From: JBM <jbm@codingame.com>
Date: Fri, 22 May 2020 15:32:41 +0000 (+0200)
Subject: Major model/view split.  Compiles and runs, but viewer is sub-par.
X-Git-Url: https://troll.desast.re/troll.git/commitdiff_plain/424174766971a11af0e953a6d5a328d466b8f68b?ds=sidebyside

Major model/view split.  Compiles and runs, but viewer is sub-par.
---

diff --git a/src/main/java/com/codingame/game/Model.java b/src/main/java/com/codingame/game/Model.java
index b310fdd..4cd1280 100644
--- a/src/main/java/com/codingame/game/Model.java
+++ b/src/main/java/com/codingame/game/Model.java
@@ -2,11 +2,54 @@ package com.codingame.game;
 
 import java.util.Random;
 
+import com.codingame.gameengine.core.MultiplayerGameManager;
+import com.google.inject.Inject;
+
 class Model {
+    @Inject private MultiplayerGameManager<com.codingame.game.Player> gameManager;
     Random random;
     int roadLength;
     int initialStones;
     int trollPosition;
+    Player p0, p1;
+
+    class Player {
+        com.codingame.game.Player gp;
+        int index;
+
+        Player(int i) { index = i; }
+
+        private int castlePosition;
+        public int getCastlePosition() { return castlePosition; }
+        public void setCastlePosition(int pos) { castlePosition = pos; }
+
+        private int multiplier;
+        public int getMultiplier() { return multiplier; }
+        public void setMultiplier(int m){ multiplier = m; }
+
+        private int stones;
+        public int getStones() { return stones; }
+        public void consumeStones(int n) throws InvalidAction {
+            if (n > stones) {
+                throw new InvalidAction("attempted to throw more stones than they had.");
+            }
+            setStones(stones - n);
+        }
+        public void setStones(int n) {
+            stones = n;
+        }
+        public int getOppStones() {
+            return p0.stones + p1.stones - stones;
+        }
+
+        public void adjustScore(int trollPosition) {
+            gp.setScore(Math.abs(castlePosition - trollPosition));
+        }
+
+        public int getTrollDistance() {
+            return Math.abs(castlePosition - trollPosition);
+        }
+    }
 
     void init(long seed) {
         random = new Random(seed);
@@ -30,5 +73,39 @@ class Model {
         }
 
         trollPosition = roadLength / 2;
+
+        p0 = new Player(0);
+        p0.gp = gameManager.getPlayer(0);
+        p0.setCastlePosition(0);
+        p0.setMultiplier(1);
+        p0.adjustScore(trollPosition);
+        p0.setStones(initialStones);
+
+        p1 = new Player(1);
+        p1.gp = gameManager.getPlayer(1);
+        p1.setCastlePosition(roadLength);
+        p1.setMultiplier(-1);
+        p1.adjustScore(trollPosition);
+        p1.setStones(initialStones);
+    }
+
+    private int winner;
+    boolean haveWinner() {
+        if (trollPosition == 0) {
+            winner = 1;
+            return true;
+        }
+        else if (trollPosition == roadLength) {
+            winner = 0;
+            return true;
+        }
+        else {
+            return false;
+        }
+    }
+    int getWinner() { return winner; }
+
+    boolean exhausted() {
+        return p0.getStones() <= 0 && p1.getStones() <= 0;
     }
 }
diff --git a/src/main/java/com/codingame/game/Player.java b/src/main/java/com/codingame/game/Player.java
index db51bb4..ac96489 100644
--- a/src/main/java/com/codingame/game/Player.java
+++ b/src/main/java/com/codingame/game/Player.java
@@ -1,5 +1,7 @@
 package com.codingame.game;
 
+import java.util.List;
+
 import java.util.regex.Pattern;
 import java.util.Scanner;
 import java.util.InputMismatchException;
@@ -11,50 +13,12 @@ import com.codingame.gameengine.module.entities.Text;
 import com.codingame.gameengine.module.entities.Sprite;
 
 public class Player extends AbstractMultiplayerPlayer {
-    Group avatar;
-    Text stoneCounter;
-    Text message;
-    Sprite castle;
-    Text stone;
+    Model.Player model;
+    View.Player view;
 
     private String messageString = "";
     public String getMessageString() { return messageString; }
 
-    private int castlePosition;
-    public int getCastlePosition() { return castlePosition; }
-    public void setCastlePosition(int pos) { castlePosition = pos; }
-
-    private int stones;
-    public int getStones() { return stones; }
-    public void consumeStones(int n) throws InvalidAction {
-        if (n > stones) {
-            throw new InvalidAction("attempted to throw more stones than they had.");
-        }
-        setStones(stones - n);
-    }
-    public void setStones(int n) {
-        stones = n;
-        if (stones <= 0) {
-            stoneCounter.setText("No stones!");
-            stoneCounter.setFillColor(0xff7777);
-        }
-        else if (stones == 1) {
-            stoneCounter.setText("1 stone");
-            stoneCounter.setFillColor(0xffbb77);
-        }
-        else {
-            stoneCounter.setText(stones + " stones");
-        }
-    }
-
-    private int multiplier;
-    public int getMultiplier() { return multiplier; }
-    public void setMultiplier(int m){ multiplier = m; }
-
-    public void adjustScore(int trollPosition) {
-        setScore(Math.abs(castlePosition - trollPosition));
-    }
-
     @Override
     public int getExpectedOutputLines() {
         return 1;
diff --git a/src/main/java/com/codingame/game/Referee.java b/src/main/java/com/codingame/game/Referee.java
index edcafe2..b56cade 100644
--- a/src/main/java/com/codingame/game/Referee.java
+++ b/src/main/java/com/codingame/game/Referee.java
@@ -22,157 +22,51 @@ public class Referee extends AbstractReferee {
     @Inject private GraphicEntityModule graphicEntityModule;
 
     @Inject private View view;
-
-    Model model = new Model();
-
-    // Hybrid :-(
-    Player p0, p1;
+    @Inject private Model model;
 
     @Override
     public void init() {
         model.init(gameManager.getSeed());
+        gameManager.getPlayer(0).model = model.p0;
+        gameManager.getPlayer(1).model = model.p1;
 
-        p0 = gameManager.getPlayer(0);
-        p0.setCastlePosition(0);
-        p0.setMultiplier(1);
-        p0.adjustScore(model.trollPosition);
-        p0.sendInputLine(String.format("%d %d", model.roadLength, model.initialStones));
-
-        p1 = gameManager.getPlayer(1);
-        p1.setCastlePosition(model.roadLength);
-        p1.setMultiplier(-1);
-        p1.adjustScore(model.trollPosition);
-        p1.sendInputLine(String.format("%d %d", model.roadLength, model.initialStones));
-
-        view.init();
-        drawPlayer();
-
-        // result in text display, so do last:
-        p0.setStones(model.initialStones);
-        p1.setStones(model.initialStones);
-
-        gameManager.setFrameDuration(2000); // XXX
-    }
-
-    private void drawPlayer() {
-        for (Player player : gameManager.getPlayers()) {
-            boolean p0 = player.getIndex() == 0;
-            int x = p0 ? 280 : 1920 - 280;
-            int y = 220;
-
-            Rectangle border1 = graphicEntityModule
-                    .createRectangle()
-                    .setWidth(140)
-                    .setHeight(140)
-                    .setX(x - 70)
-                    .setY(y - 70)
-                    .setLineWidth(0)
-                    .setFillColor(player.getColorToken());
-
-            Rectangle border2 = graphicEntityModule
-                    .createRectangle()
-                    .setWidth(120)
-                    .setHeight(120)
-                    .setX(x - 60)
-                    .setY(y - 60)
-                    .setLineWidth(0)
-                    .setFillColor(0xffffff);
-
-            Sprite avatarSprite = graphicEntityModule.createSprite()
-                    .setX(x)
-                    .setY(y)
-                    .setZIndex(20)
-                    .setImage(player.getAvatarToken())
-                    .setAnchor(0.5)
-                    .setBaseHeight(116)
-                    .setBaseWidth(116);
-
-            player.avatar = graphicEntityModule.createGroup(border1, border2, avatarSprite);
-
-            Text text = graphicEntityModule.createText(player.getNicknameToken())
-                    .setX(x)
-                    .setY(y + 120)
-                    .setZIndex(20)
-                    .setFontSize(40)
-                    .setFillColor(0x7f3f00)
-                    .setAnchor(0.5);
-
-            player.stoneCounter = graphicEntityModule.createText("S")
-                .setX(x)
-                .setY(y+200)
-                .setZIndex(20)
-                .setFontSize(40)
-                .setFillColor(0x7f3f00)
-                .setAnchor(0.5);
-
-            player.message = graphicEntityModule.createText()
-                .setX(p0 ? 15 : 1920-15)
-                .setY(680)
-                .setZIndex(1)
-                .setFontSize(40)
-                .setStrokeColor(0x000000)
-                .setFillColor(0xffbf7f)
-                .setAnchorX(p0 ? 0 : 1)
-                .setAnchorY(1);
-
-            player.castle = graphicEntityModule.createSprite()
-                .setImage("castle.png")
-                .setTint(player.getColorToken())
-                .setX(p0 ? 160 : 1920-160)
-                .setY(p0 ? 890 : 880)
-                .setZIndex(1)
-                .setAnchorX(0.5)
-                .setAnchorY(1)
-                .setScaleX(p0 ? 1 : -1);
-
-            player.stone = graphicEntityModule.createText()
-                .setZIndex(3)
-                .setFontSize(150)
-                .setFillColor(0x12322a)
-                .setAnchor(0.5)
-                .setAlpha(0);
+        for (Player p : gameManager.getPlayers()) {
+            p.sendInputLine(String.format("%d %d", model.roadLength, model.initialStones));
         }
-    }
 
-    private void moveTroll() {
-        graphicEntityModule.commitEntityState(0.5, view.troll, view.trollPositionGauge);
-        int x0 = p0.castle.getX(), x1 = p1.castle.getX();
-        int y0 = p0.castle.getY(), y1 = p1.castle.getY();
-        view.troll.setX(x0 + model.trollPosition * (x1-x0) / model.roadLength,
-                   Curve.ELASTIC);
-        view.troll.setY(y0 + model.trollPosition * (y1-y0) / model.roadLength,
-                   Curve.ELASTIC);
+        view.init(model);
+        gameManager.getPlayer(0).view = view.p0;
+        gameManager.getPlayer(1).view = view.p1;
 
-        view.trollPositionGauge.setX((view.trollPositionGauge.getX() + view.troll.getX()) / 2);
-        int delta = model.trollPosition - model.roadLength / 2;
-        if (delta < 0) {
-            view.trollPositionGauge.setText("← " + Math.abs(delta));
-        }
-        else if (delta > 0) {
-            view.trollPositionGauge.setText(Math.abs(delta) + " →");
-        }
-        else {
-            view.trollPositionGauge.setText("↔");
-        }
-        graphicEntityModule.commitEntityState(0.75, view.trollPositionGauge);
-        view.trollPositionGauge.setX(view.troll.getX());
+        gameManager.setFrameDuration(2000); // XXX
     }
 
     @Override
     public void gameTurn(int turn) {
+        // System.err.println("Starting turn " + turn);
 
-        p0.sendInputLine(String.format("%d %d %d", p0.getScore(), p0.getStones(), p1.getStones()));
-        p1.sendInputLine(String.format("%d %d %d", p1.getScore(), p1.getStones(), p0.getStones()));
+        boolean disqual = false;
+        boolean victory = false;
+        boolean exhausted = false;
 
+        int delta = 0;
         for (Player player : gameManager.getActivePlayers()) {
+            Model.Player p = player.model;
+            {
+                int trollDistance = p.getTrollDistance();
+                int stones = p.getStones();
+                int oppStones = p.getOppStones();
+                player.sendInputLine(String.format("%d %d %d", trollDistance, stones, oppStones));
+            }
             player.execute();
         }
 
-        int delta = 0;
         for (Player player : gameManager.getActivePlayers()) {
+            Model.Player p = player.model;
+
             try {
                 int stones = player.getAction();
-                if (stones == 0 && player.getStones() > 0) {
+                if (stones == 0 && p.getStones() > 0) {
                     if (model.random.nextInt(10) > 0) {
                         gameManager.addToGameSummary(GameManager.formatErrorMessage(player.getNicknameToken() + " tried not throwing stones.  Fixing that for them because I'm in a good mood today."));
                         stones = 1;
@@ -181,116 +75,96 @@ public class Referee extends AbstractReferee {
                         throw new InvalidAction("tried not throwing any stone.  They were then eaten by a grue.");
                     }
                 }
-                player.consumeStones(stones);
+                p.consumeStones(stones);
                 gameManager.addToGameSummary(String.format("%s throws %d stone%s at the troll.", player.getNicknameToken(), stones, stones == 1 ? "" : "s"));
-                delta += player.getMultiplier() * stones;
+                delta += player.model.getMultiplier() * stones;
 
                 if (stones < 0) {
                     player.deactivate(player.getNicknameToken() + " CHEAT");
                     gameManager.addToGameSummary(GameManager.formatErrorMessage(player.getNicknameToken() + " cheated.  Banning account."));
                     player.setScore(-1);
-                    endGame();
+                    disqual = true;
                 }
                 else if (stones > 0) {
-                    player.stone.setX(player.castle.getX());
-                    player.stone.setY(player.castle.getY() - 100);
-                    player.stone.setText(new Integer(stones).toString());
-                    player.stone.setAlpha(1);
-                    graphicEntityModule.commitEntityState(0, player.stone);
-    
-                    int peakX = (player.castle.getX() + view.troll.getX()) / 2;
-                    int peakY = 540;
-                    player.stone.setX(peakX);
-                    player.stone.setY(peakY, Curve.EASE_OUT);
-                    graphicEntityModule.commitEntityState(0.25, player.stone,
-                                                          player.stoneCounter);
-    
-                    player.stone.setX(view.troll.getX());
-                    player.stone.setY(view.troll.getY() - 50, Curve.EASE_IN);
-                    player.stone.setAlpha(0, Curve.EASE_IN);
-                    graphicEntityModule.commitEntityState(0.5, player.stone);
+                    player.view.animateStones(stones);
                 }
             }
             catch (InvalidAction e) {
                 player.deactivate(player.getNicknameToken() + " INVALID");
                 gameManager.addToGameSummary(GameManager.formatErrorMessage(player.getNicknameToken() + " " + e.getMessage()));
                 player.setScore(-1);
-                endGame();
+                disqual = true;
             }
             catch (NumberFormatException e) {
                 player.deactivate(player.getNicknameToken() + " ERROR");
                 gameManager.addToGameSummary(GameManager.formatErrorMessage(player.getNicknameToken() + " provided malformed input!"));
                 player.setScore(-1);
-                endGame();
+                disqual = true;
             }
             catch (TimeoutException e) {
                 gameManager.addToGameSummary(player.getNicknameToken() + " timed out!");
                 player.deactivate(player.getNicknameToken() + " T/O");
                 player.setScore(-1);
-                endGame();
+                disqual = true;
             }
 
-            player.message
-                .setText(player.getMessageString());
-            //  .setAnchorX(/*player == p0 ? 0 : */ 1);
-            graphicEntityModule.commitEntityState(0, player.message);
+            player.view.displayMessage(player.getMessageString());
         }
 
-        if (delta > 0) {
-            gameManager.addToGameSummary("Troll walks right.");
-            model.trollPosition++;
-            moveTroll();
-        }
-        else if (delta < 0) {
-            gameManager.addToGameSummary("Troll walks left.");
-            model.trollPosition--;
-            moveTroll();
-        }
-        else {
-            gameManager.addToGameSummary("Troll stands still.");
-        }
+        if (! disqual) {
+            if (delta > 0) {
+                gameManager.addToGameSummary("Troll walks right.");
+                model.trollPosition++;
+            }
+            else if (delta < 0) {
+                gameManager.addToGameSummary("Troll walks left.");
+                model.trollPosition--;
+            }
+            else {
+                gameManager.addToGameSummary("Troll stands still.");
+                // XXX animate
+            }
+            view.moveTroll();
 
-        for (Player player : gameManager.getActivePlayers()) {
-            player.adjustScore(model.trollPosition);
-            if (model.trollPosition == player.getCastlePosition()) {
-                gameManager.addToGameSummary(GameManager.formatErrorMessage("Troll destroys " + player.getNicknameToken()));
-                endGame();
+            for (Player player : gameManager.getActivePlayers()) {
+                player.model.adjustScore(model.trollPosition);
             }
-        }
 
-        if (p0.getStones() <= 0 && p1.getStones() <= 0) {
-            endGame();
+            if (model.haveWinner()) {
+                int winner = model.getWinner();
+                gameManager.addToGameSummary(GameManager.formatErrorMessage("Troll destroys " + gameManager.getPlayer(winner).getNicknameToken()));
+                victory = true;
+            }
+            else if (model.exhausted()) exhausted = true;
         }
-    }
-
-    private void destroyPlayer(Player player) {
-        player.avatar.setRotation(170*Math.PI/180, Curve.ELASTIC);
 
-        graphicEntityModule.commitEntityState(0.5, player.castle);
-        player.castle.setX(player.castle.getX(), Curve.ELASTIC);
-        player.castle.setScaleY(-0.2, Curve.EASE_IN);
+        if (disqual || victory || exhausted) endGame();
     }
 
     private void endGame() {
-        if (! gameManager.isGameEnd()) {
-            gameManager.endGame();
+        gameManager.endGame();
 
-            if (p0.getScore() > p1.getScore()) {
-                gameManager.addToGameSummary(GameManager.formatSuccessMessage(p0.getNicknameToken() + " wins"));
-                destroyPlayer(p1);
-            }
-            else if (p0.getScore() < p1.getScore()) {
-                gameManager.addToGameSummary(GameManager.formatSuccessMessage(p1.getNicknameToken() + " wins"));
-                destroyPlayer(p0);
-            }
-            else if (p0.getScore() < 0) {
-                gameManager.addToGameSummary(GameManager.formatErrorMessage("Everybody loses!"));
-                destroyPlayer(p0);
-                destroyPlayer(p1);
-            }
-            else {
-                gameManager.addToGameSummary("Draw.");
-            }
+        Player p0 = gameManager.getPlayer(0);
+        Player p1 = gameManager.getPlayer(1);
+
+        int s0 = p0.getScore();
+        int s1 = p1.getScore();
+
+        if (s0 > s1) {
+            gameManager.addToGameSummary(GameManager.formatSuccessMessage(p0.getNicknameToken() + " wins"));
+            p1.view.destroy();
+        }
+        else if (s0 < s1) {
+            gameManager.addToGameSummary(GameManager.formatSuccessMessage(p1.getNicknameToken() + " wins"));
+            p0.view.destroy();
+        }
+        else if (s0 < 0) {
+            gameManager.addToGameSummary(GameManager.formatErrorMessage("Everybody loses!"));
+            p0.view.destroy();
+            p1.view.destroy();
+        }
+        else {
+            gameManager.addToGameSummary("Draw.");
         }
     }
 }
diff --git a/src/main/java/com/codingame/game/View.java b/src/main/java/com/codingame/game/View.java
index 38dcac1..65bacea 100644
--- a/src/main/java/com/codingame/game/View.java
+++ b/src/main/java/com/codingame/game/View.java
@@ -2,19 +2,173 @@ package com.codingame.game;
 
 import java.util.Random;
 
+import com.codingame.gameengine.core.MultiplayerGameManager;
 import com.codingame.gameengine.module.entities.GraphicEntityModule;
+import com.codingame.gameengine.module.entities.Rectangle;
 import com.codingame.gameengine.module.entities.Sprite;
 import com.codingame.gameengine.module.entities.Text;
+import com.codingame.gameengine.module.entities.Group;
+import com.codingame.gameengine.module.entities.Curve;
 import com.google.inject.Inject;
 
 class View {
+    @Inject private MultiplayerGameManager<com.codingame.game.Player> gameManager;
     @Inject private GraphicEntityModule graphicEntityModule;
 
+    class Player {
+        Model.Player model;
+        int colorToken;
+        String nicknameToken;
+        String avatarToken;
+
+        Group avatar;
+        Text stoneCounter;
+        Text message;
+        Sprite castle;
+        Text stone;
+
+        void init(com.codingame.game.Player p) {
+            model = p.model;
+            colorToken = p.getColorToken();
+            nicknameToken = p.getNicknameToken();
+            avatarToken = p.getAvatarToken();
+
+            boolean p0 = model.index == 0;
+            int x = p0 ? 280 : 1920 - 280;
+            int y = 220;
+
+            Rectangle border1 = graphicEntityModule
+                    .createRectangle()
+                    .setWidth(140)
+                    .setHeight(140)
+                    .setX(x - 70)
+                    .setY(y - 70)
+                    .setLineWidth(0)
+                    .setFillColor(colorToken);
+
+            Rectangle border2 = graphicEntityModule
+                    .createRectangle()
+                    .setWidth(120)
+                    .setHeight(120)
+                    .setX(x - 60)
+                    .setY(y - 60)
+                    .setLineWidth(0)
+                    .setFillColor(0xffffff);
+
+            Sprite avatarSprite = graphicEntityModule.createSprite()
+                    .setX(x)
+                    .setY(y)
+                    .setZIndex(20)
+                    .setImage(avatarToken)
+                    .setAnchor(0.5)
+                    .setBaseHeight(116)
+                    .setBaseWidth(116);
+
+            avatar = graphicEntityModule.createGroup(border1, border2, avatarSprite);
+
+            Text text = graphicEntityModule.createText(nicknameToken)
+                    .setX(x)
+                    .setY(y + 120)
+                    .setZIndex(20)
+                    .setFontSize(40)
+                    .setFillColor(0x7f3f00)
+                    .setAnchor(0.5);
+
+            stoneCounter = graphicEntityModule.createText("S")
+                .setX(x)
+                .setY(y+200)
+                .setZIndex(20)
+                .setFontSize(40)
+                .setFillColor(0x7f3f00)
+                .setAnchor(0.5);
+
+            message = graphicEntityModule.createText()
+                .setX(p0 ? 15 : 1920-15)
+                .setY(680)
+                .setZIndex(1)
+                .setFontSize(40)
+                .setStrokeColor(0x000000)
+                .setFillColor(0xffbf7f)
+                .setAnchorX(p0 ? 0 : 1)
+                .setAnchorY(1);
+
+            castle = graphicEntityModule.createSprite()
+                .setImage("castle.png")
+                .setTint(colorToken)
+                .setX(p0 ? 160 : 1920-160)
+                .setY(p0 ? 890 : 880)
+                .setZIndex(1)
+                .setAnchorX(0.5)
+                .setAnchorY(1)
+                .setScaleX(p0 ? 1 : -1);
+
+            stone = graphicEntityModule.createText()
+                .setZIndex(3)
+                .setFontSize(150)
+                .setFillColor(0x12322a)
+                .setAnchor(0.5)
+                .setAlpha(0);
+        }
+
+        void setStone() {
+            int stones = model.getStones();
+            if (stones <= 0) {
+                stoneCounter.setText("No stones!");
+                stoneCounter.setFillColor(0xff7777);
+            }
+            else if (stones == 1) {
+                stoneCounter.setText("1 stone");
+                stoneCounter.setFillColor(0xffbb77);
+            }
+            else {
+                stoneCounter.setText(stones + " stones");
+            }
+        }
+        void animateStones(int stones) {
+            stone.setX(castle.getX());
+            stone.setY(castle.getY() - 100);
+            stone.setText(new Integer(stones).toString());
+            stone.setAlpha(1);
+            graphicEntityModule.commitEntityState(0, stone);
+    
+            int peakX = (castle.getX() + troll.getX()) / 2;
+            int peakY = 540;
+            stone.setX(peakX);
+            stone.setY(peakY, Curve.EASE_OUT);
+            graphicEntityModule.commitEntityState(0.25,
+                                                  stone,
+                                                  stoneCounter);
+    
+            stone.setX(troll.getX());
+            stone.setY(troll.getY() - 50, Curve.EASE_IN);
+            stone.setAlpha(0, Curve.EASE_IN);
+            graphicEntityModule.commitEntityState(0.5, stone);
+        }
+        void displayMessage(String msg) {
+            message.setText(msg);
+            graphicEntityModule.commitEntityState(0, message);
+        }
+
+        void destroy() {
+        avatar.setRotation(170*Math.PI/180, Curve.ELASTIC);
+
+        graphicEntityModule.commitEntityState(0.5, castle);
+        castle.setX(castle.getX(), Curve.ELASTIC);
+        castle.setScaleY(-0.2, Curve.EASE_IN);
+    }
+    }
+
+    Model model;
     Random random = new Random();
     Sprite troll;
     Text trollPositionGauge;
+    Player p0 = new Player(), p1 = new Player();
+
+    void init(Model m) {
+        model = m;
+        p0.init(gameManager.getPlayer(0));
+        p1.init(gameManager.getPlayer(1));
 
-    void init() {
         drawBackground();
         drawTroll();
     }
@@ -42,4 +196,28 @@ class View {
             .setFillColor(0xffffff);
     }
 
+    void moveTroll() {
+        graphicEntityModule.commitEntityState(0.5, troll, trollPositionGauge);
+        int x0 = p0.castle.getX(), x1 = p1.castle.getX();
+        int y0 = p0.castle.getY(), y1 = p1.castle.getY();
+        troll.setX(x0 + model.trollPosition * (x1-x0) / model.roadLength,
+                   Curve.ELASTIC);
+        troll.setY(y0 + model.trollPosition * (y1-y0) / model.roadLength,
+                   Curve.ELASTIC);
+
+        trollPositionGauge.setX((trollPositionGauge.getX() + troll.getX()) / 2);
+        int delta = model.trollPosition - model.roadLength / 2;
+        if (delta < 0) {
+            trollPositionGauge.setText("← " + Math.abs(delta));
+        }
+        else if (delta > 0) {
+            trollPositionGauge.setText(Math.abs(delta) + " →");
+        }
+        else {
+            trollPositionGauge.setText("↔");
+        }
+        graphicEntityModule.commitEntityState(0.75, trollPositionGauge);
+        trollPositionGauge.setX(troll.getX());
+    }
+
 }