From 454e0da5313971d9eb8e94491ba148e0bb26db82 Mon Sep 17 00:00:00 2001
From: SmallJoker <mk939@ymail.com>
Date: Sun, 15 Oct 2017 12:05:31 +0200
Subject: [PATCH] Carts: Better wiggle prevention

---
 mods/carts/cart_entity.lua | 44 +++++++++++++++++---------------------
 1 file changed, 20 insertions(+), 24 deletions(-)

diff --git a/mods/carts/cart_entity.lua b/mods/carts/cart_entity.lua
index 4384a039..88fd2be6 100644
--- a/mods/carts/cart_entity.lua
+++ b/mods/carts/cart_entity.lua
@@ -43,16 +43,12 @@ function cart_entity:on_activate(staticdata, dtime_s)
 	if data.old_dir then
 		self.old_dir = data.old_dir
 	end
-	if data.old_vel then
-		self.old_vel = data.old_vel
-	end
 end
 
 function cart_entity:get_staticdata()
 	return minetest.serialize({
 		railtype = self.railtype,
-		old_dir = self.old_dir,
-		old_vel = self.old_vel
+		old_dir = self.old_dir
 	})
 end
 
@@ -180,21 +176,11 @@ local function rail_on_step(self, dtime)
 	end
 
 	local pos = self.object:get_pos()
+	local cart_dir = carts:velocity_to_dir(vel)
+	local same_dir = vector.equals(cart_dir, self.old_dir)
 	local update = {}
 
-	-- stop cart if velocity vector flips
-	if self.old_vel and self.old_vel.y == 0 and
-			(self.old_vel.x * vel.x < 0 or self.old_vel.z * vel.z < 0) then
-		self.old_vel = {x = 0, y = 0, z = 0}
-		self.old_pos = pos
-		self.object:set_velocity(vector.new())
-		self.object:set_acceleration(vector.new())
-		rail_on_step_event(get_railparams(pos).on_step, self, dtime)
-		return
-	end
-	self.old_vel = vector.new(vel)
-
-	if self.old_pos and not self.punched then
+	if self.old_pos and not self.punched and same_dir then
 		local flo_pos = vector.round(pos)
 		local flo_old = vector.round(self.old_pos)
 		if vector.equals(flo_pos, flo_old) then
@@ -213,7 +199,8 @@ local function rail_on_step(self, dtime)
 		end
 	end
 
-	if self.old_pos then
+	local stop_wiggle = false
+	if self.old_pos and same_dir then
 		-- Detection for "skipping" nodes
 		local found_path = carts:pathfinder(
 			pos, self.old_pos, self.old_dir, ctrl, self.old_switch, self.railtype
@@ -224,9 +211,11 @@ local function rail_on_step(self, dtime)
 			pos = vector.new(self.old_pos)
 			update.pos = true
 		end
+	elseif self.old_pos and cart_dir.y ~= -1 and not self.punched then
+		-- Stop wiggle
+		stop_wiggle = true
 	end
 
-	local cart_dir = carts:velocity_to_dir(vel)
 	local railparams
 
 	-- dir:         New moving direction of the cart
@@ -236,9 +225,16 @@ local function rail_on_step(self, dtime)
 	)
 
 	local new_acc = {x=0, y=0, z=0}
-	if vector.equals(dir, {x=0, y=0, z=0}) then
+	if stop_wiggle or vector.equals(dir, {x=0, y=0, z=0}) then
 		vel = {x = 0, y = 0, z = 0}
-		pos = vector.round(pos)
+		local pos_r = vector.round(pos)
+		if not carts:is_rail(pos_r, self.railtype) then
+			pos = self.old_pos
+		elseif not stop_wiggle then
+			pos = pos_r
+		else
+			pos.y = math.floor(pos.y + 0.5)
+		end
 		update.pos = true
 		update.vel = true
 	else
@@ -296,7 +292,7 @@ local function rail_on_step(self, dtime)
 
 	self.object:set_acceleration(new_acc)
 	self.old_pos = vector.new(pos)
-	if not vector.equals(dir, {x=0, y=0, z=0}) then
+	if not vector.equals(dir, {x=0, y=0, z=0}) and not stop_wiggle then
 		self.old_dir = vector.new(dir)
 	end
 	self.old_switch = switch_keys
@@ -332,7 +328,7 @@ local function rail_on_step(self, dtime)
 	elseif self.old_dir.z < 0 then
 		yaw = 1
 	end
-	self.object:setyaw(yaw * math.pi)
+	self.object:set_yaw(yaw * math.pi)
 
 	local anim = {x=0, y=0}
 	if dir.y == -1 then