godot/servers/physics_3d/collision_solver_3d_sw.cpp
PouleyKetchoupp 333f184734 Cylinder support in Godot Physics 3D
Cylinder collision detection uses a mix of SAT and GJKEPA.
GJKEPA is used to find the best separation axis in cases where finding
it analytically is too complex.

Changes in SAT solver:
Added support for generating separation axes for cylinder shape.
Added support for generating contact points with circle feature.

Changes in GJKEPA solver:
Updated from latest Bullet version which includes EPA fixes in some
scenarios.
Setting a lower EPA_ACCURACY to fix accuracy problems with cylinder vs.
cylinder in some cases.
2021-02-10 10:00:53 -07:00

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13 KiB
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/*************************************************************************/
/* collision_solver_3d_sw.cpp */
/*************************************************************************/
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/* Copyright (c) 2007-2021 Juan Linietsky, Ariel Manzur. */
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#include "collision_solver_3d_sw.h"
#include "collision_solver_3d_sat.h"
#include "gjk_epa.h"
#define collision_solver sat_calculate_penetration
//#define collision_solver gjk_epa_calculate_penetration
bool CollisionSolver3DSW::solve_static_plane(const Shape3DSW *p_shape_A, const Transform &p_transform_A, const Shape3DSW *p_shape_B, const Transform &p_transform_B, CallbackResult p_result_callback, void *p_userdata, bool p_swap_result) {
const PlaneShape3DSW *plane = static_cast<const PlaneShape3DSW *>(p_shape_A);
if (p_shape_B->get_type() == PhysicsServer3D::SHAPE_PLANE) {
return false;
}
Plane p = p_transform_A.xform(plane->get_plane());
static const int max_supports = 16;
Vector3 supports[max_supports];
int support_count;
Shape3DSW::FeatureType support_type;
p_shape_B->get_supports(p_transform_B.basis.xform_inv(-p.normal).normalized(), max_supports, supports, support_count, support_type);
if (support_type == Shape3DSW::FEATURE_CIRCLE) {
ERR_FAIL_COND_V(support_count != 3, false);
Vector3 circle_pos = supports[0];
Vector3 circle_axis_1 = supports[1] - circle_pos;
Vector3 circle_axis_2 = supports[2] - circle_pos;
// Use 3 equidistant points on the circle.
for (int i = 0; i < 3; ++i) {
Vector3 vertex_pos = circle_pos;
vertex_pos += circle_axis_1 * Math::cos(2.0 * Math_PI * i / 3.0);
vertex_pos += circle_axis_2 * Math::sin(2.0 * Math_PI * i / 3.0);
supports[i] = vertex_pos;
}
}
bool found = false;
for (int i = 0; i < support_count; i++) {
supports[i] = p_transform_B.xform(supports[i]);
if (p.distance_to(supports[i]) >= 0) {
continue;
}
found = true;
Vector3 support_A = p.project(supports[i]);
if (p_result_callback) {
if (p_swap_result) {
p_result_callback(supports[i], support_A, p_userdata);
} else {
p_result_callback(support_A, supports[i], p_userdata);
}
}
}
return found;
}
bool CollisionSolver3DSW::solve_ray(const Shape3DSW *p_shape_A, const Transform &p_transform_A, const Shape3DSW *p_shape_B, const Transform &p_transform_B, CallbackResult p_result_callback, void *p_userdata, bool p_swap_result) {
const RayShape3DSW *ray = static_cast<const RayShape3DSW *>(p_shape_A);
Vector3 from = p_transform_A.origin;
Vector3 to = from + p_transform_A.basis.get_axis(2) * ray->get_length();
Vector3 support_A = to;
Transform ai = p_transform_B.affine_inverse();
from = ai.xform(from);
to = ai.xform(to);
Vector3 p, n;
if (!p_shape_B->intersect_segment(from, to, p, n)) {
return false;
}
Vector3 support_B = p_transform_B.xform(p);
if (ray->get_slips_on_slope()) {
Vector3 global_n = ai.basis.xform_inv(n).normalized();
support_B = support_A + (support_B - support_A).length() * global_n;
}
if (p_result_callback) {
if (p_swap_result) {
p_result_callback(support_B, support_A, p_userdata);
} else {
p_result_callback(support_A, support_B, p_userdata);
}
}
return true;
}
struct _ConcaveCollisionInfo {
const Transform *transform_A;
const Shape3DSW *shape_A;
const Transform *transform_B;
CollisionSolver3DSW::CallbackResult result_callback;
void *userdata;
bool swap_result;
bool collided;
int aabb_tests;
int collisions;
bool tested;
real_t margin_A;
real_t margin_B;
Vector3 close_A, close_B;
};
void CollisionSolver3DSW::concave_callback(void *p_userdata, Shape3DSW *p_convex) {
_ConcaveCollisionInfo &cinfo = *(_ConcaveCollisionInfo *)(p_userdata);
cinfo.aabb_tests++;
bool collided = collision_solver(cinfo.shape_A, *cinfo.transform_A, p_convex, *cinfo.transform_B, cinfo.result_callback, cinfo.userdata, cinfo.swap_result, nullptr, cinfo.margin_A, cinfo.margin_B);
if (!collided) {
return;
}
cinfo.collided = true;
cinfo.collisions++;
}
bool CollisionSolver3DSW::solve_concave(const Shape3DSW *p_shape_A, const Transform &p_transform_A, const Shape3DSW *p_shape_B, const Transform &p_transform_B, CallbackResult p_result_callback, void *p_userdata, bool p_swap_result, real_t p_margin_A, real_t p_margin_B) {
const ConcaveShape3DSW *concave_B = static_cast<const ConcaveShape3DSW *>(p_shape_B);
_ConcaveCollisionInfo cinfo;
cinfo.transform_A = &p_transform_A;
cinfo.shape_A = p_shape_A;
cinfo.transform_B = &p_transform_B;
cinfo.result_callback = p_result_callback;
cinfo.userdata = p_userdata;
cinfo.swap_result = p_swap_result;
cinfo.collided = false;
cinfo.collisions = 0;
cinfo.margin_A = p_margin_A;
cinfo.margin_B = p_margin_B;
cinfo.aabb_tests = 0;
Transform rel_transform = p_transform_A;
rel_transform.origin -= p_transform_B.origin;
//quickly compute a local AABB
AABB local_aabb;
for (int i = 0; i < 3; i++) {
Vector3 axis(p_transform_B.basis.get_axis(i));
real_t axis_scale = 1.0 / axis.length();
axis *= axis_scale;
real_t smin, smax;
p_shape_A->project_range(axis, rel_transform, smin, smax);
smin -= p_margin_A;
smax += p_margin_A;
smin *= axis_scale;
smax *= axis_scale;
local_aabb.position[i] = smin;
local_aabb.size[i] = smax - smin;
}
concave_B->cull(local_aabb, concave_callback, &cinfo);
return cinfo.collided;
}
bool CollisionSolver3DSW::solve_static(const Shape3DSW *p_shape_A, const Transform &p_transform_A, const Shape3DSW *p_shape_B, const Transform &p_transform_B, CallbackResult p_result_callback, void *p_userdata, Vector3 *r_sep_axis, real_t p_margin_A, real_t p_margin_B) {
PhysicsServer3D::ShapeType type_A = p_shape_A->get_type();
PhysicsServer3D::ShapeType type_B = p_shape_B->get_type();
bool concave_A = p_shape_A->is_concave();
bool concave_B = p_shape_B->is_concave();
bool swap = false;
if (type_A > type_B) {
SWAP(type_A, type_B);
SWAP(concave_A, concave_B);
swap = true;
}
if (type_A == PhysicsServer3D::SHAPE_PLANE) {
if (type_B == PhysicsServer3D::SHAPE_PLANE) {
return false;
}
if (type_B == PhysicsServer3D::SHAPE_RAY) {
return false;
}
if (swap) {
return solve_static_plane(p_shape_B, p_transform_B, p_shape_A, p_transform_A, p_result_callback, p_userdata, true);
} else {
return solve_static_plane(p_shape_A, p_transform_A, p_shape_B, p_transform_B, p_result_callback, p_userdata, false);
}
} else if (type_A == PhysicsServer3D::SHAPE_RAY) {
if (type_B == PhysicsServer3D::SHAPE_RAY) {
return false;
}
if (swap) {
return solve_ray(p_shape_B, p_transform_B, p_shape_A, p_transform_A, p_result_callback, p_userdata, true);
} else {
return solve_ray(p_shape_A, p_transform_A, p_shape_B, p_transform_B, p_result_callback, p_userdata, false);
}
} else if (concave_B) {
if (concave_A) {
return false;
}
if (!swap) {
return solve_concave(p_shape_A, p_transform_A, p_shape_B, p_transform_B, p_result_callback, p_userdata, false, p_margin_A, p_margin_B);
} else {
return solve_concave(p_shape_B, p_transform_B, p_shape_A, p_transform_A, p_result_callback, p_userdata, true, p_margin_A, p_margin_B);
}
} else {
return collision_solver(p_shape_A, p_transform_A, p_shape_B, p_transform_B, p_result_callback, p_userdata, false, r_sep_axis, p_margin_A, p_margin_B);
}
}
void CollisionSolver3DSW::concave_distance_callback(void *p_userdata, Shape3DSW *p_convex) {
_ConcaveCollisionInfo &cinfo = *(_ConcaveCollisionInfo *)(p_userdata);
cinfo.aabb_tests++;
if (cinfo.collided) {
return;
}
Vector3 close_A, close_B;
cinfo.collided = !gjk_epa_calculate_distance(cinfo.shape_A, *cinfo.transform_A, p_convex, *cinfo.transform_B, close_A, close_B);
if (cinfo.collided) {
return;
}
if (!cinfo.tested || close_A.distance_squared_to(close_B) < cinfo.close_A.distance_squared_to(cinfo.close_B)) {
cinfo.close_A = close_A;
cinfo.close_B = close_B;
cinfo.tested = true;
}
cinfo.collisions++;
}
bool CollisionSolver3DSW::solve_distance_plane(const Shape3DSW *p_shape_A, const Transform &p_transform_A, const Shape3DSW *p_shape_B, const Transform &p_transform_B, Vector3 &r_point_A, Vector3 &r_point_B) {
const PlaneShape3DSW *plane = static_cast<const PlaneShape3DSW *>(p_shape_A);
if (p_shape_B->get_type() == PhysicsServer3D::SHAPE_PLANE) {
return false;
}
Plane p = p_transform_A.xform(plane->get_plane());
static const int max_supports = 16;
Vector3 supports[max_supports];
int support_count;
Shape3DSW::FeatureType support_type;
p_shape_B->get_supports(p_transform_B.basis.xform_inv(-p.normal).normalized(), max_supports, supports, support_count, support_type);
if (support_type == Shape3DSW::FEATURE_CIRCLE) {
ERR_FAIL_COND_V(support_count != 3, false);
Vector3 circle_pos = supports[0];
Vector3 circle_axis_1 = supports[1] - circle_pos;
Vector3 circle_axis_2 = supports[2] - circle_pos;
// Use 3 equidistant points on the circle.
for (int i = 0; i < 3; ++i) {
Vector3 vertex_pos = circle_pos;
vertex_pos += circle_axis_1 * Math::cos(2.0 * Math_PI * i / 3.0);
vertex_pos += circle_axis_2 * Math::sin(2.0 * Math_PI * i / 3.0);
supports[i] = vertex_pos;
}
}
bool collided = false;
Vector3 closest;
real_t closest_d = 0;
for (int i = 0; i < support_count; i++) {
supports[i] = p_transform_B.xform(supports[i]);
real_t d = p.distance_to(supports[i]);
if (i == 0 || d < closest_d) {
closest = supports[i];
closest_d = d;
if (d <= 0) {
collided = true;
}
}
}
r_point_A = p.project(closest);
r_point_B = closest;
return collided;
}
bool CollisionSolver3DSW::solve_distance(const Shape3DSW *p_shape_A, const Transform &p_transform_A, const Shape3DSW *p_shape_B, const Transform &p_transform_B, Vector3 &r_point_A, Vector3 &r_point_B, const AABB &p_concave_hint, Vector3 *r_sep_axis) {
if (p_shape_A->is_concave()) {
return false;
}
if (p_shape_B->get_type() == PhysicsServer3D::SHAPE_PLANE) {
Vector3 a, b;
bool col = solve_distance_plane(p_shape_B, p_transform_B, p_shape_A, p_transform_A, a, b);
r_point_A = b;
r_point_B = a;
return !col;
} else if (p_shape_B->is_concave()) {
if (p_shape_A->is_concave()) {
return false;
}
const ConcaveShape3DSW *concave_B = static_cast<const ConcaveShape3DSW *>(p_shape_B);
_ConcaveCollisionInfo cinfo;
cinfo.transform_A = &p_transform_A;
cinfo.shape_A = p_shape_A;
cinfo.transform_B = &p_transform_B;
cinfo.result_callback = nullptr;
cinfo.userdata = nullptr;
cinfo.swap_result = false;
cinfo.collided = false;
cinfo.collisions = 0;
cinfo.aabb_tests = 0;
cinfo.tested = false;
Transform rel_transform = p_transform_A;
rel_transform.origin -= p_transform_B.origin;
//quickly compute a local AABB
bool use_cc_hint = p_concave_hint != AABB();
AABB cc_hint_aabb;
if (use_cc_hint) {
cc_hint_aabb = p_concave_hint;
cc_hint_aabb.position -= p_transform_B.origin;
}
AABB local_aabb;
for (int i = 0; i < 3; i++) {
Vector3 axis(p_transform_B.basis.get_axis(i));
real_t axis_scale = ((real_t)1.0) / axis.length();
axis *= axis_scale;
real_t smin, smax;
if (use_cc_hint) {
cc_hint_aabb.project_range_in_plane(Plane(axis, 0), smin, smax);
} else {
p_shape_A->project_range(axis, rel_transform, smin, smax);
}
smin *= axis_scale;
smax *= axis_scale;
local_aabb.position[i] = smin;
local_aabb.size[i] = smax - smin;
}
concave_B->cull(local_aabb, concave_distance_callback, &cinfo);
if (!cinfo.collided) {
r_point_A = cinfo.close_A;
r_point_B = cinfo.close_B;
}
return !cinfo.collided;
} else {
return gjk_epa_calculate_distance(p_shape_A, p_transform_A, p_shape_B, p_transform_B, r_point_A, r_point_B); //should pass sepaxis..
}
}