virtualx-engine/core/math/quick_hull.cpp
reduz 746dddc067 Replace most uses of Map by HashMap
* Map is unnecessary and inefficient in almost every case.
* Replaced by the new HashMap.
* Renamed Map to RBMap and Set to RBSet for cases that still make sense
  (order matters) but use is discouraged.

There were very few cases where replacing by HashMap was undesired because
keeping the key order was intended.
I tried to keep those (as RBMap) as much as possible, but might have missed
some. Review appreciated!
2022-05-16 10:37:48 +02:00

455 lines
12 KiB
C++

/*************************************************************************/
/* quick_hull.cpp */
/*************************************************************************/
/* This file is part of: */
/* GODOT ENGINE */
/* https://godotengine.org */
/*************************************************************************/
/* Copyright (c) 2007-2022 Juan Linietsky, Ariel Manzur. */
/* Copyright (c) 2014-2022 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.*/
/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY */
/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, */
/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE */
/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */
/*************************************************************************/
#include "quick_hull.h"
#include "core/templates/rb_map.h"
uint32_t QuickHull::debug_stop_after = 0xFFFFFFFF;
Error QuickHull::build(const Vector<Vector3> &p_points, Geometry3D::MeshData &r_mesh) {
/* CREATE AABB VOLUME */
AABB aabb;
for (int i = 0; i < p_points.size(); i++) {
if (i == 0) {
aabb.position = p_points[i];
} else {
aabb.expand_to(p_points[i]);
}
}
if (aabb.size == Vector3()) {
return ERR_CANT_CREATE;
}
Vector<bool> valid_points;
valid_points.resize(p_points.size());
RBSet<Vector3> valid_cache;
for (int i = 0; i < p_points.size(); i++) {
Vector3 sp = p_points[i].snapped(Vector3(0.0001, 0.0001, 0.0001));
if (valid_cache.has(sp)) {
valid_points.write[i] = false;
} else {
valid_points.write[i] = true;
valid_cache.insert(sp);
}
}
/* CREATE INITIAL SIMPLEX */
int longest_axis = aabb.get_longest_axis_index();
//first two vertices are the most distant
int simplex[4] = { 0 };
{
real_t max = 0, min = 0;
for (int i = 0; i < p_points.size(); i++) {
if (!valid_points[i]) {
continue;
}
real_t d = p_points[i][longest_axis];
if (i == 0 || d < min) {
simplex[0] = i;
min = d;
}
if (i == 0 || d > max) {
simplex[1] = i;
max = d;
}
}
}
//third vertex is one most further away from the line
{
real_t maxd = 0;
Vector3 rel12 = p_points[simplex[0]] - p_points[simplex[1]];
for (int i = 0; i < p_points.size(); i++) {
if (!valid_points[i]) {
continue;
}
Vector3 n = rel12.cross(p_points[simplex[0]] - p_points[i]).cross(rel12).normalized();
real_t d = Math::abs(n.dot(p_points[simplex[0]]) - n.dot(p_points[i]));
if (i == 0 || d > maxd) {
maxd = d;
simplex[2] = i;
}
}
}
//fourth vertex is the one most further away from the plane
{
real_t maxd = 0;
Plane p(p_points[simplex[0]], p_points[simplex[1]], p_points[simplex[2]]);
for (int i = 0; i < p_points.size(); i++) {
if (!valid_points[i]) {
continue;
}
real_t d = Math::abs(p.distance_to(p_points[i]));
if (i == 0 || d > maxd) {
maxd = d;
simplex[3] = i;
}
}
}
//compute center of simplex, this is a point always warranted to be inside
Vector3 center;
for (int i = 0; i < 4; i++) {
center += p_points[simplex[i]];
}
center /= 4.0;
//add faces
List<Face> faces;
for (int i = 0; i < 4; i++) {
static const int face_order[4][3] = {
{ 0, 1, 2 },
{ 0, 1, 3 },
{ 0, 2, 3 },
{ 1, 2, 3 }
};
Face f;
for (int j = 0; j < 3; j++) {
f.vertices[j] = simplex[face_order[i][j]];
}
Plane p(p_points[f.vertices[0]], p_points[f.vertices[1]], p_points[f.vertices[2]]);
if (p.is_point_over(center)) {
//flip face to clockwise if facing inwards
SWAP(f.vertices[0], f.vertices[1]);
p = -p;
}
f.plane = p;
faces.push_back(f);
}
real_t over_tolerance = 3 * UNIT_EPSILON * (aabb.size.x + aabb.size.y + aabb.size.z);
/* COMPUTE AVAILABLE VERTICES */
for (int i = 0; i < p_points.size(); i++) {
if (i == simplex[0]) {
continue;
}
if (i == simplex[1]) {
continue;
}
if (i == simplex[2]) {
continue;
}
if (i == simplex[3]) {
continue;
}
if (!valid_points[i]) {
continue;
}
for (Face &E : faces) {
if (E.plane.distance_to(p_points[i]) > over_tolerance) {
E.points_over.push_back(i);
break;
}
}
}
faces.sort(); // sort them, so the ones with points are in the back
/* BUILD HULL */
//poop face (while still remain)
//find further away point
//find lit faces
//determine horizon edges
//build new faces with horizon edges, them assign points side from all lit faces
//remove lit faces
uint32_t debug_stop = debug_stop_after;
while (debug_stop > 0 && faces.back()->get().points_over.size()) {
debug_stop--;
Face &f = faces.back()->get();
//find vertex most outside
int next = -1;
real_t next_d = 0;
for (int i = 0; i < f.points_over.size(); i++) {
real_t d = f.plane.distance_to(p_points[f.points_over[i]]);
if (d > next_d) {
next_d = d;
next = i;
}
}
ERR_FAIL_COND_V(next == -1, ERR_BUG);
Vector3 v = p_points[f.points_over[next]];
//find lit faces and lit edges
List<List<Face>::Element *> lit_faces; //lit face is a death sentence
HashMap<Edge, FaceConnect, Edge> lit_edges; //create this on the flight, should not be that bad for performance and simplifies code a lot
for (List<Face>::Element *E = faces.front(); E; E = E->next()) {
if (E->get().plane.distance_to(v) > 0) {
lit_faces.push_back(E);
for (int i = 0; i < 3; i++) {
uint32_t a = E->get().vertices[i];
uint32_t b = E->get().vertices[(i + 1) % 3];
Edge e(a, b);
HashMap<Edge, FaceConnect, Edge>::Iterator F = lit_edges.find(e);
if (!F) {
F = lit_edges.insert(e, FaceConnect());
}
if (e.vertices[0] == a) {
//left
F->value.left = E;
} else {
F->value.right = E;
}
}
}
}
//create new faces from horizon edges
List<List<Face>::Element *> new_faces; //new faces
for (KeyValue<Edge, FaceConnect> &E : lit_edges) {
FaceConnect &fc = E.value;
if (fc.left && fc.right) {
continue; //edge is uninteresting, not on horizon
}
//create new face!
Face face;
face.vertices[0] = f.points_over[next];
face.vertices[1] = E.key.vertices[0];
face.vertices[2] = E.key.vertices[1];
Plane p(p_points[face.vertices[0]], p_points[face.vertices[1]], p_points[face.vertices[2]]);
if (p.is_point_over(center)) {
//flip face to clockwise if facing inwards
SWAP(face.vertices[0], face.vertices[1]);
p = -p;
}
face.plane = p;
new_faces.push_back(faces.push_back(face));
}
//distribute points into new faces
for (List<Face>::Element *&F : lit_faces) {
Face &lf = F->get();
for (int i = 0; i < lf.points_over.size(); i++) {
if (lf.points_over[i] == f.points_over[next]) { //do not add current one
continue;
}
Vector3 p = p_points[lf.points_over[i]];
for (List<Face>::Element *&E : new_faces) {
Face &f2 = E->get();
if (f2.plane.distance_to(p) > over_tolerance) {
f2.points_over.push_back(lf.points_over[i]);
break;
}
}
}
}
//erase lit faces
while (lit_faces.size()) {
faces.erase(lit_faces.front()->get());
lit_faces.pop_front();
}
//put faces that contain no points on the front
for (List<Face>::Element *&E : new_faces) {
Face &f2 = E->get();
if (f2.points_over.size() == 0) {
faces.move_to_front(E);
}
}
//whew, done with iteration, go next
}
/* CREATE MESHDATA */
//make a map of edges again
HashMap<Edge, RetFaceConnect, Edge> ret_edges;
List<Geometry3D::MeshData::Face> ret_faces;
for (const Face &E : faces) {
Geometry3D::MeshData::Face f;
f.plane = E.plane;
for (int i = 0; i < 3; i++) {
f.indices.push_back(E.vertices[i]);
}
List<Geometry3D::MeshData::Face>::Element *F = ret_faces.push_back(f);
for (int i = 0; i < 3; i++) {
uint32_t a = E.vertices[i];
uint32_t b = E.vertices[(i + 1) % 3];
Edge e(a, b);
HashMap<Edge, RetFaceConnect, Edge>::Iterator G = ret_edges.find(e);
if (!G) {
G = ret_edges.insert(e, RetFaceConnect());
}
if (e.vertices[0] == a) {
//left
G->value.left = F;
} else {
G->value.right = F;
}
}
}
//fill faces
for (List<Geometry3D::MeshData::Face>::Element *E = ret_faces.front(); E; E = E->next()) {
Geometry3D::MeshData::Face &f = E->get();
for (int i = 0; i < f.indices.size(); i++) {
int a = E->get().indices[i];
int b = E->get().indices[(i + 1) % f.indices.size()];
Edge e(a, b);
HashMap<Edge, RetFaceConnect, Edge>::Iterator F = ret_edges.find(e);
ERR_CONTINUE(!F);
List<Geometry3D::MeshData::Face>::Element *O = F->value.left == E ? F->value.right : F->value.left;
ERR_CONTINUE(O == E);
ERR_CONTINUE(O == nullptr);
if (O->get().plane.is_equal_approx(f.plane)) {
//merge and delete edge and contiguous face, while repointing edges (uuugh!)
int ois = O->get().indices.size();
for (int j = 0; j < ois; j++) {
//search a
if (O->get().indices[j] == a) {
//append the rest
for (int k = 0; k < ois; k++) {
int idx = O->get().indices[(k + j) % ois];
int idxn = O->get().indices[(k + j + 1) % ois];
if (idx == b && idxn == a) { //already have b!
break;
}
if (idx != a) {
f.indices.insert(i + 1, idx);
i++;
}
Edge e2(idx, idxn);
HashMap<Edge, RetFaceConnect, Edge>::Iterator F2 = ret_edges.find(e2);
ERR_CONTINUE(!F2);
//change faceconnect, point to this face instead
if (F2->value.left == O) {
F2->value.left = E;
} else if (F2->value.right == O) {
F2->value.right = E;
}
}
break;
}
}
// remove all edge connections to this face
for (KeyValue<Edge, RetFaceConnect> &G : ret_edges) {
if (G.value.left == O) {
G.value.left = nullptr;
}
if (G.value.right == O) {
G.value.right = nullptr;
}
}
ret_edges.remove(F); //remove the edge
ret_faces.erase(O); //remove the face
}
}
}
//fill mesh
r_mesh.faces.clear();
r_mesh.faces.resize(ret_faces.size());
int idx = 0;
for (const Geometry3D::MeshData::Face &E : ret_faces) {
r_mesh.faces.write[idx++] = E;
}
r_mesh.edges.resize(ret_edges.size());
idx = 0;
for (const KeyValue<Edge, RetFaceConnect> &E : ret_edges) {
Geometry3D::MeshData::Edge e;
e.a = E.key.vertices[0];
e.b = E.key.vertices[1];
r_mesh.edges.write[idx++] = e;
}
r_mesh.vertices = p_points;
return OK;
}