From 6850f2af2572f7011c4f68953bdafe304f4cf842 Mon Sep 17 00:00:00 2001
From: Pascal Batty <pascal@scalbatty.com>
Date: Sun, 28 Apr 2019 19:28:55 +0200
Subject: [PATCH] add character movement acceleration/deceleration

---
 right_coin.lua | 36 +++++++++++++++++++++++++++++++-----
 1 file changed, 31 insertions(+), 5 deletions(-)

diff --git a/right_coin.lua b/right_coin.lua
index 94d6dd2..b6e3fe0 100644
--- a/right_coin.lua
+++ b/right_coin.lua
@@ -158,18 +158,44 @@ do -- Player
 		vx=0,vy=0,
 		isFlipped=false
 	}
+	
+	local maxSp=2
+	local accel=0.3
+	local decel=0.5
   
 	function Player:direct()
 		if btn(2) then 
-			self.vx = -2
-			self.isFlipped = true
+			self:goLeft()
 		elseif btn(3) then
-			self.vx = 2
-			self.isFlipped = false
-		else self.vx = 0
+			self:goRight()
+		else self:stop()
 		end
 		if btnp(4) and self.vy == 0 then self.vy = j end
 	end
+	
+	function Player:goLeft()
+		if self.vx > 0 then self.vx=0 end
+		self.vx=self.vx - accel
+		if self.vx < -maxSp then self.vx=-maxSp end
+		self.isFlipped = true
+	end
+	
+	function Player:goRight()
+		if self.vx < 0 then self.vx=0 end
+		self.vx=self.vx + accel
+		if self.vx > maxSp then self.vx=maxSp end
+		self.isFlipped = false
+	end
+	
+	function Player:stop()
+		if self.vx < 0 then 
+			self.vx= self.vx + decel
+			if self.vx > 0 then self.vx=0 end
+		elseif self.vx > 0 then 
+			self.vx= self.vx - decel
+			if self.vx < 0 then self.vx=0 end
+		end
+	end
   
 	function Player:update()
 		self:resolve()