Fix CharacterBody motion with RayShape

Make separation ray shapes work properly in move_and_slide, wihtout the
specific code in CharacterBody like before.

Now most of the logic is handled inside the physics server. The only
thing that's needed is to use ray shapes only for recovery and ignore
them when performing the motion itself (unless we're snapping or slips
on slope is on).

5 files changed, 17 insertions, 7 deletions

diff --git a/servers/physics_2d/physics_server_2d_sw.cpp b/servers/physics_2d/physics_server_2d_sw.cpp
index 0954f3a174..5cb67d5ab9 100644
--- a/servers/physics_2d/physics_server_2d_sw.cpp
+++ b/servers/physics_2d/physics_server_2d_sw.cpp
@@ -946,7 +946,7 @@ void PhysicsServer2DSW::body_set_pickable(RID p_body, bool p_pickable) {
 	body->set_pickable(p_pickable);
 }
 
-bool PhysicsServer2DSW::body_test_motion(RID p_body, const Transform2D &p_from, const Vector2 &p_motion, real_t p_margin, MotionResult *r_result, const Set<RID> &p_exclude) {
+bool PhysicsServer2DSW::body_test_motion(RID p_body, const Transform2D &p_from, const Vector2 &p_motion, real_t p_margin, MotionResult *r_result, bool p_collide_separation_ray, const Set<RID> &p_exclude) {
 	Body2DSW *body = body_owner.getornull(p_body);
 	ERR_FAIL_COND_V(!body, false);
 	ERR_FAIL_COND_V(!body->get_space(), false);
@@ -954,7 +954,7 @@ bool PhysicsServer2DSW::body_test_motion(RID p_body, const Transform2D &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);
 }
 
 PhysicsDirectBodyState2D *PhysicsServer2DSW::body_get_direct_state(RID p_body) {
diff --git a/servers/physics_2d/physics_server_2d_sw.h b/servers/physics_2d/physics_server_2d_sw.h
index 1926eaac84..6ea5e445bc 100644
--- a/servers/physics_2d/physics_server_2d_sw.h
+++ b/servers/physics_2d/physics_server_2d_sw.h
@@ -247,7 +247,7 @@ public:
 
 	virtual void body_set_pickable(RID p_body, bool p_pickable) override;
 
-	virtual bool body_test_motion(RID p_body, const Transform2D &p_from, const Vector2 &p_motion, real_t p_margin = 0.08, MotionResult *r_result = nullptr, const Set<RID> &p_exclude = Set<RID>()) override;
+	virtual bool body_test_motion(RID p_body, const Transform2D &p_from, const Vector2 &p_motion, real_t p_margin = 0.08, 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 PhysicsDirectBodyState2D *body_get_direct_state(RID p_body) override;
diff --git a/servers/physics_2d/physics_server_2d_wrap_mt.h b/servers/physics_2d/physics_server_2d_wrap_mt.h
index 0ebccc2614..7b1cda169d 100644
--- a/servers/physics_2d/physics_server_2d_wrap_mt.h
+++ b/servers/physics_2d/physics_server_2d_wrap_mt.h
@@ -253,9 +253,9 @@ public:
 
 	FUNC2(body_set_pickable, RID, bool);
 
-	bool body_test_motion(RID p_body, const Transform2D &p_from, const Vector2 &p_motion, real_t p_margin = 0.08, MotionResult *r_result = nullptr, const Set<RID> &p_exclude = Set<RID>()) override {
+	bool body_test_motion(RID p_body, const Transform2D &p_from, const Vector2 &p_motion, real_t p_margin = 0.08, 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_2d_server->body_test_motion(p_body, p_from, p_motion, p_margin, r_result, p_exclude);
+		return physics_2d_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_2d/space_2d_sw.cpp b/servers/physics_2d/space_2d_sw.cpp
index 61ec48c090..169c419b3b 100644
--- a/servers/physics_2d/space_2d_sw.cpp
+++ b/servers/physics_2d/space_2d_sw.cpp
@@ -528,7 +528,7 @@ int Space2DSW::_cull_aabb_for_body(Body2DSW *p_body, const Rect2 &p_aabb) {
 	return amount;
 }
 
-bool Space2DSW::test_body_motion(Body2DSW *p_body, const Transform2D &p_from, const Vector2 &p_motion, real_t p_margin, PhysicsServer2D::MotionResult *r_result, const Set<RID> &p_exclude) {
+bool Space2DSW::test_body_motion(Body2DSW *p_body, const Transform2D &p_from, const Vector2 &p_motion, real_t p_margin, PhysicsServer2D::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
@@ -726,6 +726,16 @@ bool Space2DSW::test_body_motion(Body2DSW *p_body, const Transform2D &p_from, co
 			}
 
 			Shape2DSW *body_shape = p_body->get_shape(body_shape_idx);
+
+			// 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() == PhysicsServer2D::SHAPE_RAY)) {
+				// When slips on slope is on, separation ray shape acts like a regular shape.
+				if (!static_cast<RayShape2DSW *>(body_shape)->get_slips_on_slope()) {
+					continue;
+				}
+			}
+
 			Transform2D body_shape_xform = body_transform * p_body->get_shape_transform(body_shape_idx);
 
 			bool stuck = false;
diff --git a/servers/physics_2d/space_2d_sw.h b/servers/physics_2d/space_2d_sw.h
index 3be36852b0..392df9b025 100644
--- a/servers/physics_2d/space_2d_sw.h
+++ b/servers/physics_2d/space_2d_sw.h
@@ -183,7 +183,7 @@ public:
 
 	int get_collision_pairs() const { return collision_pairs; }
 
-	bool test_body_motion(Body2DSW *p_body, const Transform2D &p_from, const Vector2 &p_motion, real_t p_margin, PhysicsServer2D::MotionResult *r_result, const Set<RID> &p_exclude = Set<RID>());
+	bool test_body_motion(Body2DSW *p_body, const Transform2D &p_from, const Vector2 &p_motion, real_t p_margin, PhysicsServer2D::MotionResult *r_result, bool p_collide_separation_ray = false, const Set<RID> &p_exclude = Set<RID>());
 
 	void set_debug_contacts(int p_amount) { contact_debug.resize(p_amount); }
 	_FORCE_INLINE_ bool is_debugging_contacts() const { return !contact_debug.is_empty(); }