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blender/intern/cycles/bvh/bvh_build.cpp
Sergey Sharybin 6cc04b408c Cycles: Fix compilation on Win32 after bitscan commit 
Need to revisit utility headers a bit more carefully and perhaps
move such utilities outside of simd-related headers.
2016-03-31 16:47:57 +02:00

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/*
* 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_binning.h"
#include "bvh_build.h"
#include "bvh_node.h"
#include "bvh_params.h"
#include "bvh_split.h"
#include "mesh.h"
#include "object.h"
#include "scene.h"
#include "curves.h"
#include "util_debug.h"
#include "util_foreach.h"
#include "util_logging.h"
#include "util_progress.h"
#include "util_stack_allocator.h"
#include "util_simd.h"
#include "util_time.h"
CCL_NAMESPACE_BEGIN
/* BVH Build Task */
class BVHBuildTask : public Task {
public:
BVHBuildTask(BVHBuild *build, InnerNode *node, int child, BVHObjectBinning& range_, int level)
: range(range_)
{
run = function_bind(&BVHBuild::thread_build_node, build, node, child, &range, level);
}
BVHObjectBinning range;
};
/* Constructor / Destructor */
BVHBuild::BVHBuild(const vector<Object*>& objects_,
array<int>& prim_type_,
array<int>& prim_index_,
array<int>& prim_object_,
const BVHParams& params_,
Progress& progress_)
: objects(objects_),
prim_type(prim_type_),
prim_index(prim_index_),
prim_object(prim_object_),
params(params_),
progress(progress_),
progress_start_time(0.0)
{
spatial_min_overlap = 0.0f;
}
BVHBuild::~BVHBuild()
{
}
/* Adding References */
void BVHBuild::add_reference_mesh(BoundBox& root, BoundBox& center, Mesh *mesh, int i)
{
Attribute *attr_mP = NULL;
if(mesh->has_motion_blur())
attr_mP = mesh->attributes.find(ATTR_STD_MOTION_VERTEX_POSITION);
for(uint j = 0; j < mesh->triangles.size(); j++) {
Mesh::Triangle t = mesh->triangles[j];
BoundBox bounds = BoundBox::empty;
PrimitiveType type = PRIMITIVE_TRIANGLE;
t.bounds_grow(&mesh->verts[0], bounds);
/* motion triangles */
if(attr_mP) {
size_t mesh_size = mesh->verts.size();
size_t steps = mesh->motion_steps - 1;
float3 *vert_steps = attr_mP->data_float3();
for(size_t i = 0; i < steps; i++)
t.bounds_grow(vert_steps + i*mesh_size, bounds);
type = PRIMITIVE_MOTION_TRIANGLE;
}
if(bounds.valid()) {
references.push_back(BVHReference(bounds, j, i, type));
root.grow(bounds);
center.grow(bounds.center2());
}
}
Attribute *curve_attr_mP = NULL;
if(mesh->has_motion_blur())
curve_attr_mP = mesh->curve_attributes.find(ATTR_STD_MOTION_VERTEX_POSITION);
for(uint j = 0; j < mesh->curves.size(); j++) {
Mesh::Curve curve = mesh->curves[j];
PrimitiveType type = PRIMITIVE_CURVE;
for(int k = 0; k < curve.num_keys - 1; k++) {
BoundBox bounds = BoundBox::empty;
curve.bounds_grow(k, &mesh->curve_keys[0], bounds);
/* motion curve */
if(curve_attr_mP) {
size_t mesh_size = mesh->curve_keys.size();
size_t steps = mesh->motion_steps - 1;
float4 *key_steps = curve_attr_mP->data_float4();
for(size_t i = 0; i < steps; i++)
curve.bounds_grow(k, key_steps + i*mesh_size, bounds);
type = PRIMITIVE_MOTION_CURVE;
}
if(bounds.valid()) {
int packed_type = PRIMITIVE_PACK_SEGMENT(type, k);
references.push_back(BVHReference(bounds, j, i, packed_type));
root.grow(bounds);
center.grow(bounds.center2());
}
}
}
}
void BVHBuild::add_reference_object(BoundBox& root, BoundBox& center, 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(Mesh *mesh)
{
size_t num = 0, num_curves = mesh->curves.size();
for(size_t i = 0; i < num_curves; i++)
num += mesh->curves[i].num_keys - 1;
return num;
}
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->mesh->is_instanced()) {
num_alloc_references += ob->mesh->triangles.size();
num_alloc_references += count_curve_segments(ob->mesh);
}
else
num_alloc_references++;
}
else {
num_alloc_references += ob->mesh->triangles.size();
num_alloc_references += count_curve_segments(ob->mesh);
}
}
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->mesh->is_instanced())
add_reference_mesh(bounds, center, ob->mesh, i);
else
add_reference_object(bounds, center, ob, i);
}
else
add_reference_mesh(bounds, center, ob->mesh, i);
i++;
if(progress.get_cancel()) return;
}
/* happens mostly on empty meshes */
if(!bounds.valid())
bounds.grow(make_float3(0.0f, 0.0f, 0.0f));
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;
if(params.use_spatial_split) {
/* NOTE: The API here tries to be as much ready for multi-threaded build
* as possible, but at the same time it tries not to introduce any
* changes in behavior for until all refactoring needed for threading is
* finished.
*
* So we currently allocate single storage for now, which is only used by
* the only thread working on the spatial BVH build.
*/
spatial_storage.resize(1);
size_t num_bins = max(root.size(), (int)BVHParams::NUM_SPATIAL_BINS) - 1;
foreach(BVHSpatialStorage &storage, spatial_storage) {
storage.right_bounds.clear();
storage.right_bounds.resize(num_bins);
storage.reference_indices.clear();
storage.reference_indices.reserve(num_bins);
}
}
/* 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());
/* build recursively */
BVHNode *rootnode;
if(params.use_spatial_split) {
/* singlethreaded spatial split build */
rootnode = build_node(root, 0);
}
else {
/* multithreaded binning build */
BVHObjectBinning rootbin(root, (references.size())? &references[0]: NULL);
rootnode = build_node(rootbin, 0);
task_pool.wait_work();
}
/* delete if we canceled */
if(rootnode) {
if(progress.get_cancel()) {
rootnode->deleteSubtree();
rootnode = NULL;
VLOG(1) << "BVH build cancelled.";
}
else if(!params.use_spatial_split) {
/*rotate(rootnode, 4, 5);*/
rootnode->update_visibility();
}
if(rootnode != NULL) {
VLOG(1) << "BVH build statistics:\n"
<< " Build time: " << time_dt() - build_start_time << "\n"
<< " Total number of nodes: "
<< rootnode->getSubtreeSize(BVH_STAT_NODE_COUNT) << "\n"
<< " Number of inner nodes: "
<< rootnode->getSubtreeSize(BVH_STAT_INNER_COUNT) << "\n"
<< " Number of leaf nodes: "
<< rootnode->getSubtreeSize(BVH_STAT_LEAF_COUNT) << "\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, 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();
}
}
bool BVHBuild::range_within_max_leaf_size(const BVHRange& range) 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_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_CURVE)
num_curves++;
if(ref.prim_type() & PRIMITIVE_MOTION_CURVE)
num_motion_curves++;
else if(ref.prim_type() & PRIMITIVE_ALL_TRIANGLE)
num_triangles++;
}
return (num_triangles < params.max_triangle_leaf_size) &&
(num_curves < params.max_curve_leaf_size) &&
(num_motion_curves < params.max_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) && leafSAH < splitSAH))
return create_leaf_node(range);
}
/* perform split */
BVHObjectBinning left, right;
range.split(&references[0], left, right);
/* 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(range.bounds(), leftnode, rightnode);
}
else {
/* threaded build */
inner = new InnerNode(range.bounds());
task_pool.push(new BVHBuildTask(this, inner, 0, left, level + 1), true);
task_pool.push(new BVHBuildTask(this, inner, 1, right, level + 1), true);
}
return inner;
}
/* single threaded spatial split builder */
BVHNode* BVHBuild::build_node(const BVHRange& range, int level)
{
/* progress update */
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);
}
}
/* splitting test */
BVHMixedSplit split(*this, &spatial_storage[0], range, level);
if(!(range.size() > 0 && params.top_level && level == 0)) {
if(split.no_split) {
progress_count += range.size();
return create_leaf_node(range);
}
}
/* do split */
BVHRange left, right;
split.split(this, left, right, range);
progress_total += left.size() + right.size() - range.size();
size_t total = progress_total;
/* left node */
BVHNode *leftnode = build_node(left, level + 1);
/* right node (modify start for splits) */
right.set_start(right.start() + progress_total - total);
BVHNode *rightnode = build_node(right, level + 1);
/* inner node */
return new InnerNode(range.bounds(), leftnode, rightnode);
}
/* 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();
uint visibility = objects[ref->prim_object()]->visibility;
return new LeafNode(ref->bounds(), visibility, start, start+1);
}
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->m_bounds);
bounds.grow(leaf1->m_bounds);
return new InnerNode(bounds, leaf0, leaf1);
}
}
BVHNode *BVHBuild::create_primitive_leaf_node(const int *p_type,
const int *p_index,
const int *p_object,
const BoundBox& bounds,
uint visibility,
int start,
int num)
{
for(int i = 0; i < num; ++i) {
prim_type[start + i] = p_type[i];
prim_index[start + i] = p_index[i];
prim_object[start + i] = p_object[i];
}
return new LeafNode(bounds, visibility, start, start + num);
}
BVHNode* BVHBuild::create_leaf_node(const BVHRange& range)
{
const int MAX_ITEMS_PER_LEAF = 16;
/* 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.
* - 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<MAX_ITEMS_PER_LEAF * 8, int> LeafStackAllocator;
vector<int, LeafStackAllocator> p_type[PRIMITIVE_NUM_TOTAL];
vector<int, LeafStackAllocator> p_index[PRIMITIVE_NUM_TOTAL];
vector<int, LeafStackAllocator> p_object[PRIMITIVE_NUM_TOTAL];
uint visibility[PRIMITIVE_NUM_TOTAL] = {0};
/* NOTE: Keep initializtion in sync with actual number of primitives. */
BoundBox bounds[PRIMITIVE_NUM_TOTAL] = {BoundBox::empty,
BoundBox::empty,
BoundBox::empty,
BoundBox::empty};
int ob_num = 0;
/* Fill in per-type type/index array. */
for(int i = 0; i < range.size(); i++) {
BVHReference& ref = references[range.start() + i];
if(ref.prim_index() != -1) {
int type_index = bitscan(ref.prim_type() & PRIMITIVE_ALL);
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());
bounds[type_index].grow(ref.bounds());
visibility[type_index] |= objects[ref.prim_object()]->visibility;
}
else {
if(ob_num < i) {
references[range.start() + ob_num] = ref;
}
ob_num++;
}
}
/* Extend an array when needed. */
if(prim_type.size() < range.end()) {
assert(params.use_spatial_split);
prim_type.reserve(references.size());
prim_index.reserve(references.size());
prim_object.reserve(references.size());
prim_type.resize(range.end());
prim_index.resize(range.end());
prim_object.resize(range.end());
}
/* Create leaf nodes for every existing primitive. */
BVHNode *leaves[PRIMITIVE_NUM_TOTAL + 1] = {NULL};
int num_leaves = 0;
int start = range.start();
for(int i = 0; i < PRIMITIVE_NUM_TOTAL; ++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());
leaves[num_leaves] = create_primitive_leaf_node(&p_type[i][0],
&p_index[i][0],
&p_object[i][0],
bounds[i],
visibility[i],
start,
num);
++num_leaves;
start += num;
}
}
/* 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)? &references[range.start()]: NULL;
leaves[num_leaves] = create_object_leaf_nodes(ref, start, ob_num);
++num_leaves;
}
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]->m_bounds, leaves[2]->m_bounds);
BVHNode *inner = new InnerNode(inner_bounds, leaves[1], leaves[2]);
return new InnerNode(range.bounds(), leaves[0], inner);
} else {
/* Shpuld be doing more branches if more primitive types added. */
assert(num_leaves <= 5);
BoundBox inner_bounds_a = merge(leaves[0]->m_bounds, leaves[1]->m_bounds);
BoundBox inner_bounds_b = merge(leaves[2]->m_bounds, leaves[3]->m_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->m_bounds, inner_b->m_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;
}
}
/* 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]->m_bounds;
BoundBox bounds1 = parent->children[1]->m_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]->m_bounds;
BoundBox target1 = child->children[1]->m_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->m_bounds = merge(child->children[0]->m_bounds, child->children[1]->m_bounds);
}
CCL_NAMESPACE_END
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