
- if (xi <= 0.9f) {
- r = expf(xi * xi * 2.4f) - 1.0f;
- }
- else {
- /* TODO(sergey): Some nicer curve fit is possible here. */
- r = 15.0f;
- }
- /* Solve against scaled radius. */
- for (int i = 0; i < max_iteration_count; i++) {
- float exp_r_3 = expf(-r / 3.0f);
- float exp_r = exp_r_3 * exp_r_3 * exp_r_3;
- float f = 1.0f - 0.25f * exp_r - 0.75f * exp_r_3 - xi;
- float f_ = 0.25f * exp_r + 0.25f * exp_r_3;
-
- if (fabsf(f) < tolerance || f_ == 0.0f) {
- break;
- }
-
- r = r - f / f_;
- if (r < 0.0f) {
- r = 0.0f;
- }
- }
- return r;
-}
-
-ccl_device void bssrdf_burley_sample(const float d, float xi, float *r, float *h)
-{
- const float Rm = BURLEY_TRUNCATE * d;
- const float r_ = bssrdf_burley_root_find(xi * BURLEY_TRUNCATE_CDF) * d;
-
- *r = r_;
-
- /* h^2 + r^2 = Rm^2 */
- *h = safe_sqrtf(Rm * Rm - r_ * r_);
-}
-
-/* None BSSRDF falloff
- *
- * Samples distributed over disk with no falloff, for reference. */
-
-ccl_device float bssrdf_none_eval(const float radius, float r)
-{
- const float Rm = radius;
- return (r < Rm) ? 1.0f : 0.0f;
-}
-
-ccl_device float bssrdf_none_pdf(const float radius, float r)
-{
- /* integrate (2*pi*r)/(pi*Rm*Rm) from 0 to Rm = 1 */
- const float Rm = radius;
- const float area = (M_PI_F * Rm * Rm);
-
- return bssrdf_none_eval(radius, r) / area;
-}
-
-ccl_device void bssrdf_none_sample(const float radius, float xi, float *r, float *h)
-{
- /* xi = integrate (2*pi*r)/(pi*Rm*Rm) = r^2/Rm^2
- * r = sqrt(xi)*Rm */
- const float Rm = radius;
- const float r_ = sqrtf(xi) * Rm;
-
- *r = r_;
-
- /* h^2 + r^2 = Rm^2 */
- *h = safe_sqrtf(Rm * Rm - r_ * r_);
-}
-
-/* Generic */
+/* Setup */
ccl_device_inline Bssrdf *bssrdf_alloc(ShaderData *sd, float3 weight)
{
@@ -236,8 +110,7 @@ ccl_device int bssrdf_setup(ShaderData *sd, Bssrdf *bssrdf, ClosureType type)
/* Setup BSSRDF if radius is large enough. */
if (bssrdf_channels > 0) {
bssrdf->type = type;
- bssrdf->channels = bssrdf_channels;
- bssrdf->sample_weight = fabsf(average(bssrdf->weight)) * bssrdf->channels;
+ bssrdf->sample_weight = fabsf(average(bssrdf->weight)) * bssrdf_channels;
/* Mean free path length. */
bssrdf->radius = bssrdf_burley_compatible_mfp(bssrdf->radius);
@@ -252,57 +125,4 @@ ccl_device int bssrdf_setup(ShaderData *sd, Bssrdf *bssrdf, ClosureType type)
return flag;
}
-ccl_device void bssrdf_sample(const ShaderClosure *sc, float xi, float *r, float *h)
-{
- const Bssrdf *bssrdf = (const Bssrdf *)sc;
- float radius;
-
- /* Sample color channel and reuse random number. Only a subset of channels
- * may be used if their radius was too small to handle as BSSRDF. */
- xi *= bssrdf->channels;
-
- if (xi < 1.0f) {
- radius = (bssrdf->radius.x > 0.0f) ? bssrdf->radius.x :
- (bssrdf->radius.y > 0.0f) ? bssrdf->radius.y :
- bssrdf->radius.z;
- }
- else if (xi < 2.0f) {
- xi -= 1.0f;
- radius = (bssrdf->radius.x > 0.0f && bssrdf->radius.y > 0.0f) ? bssrdf->radius.y :
- bssrdf->radius.z;
- }
- else {
- xi -= 2.0f;
- radius = bssrdf->radius.z;
- }
-
- /* Sample BSSRDF. */
- bssrdf_burley_sample(radius, xi, r, h);
-}
-
-ccl_device float bssrdf_channel_pdf(const Bssrdf *bssrdf, float radius, float r)
-{
- if (radius == 0.0f) {
- return 0.0f;
- }
- return bssrdf_burley_pdf(radius, r);
-}
-
-ccl_device_forceinline float3 bssrdf_eval(const ShaderClosure *sc, float r)
-{
- const Bssrdf *bssrdf = (const Bssrdf *)sc;
-
- return make_float3(bssrdf_channel_pdf(bssrdf, bssrdf->radius.x, r),
- bssrdf_channel_pdf(bssrdf, bssrdf->radius.y, r),
- bssrdf_channel_pdf(bssrdf, bssrdf->radius.z, r));
-}
-
-ccl_device_forceinline float bssrdf_pdf(const ShaderClosure *sc, float r)
-{
- const Bssrdf *bssrdf = (const Bssrdf *)sc;
- float3 pdf = bssrdf_eval(sc, r);
-
- return (pdf.x + pdf.y + pdf.z) / bssrdf->channels;
-}
-
CCL_NAMESPACE_END
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