/*************************************************************************/
/*  space_2d_sw.cpp                                                      */
/*************************************************************************/
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/*                           GODOT ENGINE                                */
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/* Copyright (c) 2007-2018 Juan Linietsky, Ariel Manzur.                 */
/* Copyright (c) 2014-2018 Godot Engine contributors (cf. AUTHORS.md)    */
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#include "space_2d_sw.h"

#include "collision_solver_2d_sw.h"
#include "pair.h"
#include "physics_2d_server_sw.h"

_FORCE_INLINE_ static bool _can_collide_with(CollisionObject2DSW *p_object, uint32_t p_collision_mask, bool p_collide_with_bodies, bool p_collide_with_areas) {

	if (!(p_object->get_collision_layer() & p_collision_mask)) {
		return false;
	}

	if (p_object->get_type() == CollisionObject2DSW::TYPE_AREA && !p_collide_with_areas)
		return false;

	if (p_object->get_type() == CollisionObject2DSW::TYPE_BODY && !p_collide_with_bodies)
		return false;

	return true;
}

int Physics2DDirectSpaceStateSW::intersect_point(const Vector2 &p_point, ShapeResult *r_results, int p_result_max, const Set<RID> &p_exclude, uint32_t p_collision_mask, bool p_collide_with_bodies, bool p_collide_with_areas, bool p_pick_point) {

	if (p_result_max <= 0)
		return 0;

	Rect2 aabb;
	aabb.position = p_point - Vector2(0.00001, 0.00001);
	aabb.size = Vector2(0.00002, 0.00002);

	int amount = space->broadphase->cull_aabb(aabb, space->intersection_query_results, Space2DSW::INTERSECTION_QUERY_MAX, space->intersection_query_subindex_results);

	int cc = 0;

	for (int i = 0; i < amount; i++) {

		if (!_can_collide_with(space->intersection_query_results[i], p_collision_mask, p_collide_with_bodies, p_collide_with_areas))
			continue;

		if (p_exclude.has(space->intersection_query_results[i]->get_self()))
			continue;

		const CollisionObject2DSW *col_obj = space->intersection_query_results[i];

		if (p_pick_point && !col_obj->is_pickable())
			continue;

		int shape_idx = space->intersection_query_subindex_results[i];

		Shape2DSW *shape = col_obj->get_shape(shape_idx);

		Vector2 local_point = (col_obj->get_transform() * col_obj->get_shape_transform(shape_idx)).affine_inverse().xform(p_point);

		if (!shape->contains_point(local_point))
			continue;

		if (cc >= p_result_max)
			continue;

		r_results[cc].collider_id = col_obj->get_instance_id();
		if (r_results[cc].collider_id != 0)
			r_results[cc].collider = ObjectDB::get_instance(r_results[cc].collider_id);
		r_results[cc].rid = col_obj->get_self();
		r_results[cc].shape = shape_idx;
		r_results[cc].metadata = col_obj->get_shape_metadata(shape_idx);

		cc++;
	}

	return cc;
}

bool Physics2DDirectSpaceStateSW::intersect_ray(const Vector2 &p_from, const Vector2 &p_to, RayResult &r_result, const Set<RID> &p_exclude, uint32_t p_collision_mask, bool p_collide_with_bodies, bool p_collide_with_areas) {

	ERR_FAIL_COND_V(space->locked, false);

	Vector2 begin, end;
	Vector2 normal;
	begin = p_from;
	end = p_to;
	normal = (end - begin).normalized();

	int amount = space->broadphase->cull_segment(begin, end, space->intersection_query_results, Space2DSW::INTERSECTION_QUERY_MAX, space->intersection_query_subindex_results);

	//todo, create another array tha references results, compute AABBs and check closest point to ray origin, sort, and stop evaluating results when beyond first collision

	bool collided = false;
	Vector2 res_point, res_normal;
	int res_shape;
	const CollisionObject2DSW *res_obj;
	real_t min_d = 1e10;

	for (int i = 0; i < amount; i++) {

		if (!_can_collide_with(space->intersection_query_results[i], p_collision_mask, p_collide_with_bodies, p_collide_with_areas))
			continue;

		if (p_exclude.has(space->intersection_query_results[i]->get_self()))
			continue;

		const CollisionObject2DSW *col_obj = space->intersection_query_results[i];

		int shape_idx = space->intersection_query_subindex_results[i];
		Transform2D inv_xform = col_obj->get_shape_inv_transform(shape_idx) * col_obj->get_inv_transform();

		Vector2 local_from = inv_xform.xform(begin);
		Vector2 local_to = inv_xform.xform(end);

		/*local_from = col_obj->get_inv_transform().xform(begin);
		local_from = col_obj->get_shape_inv_transform(shape_idx).xform(local_from);

		local_to = col_obj->get_inv_transform().xform(end);
		local_to = col_obj->get_shape_inv_transform(shape_idx).xform(local_to);*/

		const Shape2DSW *shape = col_obj->get_shape(shape_idx);

		Vector2 shape_point, shape_normal;

		if (shape->intersect_segment(local_from, local_to, shape_point, shape_normal)) {

			Transform2D xform = col_obj->get_transform() * col_obj->get_shape_transform(shape_idx);
			shape_point = xform.xform(shape_point);

			real_t ld = normal.dot(shape_point);

			if (ld < min_d) {

				min_d = ld;
				res_point = shape_point;
				res_normal = inv_xform.basis_xform_inv(shape_normal).normalized();
				res_shape = shape_idx;
				res_obj = col_obj;
				collided = true;
			}
		}
	}

	if (!collided)
		return false;

	r_result.collider_id = res_obj->get_instance_id();
	if (r_result.collider_id != 0)
		r_result.collider = ObjectDB::get_instance(r_result.collider_id);
	r_result.normal = res_normal;
	r_result.metadata = res_obj->get_shape_metadata(res_shape);
	r_result.position = res_point;
	r_result.rid = res_obj->get_self();
	r_result.shape = res_shape;

	return true;
}

int Physics2DDirectSpaceStateSW::intersect_shape(const RID &p_shape, const Transform2D &p_xform, const Vector2 &p_motion, real_t p_margin, ShapeResult *r_results, int p_result_max, const Set<RID> &p_exclude, uint32_t p_collision_mask, bool p_collide_with_bodies, bool p_collide_with_areas) {

	if (p_result_max <= 0)
		return 0;

	Shape2DSW *shape = Physics2DServerSW::singletonsw->shape_owner.get(p_shape);
	ERR_FAIL_COND_V(!shape, 0);

	Rect2 aabb = p_xform.xform(shape->get_aabb());
	aabb = aabb.grow(p_margin);

	int amount = space->broadphase->cull_aabb(aabb, space->intersection_query_results, Space2DSW::INTERSECTION_QUERY_MAX, space->intersection_query_subindex_results);

	int cc = 0;

	for (int i = 0; i < amount; i++) {

		if (cc >= p_result_max)
			break;

		if (!_can_collide_with(space->intersection_query_results[i], p_collision_mask, p_collide_with_bodies, p_collide_with_areas))
			continue;

		if (p_exclude.has(space->intersection_query_results[i]->get_self()))
			continue;

		const CollisionObject2DSW *col_obj = space->intersection_query_results[i];
		int shape_idx = space->intersection_query_subindex_results[i];

		if (!CollisionSolver2DSW::solve(shape, p_xform, p_motion, col_obj->get_shape(shape_idx), col_obj->get_transform() * col_obj->get_shape_transform(shape_idx), Vector2(), NULL, NULL, NULL, p_margin))
			continue;

		r_results[cc].collider_id = col_obj->get_instance_id();
		if (r_results[cc].collider_id != 0)
			r_results[cc].collider = ObjectDB::get_instance(r_results[cc].collider_id);
		r_results[cc].rid = col_obj->get_self();
		r_results[cc].shape = shape_idx;
		r_results[cc].metadata = col_obj->get_shape_metadata(shape_idx);

		cc++;
	}

	return cc;
}

bool Physics2DDirectSpaceStateSW::cast_motion(const RID &p_shape, const Transform2D &p_xform, const Vector2 &p_motion, real_t p_margin, real_t &p_closest_safe, real_t &p_closest_unsafe, const Set<RID> &p_exclude, uint32_t p_collision_mask, bool p_collide_with_bodies, bool p_collide_with_areas) {

	Shape2DSW *shape = Physics2DServerSW::singletonsw->shape_owner.get(p_shape);
	ERR_FAIL_COND_V(!shape, false);

	Rect2 aabb = p_xform.xform(shape->get_aabb());
	aabb = aabb.merge(Rect2(aabb.position + p_motion, aabb.size)); //motion
	aabb = aabb.grow(p_margin);

	/*
	if (p_motion!=Vector2())
		print_line(p_motion);
	*/

	int amount = space->broadphase->cull_aabb(aabb, space->intersection_query_results, Space2DSW::INTERSECTION_QUERY_MAX, space->intersection_query_subindex_results);

	real_t best_safe = 1;
	real_t best_unsafe = 1;

	for (int i = 0; i < amount; i++) {

		if (!_can_collide_with(space->intersection_query_results[i], p_collision_mask, p_collide_with_bodies, p_collide_with_areas))
			continue;

		if (p_exclude.has(space->intersection_query_results[i]->get_self()))
			continue; //ignore excluded

		const CollisionObject2DSW *col_obj = space->intersection_query_results[i];
		int shape_idx = space->intersection_query_subindex_results[i];

		/*if (col_obj->get_type()==CollisionObject2DSW::TYPE_BODY) {

			const Body2DSW *body=static_cast<const Body2DSW*>(col_obj);
			if (body->get_one_way_collision_direction()!=Vector2() && p_motion.dot(body->get_one_way_collision_direction())<=CMP_EPSILON) {
				print_line("failed in motion dir");
				continue;
			}
		}*/

		Transform2D col_obj_xform = col_obj->get_transform() * col_obj->get_shape_transform(shape_idx);
		//test initial overlap, does it collide if going all the way?
		if (!CollisionSolver2DSW::solve(shape, p_xform, p_motion, col_obj->get_shape(shape_idx), col_obj_xform, Vector2(), NULL, NULL, NULL, p_margin)) {
			continue;
		}

		//test initial overlap
		if (CollisionSolver2DSW::solve(shape, p_xform, Vector2(), col_obj->get_shape(shape_idx), col_obj_xform, Vector2(), NULL, NULL, NULL, p_margin)) {

			return false;
		}

		//just do kinematic solving
		real_t low = 0;
		real_t hi = 1;
		Vector2 mnormal = p_motion.normalized();

		for (int i = 0; i < 8; i++) { //steps should be customizable..

			real_t ofs = (low + hi) * 0.5;

			Vector2 sep = mnormal; //important optimization for this to work fast enough
			bool collided = CollisionSolver2DSW::solve(shape, p_xform, p_motion * ofs, col_obj->get_shape(shape_idx), col_obj_xform, Vector2(), NULL, NULL, &sep, p_margin);

			if (collided) {

				hi = ofs;
			} else {

				low = ofs;
			}
		}

		if (low < best_safe) {
			best_safe = low;
			best_unsafe = hi;
		}
	}

	p_closest_safe = best_safe;
	p_closest_unsafe = best_unsafe;

	return true;
}

bool Physics2DDirectSpaceStateSW::collide_shape(RID p_shape, const Transform2D &p_shape_xform, const Vector2 &p_motion, real_t p_margin, Vector2 *r_results, int p_result_max, int &r_result_count, const Set<RID> &p_exclude, uint32_t p_collision_mask, bool p_collide_with_bodies, bool p_collide_with_areas) {

	if (p_result_max <= 0)
		return 0;

	Shape2DSW *shape = Physics2DServerSW::singletonsw->shape_owner.get(p_shape);
	ERR_FAIL_COND_V(!shape, 0);

	Rect2 aabb = p_shape_xform.xform(shape->get_aabb());
	aabb = aabb.merge(Rect2(aabb.position + p_motion, aabb.size)); //motion
	aabb = aabb.grow(p_margin);

	int amount = space->broadphase->cull_aabb(aabb, space->intersection_query_results, Space2DSW::INTERSECTION_QUERY_MAX, space->intersection_query_subindex_results);

	bool collided = false;
	r_result_count = 0;

	Physics2DServerSW::CollCbkData cbk;
	cbk.max = p_result_max;
	cbk.amount = 0;
	cbk.ptr = r_results;
	CollisionSolver2DSW::CallbackResult cbkres = NULL;

	Physics2DServerSW::CollCbkData *cbkptr = NULL;
	if (p_result_max > 0) {
		cbkptr = &cbk;
		cbkres = Physics2DServerSW::_shape_col_cbk;
	}

	for (int i = 0; i < amount; i++) {

		if (!_can_collide_with(space->intersection_query_results[i], p_collision_mask, p_collide_with_bodies, p_collide_with_areas))
			continue;

		const CollisionObject2DSW *col_obj = space->intersection_query_results[i];
		int shape_idx = space->intersection_query_subindex_results[i];

		if (p_exclude.has(col_obj->get_self()))
			continue;

		cbk.valid_dir = Vector2();
		cbk.valid_depth = 0;

		if (CollisionSolver2DSW::solve(shape, p_shape_xform, p_motion, col_obj->get_shape(shape_idx), col_obj->get_transform() * col_obj->get_shape_transform(shape_idx), Vector2(), cbkres, cbkptr, NULL, p_margin)) {
			collided = p_result_max == 0 || cbk.amount > 0;
		}
	}

	r_result_count = cbk.amount;

	return collided;
}

struct _RestCallbackData2D {

	const CollisionObject2DSW *object;
	const CollisionObject2DSW *best_object;
	int shape;
	int best_shape;
	Vector2 best_contact;
	Vector2 best_normal;
	real_t best_len;
	Vector2 valid_dir;
	real_t valid_depth;
};

static void _rest_cbk_result(const Vector2 &p_point_A, const Vector2 &p_point_B, void *p_userdata) {

	_RestCallbackData2D *rd = (_RestCallbackData2D *)p_userdata;

	if (rd->valid_dir != Vector2()) {
		if (p_point_A.distance_squared_to(p_point_B) > rd->valid_depth * rd->valid_depth)
			return;
		if (rd->valid_dir.dot((p_point_A - p_point_B).normalized()) < Math_PI * 0.25)
			return;
	}

	Vector2 contact_rel = p_point_B - p_point_A;
	real_t len = contact_rel.length();
	if (len <= rd->best_len)
		return;

	rd->best_len = len;
	rd->best_contact = p_point_B;
	rd->best_normal = contact_rel / len;
	rd->best_object = rd->object;
	rd->best_shape = rd->shape;
}

bool Physics2DDirectSpaceStateSW::rest_info(RID p_shape, const Transform2D &p_shape_xform, const Vector2 &p_motion, real_t p_margin, ShapeRestInfo *r_info, const Set<RID> &p_exclude, uint32_t p_collision_mask, bool p_collide_with_bodies, bool p_collide_with_areas) {

	Shape2DSW *shape = Physics2DServerSW::singletonsw->shape_owner.get(p_shape);
	ERR_FAIL_COND_V(!shape, 0);

	Rect2 aabb = p_shape_xform.xform(shape->get_aabb());
	aabb = aabb.merge(Rect2(aabb.position + p_motion, aabb.size)); //motion
	aabb = aabb.grow(p_margin);

	int amount = space->broadphase->cull_aabb(aabb, space->intersection_query_results, Space2DSW::INTERSECTION_QUERY_MAX, space->intersection_query_subindex_results);

	_RestCallbackData2D rcd;
	rcd.best_len = 0;
	rcd.best_object = NULL;
	rcd.best_shape = 0;

	for (int i = 0; i < amount; i++) {

		if (!_can_collide_with(space->intersection_query_results[i], p_collision_mask, p_collide_with_bodies, p_collide_with_areas))
			continue;

		const CollisionObject2DSW *col_obj = space->intersection_query_results[i];
		int shape_idx = space->intersection_query_subindex_results[i];

		if (p_exclude.has(col_obj->get_self()))
			continue;

		rcd.valid_dir = Vector2();
		rcd.valid_depth = 0;
		rcd.object = col_obj;
		rcd.shape = shape_idx;
		bool sc = CollisionSolver2DSW::solve(shape, p_shape_xform, p_motion, col_obj->get_shape(shape_idx), col_obj->get_transform() * col_obj->get_shape_transform(shape_idx), Vector2(), _rest_cbk_result, &rcd, NULL, p_margin);
		if (!sc)
			continue;
	}

	if (rcd.best_len == 0)
		return false;

	r_info->collider_id = rcd.best_object->get_instance_id();
	r_info->shape = rcd.best_shape;
	r_info->normal = rcd.best_normal;
	r_info->point = rcd.best_contact;
	r_info->rid = rcd.best_object->get_self();
	r_info->metadata = rcd.best_object->get_shape_metadata(rcd.best_shape);
	if (rcd.best_object->get_type() == CollisionObject2DSW::TYPE_BODY) {

		const Body2DSW *body = static_cast<const Body2DSW *>(rcd.best_object);
		Vector2 rel_vec = r_info->point - body->get_transform().get_origin();
		r_info->linear_velocity = Vector2(-body->get_angular_velocity() * rel_vec.y, body->get_angular_velocity() * rel_vec.x) + body->get_linear_velocity();

	} else {
		r_info->linear_velocity = Vector2();
	}

	return true;
}

Physics2DDirectSpaceStateSW::Physics2DDirectSpaceStateSW() {

	space = NULL;
}

////////////////////////////////////////////////////////////////////////////////////////////////////////////

int Space2DSW::_cull_aabb_for_body(Body2DSW *p_body, const Rect2 &p_aabb) {

	int amount = broadphase->cull_aabb(p_aabb, intersection_query_results, INTERSECTION_QUERY_MAX, intersection_query_subindex_results);

	for (int i = 0; i < amount; i++) {

		bool keep = true;

		if (intersection_query_results[i] == p_body)
			keep = false;
		else if (intersection_query_results[i]->get_type() == CollisionObject2DSW::TYPE_AREA)
			keep = false;
		else if ((static_cast<Body2DSW *>(intersection_query_results[i])->test_collision_mask(p_body)) == 0)
			keep = false;
		else if (static_cast<Body2DSW *>(intersection_query_results[i])->has_exception(p_body->get_self()) || p_body->has_exception(intersection_query_results[i]->get_self()))
			keep = false;
		else if (static_cast<Body2DSW *>(intersection_query_results[i])->is_shape_set_as_disabled(intersection_query_subindex_results[i]))
			keep = false;

		if (!keep) {

			if (i < amount - 1) {
				SWAP(intersection_query_results[i], intersection_query_results[amount - 1]);
				SWAP(intersection_query_subindex_results[i], intersection_query_subindex_results[amount - 1]);
			}

			amount--;
			i--;
		}
	}

	return amount;
}

int Space2DSW::test_body_ray_separation(Body2DSW *p_body, const Transform2D &p_transform, bool p_infinite_inertia, Vector2 &r_recover_motion, Physics2DServer::SeparationResult *r_results, int p_result_max, real_t p_margin) {

	Rect2 body_aabb;

	for (int i = 0; i < p_body->get_shape_count(); i++) {

		if (i == 0)
			body_aabb = p_body->get_shape_aabb(i);
		else
			body_aabb = body_aabb.merge(p_body->get_shape_aabb(i));
	}

	// Undo the currently transform the physics server is aware of and apply the provided one
	body_aabb = p_transform.xform(p_body->get_inv_transform().xform(body_aabb));
	body_aabb = body_aabb.grow(p_margin);

	Transform2D body_transform = p_transform;

	for (int i = 0; i < p_result_max; i++) {
		//reset results
		r_results[i].collision_depth = 0;
	}

	int rays_found = 0;

	{
		// raycast AND separate

		const int max_results = 32;
		int recover_attempts = 4;
		Vector2 sr[max_results * 2];
		Physics2DServerSW::CollCbkData cbk;
		cbk.max = max_results;
		Physics2DServerSW::CollCbkData *cbkptr = &cbk;
		CollisionSolver2DSW::CallbackResult cbkres = Physics2DServerSW::_shape_col_cbk;

		do {

			Vector2 recover_motion;

			bool collided = false;

			int amount = _cull_aabb_for_body(p_body, body_aabb);
			int ray_index = 0;

			for (int j = 0; j < p_body->get_shape_count(); j++) {
				if (p_body->is_shape_set_as_disabled(j))
					continue;

				Shape2DSW *body_shape = p_body->get_shape(j);

				if (body_shape->get_type() != Physics2DServer::SHAPE_RAY)
					continue;

				Transform2D body_shape_xform = body_transform * p_body->get_shape_transform(j);

				for (int i = 0; i < amount; i++) {

					const CollisionObject2DSW *col_obj = intersection_query_results[i];
					int shape_idx = intersection_query_subindex_results[i];

					cbk.amount = 0;
					cbk.ptr = sr;
					cbk.invalid_by_dir = 0;

					if (CollisionObject2DSW::TYPE_BODY == col_obj->get_type()) {
						const Body2DSW *b = static_cast<const Body2DSW *>(col_obj);
						if (p_infinite_inertia && Physics2DServer::BODY_MODE_STATIC != b->get_mode() && Physics2DServer::BODY_MODE_KINEMATIC != b->get_mode()) {
							continue;
						}
					}

					if (col_obj->is_shape_set_as_one_way_collision(shape_idx)) {

						cbk.valid_dir = body_shape_xform.get_axis(1).normalized();
						cbk.valid_depth = p_margin; //only valid depth is the collision margin
						cbk.invalid_by_dir = 0;

					} else {
						cbk.valid_dir = Vector2();
						cbk.valid_depth = 0;
						cbk.invalid_by_dir = 0;
					}

					Shape2DSW *against_shape = col_obj->get_shape(shape_idx);
					if (CollisionSolver2DSW::solve(body_shape, body_shape_xform, Vector2(), against_shape, col_obj->get_transform() * col_obj->get_shape_transform(shape_idx), Vector2(), cbkres, cbkptr, NULL, p_margin)) {
						if (cbk.amount > 0) {
							collided = true;
						}

						if (ray_index < p_result_max) {
							Physics2DServer::SeparationResult &result = r_results[ray_index];

							for (int k = 0; k < cbk.amount; k++) {
								Vector2 a = sr[k * 2 + 0];
								Vector2 b = sr[k * 2 + 1];

								recover_motion += (b - a) * 0.4;

								float depth = a.distance_to(b);
								if (depth > result.collision_depth) {

									result.collision_depth = depth;
									result.collision_point = b;
									result.collision_normal = (b - a).normalized();
									result.collision_local_shape = shape_idx;
									result.collider = col_obj->get_self();
									result.collider_id = col_obj->get_instance_id();
									result.collider_metadata = col_obj->get_shape_metadata(shape_idx);
									if (col_obj->get_type() == CollisionObject2DSW::TYPE_BODY) {
										Body2DSW *body = (Body2DSW *)col_obj;

										Vector2 rel_vec = b - body->get_transform().get_origin();
										result.collider_velocity = Vector2(-body->get_angular_velocity() * rel_vec.y, body->get_angular_velocity() * rel_vec.x) + body->get_linear_velocity();
									}
								}
							}
						}
					}
				}

				ray_index++;
			}

			rays_found = MAX(ray_index, rays_found);

			if (!collided || recover_motion == Vector2()) {
				break;
			}

			body_transform.elements[2] += recover_motion;
			body_aabb.position += recover_motion;

			recover_attempts--;
		} while (recover_attempts);
	}

	//optimize results (remove non colliding)
	for (int i = 0; i < rays_found; i++) {
		if (r_results[i].collision_depth == 0) {
			rays_found--;
			SWAP(r_results[i], r_results[rays_found]);
		}
	}

	r_recover_motion = body_transform.elements[2] - p_transform.elements[2];
	return rays_found;
}

bool Space2DSW::test_body_motion(Body2DSW *p_body, const Transform2D &p_from, const Vector2 &p_motion, bool p_infinite_inertia, real_t p_margin, Physics2DServer::MotionResult *r_result, bool p_exclude_raycast_shapes) {

	//give me back regular physics engine logic
	//this is madness
	//and most people using this function will think
	//what it does is simpler than using physics
	//this took about a week to get right..
	//but is it right? who knows at this point..

	if (r_result) {
		r_result->collider_id = 0;
		r_result->collider_shape = 0;
	}
	Rect2 body_aabb;

	for (int i = 0; i < p_body->get_shape_count(); i++) {

		if (i == 0)
			body_aabb = p_body->get_shape_aabb(i);
		else
			body_aabb = body_aabb.merge(p_body->get_shape_aabb(i));
	}

	// Undo the currently transform the physics server is aware of and apply the provided one
	body_aabb = p_from.xform(p_body->get_inv_transform().xform(body_aabb));
	body_aabb = body_aabb.grow(p_margin);

	static const int max_excluded_shape_pairs = 32;
	ExcludedShapeSW excluded_shape_pairs[max_excluded_shape_pairs];
	int excluded_shape_pair_count = 0;

	Transform2D body_transform = p_from;

	{
		//STEP 1, FREE BODY IF STUCK

		const int max_results = 32;
		int recover_attempts = 4;
		Vector2 sr[max_results * 2];

		do {

			Physics2DServerSW::CollCbkData cbk;
			cbk.max = max_results;
			cbk.amount = 0;
			cbk.ptr = sr;
			cbk.invalid_by_dir = 0;
			excluded_shape_pair_count = 0; //last step is the one valid

			Physics2DServerSW::CollCbkData *cbkptr = &cbk;
			CollisionSolver2DSW::CallbackResult cbkres = Physics2DServerSW::_shape_col_cbk;

			bool collided = false;

			int amount = _cull_aabb_for_body(p_body, body_aabb);

			for (int j = 0; j < p_body->get_shape_count(); j++) {
				if (p_body->is_shape_set_as_disabled(j))
					continue;

				Shape2DSW *body_shape = p_body->get_shape(j);
				if (p_exclude_raycast_shapes && body_shape->get_type() == Physics2DServer::SHAPE_RAY) {
					continue;
				}

				Transform2D body_shape_xform = body_transform * p_body->get_shape_transform(j);
				for (int i = 0; i < amount; i++) {

					const CollisionObject2DSW *col_obj = intersection_query_results[i];
					int shape_idx = intersection_query_subindex_results[i];

					if (CollisionObject2DSW::TYPE_BODY == col_obj->get_type()) {
						const Body2DSW *b = static_cast<const Body2DSW *>(col_obj);
						if (p_infinite_inertia && Physics2DServer::BODY_MODE_STATIC != b->get_mode() && Physics2DServer::BODY_MODE_KINEMATIC != b->get_mode()) {
							continue;
						}
					}

					if (col_obj->is_shape_set_as_one_way_collision(shape_idx)) {

						cbk.valid_dir = body_shape_xform.get_axis(1).normalized();
						cbk.valid_depth = p_margin; //only valid depth is the collision margin
						cbk.invalid_by_dir = 0;

					} else {
						cbk.valid_dir = Vector2();
						cbk.valid_depth = 0;
						cbk.invalid_by_dir = 0;
					}

					Shape2DSW *against_shape = col_obj->get_shape(shape_idx);
					if (CollisionSolver2DSW::solve(body_shape, body_shape_xform, Vector2(), against_shape, col_obj->get_transform() * col_obj->get_shape_transform(shape_idx), Vector2(), cbkres, cbkptr, NULL, p_margin)) {
						collided = cbk.amount > 0;
					}

					if (!collided && cbk.invalid_by_dir > 0) {
						//this shape must be excluded
						if (excluded_shape_pair_count < max_excluded_shape_pairs) {
							ExcludedShapeSW esp;
							esp.local_shape = body_shape;
							esp.against_object = col_obj;
							esp.against_shape_index = shape_idx;
							excluded_shape_pairs[excluded_shape_pair_count++] = esp;
						}
					}
				}
			}

			if (!collided) {
				break;
			}

			Vector2 recover_motion;

			for (int i = 0; i < cbk.amount; i++) {

				Vector2 a = sr[i * 2 + 0];
				Vector2 b = sr[i * 2 + 1];
				recover_motion += (b - a) * 0.4;
			}

			if (recover_motion == Vector2()) {
				collided = false;
				break;
			}

			body_transform.elements[2] += recover_motion;
			body_aabb.position += recover_motion;

			recover_attempts--;

		} while (recover_attempts);
	}

	real_t safe = 1.0;
	real_t unsafe = 1.0;
	int best_shape = -1;

	{
		// STEP 2 ATTEMPT MOTION

		Rect2 motion_aabb = body_aabb;
		motion_aabb.position += p_motion;
		motion_aabb = motion_aabb.merge(body_aabb);

		int amount = _cull_aabb_for_body(p_body, motion_aabb);

		for (int body_shape_idx = 0; body_shape_idx < p_body->get_shape_count(); body_shape_idx++) {

			if (p_body->is_shape_set_as_disabled(body_shape_idx))
				continue;

			Shape2DSW *body_shape = p_body->get_shape(body_shape_idx);
			if (p_exclude_raycast_shapes && body_shape->get_type() == Physics2DServer::SHAPE_RAY) {
				continue;
			}

			Transform2D body_shape_xform = body_transform * p_body->get_shape_transform(body_shape_idx);

			bool stuck = false;

			real_t best_safe = 1;
			real_t best_unsafe = 1;

			for (int i = 0; i < amount; i++) {

				const CollisionObject2DSW *col_obj = intersection_query_results[i];
				int col_shape_idx = intersection_query_subindex_results[i];
				Shape2DSW *against_shape = col_obj->get_shape(col_shape_idx);

				if (CollisionObject2DSW::TYPE_BODY == col_obj->get_type()) {
					const Body2DSW *b = static_cast<const Body2DSW *>(col_obj);
					if (p_infinite_inertia && Physics2DServer::BODY_MODE_STATIC != b->get_mode() && Physics2DServer::BODY_MODE_KINEMATIC != b->get_mode()) {
						continue;
					}
				}

				bool excluded = false;

				for (int k = 0; k < excluded_shape_pair_count; k++) {

					if (excluded_shape_pairs[k].local_shape == body_shape && excluded_shape_pairs[k].against_object == col_obj && excluded_shape_pairs[k].against_shape_index == col_shape_idx) {
						excluded = true;
						break;
					}
				}

				if (excluded) {

					continue;
				}

				Transform2D col_obj_xform = col_obj->get_transform() * col_obj->get_shape_transform(col_shape_idx);
				//test initial overlap, does it collide if going all the way?
				if (!CollisionSolver2DSW::solve(body_shape, body_shape_xform, p_motion, against_shape, col_obj_xform, Vector2(), NULL, NULL, NULL, 0)) {
					continue;
				}

				//test initial overlap
				if (CollisionSolver2DSW::solve(body_shape, body_shape_xform, Vector2(), against_shape, col_obj_xform, Vector2(), NULL, NULL, NULL, 0)) {

					if (col_obj->is_shape_set_as_one_way_collision(col_shape_idx)) {
						continue;
					}

					stuck = true;
					break;
				}

				//just do kinematic solving
				real_t low = 0;
				real_t hi = 1;
				Vector2 mnormal = p_motion.normalized();

				for (int k = 0; k < 8; k++) { //steps should be customizable..

					real_t ofs = (low + hi) * 0.5;

					Vector2 sep = mnormal; //important optimization for this to work fast enough
					bool collided = CollisionSolver2DSW::solve(body_shape, body_shape_xform, p_motion * ofs, against_shape, col_obj_xform, Vector2(), NULL, NULL, &sep, 0);

					if (collided) {

						hi = ofs;
					} else {

						low = ofs;
					}
				}

				if (col_obj->is_shape_set_as_one_way_collision(col_shape_idx)) {

					Vector2 cd[2];
					Physics2DServerSW::CollCbkData cbk;
					cbk.max = 1;
					cbk.amount = 0;
					cbk.ptr = cd;
					cbk.valid_dir = body_shape_xform.get_axis(1).normalized();

					cbk.valid_depth = 10e20;

					Vector2 sep = mnormal; //important optimization for this to work fast enough
					bool collided = CollisionSolver2DSW::solve(body_shape, body_shape_xform, p_motion * (hi + contact_max_allowed_penetration), col_obj->get_shape(col_shape_idx), col_obj_xform, Vector2(), Physics2DServerSW::_shape_col_cbk, &cbk, &sep, 0);
					if (!collided || cbk.amount == 0) {
						continue;
					}
				}

				if (low < best_safe) {
					best_safe = low;
					best_unsafe = hi;
				}
			}

			if (stuck) {

				safe = 0;
				unsafe = 0;
				best_shape = body_shape_idx; //sadly it's the best
				break;
			}
			if (best_safe == 1.0) {
				continue;
			}
			if (best_safe < safe) {

				safe = best_safe;
				unsafe = best_unsafe;
				best_shape = body_shape_idx;
			}
		}
	}

	bool collided = false;
	if (safe >= 1) {
		//not collided
		collided = false;
		if (r_result) {

			r_result->motion = p_motion;
			r_result->remainder = Vector2();
			r_result->motion += (body_transform.get_origin() - p_from.get_origin());
		}

	} else {

		//it collided, let's get the rest info in unsafe advance
		Transform2D ugt = body_transform;
		ugt.elements[2] += p_motion * unsafe;

		_RestCallbackData2D rcd;
		rcd.best_len = 0;
		rcd.best_object = NULL;
		rcd.best_shape = 0;

		Transform2D body_shape_xform = ugt * p_body->get_shape_transform(best_shape);
		Shape2DSW *body_shape = p_body->get_shape(best_shape);

		body_aabb.position += p_motion * unsafe;

		int amount = _cull_aabb_for_body(p_body, body_aabb);

		for (int i = 0; i < amount; i++) {

			const CollisionObject2DSW *col_obj = intersection_query_results[i];
			int shape_idx = intersection_query_subindex_results[i];

			if (CollisionObject2DSW::TYPE_BODY == col_obj->get_type()) {
				const Body2DSW *b = static_cast<const Body2DSW *>(col_obj);
				if (p_infinite_inertia && Physics2DServer::BODY_MODE_STATIC != b->get_mode() && Physics2DServer::BODY_MODE_KINEMATIC != b->get_mode()) {
					continue;
				}
			}

			Shape2DSW *against_shape = col_obj->get_shape(shape_idx);

			bool excluded = false;
			for (int k = 0; k < excluded_shape_pair_count; k++) {

				if (excluded_shape_pairs[k].local_shape == body_shape && excluded_shape_pairs[k].against_object == col_obj && excluded_shape_pairs[k].against_shape_index == shape_idx) {
					excluded = true;
					break;
				}
			}
			if (excluded)
				continue;

			if (col_obj->is_shape_set_as_one_way_collision(shape_idx)) {

				rcd.valid_dir = body_shape_xform.get_axis(1).normalized();
				rcd.valid_depth = 10e20;
			} else {
				rcd.valid_dir = Vector2();
				rcd.valid_depth = 0;
			}

			rcd.object = col_obj;
			rcd.shape = shape_idx;
			bool sc = CollisionSolver2DSW::solve(body_shape, body_shape_xform, Vector2(), against_shape, col_obj->get_transform() * col_obj->get_shape_transform(shape_idx), Vector2(), _rest_cbk_result, &rcd, NULL, p_margin);
			if (!sc)
				continue;
		}

		if (rcd.best_len != 0) {

			if (r_result) {
				r_result->collider = rcd.best_object->get_self();
				r_result->collider_id = rcd.best_object->get_instance_id();
				r_result->collider_shape = rcd.best_shape;
				r_result->collision_local_shape = best_shape;
				r_result->collision_normal = rcd.best_normal;
				r_result->collision_point = rcd.best_contact;
				r_result->collider_metadata = rcd.best_object->get_shape_metadata(rcd.best_shape);

				const Body2DSW *body = static_cast<const Body2DSW *>(rcd.best_object);
				Vector2 rel_vec = r_result->collision_point - body->get_transform().get_origin();
				r_result->collider_velocity = Vector2(-body->get_angular_velocity() * rel_vec.y, body->get_angular_velocity() * rel_vec.x) + body->get_linear_velocity();

				r_result->motion = safe * p_motion;
				r_result->remainder = p_motion - safe * p_motion;
				r_result->motion += (body_transform.get_origin() - p_from.get_origin());
			}

			collided = true;
		} else {
			if (r_result) {

				r_result->motion = p_motion;
				r_result->remainder = Vector2();
				r_result->motion += (body_transform.get_origin() - p_from.get_origin());
			}

			collided = false;
		}
	}

	return collided;
}

void *Space2DSW::_broadphase_pair(CollisionObject2DSW *A, int p_subindex_A, CollisionObject2DSW *B, int p_subindex_B, void *p_self) {

	CollisionObject2DSW::Type type_A = A->get_type();
	CollisionObject2DSW::Type type_B = B->get_type();
	if (type_A > type_B) {

		SWAP(A, B);
		SWAP(p_subindex_A, p_subindex_B);
		SWAP(type_A, type_B);
	}

	Space2DSW *self = (Space2DSW *)p_self;
	self->collision_pairs++;

	if (type_A == CollisionObject2DSW::TYPE_AREA) {

		Area2DSW *area = static_cast<Area2DSW *>(A);
		if (type_B == CollisionObject2DSW::TYPE_AREA) {

			Area2DSW *area_b = static_cast<Area2DSW *>(B);
			Area2Pair2DSW *area2_pair = memnew(Area2Pair2DSW(area_b, p_subindex_B, area, p_subindex_A));
			return area2_pair;
		} else {

			Body2DSW *body = static_cast<Body2DSW *>(B);
			AreaPair2DSW *area_pair = memnew(AreaPair2DSW(body, p_subindex_B, area, p_subindex_A));
			return area_pair;
		}

	} else {

		BodyPair2DSW *b = memnew(BodyPair2DSW((Body2DSW *)A, p_subindex_A, (Body2DSW *)B, p_subindex_B));
		return b;
	}

	return NULL;
}

void Space2DSW::_broadphase_unpair(CollisionObject2DSW *A, int p_subindex_A, CollisionObject2DSW *B, int p_subindex_B, void *p_data, void *p_self) {

	Space2DSW *self = (Space2DSW *)p_self;
	self->collision_pairs--;
	Constraint2DSW *c = (Constraint2DSW *)p_data;
	memdelete(c);
}

const SelfList<Body2DSW>::List &Space2DSW::get_active_body_list() const {

	return active_list;
}
void Space2DSW::body_add_to_active_list(SelfList<Body2DSW> *p_body) {

	active_list.add(p_body);
}
void Space2DSW::body_remove_from_active_list(SelfList<Body2DSW> *p_body) {

	active_list.remove(p_body);
}

void Space2DSW::body_add_to_inertia_update_list(SelfList<Body2DSW> *p_body) {

	inertia_update_list.add(p_body);
}

void Space2DSW::body_remove_from_inertia_update_list(SelfList<Body2DSW> *p_body) {

	inertia_update_list.remove(p_body);
}

BroadPhase2DSW *Space2DSW::get_broadphase() {

	return broadphase;
}

void Space2DSW::add_object(CollisionObject2DSW *p_object) {

	ERR_FAIL_COND(objects.has(p_object));
	objects.insert(p_object);
}

void Space2DSW::remove_object(CollisionObject2DSW *p_object) {

	ERR_FAIL_COND(!objects.has(p_object));
	objects.erase(p_object);
}

const Set<CollisionObject2DSW *> &Space2DSW::get_objects() const {

	return objects;
}

void Space2DSW::body_add_to_state_query_list(SelfList<Body2DSW> *p_body) {

	state_query_list.add(p_body);
}
void Space2DSW::body_remove_from_state_query_list(SelfList<Body2DSW> *p_body) {

	state_query_list.remove(p_body);
}

void Space2DSW::area_add_to_monitor_query_list(SelfList<Area2DSW> *p_area) {

	monitor_query_list.add(p_area);
}
void Space2DSW::area_remove_from_monitor_query_list(SelfList<Area2DSW> *p_area) {

	monitor_query_list.remove(p_area);
}

void Space2DSW::area_add_to_moved_list(SelfList<Area2DSW> *p_area) {

	area_moved_list.add(p_area);
}

void Space2DSW::area_remove_from_moved_list(SelfList<Area2DSW> *p_area) {

	area_moved_list.remove(p_area);
}

const SelfList<Area2DSW>::List &Space2DSW::get_moved_area_list() const {

	return area_moved_list;
}

void Space2DSW::call_queries() {

	while (state_query_list.first()) {

		Body2DSW *b = state_query_list.first()->self();
		state_query_list.remove(state_query_list.first());
		b->call_queries();
	}

	while (monitor_query_list.first()) {

		Area2DSW *a = monitor_query_list.first()->self();
		monitor_query_list.remove(monitor_query_list.first());
		a->call_queries();
	}
}

void Space2DSW::setup() {

	contact_debug_count = 0;

	while (inertia_update_list.first()) {
		inertia_update_list.first()->self()->update_inertias();
		inertia_update_list.remove(inertia_update_list.first());
	}
}

void Space2DSW::update() {

	broadphase->update();
}

void Space2DSW::set_param(Physics2DServer::SpaceParameter p_param, real_t p_value) {

	switch (p_param) {

		case Physics2DServer::SPACE_PARAM_CONTACT_RECYCLE_RADIUS: contact_recycle_radius = p_value; break;
		case Physics2DServer::SPACE_PARAM_CONTACT_MAX_SEPARATION: contact_max_separation = p_value; break;
		case Physics2DServer::SPACE_PARAM_BODY_MAX_ALLOWED_PENETRATION: contact_max_allowed_penetration = p_value; break;
		case Physics2DServer::SPACE_PARAM_BODY_LINEAR_VELOCITY_SLEEP_THRESHOLD: body_linear_velocity_sleep_threshold = p_value; break;
		case Physics2DServer::SPACE_PARAM_BODY_ANGULAR_VELOCITY_SLEEP_THRESHOLD: body_angular_velocity_sleep_threshold = p_value; break;
		case Physics2DServer::SPACE_PARAM_BODY_TIME_TO_SLEEP: body_time_to_sleep = p_value; break;
		case Physics2DServer::SPACE_PARAM_CONSTRAINT_DEFAULT_BIAS: constraint_bias = p_value; break;
	}
}

real_t Space2DSW::get_param(Physics2DServer::SpaceParameter p_param) const {

	switch (p_param) {

		case Physics2DServer::SPACE_PARAM_CONTACT_RECYCLE_RADIUS: return contact_recycle_radius;
		case Physics2DServer::SPACE_PARAM_CONTACT_MAX_SEPARATION: return contact_max_separation;
		case Physics2DServer::SPACE_PARAM_BODY_MAX_ALLOWED_PENETRATION: return contact_max_allowed_penetration;
		case Physics2DServer::SPACE_PARAM_BODY_LINEAR_VELOCITY_SLEEP_THRESHOLD: return body_linear_velocity_sleep_threshold;
		case Physics2DServer::SPACE_PARAM_BODY_ANGULAR_VELOCITY_SLEEP_THRESHOLD: return body_angular_velocity_sleep_threshold;
		case Physics2DServer::SPACE_PARAM_BODY_TIME_TO_SLEEP: return body_time_to_sleep;
		case Physics2DServer::SPACE_PARAM_CONSTRAINT_DEFAULT_BIAS: return constraint_bias;
	}
	return 0;
}

void Space2DSW::lock() {

	locked = true;
}

void Space2DSW::unlock() {

	locked = false;
}

bool Space2DSW::is_locked() const {

	return locked;
}

Physics2DDirectSpaceStateSW *Space2DSW::get_direct_state() {

	return direct_access;
}

Space2DSW::Space2DSW() {

	collision_pairs = 0;
	active_objects = 0;
	island_count = 0;

	contact_debug_count = 0;

	locked = false;
	contact_recycle_radius = 1.0;
	contact_max_separation = 1.5;
	contact_max_allowed_penetration = 0.3;

	constraint_bias = 0.2;
	body_linear_velocity_sleep_threshold = GLOBAL_DEF("physics/2d/sleep_threshold_linear", 2.0);
	body_angular_velocity_sleep_threshold = GLOBAL_DEF("physics/2d/sleep_threshold_angular", (8.0 / 180.0 * Math_PI));
	body_time_to_sleep = GLOBAL_DEF("physics/2d/time_before_sleep", 0.5);

	broadphase = BroadPhase2DSW::create_func();
	broadphase->set_pair_callback(_broadphase_pair, this);
	broadphase->set_unpair_callback(_broadphase_unpair, this);
	area = NULL;

	direct_access = memnew(Physics2DDirectSpaceStateSW);
	direct_access->space = this;

	for (int i = 0; i < ELAPSED_TIME_MAX; i++)
		elapsed_time[i] = 0;
}

Space2DSW::~Space2DSW() {

	memdelete(broadphase);
	memdelete(direct_access);
}