godot/core/math/aabb.cpp
lawnjelly b35264ad95 Fix AABB Ray intersection - return inside
* Separates find_intersects from test_intersects for rays, and wraps the former.
* Changes parameter name to "r_intersection_point".
* Fixes broken old version which returned per axis t.
* Returns whether the ray origin is within the AABB.
* Returns intersection point when origin outside.
* Returns "backtracking" intersection point when inside.
* Returns sensible normal when inside.
* Returns valid results on borders.
* Returns robust results dealing with floating point error.

Co-authored-by: Claire Blackshaw <evilkimau@gmail.com>
2024-05-09 20:41:19 +01:00

450 lines
13 KiB
C++

/**************************************************************************/
/* aabb.cpp */
/**************************************************************************/
/* This file is part of: */
/* GODOT ENGINE */
/* https://godotengine.org */
/**************************************************************************/
/* Copyright (c) 2014-present Godot Engine contributors (see AUTHORS.md). */
/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur. */
/* */
/* 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, */
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/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */
/**************************************************************************/
#include "aabb.h"
#include "core/string/ustring.h"
#include "core/variant/variant.h"
real_t AABB::get_volume() const {
return size.x * size.y * size.z;
}
bool AABB::operator==(const AABB &p_rval) const {
return ((position == p_rval.position) && (size == p_rval.size));
}
bool AABB::operator!=(const AABB &p_rval) const {
return ((position != p_rval.position) || (size != p_rval.size));
}
void AABB::merge_with(const AABB &p_aabb) {
#ifdef MATH_CHECKS
if (unlikely(size.x < 0 || size.y < 0 || size.z < 0 || p_aabb.size.x < 0 || p_aabb.size.y < 0 || p_aabb.size.z < 0)) {
ERR_PRINT("AABB size is negative, this is not supported. Use AABB.abs() to get an AABB with a positive size.");
}
#endif
Vector3 beg_1, beg_2;
Vector3 end_1, end_2;
Vector3 min, max;
beg_1 = position;
beg_2 = p_aabb.position;
end_1 = size + beg_1;
end_2 = p_aabb.size + beg_2;
min.x = (beg_1.x < beg_2.x) ? beg_1.x : beg_2.x;
min.y = (beg_1.y < beg_2.y) ? beg_1.y : beg_2.y;
min.z = (beg_1.z < beg_2.z) ? beg_1.z : beg_2.z;
max.x = (end_1.x > end_2.x) ? end_1.x : end_2.x;
max.y = (end_1.y > end_2.y) ? end_1.y : end_2.y;
max.z = (end_1.z > end_2.z) ? end_1.z : end_2.z;
position = min;
size = max - min;
}
bool AABB::is_equal_approx(const AABB &p_aabb) const {
return position.is_equal_approx(p_aabb.position) && size.is_equal_approx(p_aabb.size);
}
bool AABB::is_finite() const {
return position.is_finite() && size.is_finite();
}
AABB AABB::intersection(const AABB &p_aabb) const {
#ifdef MATH_CHECKS
if (unlikely(size.x < 0 || size.y < 0 || size.z < 0 || p_aabb.size.x < 0 || p_aabb.size.y < 0 || p_aabb.size.z < 0)) {
ERR_PRINT("AABB size is negative, this is not supported. Use AABB.abs() to get an AABB with a positive size.");
}
#endif
Vector3 src_min = position;
Vector3 src_max = position + size;
Vector3 dst_min = p_aabb.position;
Vector3 dst_max = p_aabb.position + p_aabb.size;
Vector3 min, max;
if (src_min.x > dst_max.x || src_max.x < dst_min.x) {
return AABB();
} else {
min.x = (src_min.x > dst_min.x) ? src_min.x : dst_min.x;
max.x = (src_max.x < dst_max.x) ? src_max.x : dst_max.x;
}
if (src_min.y > dst_max.y || src_max.y < dst_min.y) {
return AABB();
} else {
min.y = (src_min.y > dst_min.y) ? src_min.y : dst_min.y;
max.y = (src_max.y < dst_max.y) ? src_max.y : dst_max.y;
}
if (src_min.z > dst_max.z || src_max.z < dst_min.z) {
return AABB();
} else {
min.z = (src_min.z > dst_min.z) ? src_min.z : dst_min.z;
max.z = (src_max.z < dst_max.z) ? src_max.z : dst_max.z;
}
return AABB(min, max - min);
}
// Note that this routine returns the BACKTRACKED (i.e. behind the ray origin)
// intersection point + normal if INSIDE the AABB.
// The caller can therefore decide when INSIDE whether to use the
// backtracked intersection, or use p_from as the intersection, and
// carry on progressing without e.g. reflecting against the normal.
bool AABB::find_intersects_ray(const Vector3 &p_from, const Vector3 &p_dir, bool &r_inside, Vector3 *r_intersection_point, Vector3 *r_normal) const {
#ifdef MATH_CHECKS
if (unlikely(size.x < 0 || size.y < 0 || size.z < 0)) {
ERR_PRINT("AABB size is negative, this is not supported. Use AABB.abs() to get an AABB with a positive size.");
}
#endif
Vector3 end = position + size;
real_t tmin = -1e20;
real_t tmax = 1e20;
int axis = 0;
// Make sure r_inside is always initialized,
// to prevent reading uninitialized data in the client code.
r_inside = false;
for (int i = 0; i < 3; i++) {
if (p_dir[i] == 0) {
if ((p_from[i] < position[i]) || (p_from[i] > end[i])) {
return false;
}
} else { // ray not parallel to planes in this direction
real_t t1 = (position[i] - p_from[i]) / p_dir[i];
real_t t2 = (end[i] - p_from[i]) / p_dir[i];
if (t1 > t2) {
SWAP(t1, t2);
}
if (t1 >= tmin) {
tmin = t1;
axis = i;
}
if (t2 < tmax) {
if (t2 < 0) {
return false;
}
tmax = t2;
}
if (tmin > tmax) {
return false;
}
}
}
// Did the ray start from inside the box?
// In which case the intersection returned is the point of entry
// (behind the ray start) or the calling routine can use the ray origin as intersection point.
r_inside = tmin < 0;
if (r_intersection_point) {
*r_intersection_point = p_from + p_dir * tmin;
// Prevent float error by making sure the point is exactly
// on the AABB border on the relevant axis.
r_intersection_point->coord[axis] = (p_dir[axis] >= 0) ? position.coord[axis] : end.coord[axis];
}
if (r_normal) {
*r_normal = Vector3();
(*r_normal)[axis] = (p_dir[axis] >= 0) ? -1 : 1;
}
return true;
}
bool AABB::intersects_segment(const Vector3 &p_from, const Vector3 &p_to, Vector3 *r_intersection_point, Vector3 *r_normal) const {
#ifdef MATH_CHECKS
if (unlikely(size.x < 0 || size.y < 0 || size.z < 0)) {
ERR_PRINT("AABB size is negative, this is not supported. Use AABB.abs() to get an AABB with a positive size.");
}
#endif
real_t min = 0, max = 1;
int axis = 0;
real_t sign = 0;
for (int i = 0; i < 3; i++) {
real_t seg_from = p_from[i];
real_t seg_to = p_to[i];
real_t box_begin = position[i];
real_t box_end = box_begin + size[i];
real_t cmin, cmax;
real_t csign;
if (seg_from < seg_to) {
if (seg_from > box_end || seg_to < box_begin) {
return false;
}
real_t length = seg_to - seg_from;
cmin = (seg_from < box_begin) ? ((box_begin - seg_from) / length) : 0;
cmax = (seg_to > box_end) ? ((box_end - seg_from) / length) : 1;
csign = -1.0;
} else {
if (seg_to > box_end || seg_from < box_begin) {
return false;
}
real_t length = seg_to - seg_from;
cmin = (seg_from > box_end) ? (box_end - seg_from) / length : 0;
cmax = (seg_to < box_begin) ? (box_begin - seg_from) / length : 1;
csign = 1.0;
}
if (cmin > min) {
min = cmin;
axis = i;
sign = csign;
}
if (cmax < max) {
max = cmax;
}
if (max < min) {
return false;
}
}
Vector3 rel = p_to - p_from;
if (r_normal) {
Vector3 normal;
normal[axis] = sign;
*r_normal = normal;
}
if (r_intersection_point) {
*r_intersection_point = p_from + rel * min;
}
return true;
}
bool AABB::intersects_plane(const Plane &p_plane) const {
Vector3 points[8] = {
Vector3(position.x, position.y, position.z),
Vector3(position.x, position.y, position.z + size.z),
Vector3(position.x, position.y + size.y, position.z),
Vector3(position.x, position.y + size.y, position.z + size.z),
Vector3(position.x + size.x, position.y, position.z),
Vector3(position.x + size.x, position.y, position.z + size.z),
Vector3(position.x + size.x, position.y + size.y, position.z),
Vector3(position.x + size.x, position.y + size.y, position.z + size.z),
};
bool over = false;
bool under = false;
for (int i = 0; i < 8; i++) {
if (p_plane.distance_to(points[i]) > 0) {
over = true;
} else {
under = true;
}
}
return under && over;
}
Vector3 AABB::get_longest_axis() const {
Vector3 axis(1, 0, 0);
real_t max_size = size.x;
if (size.y > max_size) {
axis = Vector3(0, 1, 0);
max_size = size.y;
}
if (size.z > max_size) {
axis = Vector3(0, 0, 1);
}
return axis;
}
int AABB::get_longest_axis_index() const {
int axis = 0;
real_t max_size = size.x;
if (size.y > max_size) {
axis = 1;
max_size = size.y;
}
if (size.z > max_size) {
axis = 2;
}
return axis;
}
Vector3 AABB::get_shortest_axis() const {
Vector3 axis(1, 0, 0);
real_t min_size = size.x;
if (size.y < min_size) {
axis = Vector3(0, 1, 0);
min_size = size.y;
}
if (size.z < min_size) {
axis = Vector3(0, 0, 1);
}
return axis;
}
int AABB::get_shortest_axis_index() const {
int axis = 0;
real_t min_size = size.x;
if (size.y < min_size) {
axis = 1;
min_size = size.y;
}
if (size.z < min_size) {
axis = 2;
}
return axis;
}
AABB AABB::merge(const AABB &p_with) const {
AABB aabb = *this;
aabb.merge_with(p_with);
return aabb;
}
AABB AABB::expand(const Vector3 &p_vector) const {
AABB aabb = *this;
aabb.expand_to(p_vector);
return aabb;
}
AABB AABB::grow(real_t p_by) const {
AABB aabb = *this;
aabb.grow_by(p_by);
return aabb;
}
void AABB::get_edge(int p_edge, Vector3 &r_from, Vector3 &r_to) const {
ERR_FAIL_INDEX(p_edge, 12);
switch (p_edge) {
case 0: {
r_from = Vector3(position.x + size.x, position.y, position.z);
r_to = Vector3(position.x, position.y, position.z);
} break;
case 1: {
r_from = Vector3(position.x + size.x, position.y, position.z + size.z);
r_to = Vector3(position.x + size.x, position.y, position.z);
} break;
case 2: {
r_from = Vector3(position.x, position.y, position.z + size.z);
r_to = Vector3(position.x + size.x, position.y, position.z + size.z);
} break;
case 3: {
r_from = Vector3(position.x, position.y, position.z);
r_to = Vector3(position.x, position.y, position.z + size.z);
} break;
case 4: {
r_from = Vector3(position.x, position.y + size.y, position.z);
r_to = Vector3(position.x + size.x, position.y + size.y, position.z);
} break;
case 5: {
r_from = Vector3(position.x + size.x, position.y + size.y, position.z);
r_to = Vector3(position.x + size.x, position.y + size.y, position.z + size.z);
} break;
case 6: {
r_from = Vector3(position.x + size.x, position.y + size.y, position.z + size.z);
r_to = Vector3(position.x, position.y + size.y, position.z + size.z);
} break;
case 7: {
r_from = Vector3(position.x, position.y + size.y, position.z + size.z);
r_to = Vector3(position.x, position.y + size.y, position.z);
} break;
case 8: {
r_from = Vector3(position.x, position.y, position.z + size.z);
r_to = Vector3(position.x, position.y + size.y, position.z + size.z);
} break;
case 9: {
r_from = Vector3(position.x, position.y, position.z);
r_to = Vector3(position.x, position.y + size.y, position.z);
} break;
case 10: {
r_from = Vector3(position.x + size.x, position.y, position.z);
r_to = Vector3(position.x + size.x, position.y + size.y, position.z);
} break;
case 11: {
r_from = Vector3(position.x + size.x, position.y, position.z + size.z);
r_to = Vector3(position.x + size.x, position.y + size.y, position.z + size.z);
} break;
}
}
Variant AABB::intersects_segment_bind(const Vector3 &p_from, const Vector3 &p_to) const {
Vector3 inters;
if (intersects_segment(p_from, p_to, &inters)) {
return inters;
}
return Variant();
}
Variant AABB::intersects_ray_bind(const Vector3 &p_from, const Vector3 &p_dir) const {
Vector3 inters;
bool inside = false;
if (find_intersects_ray(p_from, p_dir, inside, &inters)) {
// When inside the intersection point may be BEHIND the ray,
// so for general use we return the ray origin.
if (inside) {
return p_from;
}
return inters;
}
return Variant();
}
AABB::operator String() const {
return "[P: " + position.operator String() + ", S: " + size + "]";
}