319 lines
9.9 KiB
C++
319 lines
9.9 KiB
C++
/*
|
|
* Copyright 2011-2013 Blender Foundation
|
|
*
|
|
* Licensed under the Apache License, Version 2.0 (the "License");
|
|
* you may not use this file except in compliance with the License.
|
|
* You may obtain a copy of the License at
|
|
*
|
|
* http://www.apache.org/licenses/LICENSE-2.0
|
|
*
|
|
* Unless required by applicable law or agreed to in writing, software
|
|
* distributed under the License is distributed on an "AS IS" BASIS,
|
|
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
* See the License for the specific language governing permissions and
|
|
* limitations under the License.
|
|
*/
|
|
|
|
#include "kernel/bvh/bvh.h"
|
|
#include "kernel/kernel_montecarlo.h"
|
|
#include "kernel/kernel_random.h"
|
|
|
|
CCL_NAMESPACE_BEGIN
|
|
|
|
#ifdef __SHADER_RAYTRACE__
|
|
|
|
/* Planar Cubic BSSRDF falloff, reused for bevel.
|
|
*
|
|
* This is basically (Rm - x)^3, with some factors to normalize it. For sampling
|
|
* we integrate 2*pi*x * (Rm - x)^3, which gives us a quintic equation that as
|
|
* far as I can tell has no closed form solution. So we get an iterative solution
|
|
* instead with newton-raphson. */
|
|
|
|
ccl_device float svm_bevel_cubic_eval(const float radius, float r)
|
|
{
|
|
const float Rm = radius;
|
|
|
|
if (r >= Rm)
|
|
return 0.0f;
|
|
|
|
/* integrate (2*pi*r * 10*(R - r)^3)/(pi * R^5) from 0 to R = 1 */
|
|
const float Rm5 = (Rm * Rm) * (Rm * Rm) * Rm;
|
|
const float f = Rm - r;
|
|
const float num = f * f * f;
|
|
|
|
return (10.0f * num) / (Rm5 * M_PI_F);
|
|
}
|
|
|
|
ccl_device float svm_bevel_cubic_pdf(const float radius, float r)
|
|
{
|
|
return svm_bevel_cubic_eval(radius, r);
|
|
}
|
|
|
|
/* solve 10x^2 - 20x^3 + 15x^4 - 4x^5 - xi == 0 */
|
|
ccl_device_forceinline float svm_bevel_cubic_quintic_root_find(float xi)
|
|
{
|
|
/* newton-raphson iteration, usually succeeds in 2-4 iterations, except
|
|
* outside 0.02 ... 0.98 where it can go up to 10, so overall performance
|
|
* should not be too bad */
|
|
const float tolerance = 1e-6f;
|
|
const int max_iteration_count = 10;
|
|
float x = 0.25f;
|
|
int i;
|
|
|
|
for (i = 0; i < max_iteration_count; i++) {
|
|
float x2 = x * x;
|
|
float x3 = x2 * x;
|
|
float nx = (1.0f - x);
|
|
|
|
float f = 10.0f * x2 - 20.0f * x3 + 15.0f * x2 * x2 - 4.0f * x2 * x3 - xi;
|
|
float f_ = 20.0f * (x * nx) * (nx * nx);
|
|
|
|
if (fabsf(f) < tolerance || f_ == 0.0f)
|
|
break;
|
|
|
|
x = saturate(x - f / f_);
|
|
}
|
|
|
|
return x;
|
|
}
|
|
|
|
ccl_device void svm_bevel_cubic_sample(const float radius, float xi, float *r, float *h)
|
|
{
|
|
float Rm = radius;
|
|
float r_ = svm_bevel_cubic_quintic_root_find(xi);
|
|
|
|
r_ *= Rm;
|
|
*r = r_;
|
|
|
|
/* h^2 + r^2 = Rm^2 */
|
|
*h = safe_sqrtf(Rm * Rm - r_ * r_);
|
|
}
|
|
|
|
/* Bevel shader averaging normals from nearby surfaces.
|
|
*
|
|
* Sampling strategy from: BSSRDF Importance Sampling, SIGGRAPH 2013
|
|
* http://library.imageworks.com/pdfs/imageworks-library-BSSRDF-sampling.pdf
|
|
*/
|
|
|
|
# ifdef __KERNEL_OPTIX__
|
|
extern "C" __device__ float3 __direct_callable__svm_node_bevel(INTEGRATOR_STATE_CONST_ARGS,
|
|
# else
|
|
ccl_device float3 svm_bevel(INTEGRATOR_STATE_CONST_ARGS,
|
|
# endif
|
|
ShaderData *sd,
|
|
float radius,
|
|
int num_samples)
|
|
{
|
|
/* Early out if no sampling needed. */
|
|
if (radius <= 0.0f || num_samples < 1 || sd->object == OBJECT_NONE) {
|
|
return sd->N;
|
|
}
|
|
|
|
/* Can't raytrace from shaders like displacement, before BVH exists. */
|
|
if (kernel_data.bvh.bvh_layout == BVH_LAYOUT_NONE) {
|
|
return sd->N;
|
|
}
|
|
|
|
/* Don't bevel for blurry indirect rays. */
|
|
if (INTEGRATOR_STATE(path, min_ray_pdf) < 8.0f) {
|
|
return sd->N;
|
|
}
|
|
|
|
/* Setup for multi intersection. */
|
|
LocalIntersection isect;
|
|
uint lcg_state = lcg_state_init(INTEGRATOR_STATE(path, rng_hash),
|
|
INTEGRATOR_STATE(path, rng_offset),
|
|
INTEGRATOR_STATE(path, sample),
|
|
0x64c6a40e);
|
|
|
|
/* Sample normals from surrounding points on surface. */
|
|
float3 sum_N = make_float3(0.0f, 0.0f, 0.0f);
|
|
|
|
/* TODO: support ray-tracing in shadow shader evaluation? */
|
|
RNGState rng_state;
|
|
path_state_rng_load(INTEGRATOR_STATE_PASS, &rng_state);
|
|
|
|
for (int sample = 0; sample < num_samples; sample++) {
|
|
float disk_u, disk_v;
|
|
path_branched_rng_2D(kg, &rng_state, sample, num_samples, PRNG_BEVEL_U, &disk_u, &disk_v);
|
|
|
|
/* Pick random axis in local frame and point on disk. */
|
|
float3 disk_N, disk_T, disk_B;
|
|
float pick_pdf_N, pick_pdf_T, pick_pdf_B;
|
|
|
|
disk_N = sd->Ng;
|
|
make_orthonormals(disk_N, &disk_T, &disk_B);
|
|
|
|
float axisu = disk_u;
|
|
|
|
if (axisu < 0.5f) {
|
|
pick_pdf_N = 0.5f;
|
|
pick_pdf_T = 0.25f;
|
|
pick_pdf_B = 0.25f;
|
|
disk_u *= 2.0f;
|
|
}
|
|
else if (axisu < 0.75f) {
|
|
float3 tmp = disk_N;
|
|
disk_N = disk_T;
|
|
disk_T = tmp;
|
|
pick_pdf_N = 0.25f;
|
|
pick_pdf_T = 0.5f;
|
|
pick_pdf_B = 0.25f;
|
|
disk_u = (disk_u - 0.5f) * 4.0f;
|
|
}
|
|
else {
|
|
float3 tmp = disk_N;
|
|
disk_N = disk_B;
|
|
disk_B = tmp;
|
|
pick_pdf_N = 0.25f;
|
|
pick_pdf_T = 0.25f;
|
|
pick_pdf_B = 0.5f;
|
|
disk_u = (disk_u - 0.75f) * 4.0f;
|
|
}
|
|
|
|
/* Sample point on disk. */
|
|
float phi = M_2PI_F * disk_u;
|
|
float disk_r = disk_v;
|
|
float disk_height;
|
|
|
|
/* Perhaps find something better than Cubic BSSRDF, but happens to work well. */
|
|
svm_bevel_cubic_sample(radius, disk_r, &disk_r, &disk_height);
|
|
|
|
float3 disk_P = (disk_r * cosf(phi)) * disk_T + (disk_r * sinf(phi)) * disk_B;
|
|
|
|
/* Create ray. */
|
|
Ray *ray = &isect.ray;
|
|
ray->P = sd->P + disk_N * disk_height + disk_P;
|
|
ray->D = -disk_N;
|
|
ray->t = 2.0f * disk_height;
|
|
ray->dP = differential_zero_compact();
|
|
ray->dD = differential_zero_compact();
|
|
ray->time = sd->time;
|
|
|
|
/* Intersect with the same object. if multiple intersections are found it
|
|
* will use at most LOCAL_MAX_HITS hits, a random subset of all hits. */
|
|
scene_intersect_local(kg, ray, &isect, sd->object, &lcg_state, LOCAL_MAX_HITS);
|
|
|
|
int num_eval_hits = min(isect.num_hits, LOCAL_MAX_HITS);
|
|
|
|
for (int hit = 0; hit < num_eval_hits; hit++) {
|
|
/* Quickly retrieve P and Ng without setting up ShaderData. */
|
|
float3 hit_P;
|
|
if (sd->type & PRIMITIVE_TRIANGLE) {
|
|
hit_P = triangle_refine_local(
|
|
kg, sd, ray->P, ray->D, ray->t, isect.hits[hit].object, isect.hits[hit].prim);
|
|
}
|
|
# ifdef __OBJECT_MOTION__
|
|
else if (sd->type & PRIMITIVE_MOTION_TRIANGLE) {
|
|
float3 verts[3];
|
|
motion_triangle_vertices(
|
|
kg, sd->object, kernel_tex_fetch(__prim_index, isect.hits[hit].prim), sd->time, verts);
|
|
hit_P = motion_triangle_refine_local(
|
|
kg, sd, ray->P, ray->D, ray->t, isect.hits[hit].object, isect.hits[hit].prim, verts);
|
|
}
|
|
# endif /* __OBJECT_MOTION__ */
|
|
|
|
/* Get geometric normal. */
|
|
float3 hit_Ng = isect.Ng[hit];
|
|
int object = (isect.hits[hit].object == OBJECT_NONE) ?
|
|
kernel_tex_fetch(__prim_object, isect.hits[hit].prim) :
|
|
isect.hits[hit].object;
|
|
int object_flag = kernel_tex_fetch(__object_flag, object);
|
|
if (object_flag & SD_OBJECT_NEGATIVE_SCALE_APPLIED) {
|
|
hit_Ng = -hit_Ng;
|
|
}
|
|
|
|
/* Compute smooth normal. */
|
|
float3 N = hit_Ng;
|
|
int prim = kernel_tex_fetch(__prim_index, isect.hits[hit].prim);
|
|
int shader = kernel_tex_fetch(__tri_shader, prim);
|
|
|
|
if (shader & SHADER_SMOOTH_NORMAL) {
|
|
float u = isect.hits[hit].u;
|
|
float v = isect.hits[hit].v;
|
|
|
|
if (sd->type & PRIMITIVE_TRIANGLE) {
|
|
N = triangle_smooth_normal(kg, N, prim, u, v);
|
|
}
|
|
# ifdef __OBJECT_MOTION__
|
|
else if (sd->type & PRIMITIVE_MOTION_TRIANGLE) {
|
|
N = motion_triangle_smooth_normal(kg, N, sd->object, prim, u, v, sd->time);
|
|
}
|
|
# endif /* __OBJECT_MOTION__ */
|
|
}
|
|
|
|
/* Transform normals to world space. */
|
|
if (!(object_flag & SD_OBJECT_TRANSFORM_APPLIED)) {
|
|
object_normal_transform(kg, sd, &N);
|
|
object_normal_transform(kg, sd, &hit_Ng);
|
|
}
|
|
|
|
/* Probability densities for local frame axes. */
|
|
float pdf_N = pick_pdf_N * fabsf(dot(disk_N, hit_Ng));
|
|
float pdf_T = pick_pdf_T * fabsf(dot(disk_T, hit_Ng));
|
|
float pdf_B = pick_pdf_B * fabsf(dot(disk_B, hit_Ng));
|
|
|
|
/* Multiple importance sample between 3 axes, power heuristic
|
|
* found to be slightly better than balance heuristic. pdf_N
|
|
* in the MIS weight and denominator canceled out. */
|
|
float w = pdf_N / (sqr(pdf_N) + sqr(pdf_T) + sqr(pdf_B));
|
|
if (isect.num_hits > LOCAL_MAX_HITS) {
|
|
w *= isect.num_hits / (float)LOCAL_MAX_HITS;
|
|
}
|
|
|
|
/* Real distance to sampled point. */
|
|
float r = len(hit_P - sd->P);
|
|
|
|
/* Compute weight. */
|
|
float pdf = svm_bevel_cubic_pdf(radius, r);
|
|
float disk_pdf = svm_bevel_cubic_pdf(radius, disk_r);
|
|
|
|
w *= pdf / disk_pdf;
|
|
|
|
/* Sum normal and weight. */
|
|
sum_N += w * N;
|
|
}
|
|
}
|
|
|
|
/* Normalize. */
|
|
float3 N = safe_normalize(sum_N);
|
|
return is_zero(N) ? sd->N : (sd->flag & SD_BACKFACING) ? -N : N;
|
|
}
|
|
|
|
template<uint node_feature_mask>
|
|
# if defined(__KERNEL_OPTIX__)
|
|
ccl_device_inline
|
|
# else
|
|
ccl_device_noinline
|
|
# endif
|
|
void
|
|
svm_node_bevel(INTEGRATOR_STATE_CONST_ARGS, ShaderData *sd, float *stack, uint4 node)
|
|
{
|
|
uint num_samples, radius_offset, normal_offset, out_offset;
|
|
svm_unpack_node_uchar4(node.y, &num_samples, &radius_offset, &normal_offset, &out_offset);
|
|
|
|
float radius = stack_load_float(stack, radius_offset);
|
|
|
|
float3 bevel_N = sd->N;
|
|
|
|
if (KERNEL_NODES_FEATURE(RAYTRACE)) {
|
|
# ifdef __KERNEL_OPTIX__
|
|
bevel_N = optixDirectCall<float3>(1, INTEGRATOR_STATE_PASS, sd, radius, num_samples);
|
|
# else
|
|
bevel_N = svm_bevel(INTEGRATOR_STATE_PASS, sd, radius, num_samples);
|
|
# endif
|
|
|
|
if (stack_valid(normal_offset)) {
|
|
/* Preserve input normal. */
|
|
float3 ref_N = stack_load_float3(stack, normal_offset);
|
|
bevel_N = normalize(ref_N + (bevel_N - sd->N));
|
|
}
|
|
}
|
|
|
|
stack_store_float3(stack, out_offset, bevel_N);
|
|
}
|
|
|
|
#endif /* __SHADER_RAYTRACE__ */
|
|
|
|
CCL_NAMESPACE_END
|