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Diffstat (limited to 'intern/cycles/kernel/svm/bevel.h')
| -rw-r--r-- | intern/cycles/kernel/svm/bevel.h | 327 |
1 files changed, 327 insertions, 0 deletions
diff --git a/intern/cycles/kernel/svm/bevel.h b/intern/cycles/kernel/svm/bevel.h new file mode 100644 index 00000000000..6799489514f --- /dev/null +++ b/intern/cycles/kernel/svm/bevel.h @@ -0,0 +1,327 @@ +/* + * 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. + */ + +#pragma once + +#include "kernel/bvh/bvh.h" +#include "kernel/sample/mapping.h" +#include "kernel/sample/pattern.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 = saturatef(x - f / f_); + } + + return x; +} + +ccl_device void svm_bevel_cubic_sample(const float radius, + float xi, + ccl_private float *r, + ccl_private 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( +# else +ccl_device float3 svm_bevel( +# endif + KernelGlobals kg, + ConstIntegratorState state, + ccl_private 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(state, path, min_ray_pdf) < 8.0f) { + return sd->N; + } + + /* Setup for multi intersection. */ + LocalIntersection isect; + uint lcg_state = lcg_state_init(INTEGRATOR_STATE(state, path, rng_hash), + INTEGRATOR_STATE(state, path, rng_offset), + INTEGRATOR_STATE(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(state, &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 ccl_optional_struct_init; + 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, 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; + 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 = 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, typename ConstIntegratorGenericState> +# if defined(__KERNEL_OPTIX__) +ccl_device_inline +# else +ccl_device_noinline +# endif + void + svm_node_bevel(KernelGlobals kg, + ConstIntegratorGenericState state, + ccl_private ShaderData *sd, + ccl_private 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); + + float3 bevel_N = sd->N; + + IF_KERNEL_NODES_FEATURE(RAYTRACE) + { + float radius = stack_load_float(stack, radius_offset); + +# ifdef __KERNEL_OPTIX__ + bevel_N = optixDirectCall<float3>(1, kg, state, sd, radius, num_samples); +# else + bevel_N = svm_bevel(kg, state, 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 |