diff options
Diffstat (limited to 'intern/cycles/kernel/svm/svm_bevel.h')
| -rw-r--r-- | intern/cycles/kernel/svm/svm_bevel.h | 226 |
1 files changed, 226 insertions, 0 deletions
diff --git a/intern/cycles/kernel/svm/svm_bevel.h b/intern/cycles/kernel/svm/svm_bevel.h new file mode 100644 index 00000000000..89f4a98e846 --- /dev/null +++ b/intern/cycles/kernel/svm/svm_bevel.h @@ -0,0 +1,226 @@ +/* + * 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. + */ + +CCL_NAMESPACE_BEGIN + +/* 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 + */ + +ccl_device_noinline float3 svm_bevel( + KernelGlobals *kg, + ShaderData *sd, + ccl_addr_space PathState *state, + 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; + } + + /* Don't bevel for blurry indirect rays. */ + if(state->min_ray_pdf < 8.0f) { + return sd->N; + } + + /* Setup for multi intersection. */ + LocalIntersection isect; + uint lcg_state = lcg_state_init_addrspace(state, 0x64c6a40e); + + /* Sample normals from surrounding points on surface. */ + float3 sum_N = make_float3(0.0f, 0.0f, 0.0f); + + for(int sample = 0; sample < num_samples; sample++) { + float disk_u, disk_v; + path_branched_rng_2D(kg, state->rng_hash, 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. */ + bssrdf_cubic_sample(radius, 0.0f, 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 = sd->dP; + ray->dD = differential3_zero(); + 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, + &isect.hits[hit], + ray); + } +#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, + &isect.hits[hit], + ray, + verts); + } +#endif /* __OBJECT_MOTION__ */ + + float3 hit_Ng = isect.Ng[hit]; + + /* 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(isect.hits[hit].object != OBJECT_NONE) { + 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 cancelled 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 = bssrdf_cubic_pdf(radius, 0.0f, r); + float disk_pdf = bssrdf_cubic_pdf(radius, 0.0f, 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; +} + +ccl_device void svm_node_bevel( + KernelGlobals *kg, + ShaderData *sd, + ccl_addr_space PathState *state, + float *stack, + uint4 node) +{ + uint num_samples, radius_offset, normal_offset, out_offset; + decode_node_uchar4(node.y, &num_samples, &radius_offset, &normal_offset, &out_offset); + + float radius = stack_load_float(stack, radius_offset); + float3 bevel_N = svm_bevel(kg, sd, state, radius, num_samples); + + 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); +} + +CCL_NAMESPACE_END + |