Added P2 netlag assistance

Specifically, a gray circle will appear 3 spaces ahead of the red player to help give an idea of where they will turn, because of netlag.
This only shows up when using skynet, though.
P2 now also has a ping counter.

tron.lua

@@ -17,7 +17,7 @@ local isColor = term.isColor()
 -- lower value = faster game. I'd reccommend 0.1 for SMP play.
 local gameDelayInit = 0.1
 local doDrawPlayerNames = false
-local useSetVisible = true
+local useSetVisible = false
 
 local initGrid = {
 	x1 = -100,
@@ -204,6 +204,13 @@ local tsv = function(visible)
 	end
 end
 
+local round = function(num, places)
+	return math.floor(num * 10^places) / 10^places
+end
+
+-- used in skynet matches if you are player 2
+local ping = 0
+
 local copyTable
 copyTable = function(tbl, ...)
 	local output = {}
@@ -520,7 +527,7 @@ local drawGrid = function(x, y, onlyDrawGrid, useSetVisible)
 	local foreX, foreY
 	local backX, backY
 	local adjX, adjY
-	local trailChar, trailColor, trailAge, isPlayer
+	local trailChar, trailColor, trailAge, isPlayer, isPredict
 	for sy = 1, scr_y do
 		bg[1][sy] = ""
 		bg[2][sy] = ""
@@ -534,11 +541,18 @@ local drawGrid = function(x, y, onlyDrawGrid, useSetVisible)
 			backY = 1 + mathfloor(sy + (y / 2)) % #gridBack
 			trailChar, trailColor, trailAge = getTrail(adjX, adjY)
 			isPlayer = false
+			isPredict = false
 			if not onlyDrawGrid then
 				for i = 1, #player do
 					if player[i].x == adjX and player[i].y == adjY then
 						isPlayer = i
 						break
+					elseif (not isHost) and useSkynet and i == you and (
+						adjX == math.floor(player[i].x + (0.03 * round(ping, 0)) * math.cos(math.rad(player[i].direction * 90))) and
+						adjY == math.floor(player[i].y + (0.03 * round(ping, 0)) * math.sin(math.rad(player[i].direction * 90)))
+					) then
+						isPredict = i
+						break
 					end
 				end
 			end
@@ -546,6 +560,10 @@ local drawGrid = function(x, y, onlyDrawGrid, useSetVisible)
 				bg[1][sy] = bg[1][sy] .. dirArrow[player[isPlayer].direction]
 				bg[2][sy] = bg[2][sy] .. toblit[player[isPlayer].color[1]]
 				bg[3][sy] = bg[3][sy] .. grid.voidcol
+			elseif isPredict and (not onlyDrawGrid) and (not doesIntersectBorder(adjX, adjY)) then
+				bg[1][sy] = bg[1][sy] .. "o"
+				bg[2][sy] = bg[2][sy] .. grid.forecol
+				bg[3][sy] = bg[3][sy] .. grid.voidcol
 			else
 				if (not onlyDrawGrid) and trailChar and trailColor then
 					trailColor = trailColor[1 + ((trailAge - 1) % #trailColor)]
@@ -609,13 +627,18 @@ local drawGrid = function(x, y, onlyDrawGrid, useSetVisible)
 	end
 end
 
-local render = function(useSetVisible)
+local render = function(useSetVisible, netTime)
 	local p = player[you]
 	drawGrid(scrollX + scrollAdjX, scrollY + scrollAdjY, false, useSetVisible)
 	termsetCursorPos(1,1)
 	termsetTextColor(player[you].color[1])
 	termsetBackgroundColor(tocolors[grid.voidcol])
 	term.write("P" .. you)
+	term.setTextColor(colors.white)
+	if netTime and useSkynet then
+		ping = (os.epoch() - netTime) / round(72, 2)
+		term.write(" " .. tostring(ping) .. " ms")
+	end
 	if debugShowKeys then
 		term.setCursorPos(1,2)
 		term.write("dir = " .. player[you].direction .. " ")
@@ -921,6 +944,7 @@ local sendInfo = function(gameID)
 		name = player[you].name,
 		putTrail = isPuttingDown,
 		gameID = gameID,
+		time = os.epoch(),
 		keysDown = isHost and nil or keysDown,
 		trail = isHost and lastTrails or nil,
 		deadGuys = isHost and deadGuys or nil,
@@ -1016,19 +1040,28 @@ end
 local setDirection = function(p, checkDir, lastDir)
 	if (lastDir == control.left) and (checkDir or p.direction) ~= 0 then
 		p.direction = 2
+		return true
 	elseif (lastDir == control.right) and (checkDir or p.direction) ~= 2 then
 		p.direction = 0
+		return true
 	elseif (lastDir == control.up) and (checkDir or p.direction) ~= 1 then
 		p.direction = -1
+		return true
 	elseif (lastDir == control.down) and (checkDir or p.direction) ~= -1 then
 		p.direction = 1
+		return true
+	elseif isPuttingDown == keysDown[control.release] then
+		return true
+	else
+		return false
 	end
 end
 
 local game = function()
 	local outcome
-	local p, np, timeoutID, tID, evt
+	local p, np, timeoutID, tID, evt, netTime
 	while true do
+		netTime = nil
 		if isHost then
 			sleep(gameDelay)
 		else
@@ -1040,6 +1073,8 @@ local game = function()
 				os.queueEvent("tron_complete", "timeout", isHost, player[nou].name)
 				parallel.waitForAny(function() imageAnim(images.timeout) end, waitForKey)
 				return
+			elseif evt == "move_tick" then
+				netTime = tID
 			end
 		end
 		p = player[you]
@@ -1052,8 +1087,10 @@ local game = function()
 		else
 			setDirection(p, nil, control[lastDirectionPressed])
 			isPuttingDown = not keysDown[control.release]
+			sendInfo(gamename)
 		end
 
+
 		if keysDown[control.lookLeft] then
 			scrollAdjX = scrollAdjX - 2
 		end
@@ -1073,7 +1110,7 @@ local game = function()
 		if isHost then
 			outcome = moveTick(true)
 		else
-			outcome = deadAnimation(true)
+			outcome = deadAnimation(false)
 		end
 		ageTrails()
 		if outcome == "end" then
@@ -1081,7 +1118,7 @@ local game = function()
 		else
 			scrollX = p.x - mathfloor(scr_x / 2)
 			scrollY = p.y - mathfloor(scr_y / 2)
-			render(true)
+			render(true, (not isHost) and netTime)
 		end
 	end
 end
@@ -1097,6 +1134,8 @@ local networking = function()
 		if channel == port and type(msg) == "table" then
 			if type(msg.gameID) == "string" then
 				if waitingForGame and (type(msg.new) == "number") then
+
+					-- called while waiting for match
 					if msg.new < os.time() then
 						isHost = false
 						gamename = msg.gameID
@@ -1113,13 +1152,17 @@ local networking = function()
 						player = player,
 						gameID = gamename,
 						new = isHost and (-math.huge) or (math.huge),
+						time = os.epoch(),
 						grid = initGrid
 					})
 					waitingForGame = false
 					netKeysDown = {}
 					os.queueEvent("new_game", gameID)
 					return gameID
+
 				elseif msg.gameID == gamename then
+
+					-- called during gameplay
 					if not isHost then
 						if type(msg.player) == "table" then
 							player[nou].name = msg.name or player[nou].name
@@ -1130,7 +1173,7 @@ local networking = function()
 								end
 							end
 							deadGuys = msg.deadGuys
-							os.queueEvent("move_tick")
+							os.queueEvent("move_tick", msg.time)
 						end
 					elseif type(msg.keysDown) == "table" then
 						netKeysDown = msg.keysDown
@@ -1138,6 +1181,7 @@ local networking = function()
 						player[nou].putTrail = msg.putTrail
 						player[nou].name = msg.name or player[nou].name
 					end
+
 				end
 			end
 		end
@@ -1154,6 +1198,11 @@ local helpScreen = function()
 		Pan the camera with WASD.
 		Hold SPACE to create gaps.
 
+		If you're P2 (red), a gray
+		circle will indicate where
+		you'll turn, to help with
+		skynet's netlag.
+
 		That's basically it.
 		Press any key to go back.
 	]])
@@ -1181,6 +1230,7 @@ local startGame = function()
 		gameID = gamename,
 		new = os.time(),
 		gameDelay = gameDelayInit,
+		time = os.epoch(),
 		name = argumentName or player[you].name,
 		grid = initGrid
 	})