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godot/core/math/delaunay_3d.h

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/*************************************************************************/
/* delaunay_3d.h */
/*************************************************************************/
/* 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. */
/*************************************************************************/
#ifndef DELAUNAY_3D_H
#define DELAUNAY_3D_H
#include "core/io/file_access.h"
#include "core/math/aabb.h"
#include "core/math/projection.h"
#include "core/math/vector3.h"
#include "core/templates/local_vector.h"
#include "core/templates/oa_hash_map.h"
#include "core/templates/vector.h"
#include "core/variant/variant.h"
#include "thirdparty/misc/r128.h"
class Delaunay3D {
struct Simplex;
enum {
ACCEL_GRID_SIZE = 16
};
struct GridPos {
Vector3i pos;
List<Simplex *>::Element *E = nullptr;
};
struct Simplex {
uint32_t points[4];
R128 circum_center_x;
R128 circum_center_y;
R128 circum_center_z;
R128 circum_r2;
LocalVector<GridPos> grid_positions;
List<Simplex *>::Element *SE = nullptr;
_FORCE_INLINE_ Simplex() {}
_FORCE_INLINE_ Simplex(uint32_t p_a, uint32_t p_b, uint32_t p_c, uint32_t p_d) {
points[0] = p_a;
points[1] = p_b;
points[2] = p_c;
points[3] = p_d;
}
};
struct Triangle {
uint32_t triangle[3];
bool bad = false;
_FORCE_INLINE_ bool operator==(const Triangle &p_triangle) const {
return triangle[0] == p_triangle.triangle[0] && triangle[1] == p_triangle.triangle[1] && triangle[2] == p_triangle.triangle[2];
}
_FORCE_INLINE_ Triangle() {}
_FORCE_INLINE_ Triangle(uint32_t p_a, uint32_t p_b, uint32_t p_c) {
if (p_a > p_b) {
SWAP(p_a, p_b);
}
if (p_b > p_c) {
SWAP(p_b, p_c);
}
if (p_a > p_b) {
SWAP(p_a, p_b);
}
triangle[0] = p_a;
triangle[1] = p_b;
triangle[2] = p_c;
}
};
struct TriangleHasher {
_FORCE_INLINE_ static uint32_t hash(const Triangle &p_triangle) {
uint32_t h = hash_djb2_one_32(p_triangle.triangle[0]);
h = hash_djb2_one_32(p_triangle.triangle[1], h);
return hash_fmix32(hash_djb2_one_32(p_triangle.triangle[2], h));
}
};
_FORCE_INLINE_ static void circum_sphere_compute(const Vector3 *p_points, Simplex *p_simplex) {
// the only part in the algorithm where there may be precision errors is this one, so ensure that
// we do it as maximum precision as possible
R128 v0_x = p_points[p_simplex->points[0]].x;
R128 v0_y = p_points[p_simplex->points[0]].y;
R128 v0_z = p_points[p_simplex->points[0]].z;
R128 v1_x = p_points[p_simplex->points[1]].x;
R128 v1_y = p_points[p_simplex->points[1]].y;
R128 v1_z = p_points[p_simplex->points[1]].z;
R128 v2_x = p_points[p_simplex->points[2]].x;
R128 v2_y = p_points[p_simplex->points[2]].y;
R128 v2_z = p_points[p_simplex->points[2]].z;
R128 v3_x = p_points[p_simplex->points[3]].x;
R128 v3_y = p_points[p_simplex->points[3]].y;
R128 v3_z = p_points[p_simplex->points[3]].z;
//Create the rows of our "unrolled" 3x3 matrix
R128 row1_x = v1_x - v0_x;
R128 row1_y = v1_y - v0_y;
R128 row1_z = v1_z - v0_z;
R128 row2_x = v2_x - v0_x;
R128 row2_y = v2_y - v0_y;
R128 row2_z = v2_z - v0_z;
R128 row3_x = v3_x - v0_x;
R128 row3_y = v3_y - v0_y;
R128 row3_z = v3_z - v0_z;
R128 sq_lenght1 = row1_x * row1_x + row1_y * row1_y + row1_z * row1_z;
R128 sq_lenght2 = row2_x * row2_x + row2_y * row2_y + row2_z * row2_z;
R128 sq_lenght3 = row3_x * row3_x + row3_y * row3_y + row3_z * row3_z;
//Compute the determinant of said matrix
R128 determinant = row1_x * (row2_y * row3_z - row3_y * row2_z) - row2_x * (row1_y * row3_z - row3_y * row1_z) + row3_x * (row1_y * row2_z - row2_y * row1_z);
// Compute the volume of the tetrahedron, and precompute a scalar quantity for re-use in the formula
R128 volume = determinant / R128(6.f);
R128 i12volume = R128(1.f) / (volume * R128(12.f));
R128 center_x = v0_x + i12volume * ((row2_y * row3_z - row3_y * row2_z) * sq_lenght1 - (row1_y * row3_z - row3_y * row1_z) * sq_lenght2 + (row1_y * row2_z - row2_y * row1_z) * sq_lenght3);
R128 center_y = v0_y + i12volume * (-(row2_x * row3_z - row3_x * row2_z) * sq_lenght1 + (row1_x * row3_z - row3_x * row1_z) * sq_lenght2 - (row1_x * row2_z - row2_x * row1_z) * sq_lenght3);
R128 center_z = v0_z + i12volume * ((row2_x * row3_y - row3_x * row2_y) * sq_lenght1 - (row1_x * row3_y - row3_x * row1_y) * sq_lenght2 + (row1_x * row2_y - row2_x * row1_y) * sq_lenght3);
//Once we know the center, the radius is clearly the distance to any vertex
R128 rel1_x = center_x - v0_x;
R128 rel1_y = center_y - v0_y;
R128 rel1_z = center_z - v0_z;
R128 radius1 = rel1_x * rel1_x + rel1_y * rel1_y + rel1_z * rel1_z;
p_simplex->circum_center_x = center_x;
p_simplex->circum_center_y = center_y;
p_simplex->circum_center_z = center_z;
p_simplex->circum_r2 = radius1;
}
_FORCE_INLINE_ static bool simplex_contains(const Vector3 *p_points, const Simplex &p_simplex, uint32_t p_vertex) {
R128 v_x = p_points[p_vertex].x;
R128 v_y = p_points[p_vertex].y;
R128 v_z = p_points[p_vertex].z;
R128 rel2_x = p_simplex.circum_center_x - v_x;
R128 rel2_y = p_simplex.circum_center_y - v_y;
R128 rel2_z = p_simplex.circum_center_z - v_z;
R128 radius2 = rel2_x * rel2_x + rel2_y * rel2_y + rel2_z * rel2_z;
return radius2 < (p_simplex.circum_r2 - R128(0.00001));
}
static bool simplex_is_coplanar(const Vector3 *p_points, const Simplex &p_simplex) {
Plane p(p_points[p_simplex.points[0]], p_points[p_simplex.points[1]], p_points[p_simplex.points[2]]);
if (ABS(p.distance_to(p_points[p_simplex.points[3]])) < CMP_EPSILON) {
return true;
}
Projection cm;
cm.columns[0][0] = p_points[p_simplex.points[0]].x;
cm.columns[0][1] = p_points[p_simplex.points[1]].x;
cm.columns[0][2] = p_points[p_simplex.points[2]].x;
cm.columns[0][3] = p_points[p_simplex.points[3]].x;
cm.columns[1][0] = p_points[p_simplex.points[0]].y;
cm.columns[1][1] = p_points[p_simplex.points[1]].y;
cm.columns[1][2] = p_points[p_simplex.points[2]].y;
cm.columns[1][3] = p_points[p_simplex.points[3]].y;
cm.columns[2][0] = p_points[p_simplex.points[0]].z;
cm.columns[2][1] = p_points[p_simplex.points[1]].z;
cm.columns[2][2] = p_points[p_simplex.points[2]].z;
cm.columns[2][3] = p_points[p_simplex.points[3]].z;
cm.columns[3][0] = 1.0;
cm.columns[3][1] = 1.0;
cm.columns[3][2] = 1.0;
cm.columns[3][3] = 1.0;
return ABS(cm.determinant()) <= CMP_EPSILON;
}
public:
struct OutputSimplex {
uint32_t points[4];
};
static Vector<OutputSimplex> tetrahedralize(const Vector<Vector3> &p_points) {
uint32_t point_count = p_points.size();
Vector3 *points = (Vector3 *)memalloc(sizeof(Vector3) * (point_count + 4));
{
const Vector3 *src_points = p_points.ptr();
AABB rect;
for (uint32_t i = 0; i < point_count; i++) {
Vector3 point = src_points[i];
if (i == 0) {
rect.position = point;
} else {
rect.expand_to(point);
}
points[i] = point;
}
for (uint32_t i = 0; i < point_count; i++) {
points[i] = (points[i] - rect.position) / rect.size;
}
float delta_max = Math::sqrt(2.0) * 20.0;
Vector3 center = Vector3(0.5, 0.5, 0.5);
// any simplex that contains everything is good
points[point_count + 0] = center + Vector3(0, 1, 0) * delta_max;
points[point_count + 1] = center + Vector3(0, -1, 1) * delta_max;
points[point_count + 2] = center + Vector3(1, -1, -1) * delta_max;
points[point_count + 3] = center + Vector3(-1, -1, -1) * delta_max;
}
List<Simplex *> acceleration_grid[ACCEL_GRID_SIZE][ACCEL_GRID_SIZE][ACCEL_GRID_SIZE];
List<Simplex *> simplex_list;
{
//create root simplex
Simplex *root = memnew(Simplex(point_count + 0, point_count + 1, point_count + 2, point_count + 3));
root->SE = simplex_list.push_back(root);
for (uint32_t i = 0; i < ACCEL_GRID_SIZE; i++) {
for (uint32_t j = 0; j < ACCEL_GRID_SIZE; j++) {
for (uint32_t k = 0; k < ACCEL_GRID_SIZE; k++) {
GridPos gp;
gp.E = acceleration_grid[i][j][k].push_back(root);
gp.pos = Vector3i(i, j, k);
root->grid_positions.push_back(gp);
}
}
}
circum_sphere_compute(points, root);
}
OAHashMap<Triangle, uint32_t, TriangleHasher> triangles_inserted;
LocalVector<Triangle> triangles;
for (uint32_t i = 0; i < point_count; i++) {
bool unique = true;
for (uint32_t j = i + 1; j < point_count; j++) {
if (points[i].is_equal_approx(points[j])) {
unique = false;
break;
}
}
if (!unique) {
continue;
}
Vector3i grid_pos = Vector3i(points[i] * ACCEL_GRID_SIZE);
grid_pos.x = CLAMP(grid_pos.x, 0, ACCEL_GRID_SIZE - 1);
grid_pos.y = CLAMP(grid_pos.y, 0, ACCEL_GRID_SIZE - 1);
grid_pos.z = CLAMP(grid_pos.z, 0, ACCEL_GRID_SIZE - 1);
for (List<Simplex *>::Element *E = acceleration_grid[grid_pos.x][grid_pos.y][grid_pos.z].front(); E;) {
List<Simplex *>::Element *N = E->next(); //may be deleted
Simplex *simplex = E->get();
if (simplex_contains(points, *simplex, i)) {
static const uint32_t triangle_order[4][3] = {
{ 0, 1, 2 },
{ 0, 1, 3 },
{ 0, 2, 3 },
{ 1, 2, 3 },
};
for (uint32_t k = 0; k < 4; k++) {
Triangle t = Triangle(simplex->points[triangle_order[k][0]], simplex->points[triangle_order[k][1]], simplex->points[triangle_order[k][2]]);
uint32_t *p = triangles_inserted.lookup_ptr(t);
if (p) {
triangles[*p].bad = true;
} else {
triangles_inserted.insert(t, triangles.size());
triangles.push_back(t);
}
}
//remove simplex and continue
simplex_list.erase(simplex->SE);
for (uint32_t k = 0; k < simplex->grid_positions.size(); k++) {
Vector3i p = simplex->grid_positions[k].pos;
acceleration_grid[p.x][p.y][p.z].erase(simplex->grid_positions[k].E);
}
memdelete(simplex);
}
E = N;
}
for (uint32_t j = 0; j < triangles.size(); j++) {
if (triangles[j].bad) {
continue;
}
Simplex *new_simplex = memnew(Simplex(triangles[j].triangle[0], triangles[j].triangle[1], triangles[j].triangle[2], i));
circum_sphere_compute(points, new_simplex);
new_simplex->SE = simplex_list.push_back(new_simplex);
{
Vector3 center;
center.x = double(new_simplex->circum_center_x);
center.y = double(new_simplex->circum_center_y);
center.z = double(new_simplex->circum_center_z);
float radius2 = Math::sqrt(double(new_simplex->circum_r2));
radius2 += 0.0001; //
Vector3 extents = Vector3(radius2, radius2, radius2);
Vector3i from = Vector3i((center - extents) * ACCEL_GRID_SIZE);
Vector3i to = Vector3i((center + extents) * ACCEL_GRID_SIZE);
from.x = CLAMP(from.x, 0, ACCEL_GRID_SIZE - 1);
from.y = CLAMP(from.y, 0, ACCEL_GRID_SIZE - 1);
from.z = CLAMP(from.z, 0, ACCEL_GRID_SIZE - 1);
to.x = CLAMP(to.x, 0, ACCEL_GRID_SIZE - 1);
to.y = CLAMP(to.y, 0, ACCEL_GRID_SIZE - 1);
to.z = CLAMP(to.z, 0, ACCEL_GRID_SIZE - 1);
for (int32_t x = from.x; x <= to.x; x++) {
for (int32_t y = from.y; y <= to.y; y++) {
for (int32_t z = from.z; z <= to.z; z++) {
GridPos gp;
gp.pos = Vector3(x, y, z);
gp.E = acceleration_grid[x][y][z].push_back(new_simplex);
new_simplex->grid_positions.push_back(gp);
}
}
}
}
}
triangles.clear();
triangles_inserted.clear();
}
//print_line("end with simplices: " + itos(simplex_list.size()));
Vector<OutputSimplex> ret_simplices;
ret_simplices.resize(simplex_list.size());
OutputSimplex *ret_simplicesw = ret_simplices.ptrw();
uint32_t simplices_written = 0;
for (Simplex *simplex : simplex_list) {
bool invalid = false;
for (int j = 0; j < 4; j++) {
if (simplex->points[j] >= point_count) {
invalid = true;
break;
}
}
if (invalid || simplex_is_coplanar(points, *simplex)) {
memdelete(simplex);
continue;
}
ret_simplicesw[simplices_written].points[0] = simplex->points[0];
ret_simplicesw[simplices_written].points[1] = simplex->points[1];
ret_simplicesw[simplices_written].points[2] = simplex->points[2];
ret_simplicesw[simplices_written].points[3] = simplex->points[3];
simplices_written++;
memdelete(simplex);
}
ret_simplices.resize(simplices_written);
memfree(points);
return ret_simplices;
}
};
#endif // DELAUNAY_3D_H
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