From 8b400329a03502b469f50bd30b2a8ae0429573ef Mon Sep 17 00:00:00 2001
From: orwell96 <mono96.mml@gmail.com>
Date: Thu, 29 Sep 2016 08:41:05 +0200
Subject: [PATCH] add acceleration calculation

---
 trainlogic.lua |  5 ++++-
 wagons.lua     | 13 +++++++++++--
 2 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/trainlogic.lua b/trainlogic.lua
index 6e2b3c8..0291e8f 100644
--- a/trainlogic.lua
+++ b/trainlogic.lua
@@ -318,7 +318,10 @@ function advtrains.train_step(id, train, dtime)
 				applydiff=(math.min((advtrains.train_brake_force*dtime), math.abs(diff)))
 			end
 		end
-		train.velocity=train.velocity+(applydiff*math.sign(train.tarvelocity-train.velocity))
+		train.last_accel=(applydiff*math.sign(train.tarvelocity-train.velocity))
+		train.velocity=train.velocity+train.last_accel
+	else
+		train.last_accel=0
 	end
 	
 	--move
diff --git a/wagons.lua b/wagons.lua
index 304061b..540a882 100644
--- a/wagons.lua
+++ b/wagons.lua
@@ -302,9 +302,11 @@ function wagon:on_step(dtime)
 	
 	--FIX: use index of the wagon, not of the train.
 	local velocity=gp.velocity/(gp.path_dist[math.floor(index)] or 1)
+	local acceleration=(gp.last_accel or 0)/(gp.path_dist[math.floor(index)] or 1)
 	local factor=index-math.floor(index)
 	local actual_pos={x=first_pos.x-(first_pos.x-second_pos.x)*factor, y=first_pos.y-(first_pos.y-second_pos.y)*factor, z=first_pos.z-(first_pos.z-second_pos.z)*factor,}
 	local velocityvec={x=(first_pos.x-second_pos.x)*velocity*-1, z=(first_pos.z-second_pos.z)*velocity*-1, y=(first_pos.y-second_pos.y)*velocity*-1}
+	local accelerationvec={x=(first_pos.x-second_pos.x)*acceleration*-1, z=(first_pos.z-second_pos.z)*acceleration*-1, y=(first_pos.y-second_pos.y)*acceleration*-1}
 	
 	--some additional positions to determine orientation
 	local aposfwd=gp.path[math.floor(index+2)]
@@ -321,9 +323,15 @@ function wagon:on_step(dtime)
 	end
 	
 	self.updatepct_timer=(self.updatepct_timer or 0)-dtime
-	if not self.old_velocity_vector or not vector.equals(velocityvec, self.old_velocity_vector) or self.old_yaw~=yaw or self.updatepct_timer<=0 then--only send update packet if something changed
-		self.object:setpos(actual_pos)
+	if not self.old_velocity_vector 
+			or not vector.equals(velocityvec, self.old_velocity_vector)
+			or not self.old_acceleration_vector 
+			or not vector.equals(accelerationvec, self.old_acceleration_vector)
+			or self.old_yaw~=yaw
+			or self.updatepct_timer<=0 then--only send update packet if something changed
+			self.object:setpos(actual_pos)
 		self.object:setvelocity(velocityvec)
+		self.object:setacceleration(accelerationvec)
 		self.object:setyaw(yaw)
 		self.updatepct_timer=2
 		if self.update_animation then
@@ -332,6 +340,7 @@ function wagon:on_step(dtime)
 	end
 	
 	self.old_velocity_vector=velocityvec
+	self.old_acceleration_vector=accelerationvec
 	self.old_yaw=yaw
 	printbm("wagon step", t)
 end