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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_progress.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_,
vector<int>& prim_type_, vector<int>& prim_index_, vector<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->transform_applied) {
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->transform_applied)
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) /* todo: get rid of this */
params.use_spatial_split = false;
spatial_min_overlap = root.bounds().safe_area() * params.spatial_split_alpha;
spatial_right_bounds.clear();
spatial_right_bounds.resize(max(root.size(), (int)BVHParams::NUM_SPATIAL_BINS) - 1);
/* init progress updates */
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;
}
else if(!params.use_spatial_split) {
/*rotate(rootnode, 4, 5);*/
rootnode->update_visibility();
}
}
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();
}
}
/* multithreaded binning builder */
BVHNode* BVHBuild::build_node(const BVHObjectBinning& range, int level)
{
size_t size = range.size();
float leafSAH = params.sah_triangle_cost * range.leafSAH;
float splitSAH = params.sah_node_cost * range.bounds().half_area() + params.sah_triangle_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) || (size <= params.max_leaf_size && 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, 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;
/* leaft 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) {
if(start == prim_index.size()) {
assert(params.use_spatial_split);
prim_type.push_back(ref->prim_type());
prim_index.push_back(ref->prim_index());
prim_object.push_back(ref->prim_object());
}
else {
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_leaf_node(const BVHRange& range)
{
vector<int>& p_type = prim_type;
vector<int>& p_index = prim_index;
vector<int>& p_object = prim_object;
BoundBox bounds = BoundBox::empty;
int num = 0, ob_num = 0;
uint visibility = 0;
for(int i = 0; i < range.size(); i++) {
BVHReference& ref = references[range.start() + i];
if(ref.prim_index() != -1) {
if(range.start() + num == prim_index.size()) {
assert(params.use_spatial_split);
p_type.push_back(ref.prim_type());
p_index.push_back(ref.prim_index());
p_object.push_back(ref.prim_object());
}
else {
p_type[range.start() + num] = ref.prim_type();
p_index[range.start() + num] = ref.prim_index();
p_object[range.start() + num] = ref.prim_object();
}
bounds.grow(ref.bounds());
visibility |= objects[ref.prim_object()]->visibility;
num++;
}
else {
if(ob_num < i)
references[range.start() + ob_num] = ref;
ob_num++;
}
}
BVHNode *leaf = NULL;
if(num > 0) {
leaf = new LeafNode(bounds, visibility, range.start(), range.start() + num);
if(num == range.size())
return leaf;
}
/* while there may be multiple triangles in a leaf, for object primitives
* we want there to be the only one, so we keep splitting */
const BVHReference *ref = (ob_num)? &references[range.start()]: NULL;
BVHNode *oleaf = create_object_leaf_nodes(ref, range.start() + num, ob_num);
if(leaf)
return new InnerNode(range.bounds(), leaf, oleaf);
else
return oleaf;
}
/* 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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