Finish the new article.

projects/DoublePiston/index.html

@@ -61,6 +61,7 @@
 
 			<h4>Step 4: Programming</h4>
 			<p>If you don't know much about Luacontrollers, you might find the <a href="http://mesecons.net/luacontroller/">Luacontroller tutorial</a> handy.</p>
+			<p>Port A is facing our switch.</p>
 			<p>We're going to first outline the basic actions the controller will perform:</p>
 			<pre data-language="lua">if pin.a then
   --extend

projects/TicTacToe/index.html

@@ -28,7 +28,7 @@
 			</p>
 			<p>This article assumes you have the <a href="https://github.com/Jeija/minetest-mod-digilines/">Digilines mod</a>, which I generally consider a de facto part of Mesecons. It is still possible to complete it without this mod, but replacing its functionality with fancy wiring is an exercise left to the reader. Having <a href="https://github.com/Uberi/MineTest-WorldEdit">WorldEdit</a> is helpful as well.</p>
 			<p>Unless you've been living under a rock five hundred meters below the surface of Europa, you've probably heard of tic-tac-toe. Maybe. In any case, I won't be explaining how it's played; if you care to refresh your memory, here's a lovely <a href="http://en.wikipedia.org/wiki/Tic-tac-toe">Wikipedia article</a>. Better? Better.</p>
-			<img src="img/Machine.png" alt="Tic-tac-toe machine">
+			<img src="img/Machine.png" alt="Tic-tac-toe machine" class="picture">
 			<h2>This article is a work-in-progress! Check out some of the other articles at the <a href="../../index.html" class="title">homepage</a>!</h2>
 			<p>Tic-tac-toe is a nice game to build - the rules are quite simple, so we can focus more on the aesthetics and design rather than worrying about the little details.</p>
 
@@ -44,9 +44,9 @@
 			<h4>Step 2: Creating the screen</h4>
 			<p>The screen is a good place to start. After all, it's where players will check on their progress. We want to make the screen as seamless and useful as possible.</p>
 			<p>The screen will have nine cells in total, and each cell needs to be able to display either an X, an O, or a blank space. Here's the design that I used:</p>
-			<img src="img/Cell.gif" alt="Tic-tac-toe cell">
+			<img src="img/Cell.gif" alt="Tic-tac-toe cell" class="picture">
 			<p>Now to add the control mechanism. We want a nice, simple interface that lets us set the value of any cell. For that, I'm going to set up some Luacontrollers and wire them together with digilines:</p>
-			<img src="img/CellWired.png" alt="Fully wired cell">
+			<img src="img/CellWired.png" alt="Fully wired cell" class="picture">
 			<p>The top and bottom Luacontrollers have the following code:</p>
 			<pre data-language="lua">if event.channel == "set11" then
   if event.msg == 1 then
@@ -74,7 +74,7 @@ end</pre>
 			<p>You'll notice that the cell now responds to a digiline signal on the "set11" channel. The channel message, being one of the numbers 0 to 3, set the cell to blank, X, or O, respectively.</p>
 			<p>Before we continue, I should explain the way the screen works. The idea is that there is a single digiline conduit leading out of it, on which you can send a digiline signal "1" on channel "set23" and have the cell in column 2, row 3 be set to X (remember, 0-3 denotes blank, X, and Y, respectively).</p>
 			<p>We now have the smallest possible cell that can display all the symbols we want, only 3 by 3 by 3! Let's build 8 more of them:</p>
-			<img src="img/Screen.png" alt="Cell display screen">
+			<img src="img/Screen.png" alt="Cell display screen" class="picture">
 			<p>I also added a border, so the players can distinguish between individual cells, and wired together the digilines for each cell. Now we can control the whole screen using only one digiline!</p>
 			<p>Now we program each Luacontroller to respond on its own channel. For example, the bottom-right one in the image would respond to signals on the channel "set11", and the top-left would respond on the channel "set33". The numbers go from right to left and top to bottom, since in the image we are looking at the back of the screen. For example, the code for the middle Luacontroller in the left-center cell appears as follows:</p>
 			<pre data-language="lua">if event.channel == "set32" then -- &lt;&lt;&lt;&lt;&lt;&lt; THIS PART WAS CHANGED
@@ -89,6 +89,109 @@ elseif event.channel == "clear" then
     port.a, port.b, port.d = false, false, false
 end</pre>
 			<p>The only thing changed from the original cell is that "set11" has been replaced by "set32" in the Luacontrollers, representing column 3, row 2.</p>
+
+			<h4>Step 3: Creating the keypad</h4>
+			<p>A tic-tac-toe screen is pretty neat, but it's not very useful unless the game is actually playable. The next component we need is a keypad, where we can enter the moves. You can go about this in two main ways - one keypad for both players, or two keypads, one for each player. I decided to go with one keypad for simplicity reasons:<p>
+			<img src="img/Keypad.png" alt="Keypad front" class="picture">
+			<p>Now to wire the back up. I connected each button to a port of a Luacontroller, which sends a digiline signal on the channel "press" with the message being the column and row index, such as "12" to represent column 1, row 2:</p>
+			<img src="img/KeypadWiring.png" alt="Keypad back" class="picture">
+			<p>Port A is facing the steel block wall.</p>
+			<p>The top Luacontroller has the following code:</p>
+			<pre>if event.type == "on" then
+  if event.pin == "A" then
+    digiline_send("press", "32")
+  elseif event.pin == "B" then
+    digiline_send("press", "31")
+  elseif event.pin == "D" then
+    digiline_send("press", "33")
+  end
+end</pre>
+			<p>The middle Luacontroller has the following code:</p>
+			<pre>if event.type == "on" then
+  if event.pin == "A" then
+    digiline_send("press", "22")
+  elseif event.pin == "B" then
+    digiline_send("press", "21")
+  elseif event.pin == "D" then
+    digiline_send("press", "23")
+  end
+end</pre>
+			<p>The bottom Luacontroller has the following code:</p>
+			<pre>if event.type == "on" then
+  if event.pin == "A" then
+    digiline_send("press", "12")
+  elseif event.pin == "B" then
+    digiline_send("press", "11")
+  elseif event.pin == "D" then
+    digiline_send("press", "13")
+  end/join #a
+end</pre>
+			<p>As you can see, each Luacontroller is responsible for one row of buttons. When a button is pressed, a digiline signal is sent identifying which button it was.</p>
+
+			<h4>Step 4: Creating the master controller</h4>
+			<p>A technique that is useful with circuits that have many components is to build each part separately, each with an interface, and then connect them all together at a "hub", which manages everything at the highest level. This is what we'll be doing here. The hub is responsible for a few things:</p>
+			<ol>
+				<li>Recording the moves each player makes.</li>
+				<li>Checking for win conditions and displaying winners.</li>
+				<li>Showing who's turn it is while playing.</li>
+				<li>Sending the reset signal when necessary.</li>
+			</ol>
+			<p>Let's add a Luacontroller off to one side, and program it so that it does what it's supposed to:</p>
+			<pre>mem.map = mem.map or {{0, 0, 0}, {0, 0, 0}, {0, 0, 0}}
+if event.channel == "press" then
+  x, y = tonumber(event.msg:sub(1, 1)), tonumber(event.msg:sub(2, 2))
+  value = port.a and 2 or 1
+  m = mem.map
+  prev = m[x][y]
+  m[x][y] = value
+  if (m[1][1] == m[1][2] and m[1][2] == m[1][3] and m[1][1] ~= 0)
+  or (m[2][1] == m[2][2] and m[2][2] == m[2][3] and m[2][1] ~= 0)
+  or (m[3][1] == m[3][2] and m[3][2] == m[3][3] and m[3][1] ~= 0)
+  or (m[1][1] == m[2][1] and m[2][1] == m[3][1] and m[1][1] ~= 0)
+  or (m[1][2] == m[2][2] and m[2][2] == m[3][2] and m[1][2] ~= 0)
+  or (m[1][3] == m[2][3] and m[2][3] == m[3][3] and m[1][3] ~= 0)
+  or (m[1][1] == m[2][2] and m[2][2] == m[3][3] and m[1][1] ~= 0)
+  or (m[3][1] == m[2][2] and m[2][2] == m[1][3] and m[3][1] ~= 0) then --check win
+    if mem.won then
+      m[x][y] = prev --restore value
+    else --just won
+      if value == 1 then --player 1 wins
+        port.c = true
+      else --player 2 wins
+        port.d = true
+      end
+      mem.won = true
+      digiline_send("set" .. x .. y, value)
+    end
+  else
+    port.a = not port.a
+    digiline_send("set" .. x .. y, value)
+  end
+elseif event.type == "on" and pin.b then
+  mem.map = nil
+  mem.won = nil
+  port.a = false
+  port.c, port.d = false, false
+  digiline_send("clear")
+end</pre>
+			<p>I've sparsely commented the code, but pin B clears everything, port A is the current turn (off for player 1, on for player 2), and port C and D represent whether player 1 or 2 has won, respectively.</p>
+			<p>Putting this off to one side, we'll wire it all together with digilines, each component to the master controller:</p>
+			<img src="img/Connecting.png" alt="Connecting components together" class="picture">
+			<p>The button is connected to pin B, so it will cause the machine to reset. The digilines from each part are connected to the master controller. To prevent the messages from the keypad interfering with the screen, separate the digilines so that the "press" signals don't get sent there.</p>
+			<p>Now just wire up the winner indicators. As mentioned before, these are on port C and D:</p>
+			<img src="img/Winner.png" alt="Winner indicator" class="picture">
+
+			<h4>Step 5: Improvements</h4>
+			<p>Congratulations! You have a working tic-tac-toe machine!</p>
+			<p>But that looks a little bit messy. I'm sure you can make it look a lot neater:</p>
+			<img src="img/Final.png" alt="Winner indicator" class="picture">
+			<p>Here I put the win indicator lights above the turn lights, and compacted the wiring a lot. Also, a nice seamless front panel with signs explaining how to operate the machine.</p>
+			<p>Compaction is done simply by moving the parts, which are quite compact by themselves, closer together, to make a smaller overall circuit. The result is a nice thin display, with a tiny control unit off to one side. Not to mention an interesting showpiece to have in your game world.</p>
+
+			<h4>Downloads</h4>
+			<p>All files are available under the same license as this article. The WEM schematics can be loaded using the //metaload command in <a href="https://github.com/Uberi/MineTest-WorldEdit">WorldEdit</a>.</p>
+			<p><a href="TicTacToe.wem" class="post">Tic-tac-toe machine in WorldEdit-Meta format (WEM)</a></p>
+
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