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[BVH precision] Make 3D physics use precision-proof version of BVH::ray_query() #100604

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[BVH precision] Make 3D physics use precision-proof version of BVH::ray_query() #100604

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4456c09
Fix `BVH::ray_query()` numerical precision
Flarkk Dec 16, 2024
021dfc0
Remove duplicate code between `intersects_ray` and `intersects_segment`
Flarkk Dec 17, 2024
fe7e87f
Merge branch 'ray_segment_intersect' into fix_bvh_softbody
Flarkk Dec 17, 2024
b9f35fb
Make 3D physics use precision-proof BVH::ray_query()
Flarkk Dec 19, 2024
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69 changes: 2 additions & 67 deletions core/math/aabb.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -122,7 +122,7 @@ AABB AABB::intersection(const AABB &p_aabb) const {
// 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 {
bool AABB::find_intersects_ray(const Vector3 &p_from, const Vector3 &p_dir, bool &r_inside, Vector3 *r_intersection_point, Vector3 *r_normal, real_t p_max_distance) 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.");
Expand Down Expand Up @@ -159,7 +159,7 @@ bool AABB::find_intersects_ray(const Vector3 &p_from, const Vector3 &p_dir, bool
}
tmax = t2;
}
if (tmin > tmax) {
if (tmin > tmax || (p_max_distance > 0 && tmin > p_max_distance)) {
return false;
}
}
Expand All @@ -185,71 +185,6 @@ bool AABB::find_intersects_ray(const Vector3 &p_from, const Vector3 &p_dir, bool
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),
Expand Down
19 changes: 17 additions & 2 deletions core/math/aabb.h
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Original file line number Diff line number Diff line change
Expand Up @@ -73,12 +73,27 @@ struct [[nodiscard]] AABB {
AABB intersection(const AABB &p_aabb) const; ///get box where two intersect, empty if no intersection occurs
_FORCE_INLINE_ bool smits_intersect_ray(const Vector3 &p_from, const Vector3 &p_dir, real_t p_t0, real_t p_t1) const;

bool intersects_segment(const Vector3 &p_from, const Vector3 &p_to, Vector3 *r_intersection_point = nullptr, Vector3 *r_normal = nullptr) const;
bool intersects_segment(const Vector3 &p_from, const Vector3 &p_to, Vector3 *r_intersection_point = nullptr, Vector3 *r_normal = nullptr) const {
Vector3 segment = p_to - p_from;
real_t length = segment.length();
Vector3 ray = Math::is_equal_approx(length, 0) ? Vector3() : segment / length;
bool inside;
bool inter = find_intersects_ray(p_from, ray, inside, r_intersection_point, r_normal, length);
if (inter && inside) {
if (r_intersection_point != nullptr) {
*r_intersection_point = p_from;
}
if (r_normal != nullptr) {
*r_normal = Vector3();
}
}
return inter;
}
bool intersects_ray(const Vector3 &p_from, const Vector3 &p_dir) const {
bool inside;
return find_intersects_ray(p_from, p_dir, inside);
}
bool find_intersects_ray(const Vector3 &p_from, const Vector3 &p_dir, bool &r_inside, Vector3 *r_intersection_point = nullptr, Vector3 *r_normal = nullptr) const;
bool find_intersects_ray(const Vector3 &p_from, const Vector3 &p_dir, bool &r_inside, Vector3 *r_intersection_point = nullptr, Vector3 *r_normal = nullptr, real_t p_max_distance = 0) const;

_FORCE_INLINE_ bool intersects_convex_shape(const Plane *p_planes, int p_plane_count, const Vector3 *p_points, int p_point_count) const;
_FORCE_INLINE_ bool inside_convex_shape(const Plane *p_planes, int p_plane_count) const;
Expand Down
9 changes: 4 additions & 5 deletions core/math/dynamic_bvh.h
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Original file line number Diff line number Diff line change
Expand Up @@ -310,7 +310,7 @@ class DynamicBVH {
template <typename QueryResult>
_FORCE_INLINE_ void convex_query(const Plane *p_planes, int p_plane_count, const Vector3 *p_points, int p_point_count, QueryResult &r_result);
template <typename QueryResult>
_FORCE_INLINE_ void ray_query(const Vector3 &p_from, const Vector3 &p_to, QueryResult &r_result);
_FORCE_INLINE_ void ray_query(const Vector3 &p_from, const Vector3 &p_dir, real_t p_length, QueryResult &r_result);

void set_index(uint32_t p_index);
uint32_t get_index() const;
Expand Down Expand Up @@ -416,13 +416,12 @@ void DynamicBVH::convex_query(const Plane *p_planes, int p_plane_count, const Ve
} while (depth > 0);
}
template <typename QueryResult>
void DynamicBVH::ray_query(const Vector3 &p_from, const Vector3 &p_to, QueryResult &r_result) {
void DynamicBVH::ray_query(const Vector3 &p_from, const Vector3 &p_dir, real_t p_length, QueryResult &r_result) {
if (!bvh_root) {
return;
}

Vector3 ray_dir = (p_to - p_from);
ray_dir.normalize();
Vector3 ray_dir = p_dir;

///what about division by zero? --> just set rayDirection[i] to INF/B3_LARGE_FLOAT
Vector3 inv_dir;
Expand All @@ -431,7 +430,7 @@ void DynamicBVH::ray_query(const Vector3 &p_from, const Vector3 &p_to, QueryResu
inv_dir[2] = ray_dir[2] == real_t(0.0) ? real_t(1e20) : real_t(1.0) / ray_dir[2];
unsigned int signs[3] = { inv_dir[0] < 0.0, inv_dir[1] < 0.0, inv_dir[2] < 0.0 };

real_t lambda_max = ray_dir.dot(p_to - p_from);
real_t lambda_max = p_length;

Vector3 bounds[2];

Expand Down
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