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Diffstat (limited to 'intern/cycles/bvh/build.cpp')
| -rw-r--r-- | intern/cycles/bvh/build.cpp | 1144 |
1 files changed, 1144 insertions, 0 deletions
diff --git a/intern/cycles/bvh/build.cpp b/intern/cycles/bvh/build.cpp new file mode 100644 index 00000000000..3ce268dfb25 --- /dev/null +++ b/intern/cycles/bvh/build.cpp @@ -0,0 +1,1144 @@ +/* + * Adapted from code copyright 2009-2010 NVIDIA Corporation + * Modifications Copyright 2011, 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 "bvh/build.h" + +#include "bvh/binning.h" +#include "bvh/node.h" +#include "bvh/params.h" +#include "bvh/split.h" + +#include "scene/curves.h" +#include "scene/hair.h" +#include "scene/mesh.h" +#include "scene/object.h" +#include "scene/scene.h" + +#include "util/algorithm.h" +#include "util/foreach.h" +#include "util/log.h" +#include "util/progress.h" +#include "util/queue.h" +#include "util/simd.h" +#include "util/stack_allocator.h" +#include "util/time.h" + +CCL_NAMESPACE_BEGIN + +/* Constructor / Destructor */ + +BVHBuild::BVHBuild(const vector<Object *> &objects_, + array<int> &prim_type_, + array<int> &prim_index_, + array<int> &prim_object_, + array<float2> &prim_time_, + const BVHParams ¶ms_, + Progress &progress_) + : objects(objects_), + prim_type(prim_type_), + prim_index(prim_index_), + prim_object(prim_object_), + prim_time(prim_time_), + params(params_), + progress(progress_), + progress_start_time(0.0), + unaligned_heuristic(objects_) +{ + spatial_min_overlap = 0.0f; +} + +BVHBuild::~BVHBuild() +{ +} + +/* Adding References */ + +void BVHBuild::add_reference_triangles(BoundBox &root, + BoundBox ¢er, + Mesh *mesh, + int object_index) +{ + const PrimitiveType primitive_type = mesh->primitive_type(); + const Attribute *attr_mP = NULL; + if (mesh->has_motion_blur()) { + attr_mP = mesh->attributes.find(ATTR_STD_MOTION_VERTEX_POSITION); + } + const size_t num_triangles = mesh->num_triangles(); + for (uint j = 0; j < num_triangles; j++) { + Mesh::Triangle t = mesh->get_triangle(j); + const float3 *verts = &mesh->verts[0]; + if (attr_mP == NULL) { + BoundBox bounds = BoundBox::empty; + t.bounds_grow(verts, bounds); + if (bounds.valid() && t.valid(verts)) { + references.push_back(BVHReference(bounds, j, object_index, primitive_type)); + root.grow(bounds); + center.grow(bounds.center2()); + } + } + else if (params.num_motion_triangle_steps == 0 || params.use_spatial_split) { + /* Motion triangles, simple case: single node for the whole + * primitive. Lowest memory footprint and faster BVH build but + * least optimal ray-tracing. + */ + /* TODO(sergey): Support motion steps for spatially split BVH. */ + const size_t num_verts = mesh->verts.size(); + const size_t num_steps = mesh->motion_steps; + const float3 *vert_steps = attr_mP->data_float3(); + BoundBox bounds = BoundBox::empty; + t.bounds_grow(verts, bounds); + for (size_t step = 0; step < num_steps - 1; step++) { + t.bounds_grow(vert_steps + step * num_verts, bounds); + } + if (bounds.valid()) { + references.push_back(BVHReference(bounds, j, object_index, primitive_type)); + root.grow(bounds); + center.grow(bounds.center2()); + } + } + else { + /* Motion triangles, trace optimized case: we split triangle + * primitives into separate nodes for each of the time steps. + * This way we minimize overlap of neighbor curve primitives. + */ + const int num_bvh_steps = params.num_motion_curve_steps * 2 + 1; + const float num_bvh_steps_inv_1 = 1.0f / (num_bvh_steps - 1); + const size_t num_verts = mesh->verts.size(); + const size_t num_steps = mesh->motion_steps; + const float3 *vert_steps = attr_mP->data_float3(); + /* Calculate bounding box of the previous time step. + * Will be reused later to avoid duplicated work on + * calculating BVH time step boundbox. + */ + float3 prev_verts[3]; + t.motion_verts(verts, vert_steps, num_verts, num_steps, 0.0f, prev_verts); + BoundBox prev_bounds = BoundBox::empty; + prev_bounds.grow(prev_verts[0]); + prev_bounds.grow(prev_verts[1]); + prev_bounds.grow(prev_verts[2]); + /* Create all primitive time steps, */ + for (int bvh_step = 1; bvh_step < num_bvh_steps; ++bvh_step) { + const float curr_time = (float)(bvh_step)*num_bvh_steps_inv_1; + float3 curr_verts[3]; + t.motion_verts(verts, vert_steps, num_verts, num_steps, curr_time, curr_verts); + BoundBox curr_bounds = BoundBox::empty; + curr_bounds.grow(curr_verts[0]); + curr_bounds.grow(curr_verts[1]); + curr_bounds.grow(curr_verts[2]); + BoundBox bounds = prev_bounds; + bounds.grow(curr_bounds); + if (bounds.valid()) { + const float prev_time = (float)(bvh_step - 1) * num_bvh_steps_inv_1; + references.push_back( + BVHReference(bounds, j, object_index, primitive_type, prev_time, curr_time)); + root.grow(bounds); + center.grow(bounds.center2()); + } + /* Current time boundbox becomes previous one for the + * next time step. + */ + prev_bounds = curr_bounds; + } + } + } +} + +void BVHBuild::add_reference_curves(BoundBox &root, BoundBox ¢er, Hair *hair, int object_index) +{ + const Attribute *curve_attr_mP = NULL; + if (hair->has_motion_blur()) { + curve_attr_mP = hair->attributes.find(ATTR_STD_MOTION_VERTEX_POSITION); + } + + const PrimitiveType primitive_type = hair->primitive_type(); + + const size_t num_curves = hair->num_curves(); + for (uint j = 0; j < num_curves; j++) { + const Hair::Curve curve = hair->get_curve(j); + const float *curve_radius = &hair->get_curve_radius()[0]; + for (int k = 0; k < curve.num_keys - 1; k++) { + if (curve_attr_mP == NULL) { + /* Really simple logic for static hair. */ + BoundBox bounds = BoundBox::empty; + curve.bounds_grow(k, &hair->get_curve_keys()[0], curve_radius, bounds); + if (bounds.valid()) { + int packed_type = PRIMITIVE_PACK_SEGMENT(primitive_type, k); + references.push_back(BVHReference(bounds, j, object_index, packed_type)); + root.grow(bounds); + center.grow(bounds.center2()); + } + } + else if (params.num_motion_curve_steps == 0 || params.use_spatial_split) { + /* Simple case of motion curves: single node for the while + * shutter time. Lowest memory usage but less optimal + * rendering. + */ + /* TODO(sergey): Support motion steps for spatially split BVH. */ + BoundBox bounds = BoundBox::empty; + curve.bounds_grow(k, &hair->get_curve_keys()[0], curve_radius, bounds); + const size_t num_keys = hair->get_curve_keys().size(); + const size_t num_steps = hair->get_motion_steps(); + const float3 *key_steps = curve_attr_mP->data_float3(); + for (size_t step = 0; step < num_steps - 1; step++) { + curve.bounds_grow(k, key_steps + step * num_keys, curve_radius, bounds); + } + if (bounds.valid()) { + int packed_type = PRIMITIVE_PACK_SEGMENT(primitive_type, k); + references.push_back(BVHReference(bounds, j, object_index, packed_type)); + root.grow(bounds); + center.grow(bounds.center2()); + } + } + else { + /* Motion curves, trace optimized case: we split curve keys + * primitives into separate nodes for each of the time steps. + * This way we minimize overlap of neighbor curve primitives. + */ + const int num_bvh_steps = params.num_motion_curve_steps * 2 + 1; + const float num_bvh_steps_inv_1 = 1.0f / (num_bvh_steps - 1); + const size_t num_steps = hair->get_motion_steps(); + const float3 *curve_keys = &hair->get_curve_keys()[0]; + const float3 *key_steps = curve_attr_mP->data_float3(); + const size_t num_keys = hair->get_curve_keys().size(); + /* Calculate bounding box of the previous time step. + * Will be reused later to avoid duplicated work on + * calculating BVH time step boundbox. + */ + float4 prev_keys[4]; + curve.cardinal_motion_keys(curve_keys, + curve_radius, + key_steps, + num_keys, + num_steps, + 0.0f, + k - 1, + k, + k + 1, + k + 2, + prev_keys); + BoundBox prev_bounds = BoundBox::empty; + curve.bounds_grow(prev_keys, prev_bounds); + /* Create all primitive time steps, */ + for (int bvh_step = 1; bvh_step < num_bvh_steps; ++bvh_step) { + const float curr_time = (float)(bvh_step)*num_bvh_steps_inv_1; + float4 curr_keys[4]; + curve.cardinal_motion_keys(curve_keys, + curve_radius, + key_steps, + num_keys, + num_steps, + curr_time, + k - 1, + k, + k + 1, + k + 2, + curr_keys); + BoundBox curr_bounds = BoundBox::empty; + curve.bounds_grow(curr_keys, curr_bounds); + BoundBox bounds = prev_bounds; + bounds.grow(curr_bounds); + if (bounds.valid()) { + const float prev_time = (float)(bvh_step - 1) * num_bvh_steps_inv_1; + int packed_type = PRIMITIVE_PACK_SEGMENT(primitive_type, k); + references.push_back( + BVHReference(bounds, j, object_index, packed_type, prev_time, curr_time)); + root.grow(bounds); + center.grow(bounds.center2()); + } + /* Current time boundbox becomes previous one for the + * next time step. + */ + prev_bounds = curr_bounds; + } + } + } + } +} + +void BVHBuild::add_reference_geometry(BoundBox &root, + BoundBox ¢er, + Geometry *geom, + int object_index) +{ + if (geom->geometry_type == Geometry::MESH || geom->geometry_type == Geometry::VOLUME) { + Mesh *mesh = static_cast<Mesh *>(geom); + add_reference_triangles(root, center, mesh, object_index); + } + else if (geom->geometry_type == Geometry::HAIR) { + Hair *hair = static_cast<Hair *>(geom); + add_reference_curves(root, center, hair, object_index); + } +} + +void BVHBuild::add_reference_object(BoundBox &root, BoundBox ¢er, Object *ob, int i) +{ + references.push_back(BVHReference(ob->bounds, -1, i, 0)); + root.grow(ob->bounds); + center.grow(ob->bounds.center2()); +} + +static size_t count_curve_segments(Hair *hair) +{ + size_t num = 0, num_curves = hair->num_curves(); + + for (size_t i = 0; i < num_curves; i++) + num += hair->get_curve(i).num_keys - 1; + + return num; +} + +static size_t count_primitives(Geometry *geom) +{ + if (geom->geometry_type == Geometry::MESH || geom->geometry_type == Geometry::VOLUME) { + Mesh *mesh = static_cast<Mesh *>(geom); + return mesh->num_triangles(); + } + else if (geom->geometry_type == Geometry::HAIR) { + Hair *hair = static_cast<Hair *>(geom); + return count_curve_segments(hair); + } + + return 0; +} + +void BVHBuild::add_references(BVHRange &root) +{ + /* reserve space for references */ + size_t num_alloc_references = 0; + + foreach (Object *ob, objects) { + if (params.top_level) { + if (!ob->is_traceable()) { + continue; + } + if (!ob->get_geometry()->is_instanced()) { + num_alloc_references += count_primitives(ob->get_geometry()); + } + else + num_alloc_references++; + } + else { + num_alloc_references += count_primitives(ob->get_geometry()); + } + } + + references.reserve(num_alloc_references); + + /* add references from objects */ + BoundBox bounds = BoundBox::empty, center = BoundBox::empty; + int i = 0; + + foreach (Object *ob, objects) { + if (params.top_level) { + if (!ob->is_traceable()) { + ++i; + continue; + } + if (!ob->get_geometry()->is_instanced()) + add_reference_geometry(bounds, center, ob->get_geometry(), i); + else + add_reference_object(bounds, center, ob, i); + } + else + add_reference_geometry(bounds, center, ob->get_geometry(), i); + + i++; + + if (progress.get_cancel()) + return; + } + + /* happens mostly on empty meshes */ + if (!bounds.valid()) + bounds.grow(zero_float3()); + + root = BVHRange(bounds, center, 0, references.size()); +} + +/* Build */ + +BVHNode *BVHBuild::run() +{ + BVHRange root; + + /* add references */ + add_references(root); + + if (progress.get_cancel()) + return NULL; + + /* init spatial splits */ + if (params.top_level) { + /* NOTE: Technically it is supported by the builder but it's not really + * optimized for speed yet and not really clear yet if it has measurable + * improvement on render time. Needs some extra investigation before + * enabling spatial split for top level BVH. + */ + params.use_spatial_split = false; + } + + spatial_min_overlap = root.bounds().safe_area() * params.spatial_split_alpha; + spatial_free_index = 0; + + need_prim_time = params.num_motion_curve_steps > 0 || params.num_motion_triangle_steps > 0; + + /* init progress updates */ + double build_start_time; + build_start_time = progress_start_time = time_dt(); + progress_count = 0; + progress_total = references.size(); + progress_original_total = progress_total; + + prim_type.resize(references.size()); + prim_index.resize(references.size()); + prim_object.resize(references.size()); + if (need_prim_time) { + prim_time.resize(references.size()); + } + else { + prim_time.resize(0); + } + + /* build recursively */ + BVHNode *rootnode; + + if (params.use_spatial_split) { + /* Perform multithreaded spatial split build. */ + BVHSpatialStorage *local_storage = &spatial_storage.local(); + rootnode = build_node(root, references, 0, local_storage); + task_pool.wait_work(); + } + else { + /* Perform multithreaded binning build. */ + BVHObjectBinning rootbin(root, (references.size()) ? &references[0] : NULL); + rootnode = build_node(rootbin, 0); + task_pool.wait_work(); + } + + /* clean up temporary memory usage by threads */ + spatial_storage.clear(); + + /* delete if we canceled */ + if (rootnode) { + if (progress.get_cancel()) { + rootnode->deleteSubtree(); + rootnode = NULL; + VLOG(1) << "BVH build cancelled."; + } + else { + /*rotate(rootnode, 4, 5);*/ + rootnode->update_visibility(); + rootnode->update_time(); + } + if (rootnode != NULL) { + VLOG(1) << "BVH build statistics:\n" + << " Build time: " << time_dt() - build_start_time << "\n" + << " Total number of nodes: " + << string_human_readable_number(rootnode->getSubtreeSize(BVH_STAT_NODE_COUNT)) + << "\n" + << " Number of inner nodes: " + << string_human_readable_number(rootnode->getSubtreeSize(BVH_STAT_INNER_COUNT)) + << "\n" + << " Number of leaf nodes: " + << string_human_readable_number(rootnode->getSubtreeSize(BVH_STAT_LEAF_COUNT)) + << "\n" + << " Number of unaligned nodes: " + << string_human_readable_number(rootnode->getSubtreeSize(BVH_STAT_UNALIGNED_COUNT)) + << "\n" + << " Allocation slop factor: " + << ((prim_type.capacity() != 0) ? (float)prim_type.size() / prim_type.capacity() : + 1.0f) + << "\n" + << " Maximum depth: " + << string_human_readable_number(rootnode->getSubtreeSize(BVH_STAT_DEPTH)) << "\n"; + } + } + + return rootnode; +} + +void BVHBuild::progress_update() +{ + if (time_dt() - progress_start_time < 0.25) + return; + + double progress_start = (double)progress_count / (double)progress_total; + double duplicates = (double)(progress_total - progress_original_total) / (double)progress_total; + + string msg = string_printf( + "Building BVH %.0f%%, duplicates %.0f%%", progress_start * 100.0, duplicates * 100.0); + + progress.set_substatus(msg); + progress_start_time = time_dt(); +} + +void BVHBuild::thread_build_node(InnerNode *inner, + int child, + const BVHObjectBinning &range, + int level) +{ + if (progress.get_cancel()) + return; + + /* build nodes */ + BVHNode *node = build_node(range, level); + + /* set child in inner node */ + inner->children[child] = node; + + /* update progress */ + if (range.size() < THREAD_TASK_SIZE) { + /*rotate(node, INT_MAX, 5);*/ + + thread_scoped_lock lock(build_mutex); + + progress_count += range.size(); + progress_update(); + } +} + +void BVHBuild::thread_build_spatial_split_node(InnerNode *inner, + int child, + const BVHRange &range, + vector<BVHReference> &references, + int level) +{ + if (progress.get_cancel()) { + return; + } + + /* Get per-thread memory for spatial split. */ + BVHSpatialStorage *local_storage = &spatial_storage.local(); + + /* build nodes */ + BVHNode *node = build_node(range, references, level, local_storage); + + /* set child in inner node */ + inner->children[child] = node; +} + +bool BVHBuild::range_within_max_leaf_size(const BVHRange &range, + const vector<BVHReference> &references) const +{ + size_t size = range.size(); + size_t max_leaf_size = max(params.max_triangle_leaf_size, params.max_curve_leaf_size); + + if (size > max_leaf_size) + return false; + + size_t num_triangles = 0; + size_t num_motion_triangles = 0; + size_t num_curves = 0; + size_t num_motion_curves = 0; + + for (int i = 0; i < size; i++) { + const BVHReference &ref = references[range.start() + i]; + + if (ref.prim_type() & PRIMITIVE_ALL_CURVE) { + if (ref.prim_type() & PRIMITIVE_ALL_MOTION) { + num_motion_curves++; + } + else { + num_curves++; + } + } + else if (ref.prim_type() & PRIMITIVE_ALL_TRIANGLE) { + if (ref.prim_type() & PRIMITIVE_ALL_MOTION) { + num_motion_triangles++; + } + else { + num_triangles++; + } + } + } + + return (num_triangles <= params.max_triangle_leaf_size) && + (num_motion_triangles <= params.max_motion_triangle_leaf_size) && + (num_curves <= params.max_curve_leaf_size) && + (num_motion_curves <= params.max_motion_curve_leaf_size); +} + +/* multithreaded binning builder */ +BVHNode *BVHBuild::build_node(const BVHObjectBinning &range, int level) +{ + size_t size = range.size(); + float leafSAH = params.sah_primitive_cost * range.leafSAH; + float splitSAH = params.sah_node_cost * range.bounds().half_area() + + params.sah_primitive_cost * range.splitSAH; + + /* Have at least one inner node on top level, for performance and correct + * visibility tests, since object instances do not check visibility flag. + */ + if (!(range.size() > 0 && params.top_level && level == 0)) { + /* Make leaf node when threshold reached or SAH tells us. */ + if ((params.small_enough_for_leaf(size, level)) || + (range_within_max_leaf_size(range, references) && leafSAH < splitSAH)) { + return create_leaf_node(range, references); + } + } + + BVHObjectBinning unaligned_range; + float unalignedSplitSAH = FLT_MAX; + float unalignedLeafSAH = FLT_MAX; + Transform aligned_space; + bool do_unalinged_split = false; + if (params.use_unaligned_nodes && splitSAH > params.unaligned_split_threshold * leafSAH) { + aligned_space = unaligned_heuristic.compute_aligned_space(range, &references[0]); + unaligned_range = BVHObjectBinning( + range, &references[0], &unaligned_heuristic, &aligned_space); + unalignedSplitSAH = params.sah_node_cost * unaligned_range.unaligned_bounds().half_area() + + params.sah_primitive_cost * unaligned_range.splitSAH; + unalignedLeafSAH = params.sah_primitive_cost * unaligned_range.leafSAH; + if (!(range.size() > 0 && params.top_level && level == 0)) { + if (unalignedLeafSAH < unalignedSplitSAH && unalignedSplitSAH < splitSAH && + range_within_max_leaf_size(range, references)) { + return create_leaf_node(range, references); + } + } + /* Check whether unaligned split is better than the regular one. */ + if (unalignedSplitSAH < splitSAH) { + do_unalinged_split = true; + } + } + + /* Perform split. */ + BVHObjectBinning left, right; + if (do_unalinged_split) { + unaligned_range.split(&references[0], left, right); + } + else { + range.split(&references[0], left, right); + } + + BoundBox bounds; + if (do_unalinged_split) { + bounds = unaligned_heuristic.compute_aligned_boundbox(range, &references[0], aligned_space); + } + else { + bounds = range.bounds(); + } + + /* Create inner node. */ + InnerNode *inner; + if (range.size() < THREAD_TASK_SIZE) { + /* local build */ + BVHNode *leftnode = build_node(left, level + 1); + BVHNode *rightnode = build_node(right, level + 1); + + inner = new InnerNode(bounds, leftnode, rightnode); + } + else { + /* Threaded build */ + inner = new InnerNode(bounds); + + task_pool.push([=] { thread_build_node(inner, 0, left, level + 1); }); + task_pool.push([=] { thread_build_node(inner, 1, right, level + 1); }); + } + + if (do_unalinged_split) { + inner->set_aligned_space(aligned_space); + } + + return inner; +} + +/* multithreaded spatial split builder */ +BVHNode *BVHBuild::build_node(const BVHRange &range, + vector<BVHReference> &references, + int level, + BVHSpatialStorage *storage) +{ + /* Update progress. + * + * TODO(sergey): Currently it matches old behavior, but we can move it to the + * task thread (which will mimic non=split builder) and save some CPU ticks + * on checking cancel status. + */ + progress_update(); + if (progress.get_cancel()) { + return NULL; + } + + /* Small enough or too deep => create leaf. */ + if (!(range.size() > 0 && params.top_level && level == 0)) { + if (params.small_enough_for_leaf(range.size(), level)) { + progress_count += range.size(); + return create_leaf_node(range, references); + } + } + + /* Perform splitting test. */ + BVHMixedSplit split(this, storage, range, references, level); + + if (!(range.size() > 0 && params.top_level && level == 0)) { + if (split.no_split) { + progress_count += range.size(); + return create_leaf_node(range, references); + } + } + float leafSAH = params.sah_primitive_cost * split.leafSAH; + float splitSAH = params.sah_node_cost * range.bounds().half_area() + + params.sah_primitive_cost * split.nodeSAH; + + BVHMixedSplit unaligned_split; + float unalignedSplitSAH = FLT_MAX; + /* float unalignedLeafSAH = FLT_MAX; */ + Transform aligned_space; + bool do_unalinged_split = false; + if (params.use_unaligned_nodes && splitSAH > params.unaligned_split_threshold * leafSAH) { + aligned_space = unaligned_heuristic.compute_aligned_space(range, &references.at(0)); + unaligned_split = BVHMixedSplit( + this, storage, range, references, level, &unaligned_heuristic, &aligned_space); + /* unalignedLeafSAH = params.sah_primitive_cost * split.leafSAH; */ + unalignedSplitSAH = params.sah_node_cost * unaligned_split.bounds.half_area() + + params.sah_primitive_cost * unaligned_split.nodeSAH; + /* TOOD(sergey): Check we can create leaf already. */ + /* Check whether unaligned split is better than the regular one. */ + if (unalignedSplitSAH < splitSAH) { + do_unalinged_split = true; + } + } + + /* Do split. */ + BVHRange left, right; + if (do_unalinged_split) { + unaligned_split.split(this, left, right, range); + } + else { + split.split(this, left, right, range); + } + + progress_total += left.size() + right.size() - range.size(); + + BoundBox bounds; + if (do_unalinged_split) { + bounds = unaligned_heuristic.compute_aligned_boundbox(range, &references.at(0), aligned_space); + } + else { + bounds = range.bounds(); + } + + /* Create inner node. */ + InnerNode *inner; + if (range.size() < THREAD_TASK_SIZE) { + /* Local build. */ + + /* Build left node. */ + vector<BVHReference> right_references(references.begin() + right.start(), + references.begin() + right.end()); + right.set_start(0); + + BVHNode *leftnode = build_node(left, references, level + 1, storage); + + /* Build right node. */ + BVHNode *rightnode = build_node(right, right_references, level + 1, storage); + + inner = new InnerNode(bounds, leftnode, rightnode); + } + else { + /* Threaded build. */ + inner = new InnerNode(bounds); + + vector<BVHReference> left_references(references.begin() + left.start(), + references.begin() + left.end()); + vector<BVHReference> right_references(references.begin() + right.start(), + references.begin() + right.end()); + right.set_start(0); + + /* Create tasks for left and right nodes, using copy for most arguments and + * move for reference to avoid memory copies. */ + task_pool.push([=, refs = std::move(left_references)]() mutable { + thread_build_spatial_split_node(inner, 0, left, refs, level + 1); + }); + task_pool.push([=, refs = std::move(right_references)]() mutable { + thread_build_spatial_split_node(inner, 1, right, refs, level + 1); + }); + } + + if (do_unalinged_split) { + inner->set_aligned_space(aligned_space); + } + + return inner; +} + +/* Create Nodes */ + +BVHNode *BVHBuild::create_object_leaf_nodes(const BVHReference *ref, int start, int num) +{ + if (num == 0) { + BoundBox bounds = BoundBox::empty; + return new LeafNode(bounds, 0, 0, 0); + } + else if (num == 1) { + assert(start < prim_type.size()); + prim_type[start] = ref->prim_type(); + prim_index[start] = ref->prim_index(); + prim_object[start] = ref->prim_object(); + if (need_prim_time) { + prim_time[start] = make_float2(ref->time_from(), ref->time_to()); + } + + const uint visibility = objects[ref->prim_object()]->visibility_for_tracing(); + BVHNode *leaf_node = new LeafNode(ref->bounds(), visibility, start, start + 1); + leaf_node->time_from = ref->time_from(); + leaf_node->time_to = ref->time_to(); + return leaf_node; + } + else { + int mid = num / 2; + BVHNode *leaf0 = create_object_leaf_nodes(ref, start, mid); + BVHNode *leaf1 = create_object_leaf_nodes(ref + mid, start + mid, num - mid); + + BoundBox bounds = BoundBox::empty; + bounds.grow(leaf0->bounds); + bounds.grow(leaf1->bounds); + + BVHNode *inner_node = new InnerNode(bounds, leaf0, leaf1); + inner_node->time_from = min(leaf0->time_from, leaf1->time_from); + inner_node->time_to = max(leaf0->time_to, leaf1->time_to); + return inner_node; + } +} + +BVHNode *BVHBuild::create_leaf_node(const BVHRange &range, const vector<BVHReference> &references) +{ + /* This is a bit overallocating here (considering leaf size into account), + * but chunk-based re-allocation in vector makes it difficult to use small + * size of stack storage here. Some tweaks are possible tho. + * + * NOTES: + * - If the size is too big, we'll have inefficient stack usage, + * and lots of cache misses. + * - If the size is too small, then we can run out of memory + * allowed to be used by vector. + * In practice it wouldn't mean crash, just allocator will fallback + * to heap which is slower. + * - Optimistic re-allocation in STL could jump us out of stack usage + * because re-allocation happens in chunks and size of those chunks we + * can not control. + */ + typedef StackAllocator<256, int> LeafStackAllocator; + typedef StackAllocator<256, float2> LeafTimeStackAllocator; + typedef StackAllocator<256, BVHReference> LeafReferenceStackAllocator; + + vector<int, LeafStackAllocator> p_type[PRIMITIVE_NUM]; + vector<int, LeafStackAllocator> p_index[PRIMITIVE_NUM]; + vector<int, LeafStackAllocator> p_object[PRIMITIVE_NUM]; + vector<float2, LeafTimeStackAllocator> p_time[PRIMITIVE_NUM]; + vector<BVHReference, LeafReferenceStackAllocator> p_ref[PRIMITIVE_NUM]; + + /* TODO(sergey): In theory we should be able to store references. */ + vector<BVHReference, LeafReferenceStackAllocator> object_references; + + uint visibility[PRIMITIVE_NUM] = {0}; + /* NOTE: Keep initialization in sync with actual number of primitives. */ + BoundBox bounds[PRIMITIVE_NUM] = { + BoundBox::empty, BoundBox::empty, BoundBox::empty, BoundBox::empty}; + int ob_num = 0; + int num_new_prims = 0; + /* Fill in per-type type/index array. */ + for (int i = 0; i < range.size(); i++) { + const BVHReference &ref = references[range.start() + i]; + if (ref.prim_index() != -1) { + uint32_t type_index = bitscan((uint32_t)(ref.prim_type() & PRIMITIVE_ALL)); + p_ref[type_index].push_back(ref); + p_type[type_index].push_back(ref.prim_type()); + p_index[type_index].push_back(ref.prim_index()); + p_object[type_index].push_back(ref.prim_object()); + p_time[type_index].push_back(make_float2(ref.time_from(), ref.time_to())); + + bounds[type_index].grow(ref.bounds()); + visibility[type_index] |= objects[ref.prim_object()]->visibility_for_tracing(); + ++num_new_prims; + } + else { + object_references.push_back(ref); + ++ob_num; + } + } + + /* Create leaf nodes for every existing primitive. + * + * Here we write primitive types, indices and objects to a temporary array. + * This way we keep all the heavy memory allocation code outside of the + * thread lock in the case of spatial split building. + * + * TODO(sergey): With some pointer trickery we can write directly to the + * destination buffers for the non-spatial split BVH. + */ + BVHNode *leaves[PRIMITIVE_NUM + 1] = {NULL}; + int num_leaves = 0; + size_t start_index = 0; + vector<int, LeafStackAllocator> local_prim_type, local_prim_index, local_prim_object; + vector<float2, LeafTimeStackAllocator> local_prim_time; + local_prim_type.resize(num_new_prims); + local_prim_index.resize(num_new_prims); + local_prim_object.resize(num_new_prims); + if (need_prim_time) { + local_prim_time.resize(num_new_prims); + } + for (int i = 0; i < PRIMITIVE_NUM; ++i) { + int num = (int)p_type[i].size(); + if (num != 0) { + assert(p_type[i].size() == p_index[i].size()); + assert(p_type[i].size() == p_object[i].size()); + Transform aligned_space; + bool alignment_found = false; + for (int j = 0; j < num; ++j) { + const int index = start_index + j; + local_prim_type[index] = p_type[i][j]; + local_prim_index[index] = p_index[i][j]; + local_prim_object[index] = p_object[i][j]; + if (need_prim_time) { + local_prim_time[index] = p_time[i][j]; + } + if (params.use_unaligned_nodes && !alignment_found) { + alignment_found = unaligned_heuristic.compute_aligned_space(p_ref[i][j], &aligned_space); + } + } + LeafNode *leaf_node = new LeafNode(bounds[i], visibility[i], start_index, start_index + num); + if (true) { + float time_from = 1.0f, time_to = 0.0f; + for (int j = 0; j < num; ++j) { + const BVHReference &ref = p_ref[i][j]; + time_from = min(time_from, ref.time_from()); + time_to = max(time_to, ref.time_to()); + } + leaf_node->time_from = time_from; + leaf_node->time_to = time_to; + } + if (alignment_found) { + /* Need to recalculate leaf bounds with new alignment. */ + leaf_node->bounds = BoundBox::empty; + for (int j = 0; j < num; ++j) { + const BVHReference &ref = p_ref[i][j]; + BoundBox ref_bounds = unaligned_heuristic.compute_aligned_prim_boundbox(ref, + aligned_space); + leaf_node->bounds.grow(ref_bounds); + } + /* Set alignment space. */ + leaf_node->set_aligned_space(aligned_space); + } + leaves[num_leaves++] = leaf_node; + start_index += num; + } + } + /* Get size of new data to be copied to the packed arrays. */ + const int num_new_leaf_data = start_index; + const size_t new_leaf_data_size = sizeof(int) * num_new_leaf_data; + /* Copy actual data to the packed array. */ + if (params.use_spatial_split) { + spatial_spin_lock.lock(); + /* We use first free index in the packed arrays and mode pointer to the + * end of the current range. + * + * This doesn't give deterministic packed arrays, but it shouldn't really + * matter because order of children in BVH is deterministic. + */ + start_index = spatial_free_index; + spatial_free_index += range.size(); + /* Extend an array when needed. */ + const size_t range_end = start_index + range.size(); + if (prim_type.size() < range_end) { + /* Avoid extra re-allocations by pre-allocating bigger array in an + * advance. + */ + if (range_end >= prim_type.capacity()) { + float progress = (float)progress_count / (float)progress_total; + float factor = (1.0f - progress); + const size_t reserve = (size_t)(range_end + (float)range_end * factor); + prim_type.reserve(reserve); + prim_index.reserve(reserve); + prim_object.reserve(reserve); + if (need_prim_time) { + prim_time.reserve(reserve); + } + } + + prim_type.resize(range_end); + prim_index.resize(range_end); + prim_object.resize(range_end); + if (need_prim_time) { + prim_time.resize(range_end); + } + } + /* Perform actual data copy. */ + if (new_leaf_data_size > 0) { + memcpy(&prim_type[start_index], &local_prim_type[0], new_leaf_data_size); + memcpy(&prim_index[start_index], &local_prim_index[0], new_leaf_data_size); + memcpy(&prim_object[start_index], &local_prim_object[0], new_leaf_data_size); + if (need_prim_time) { + memcpy(&prim_time[start_index], &local_prim_time[0], sizeof(float2) * num_new_leaf_data); + } + } + spatial_spin_lock.unlock(); + } + else { + /* For the regular BVH builder we simply copy new data starting at the + * range start. This is totally thread-safe, all threads are living + * inside of their own range. + */ + start_index = range.start(); + if (new_leaf_data_size > 0) { + memcpy(&prim_type[start_index], &local_prim_type[0], new_leaf_data_size); + memcpy(&prim_index[start_index], &local_prim_index[0], new_leaf_data_size); + memcpy(&prim_object[start_index], &local_prim_object[0], new_leaf_data_size); + if (need_prim_time) { + memcpy(&prim_time[start_index], &local_prim_time[0], sizeof(float2) * num_new_leaf_data); + } + } + } + + /* So far leaves were created with the zero-based index in an arrays, + * here we modify the indices to correspond to actual packed array start + * index. + */ + for (int i = 0; i < num_leaves; ++i) { + LeafNode *leaf = (LeafNode *)leaves[i]; + leaf->lo += start_index; + leaf->hi += start_index; + } + + /* Create leaf node for object. */ + if (num_leaves == 0 || ob_num) { + /* Only create object leaf nodes if there are objects or no other + * nodes created. + */ + const BVHReference *ref = (ob_num) ? &object_references[0] : NULL; + leaves[num_leaves] = create_object_leaf_nodes(ref, start_index + num_new_leaf_data, ob_num); + ++num_leaves; + } + + /* TODO(sergey): Need to take care of alignment when number of leaves + * is more than 1. + */ + if (num_leaves == 1) { + /* Simplest case: single leaf, just return it. + * In all the rest cases we'll be creating intermediate inner node with + * an appropriate bounding box. + */ + return leaves[0]; + } + else if (num_leaves == 2) { + return new InnerNode(range.bounds(), leaves[0], leaves[1]); + } + else if (num_leaves == 3) { + BoundBox inner_bounds = merge(leaves[1]->bounds, leaves[2]->bounds); + BVHNode *inner = new InnerNode(inner_bounds, leaves[1], leaves[2]); + return new InnerNode(range.bounds(), leaves[0], inner); + } + else { + /* Should be doing more branches if more primitive types added. */ + assert(num_leaves <= 5); + BoundBox inner_bounds_a = merge(leaves[0]->bounds, leaves[1]->bounds); + BoundBox inner_bounds_b = merge(leaves[2]->bounds, leaves[3]->bounds); + BVHNode *inner_a = new InnerNode(inner_bounds_a, leaves[0], leaves[1]); + BVHNode *inner_b = new InnerNode(inner_bounds_b, leaves[2], leaves[3]); + BoundBox inner_bounds_c = merge(inner_a->bounds, inner_b->bounds); + BVHNode *inner_c = new InnerNode(inner_bounds_c, inner_a, inner_b); + if (num_leaves == 5) { + return new InnerNode(range.bounds(), inner_c, leaves[4]); + } + return inner_c; + } + +#undef MAX_ITEMS_PER_LEAF +} + +/* Tree Rotations */ + +void BVHBuild::rotate(BVHNode *node, int max_depth, int iterations) +{ + /* in tested scenes, this resulted in slightly slower raytracing, so disabled + * it for now. could be implementation bug, or depend on the scene */ + if (node) + for (int i = 0; i < iterations; i++) + rotate(node, max_depth); +} + +void BVHBuild::rotate(BVHNode *node, int max_depth) +{ + /* nothing to rotate if we reached a leaf node. */ + if (node->is_leaf() || max_depth < 0) + return; + + InnerNode *parent = (InnerNode *)node; + + /* rotate all children first */ + for (size_t c = 0; c < 2; c++) + rotate(parent->children[c], max_depth - 1); + + /* compute current area of all children */ + BoundBox bounds0 = parent->children[0]->bounds; + BoundBox bounds1 = parent->children[1]->bounds; + + float area0 = bounds0.half_area(); + float area1 = bounds1.half_area(); + float4 child_area = make_float4(area0, area1, 0.0f, 0.0f); + + /* find best rotation. we pick a target child of a first child, and swap + * this with an other child. we perform the best such swap. */ + float best_cost = FLT_MAX; + int best_child = -1, best_target = -1, best_other = -1; + + for (size_t c = 0; c < 2; c++) { + /* ignore leaf nodes as we cannot descent into */ + if (parent->children[c]->is_leaf()) + continue; + + InnerNode *child = (InnerNode *)parent->children[c]; + BoundBox &other = (c == 0) ? bounds1 : bounds0; + + /* transpose child bounds */ + BoundBox target0 = child->children[0]->bounds; + BoundBox target1 = child->children[1]->bounds; + + /* compute cost for both possible swaps */ + float cost0 = merge(other, target1).half_area() - child_area[c]; + float cost1 = merge(target0, other).half_area() - child_area[c]; + + if (min(cost0, cost1) < best_cost) { + best_child = (int)c; + best_other = (int)(1 - c); + + if (cost0 < cost1) { + best_cost = cost0; + best_target = 0; + } + else { + best_cost = cost0; + best_target = 1; + } + } + } + + /* if we did not find a swap that improves the SAH then do nothing */ + if (best_cost >= 0) + return; + + assert(best_child == 0 || best_child == 1); + assert(best_target != -1); + + /* perform the best found tree rotation */ + InnerNode *child = (InnerNode *)parent->children[best_child]; + + swap(parent->children[best_other], child->children[best_target]); + child->bounds = merge(child->children[0]->bounds, child->children[1]->bounds); +} + +CCL_NAMESPACE_END |