5 files changed, 18 insertions, 8 deletions
diff --git a/servers/physics_3d/physics_server_3d_sw.cpp b/servers/physics_3d/physics_server_3d_sw.cpp
index a1d776922e..1cf6b12623 100644
--- a/servers/physics_3d/physics_server_3d_sw.cpp
+++ b/servers/physics_3d/physics_server_3d_sw.cpp
@@ -854,7 +854,7 @@ void PhysicsServer3DSW::body_set_ray_pickable(RID p_body, bool p_enable) {
 	body->set_ray_pickable(p_enable);
 }
 
-bool PhysicsServer3DSW::body_test_motion(RID p_body, const Transform3D &p_from, const Vector3 &p_motion, real_t p_margin, MotionResult *r_result, const Set<RID> &p_exclude) {
+bool PhysicsServer3DSW::body_test_motion(RID p_body, const Transform3D &p_from, const Vector3 &p_motion, real_t p_margin, MotionResult *r_result, bool p_collide_separation_ray, const Set<RID> &p_exclude) {
 	Body3DSW *body = body_owner.getornull(p_body);
 	ERR_FAIL_COND_V(!body, false);
 	ERR_FAIL_COND_V(!body->get_space(), false);
@@ -862,7 +862,7 @@ bool PhysicsServer3DSW::body_test_motion(RID p_body, const Transform3D &p_from,
 
 	_update_shapes();
 
-	return body->get_space()->test_body_motion(body, p_from, p_motion, p_margin, r_result, p_exclude);
+	return body->get_space()->test_body_motion(body, p_from, p_motion, p_margin, r_result, p_collide_separation_ray, p_exclude);
 }
 
 PhysicsDirectBodyState3D *PhysicsServer3DSW::body_get_direct_state(RID p_body) {
diff --git a/servers/physics_3d/physics_server_3d_sw.h b/servers/physics_3d/physics_server_3d_sw.h
index f2322a0e76..341ce06a5d 100644
--- a/servers/physics_3d/physics_server_3d_sw.h
+++ b/servers/physics_3d/physics_server_3d_sw.h
@@ -242,7 +242,7 @@ public:
 
 	virtual void body_set_ray_pickable(RID p_body, bool p_enable) override;
 
-	virtual bool body_test_motion(RID p_body, const Transform3D &p_from, const Vector3 &p_motion, real_t p_margin = 0.001, MotionResult *r_result = nullptr, const Set<RID> &p_exclude = Set<RID>()) override;
+	virtual bool body_test_motion(RID p_body, const Transform3D &p_from, const Vector3 &p_motion, real_t p_margin = 0.001, MotionResult *r_result = nullptr, bool p_collide_separation_ray = false, const Set<RID> &p_exclude = Set<RID>()) override;
 
 	// this function only works on physics process, errors and returns null otherwise
 	virtual PhysicsDirectBodyState3D *body_get_direct_state(RID p_body) override;
diff --git a/servers/physics_3d/physics_server_3d_wrap_mt.h b/servers/physics_3d/physics_server_3d_wrap_mt.h
index d807e73731..24bf203d51 100644
--- a/servers/physics_3d/physics_server_3d_wrap_mt.h
+++ b/servers/physics_3d/physics_server_3d_wrap_mt.h
@@ -250,9 +250,9 @@ public:
 
 	FUNC2(body_set_ray_pickable, RID, bool);
 
-	bool body_test_motion(RID p_body, const Transform3D &p_from, const Vector3 &p_motion, real_t p_margin = 0.001, MotionResult *r_result = nullptr, const Set<RID> &p_exclude = Set<RID>()) override {
+	bool body_test_motion(RID p_body, const Transform3D &p_from, const Vector3 &p_motion, real_t p_margin = 0.001, MotionResult *r_result = nullptr, bool p_collide_separation_ray = false, const Set<RID> &p_exclude = Set<RID>()) override {
 		ERR_FAIL_COND_V(main_thread != Thread::get_caller_id(), false);
-		return physics_3d_server->body_test_motion(p_body, p_from, p_motion, p_margin, r_result, p_exclude);
+		return physics_3d_server->body_test_motion(p_body, p_from, p_motion, p_margin, r_result, p_collide_separation_ray, p_exclude);
 	}
 
 	// this function only works on physics process, errors and returns null otherwise
diff --git a/servers/physics_3d/space_3d_sw.cpp b/servers/physics_3d/space_3d_sw.cpp
index f9e55ad525..7ed17d6284 100644
--- a/servers/physics_3d/space_3d_sw.cpp
+++ b/servers/physics_3d/space_3d_sw.cpp
@@ -569,7 +569,7 @@ int Space3DSW::_cull_aabb_for_body(Body3DSW *p_body, const AABB &p_aabb) {
 	return amount;
 }
 
-bool Space3DSW::test_body_motion(Body3DSW *p_body, const Transform3D &p_from, const Vector3 &p_motion, real_t p_margin, PhysicsServer3D::MotionResult *r_result, const Set<RID> &p_exclude) {
+bool Space3DSW::test_body_motion(Body3DSW *p_body, const Transform3D &p_from, const Vector3 &p_motion, real_t p_margin, PhysicsServer3D::MotionResult *r_result, bool p_collide_separation_ray, const Set<RID> &p_exclude) {
 	//give me back regular physics engine logic
 	//this is madness
 	//and most people using this function will think
@@ -714,9 +714,19 @@ bool Space3DSW::test_body_motion(Body3DSW *p_body, const Transform3D &p_from, co
 				continue;
 			}
 
-			Transform3D body_shape_xform = body_transform * p_body->get_shape_transform(j);
 			Shape3DSW *body_shape = p_body->get_shape(j);
 
+			// Colliding separation rays allows to properly snap to the ground,
+			// otherwise it's not needed in regular motion.
+			if (!p_collide_separation_ray && (body_shape->get_type() == PhysicsServer3D::SHAPE_RAY)) {
+				// When slips on slope is on, separation ray shape acts like a regular shape.
+				if (!static_cast<RayShape3DSW *>(body_shape)->get_slips_on_slope()) {
+					continue;
+				}
+			}
+
+			Transform3D body_shape_xform = body_transform * p_body->get_shape_transform(j);
+
 			Transform3D body_shape_xform_inv = body_shape_xform.affine_inverse();
 			MotionShape3DSW mshape;
 			mshape.shape = body_shape;
diff --git a/servers/physics_3d/space_3d_sw.h b/servers/physics_3d/space_3d_sw.h
index 9b5b4de069..1c3d1cf9f6 100644
--- a/servers/physics_3d/space_3d_sw.h
+++ b/servers/physics_3d/space_3d_sw.h
@@ -203,7 +203,7 @@ public:
 	void set_elapsed_time(ElapsedTime p_time, uint64_t p_msec) { elapsed_time[p_time] = p_msec; }
 	uint64_t get_elapsed_time(ElapsedTime p_time) const { return elapsed_time[p_time]; }
 
-	bool test_body_motion(Body3DSW *p_body, const Transform3D &p_from, const Vector3 &p_motion, real_t p_margin, PhysicsServer3D::MotionResult *r_result, const Set<RID> &p_exclude = Set<RID>());
+	bool test_body_motion(Body3DSW *p_body, const Transform3D &p_from, const Vector3 &p_motion, real_t p_margin, PhysicsServer3D::MotionResult *r_result, bool p_collide_separation_ray = false, const Set<RID> &p_exclude = Set<RID>());
 
 	Space3DSW();
 	~Space3DSW();