godot/core/math/bvh.h

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/*************************************************************************/
/* bvh.h */
/*************************************************************************/
/* This file is part of: */
/* GODOT ENGINE */
/* https://godotengine.org */
/*************************************************************************/
/* Copyright (c) 2007-2021 Juan Linietsky, Ariel Manzur. */
/* Copyright (c) 2014-2021 Godot Engine contributors (cf. AUTHORS.md). */
/* */
/* Permission is hereby granted, free of charge, to any person obtaining */
/* a copy of this software and associated documentation files (the */
/* "Software"), to deal in the Software without restriction, including */
/* without limitation the rights to use, copy, modify, merge, publish, */
/* distribute, sublicense, and/or sell copies of the Software, and to */
/* permit persons to whom the Software is furnished to do so, subject to */
/* the following conditions: */
/* */
/* The above copyright notice and this permission notice shall be */
/* included in all copies or substantial portions of the Software. */
/* */
/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, */
/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF */
/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
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/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE */
/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */
/*************************************************************************/
#ifndef BVH_H
#define BVH_H
// BVH
// This class provides a wrapper around BVH tree, which contains most of the functionality
// for a dynamic BVH with templated leaf size.
// However BVH also adds facilities for pairing, to maintain compatibility with Godot 3.2.
// Pairing is a collision pairing system, on top of the basic BVH.
// Some notes on the use of BVH / Octree from Godot 3.2.
// This is not well explained elsewhere.
// The rendering tree mask and types that are sent to the BVH are NOT layer masks.
// They are INSTANCE_TYPES (defined in visual_server.h), e.g. MESH, MULTIMESH, PARTICLES etc.
// Thus the lights do no cull by layer mask in the BVH.
// Layer masks are implemented in the renderers as a later step, and light_cull_mask appears to be
// implemented in GLES3 but not GLES2. Layer masks are not yet implemented for directional lights.
#include "bvh_tree.h"
#define BVHTREE_CLASS BVH_Tree<T, 2, MAX_ITEMS, USE_PAIRS, Bounds, Point>
template <class T, bool USE_PAIRS = false, int MAX_ITEMS = 32, class Bounds = AABB, class Point = Vector3>
class BVH_Manager {
public:
// note we are using uint32_t instead of BVHHandle, losing type safety, but this
// is for compatibility with octree
typedef void *(*PairCallback)(void *, uint32_t, T *, int, uint32_t, T *, int);
typedef void (*UnpairCallback)(void *, uint32_t, T *, int, uint32_t, T *, int, void *);
// these 2 are crucial for fine tuning, and can be applied manually
// see the variable declarations for more info.
void params_set_node_expansion(real_t p_value) {
if (p_value >= 0.0) {
tree._node_expansion = p_value;
tree._auto_node_expansion = false;
} else {
tree._auto_node_expansion = true;
}
}
void params_set_pairing_expansion(real_t p_value) {
if (p_value >= 0.0) {
tree._pairing_expansion = p_value;
tree._auto_pairing_expansion = false;
} else {
tree._auto_pairing_expansion = true;
}
}
void set_pair_callback(PairCallback p_callback, void *p_userdata) {
pair_callback = p_callback;
pair_callback_userdata = p_userdata;
}
void set_unpair_callback(UnpairCallback p_callback, void *p_userdata) {
unpair_callback = p_callback;
unpair_callback_userdata = p_userdata;
}
BVHHandle create(T *p_userdata, bool p_active, const Bounds &p_aabb = Bounds(), int p_subindex = 0, bool p_pairable = false, uint32_t p_pairable_type = 0, uint32_t p_pairable_mask = 1) {
// not sure if absolutely necessary to flush collisions here. It will cost performance to, instead
// of waiting for update, so only uncomment this if there are bugs.
if (USE_PAIRS) {
//_check_for_collisions();
}
#ifdef TOOLS_ENABLED
if (!USE_PAIRS) {
if (p_pairable) {
WARN_PRINT_ONCE("creating pairable item in BVH with USE_PAIRS set to false");
}
}
#endif
BVHHandle h = tree.item_add(p_userdata, p_active, p_aabb, p_subindex, p_pairable, p_pairable_type, p_pairable_mask);
if (USE_PAIRS) {
// for safety initialize the expanded AABB
Bounds &expanded_aabb = tree._pairs[h.id()].expanded_aabb;
expanded_aabb = p_aabb;
expanded_aabb.grow_by(tree._pairing_expansion);
// force a collision check no matter the AABB
if (p_active) {
_add_changed_item(h, p_aabb, false);
_check_for_collisions(true);
}
}
return h;
}
////////////////////////////////////////////////////
// wrapper versions that use uint32_t instead of handle
// for backward compatibility. Less type safe
void move(uint32_t p_handle, const Bounds &p_aabb) {
BVHHandle h;
h.set(p_handle);
move(h, p_aabb);
}
void erase(uint32_t p_handle) {
BVHHandle h;
h.set(p_handle);
erase(h);
}
void force_collision_check(uint32_t p_handle) {
BVHHandle h;
h.set(p_handle);
force_collision_check(h);
}
bool activate(uint32_t p_handle, const Bounds &p_aabb, bool p_delay_collision_check = false) {
BVHHandle h;
h.set(p_handle);
return activate(h, p_aabb, p_delay_collision_check);
}
bool deactivate(uint32_t p_handle) {
BVHHandle h;
h.set(p_handle);
return deactivate(h);
}
void set_pairable(uint32_t p_handle, bool p_pairable, uint32_t p_pairable_type, uint32_t p_pairable_mask, bool p_force_collision_check = true) {
BVHHandle h;
h.set(p_handle);
set_pairable(h, p_pairable, p_pairable_type, p_pairable_mask, p_force_collision_check);
}
bool is_pairable(uint32_t p_handle) const {
BVHHandle h;
h.set(p_handle);
return item_is_pairable(h);
}
int get_subindex(uint32_t p_handle) const {
BVHHandle h;
h.set(p_handle);
return item_get_subindex(h);
}
T *get(uint32_t p_handle) const {
BVHHandle h;
h.set(p_handle);
return item_get_userdata(h);
}
////////////////////////////////////////////////////
void move(BVHHandle p_handle, const Bounds &p_aabb) {
if (tree.item_move(p_handle, p_aabb)) {
if (USE_PAIRS) {
_add_changed_item(p_handle, p_aabb);
}
}
}
void erase(BVHHandle p_handle) {
// call unpair and remove all references to the item
// before deleting from the tree
if (USE_PAIRS) {
_remove_changed_item(p_handle);
}
tree.item_remove(p_handle);
_check_for_collisions(true);
}
// use in conjunction with activate if you have deferred the collision check, and
// set pairable has never been called.
// (deferred collision checks are a workaround for visual server for historical reasons)
void force_collision_check(BVHHandle p_handle) {
if (USE_PAIRS) {
// the aabb should already be up to date in the BVH
Bounds aabb;
item_get_AABB(p_handle, aabb);
// add it as changed even if aabb not different
_add_changed_item(p_handle, aabb, false);
// force an immediate full collision check, much like calls to set_pairable
_check_for_collisions(true);
}
}
// these should be read as set_visible for render trees,
// but generically this makes items add or remove from the
// tree internally, to speed things up by ignoring inactive items
bool activate(BVHHandle p_handle, const Bounds &p_aabb, bool p_delay_collision_check = false) {
// sending the aabb here prevents the need for the BVH to maintain
// a redundant copy of the aabb.
// returns success
if (tree.item_activate(p_handle, p_aabb)) {
if (USE_PAIRS) {
// in the special case of the render tree, when setting visibility we are using the combination of
// activate then set_pairable. This would case 2 sets of collision checks. For efficiency here we allow
// deferring to have a single collision check at the set_pairable call.
// Watch for bugs! This may cause bugs if set_pairable is not called.
if (!p_delay_collision_check) {
_add_changed_item(p_handle, p_aabb, false);
// force an immediate collision check, much like calls to set_pairable
_check_for_collisions(true);
}
}
return true;
}
return false;
}
bool deactivate(BVHHandle p_handle) {
// returns success
if (tree.item_deactivate(p_handle)) {
// call unpair and remove all references to the item
// before deleting from the tree
if (USE_PAIRS) {
_remove_changed_item(p_handle);
// force check for collisions, much like an erase was called
_check_for_collisions(true);
}
return true;
}
return false;
}
bool get_active(BVHHandle p_handle) const {
return tree.item_get_active(p_handle);
}
// call e.g. once per frame (this does a trickle optimize)
void update() {
tree.update();
_check_for_collisions();
#ifdef BVH_INTEGRITY_CHECKS
tree.integrity_check_all();
#endif
}
// this can be called more frequently than per frame if necessary
void update_collisions() {
_check_for_collisions();
}
// prefer calling this directly as type safe
void set_pairable(const BVHHandle &p_handle, bool p_pairable, uint32_t p_pairable_type, uint32_t p_pairable_mask, bool p_force_collision_check = true) {
// Returns true if the pairing state has changed.
bool state_changed = tree.item_set_pairable(p_handle, p_pairable, p_pairable_type, p_pairable_mask);
if (USE_PAIRS) {
// not sure if absolutely necessary to flush collisions here. It will cost performance to, instead
// of waiting for update, so only uncomment this if there are bugs.
//_check_for_collisions();
if ((p_force_collision_check || state_changed) && get_active(p_handle)) {
// when the pairable state changes, we need to force a collision check because newly pairable
// items may be in collision, and unpairable items might move out of collision.
// We cannot depend on waiting for the next update, because that may come much later.
Bounds aabb;
item_get_AABB(p_handle, aabb);
// passing false disables the optimization which prevents collision checks if
// the aabb hasn't changed
_add_changed_item(p_handle, aabb, false);
// force an immediate collision check (probably just for this one item)
// but it must be a FULL collision check, also checking pairable state and masks.
// This is because AABB intersecting objects may have changed pairable state / mask
// such that they should no longer be paired. E.g. lights.
_check_for_collisions(true);
} // only if active
}
}
// cull tests
int cull_aabb(const Bounds &p_aabb, T **p_result_array, int p_result_max, int *p_subindex_array = nullptr, uint32_t p_mask = 0xFFFFFFFF) {
typename BVHTREE_CLASS::CullParams params;
params.result_count_overall = 0;
params.result_max = p_result_max;
params.result_array = p_result_array;
params.subindex_array = p_subindex_array;
params.mask = p_mask;
params.pairable_type = 0;
params.test_pairable_only = false;
params.abb.from(p_aabb);
tree.cull_aabb(params);
return params.result_count_overall;
}
int cull_segment(const Point &p_from, const Point &p_to, T **p_result_array, int p_result_max, int *p_subindex_array = nullptr, uint32_t p_mask = 0xFFFFFFFF) {
typename BVHTREE_CLASS::CullParams params;
params.result_count_overall = 0;
params.result_max = p_result_max;
params.result_array = p_result_array;
params.subindex_array = p_subindex_array;
params.mask = p_mask;
params.pairable_type = 0;
params.segment.from = p_from;
params.segment.to = p_to;
tree.cull_segment(params);
return params.result_count_overall;
}
int cull_point(const Point &p_point, T **p_result_array, int p_result_max, int *p_subindex_array = nullptr, uint32_t p_mask = 0xFFFFFFFF) {
typename BVHTREE_CLASS::CullParams params;
params.result_count_overall = 0;
params.result_max = p_result_max;
params.result_array = p_result_array;
params.subindex_array = p_subindex_array;
params.mask = p_mask;
params.pairable_type = 0;
params.point = p_point;
tree.cull_point(params);
return params.result_count_overall;
}
int cull_convex(const Vector<Plane> &p_convex, T **p_result_array, int p_result_max, uint32_t p_mask = 0xFFFFFFFF) {
if (!p_convex.size()) {
return 0;
}
Vector<Vector3> convex_points = Geometry3D::compute_convex_mesh_points(&p_convex[0], p_convex.size());
if (convex_points.size() == 0) {
return 0;
}
typename BVHTREE_CLASS::CullParams params;
params.result_count_overall = 0;
params.result_max = p_result_max;
params.result_array = p_result_array;
params.subindex_array = nullptr;
params.mask = p_mask;
params.pairable_type = 0;
params.hull.planes = &p_convex[0];
params.hull.num_planes = p_convex.size();
params.hull.points = &convex_points[0];
params.hull.num_points = convex_points.size();
tree.cull_convex(params);
return params.result_count_overall;
}
private:
// do this after moving etc.
void _check_for_collisions(bool p_full_check = false) {
if (!changed_items.size()) {
// noop
return;
}
Bounds bb;
typename BVHTREE_CLASS::CullParams params;
params.result_count_overall = 0;
params.result_max = INT_MAX;
params.result_array = nullptr;
params.subindex_array = nullptr;
params.mask = 0xFFFFFFFF;
params.pairable_type = 0;
for (unsigned int n = 0; n < changed_items.size(); n++) {
const BVHHandle &h = changed_items[n];
// use the expanded aabb for pairing
const Bounds &expanded_aabb = tree._pairs[h.id()].expanded_aabb;
BVHABB_CLASS abb;
abb.from(expanded_aabb);
// find all the existing paired aabbs that are no longer
// paired, and send callbacks
_find_leavers(h, abb, p_full_check);
uint32_t changed_item_ref_id = h.id();
// set up the test from this item.
// this includes whether to test the non pairable tree,
// and the item mask.
tree.item_fill_cullparams(h, params);
params.abb = abb;
params.result_count_overall = 0; // might not be needed
tree.cull_aabb(params, false);
for (unsigned int i = 0; i < tree._cull_hits.size(); i++) {
uint32_t ref_id = tree._cull_hits[i];
// don't collide against ourself
if (ref_id == changed_item_ref_id) {
continue;
}
#ifdef BVH_CHECKS
// if neither are pairable, they should ignore each other
// THIS SHOULD NEVER HAPPEN .. now we only test the pairable tree
// if the changed item is not pairable
CRASH_COND(params.test_pairable_only && !tree._extra[ref_id].pairable);
#endif
// checkmasks is already done in the cull routine.
BVHHandle h_collidee;
h_collidee.set_id(ref_id);
// find NEW enterers, and send callbacks for them only
_collide(h, h_collidee);
}
}
_reset();
}
public:
void item_get_AABB(BVHHandle p_handle, Bounds &r_aabb) {
BVHABB_CLASS abb;
tree.item_get_ABB(p_handle, abb);
abb.to(r_aabb);
}
private:
// supplemental funcs
bool item_is_pairable(BVHHandle p_handle) const { return _get_extra(p_handle).pairable; }
T *item_get_userdata(BVHHandle p_handle) const { return _get_extra(p_handle).userdata; }
int item_get_subindex(BVHHandle p_handle) const { return _get_extra(p_handle).subindex; }
void _unpair(BVHHandle p_from, BVHHandle p_to) {
tree._handle_sort(p_from, p_to);
typename BVHTREE_CLASS::ItemExtra &exa = tree._extra[p_from.id()];
typename BVHTREE_CLASS::ItemExtra &exb = tree._extra[p_to.id()];
// if the userdata is the same, no collisions should occur
if ((exa.userdata == exb.userdata) && exa.userdata) {
return;
}
typename BVHTREE_CLASS::ItemPairs &pairs_from = tree._pairs[p_from.id()];
typename BVHTREE_CLASS::ItemPairs &pairs_to = tree._pairs[p_to.id()];
void *ud_from = pairs_from.remove_pair_to(p_to);
pairs_to.remove_pair_to(p_from);
// callback
if (unpair_callback) {
unpair_callback(pair_callback_userdata, p_from, exa.userdata, exa.subindex, p_to, exb.userdata, exb.subindex, ud_from);
}
}
// returns true if unpair
bool _find_leavers_process_pair(typename BVHTREE_CLASS::ItemPairs &p_pairs_from, const BVHABB_CLASS &p_abb_from, BVHHandle p_from, BVHHandle p_to, bool p_full_check) {
BVHABB_CLASS abb_to;
tree.item_get_ABB(p_to, abb_to);
// do they overlap?
if (p_abb_from.intersects(abb_to)) {
// the full check for pairable / non pairable and mask changes is extra expense
// this need not be done in most cases (for speed) except in the case where set_pairable is called
// where the masks etc of the objects in question may have changed
if (!p_full_check) {
return false;
}
const typename BVHTREE_CLASS::ItemExtra &exa = _get_extra(p_from);
const typename BVHTREE_CLASS::ItemExtra &exb = _get_extra(p_to);
// one of the two must be pairable to still pair
// if neither are pairable, we always unpair
if (exa.pairable || exb.pairable) {
// the masks must still be compatible to pair
// i.e. if there is a hit between the two, then they should stay paired
if (tree._cull_pairing_mask_test_hit(exa.pairable_mask, exa.pairable_type, exb.pairable_mask, exb.pairable_type)) {
return false;
}
}
}
_unpair(p_from, p_to);
return true;
}
// find all the existing paired aabbs that are no longer
// paired, and send callbacks
void _find_leavers(BVHHandle p_handle, const BVHABB_CLASS &expanded_abb_from, bool p_full_check) {
typename BVHTREE_CLASS::ItemPairs &p_from = tree._pairs[p_handle.id()];
BVHABB_CLASS abb_from = expanded_abb_from;
// remove from pairing list for every partner
for (unsigned int n = 0; n < p_from.extended_pairs.size(); n++) {
BVHHandle h_to = p_from.extended_pairs[n].handle;
if (_find_leavers_process_pair(p_from, abb_from, p_handle, h_to, p_full_check)) {
// we need to keep the counter n up to date if we deleted a pair
// as the number of items in p_from.extended_pairs will have decreased by 1
// and we don't want to miss an item
n--;
}
}
}
// find NEW enterers, and send callbacks for them only
// handle a and b
void _collide(BVHHandle p_ha, BVHHandle p_hb) {
// only have to do this oneway, lower ID then higher ID
tree._handle_sort(p_ha, p_hb);
const typename BVHTREE_CLASS::ItemExtra &exa = _get_extra(p_ha);
const typename BVHTREE_CLASS::ItemExtra &exb = _get_extra(p_hb);
// if the userdata is the same, no collisions should occur
if ((exa.userdata == exb.userdata) && exa.userdata) {
return;
}
typename BVHTREE_CLASS::ItemPairs &p_from = tree._pairs[p_ha.id()];
typename BVHTREE_CLASS::ItemPairs &p_to = tree._pairs[p_hb.id()];
// does this pair exist already?
// or only check the one with lower number of pairs for greater speed
if (p_from.num_pairs <= p_to.num_pairs) {
if (p_from.contains_pair_to(p_hb)) {
return;
}
} else {
if (p_to.contains_pair_to(p_ha)) {
return;
}
}
// callback
void *callback_userdata = nullptr;
if (pair_callback) {
callback_userdata = pair_callback(pair_callback_userdata, p_ha, exa.userdata, exa.subindex, p_hb, exb.userdata, exb.subindex);
}
// new pair! .. only really need to store the userdata on the lower handle, but both have storage so...
p_from.add_pair_to(p_hb, callback_userdata);
p_to.add_pair_to(p_ha, callback_userdata);
}
// if we remove an item, we need to immediately remove the pairs, to prevent reading the pair after deletion
void _remove_pairs_containing(BVHHandle p_handle) {
typename BVHTREE_CLASS::ItemPairs &p_from = tree._pairs[p_handle.id()];
// remove from pairing list for every partner.
// can't easily use a for loop here, because removing changes the size of the list
while (p_from.extended_pairs.size()) {
BVHHandle h_to = p_from.extended_pairs[0].handle;
_unpair(p_handle, h_to);
}
}
private:
const typename BVHTREE_CLASS::ItemExtra &_get_extra(BVHHandle p_handle) const {
return tree._extra[p_handle.id()];
}
const typename BVHTREE_CLASS::ItemRef &_get_ref(BVHHandle p_handle) const {
return tree._refs[p_handle.id()];
}
void _reset() {
changed_items.clear();
_tick++;
}
void _add_changed_item(BVHHandle p_handle, const Bounds &aabb, bool p_check_aabb = true) {
// Note that non pairable items can pair with pairable,
// so all types must be added to the list
// aabb check with expanded aabb. This greatly decreases processing
// at the cost of slightly less accurate pairing checks
// Note this pairing AABB is separate from the AABB in the actual tree
Bounds &expanded_aabb = tree._pairs[p_handle.id()].expanded_aabb;
// passing p_check_aabb false disables the optimization which prevents collision checks if
// the aabb hasn't changed. This is needed where set_pairable has been called, but the position
// has not changed.
if (p_check_aabb && expanded_aabb.encloses(aabb)) {
return;
}
// ALWAYS update the new expanded aabb, even if already changed once
// this tick, because it is vital that the AABB is kept up to date
expanded_aabb = aabb;
expanded_aabb.grow_by(tree._pairing_expansion);
// this code is to ensure that changed items only appear once on the updated list
// collision checking them multiple times is not needed, and repeats the same thing
uint32_t &last_updated_tick = tree._extra[p_handle.id()].last_updated_tick;
if (last_updated_tick == _tick) {
return; // already on changed list
}
// mark as on list
last_updated_tick = _tick;
// add to the list
changed_items.push_back(p_handle);
}
void _remove_changed_item(BVHHandle p_handle) {
// Care has to be taken here for items that are deleted. The ref ID
// could be reused on the same tick for new items. This is probably
// rare but should be taken into consideration
// callbacks
_remove_pairs_containing(p_handle);
// remove from changed items (not very efficient yet)
for (int n = 0; n < (int)changed_items.size(); n++) {
if (changed_items[n] == p_handle) {
changed_items.remove_unordered(n);
// because we are using an unordered remove,
// the last changed item will now be at spot 'n',
// and we need to redo it, so we prevent moving on to
// the next n at the next for iteration.
n--;
}
}
// reset the last updated tick (may not be necessary but just in case)
tree._extra[p_handle.id()].last_updated_tick = 0;
}
PairCallback pair_callback;
UnpairCallback unpair_callback;
void *pair_callback_userdata;
void *unpair_callback_userdata;
BVHTREE_CLASS tree;
// for collision pairing,
// maintain a list of all items moved etc on each frame / tick
LocalVector<BVHHandle, uint32_t, true> changed_items;
uint32_t _tick;
public:
BVH_Manager() {
_tick = 1; // start from 1 so items with 0 indicate never updated
pair_callback = nullptr;
unpair_callback = nullptr;
pair_callback_userdata = nullptr;
unpair_callback_userdata = nullptr;
}
};
#undef BVHTREE_CLASS
#endif // BVH_H