Added better camera transforms and whatnot.

src/main/java/nl/andrewl/starship_arena/StarshipArena.java

@@ -2,8 +2,6 @@ package nl.andrewl.starship_arena;
 
 import nl.andrewl.starship_arena.model.Arena;
 import nl.andrewl.starship_arena.model.Ship;
-import nl.andrewl.starship_arena.model.ShipModel;
-import nl.andrewl.starship_arena.util.ResourceUtils;
 import nl.andrewl.starship_arena.view.ArenaWindow;
 
 /**
@@ -11,10 +9,17 @@ import nl.andrewl.starship_arena.view.ArenaWindow;
  */
 public class StarshipArena {
 	public static void main(String[] args) {
-		ShipModel corvette = ShipModel.load(ResourceUtils.getString("/ships/corvette.json"));
-		Ship s = new Ship(corvette);
+		Ship s1 = new Ship("/ships/corvette.json");
+		s1.setVelocity(0, -0.5f);
+		s1.setRotationSpeed(0.5f);
 		Arena arena = new Arena();
-		arena.getShips().add(s);
+		arena.getShips().add(s1);
+		Ship s2 = new Ship("/ships/corvette.json");
+		s2.setRotation((float) (Math.PI / 6));
+		s2.getPosition().x = 3;
+		s2.getPosition().y = -5;
+		arena.getShips().add(s2);
+		arena.getCamera().setFocus(s1);
 		var window = new ArenaWindow(arena);
 		window.setVisible(true);
 	}

src/main/java/nl/andrewl/starship_arena/control/CameraController.java

@@ -0,0 +1,50 @@
+package nl.andrewl.starship_arena.control;
+
+import nl.andrewl.starship_arena.model.Camera;
+import nl.andrewl.starship_arena.model.PhysicsObject;
+
+import java.awt.event.KeyEvent;
+import java.awt.event.KeyListener;
+import java.awt.event.MouseWheelEvent;
+import java.awt.event.MouseWheelListener;
+
+public class CameraController implements MouseWheelListener, KeyListener {
+	private final Camera camera;
+
+	public CameraController(Camera camera) {
+		this.camera = camera;
+	}
+
+	@Override
+	public void mouseWheelMoved(MouseWheelEvent e) {
+		if (e.getWheelRotation() > 0) {
+			camera.zoomOut();
+		} else {
+			camera.zoomIn();
+		}
+	}
+
+	@Override
+	public void keyTyped(KeyEvent e) {}
+
+	@Override
+	public void keyPressed(KeyEvent e) {
+		// Reset view.
+		if (e.getKeyCode() == KeyEvent.VK_SPACE && e.isControlDown()) {
+			System.out.println("Resetting view");
+			camera.setRotation(0);
+			camera.setPosition(0, 0);
+			camera.resetScale();
+		}
+		if (e.getKeyCode() == KeyEvent.VK_ESCAPE && camera.getFocus() != null) {
+			System.out.println("Leaving focus!");
+			PhysicsObject f = camera.getFocus();
+			camera.setRotation(0);
+			camera.setPosition(f.getPosition().x, f.getPosition().y);
+			camera.setFocus(null);
+		}
+	}
+
+	@Override
+	public void keyReleased(KeyEvent e) {}
+}

src/main/java/nl/andrewl/starship_arena/control/GameUpdater.java

@@ -0,0 +1,65 @@
+package nl.andrewl.starship_arena.control;
+
+import nl.andrewl.starship_arena.model.Arena;
+import nl.andrewl.starship_arena.view.ArenaPanel;
+
+import javax.swing.*;
+
+public class GameUpdater extends Thread {
+	public static final double PHYSICS_FPS = 60.0;
+	public static final double MILLISECONDS_PER_PHYSICS_TICK = 1000.0 / PHYSICS_FPS;
+	public static final double PHYSICS_SPEED = 1.0;
+
+	public static final double DISPLAY_FPS = 60.0;
+	public static final double MILLISECONDS_PER_DISPLAY_FRAME = 1000.0 / DISPLAY_FPS;
+
+	private final Arena arena;
+	private final ArenaPanel arenaPanel;
+	private volatile boolean running = true;
+
+	public GameUpdater(Arena arena, ArenaPanel arenaPanel) {
+		this.arena = arena;
+		this.arenaPanel = arenaPanel;
+	}
+
+	public void setRunning(boolean running) {
+		this.running = running;
+	}
+
+	@Override
+	public void run() {
+		long lastPhysicsUpdate = System.currentTimeMillis();
+		long lastDisplayUpdate = System.currentTimeMillis();
+		while (running) {
+			long currentTime = System.currentTimeMillis();
+			long timeSinceLastPhysicsUpdate = currentTime - lastPhysicsUpdate;
+			long timeSinceLastDisplayUpdate = currentTime - lastDisplayUpdate;
+			if (timeSinceLastPhysicsUpdate >= MILLISECONDS_PER_PHYSICS_TICK) {
+				double elapsedSeconds = timeSinceLastPhysicsUpdate / 1000.0;
+				updateArena(elapsedSeconds * PHYSICS_SPEED);
+				lastPhysicsUpdate = currentTime;
+				timeSinceLastPhysicsUpdate = 0L;
+			}
+			if (timeSinceLastDisplayUpdate >= MILLISECONDS_PER_DISPLAY_FRAME) {
+				SwingUtilities.invokeLater(arenaPanel::repaint);
+				lastDisplayUpdate = currentTime;
+				timeSinceLastDisplayUpdate = 0L;
+			}
+			long timeUntilNextPhysicsUpdate = (long) (MILLISECONDS_PER_PHYSICS_TICK - timeSinceLastPhysicsUpdate);
+			long timeUntilNextDisplayUpdate = (long) (MILLISECONDS_PER_DISPLAY_FRAME - timeSinceLastDisplayUpdate);
+
+			// Sleep to reduce CPU usage.
+			try {
+				Thread.sleep(Math.min(timeUntilNextPhysicsUpdate, timeUntilNextDisplayUpdate));
+			} catch (InterruptedException e) {
+				e.printStackTrace();
+			}
+		}
+	}
+
+	private void updateArena(double t) {
+		for (var s : arena.getShips()) {
+			s.update(t);
+		}
+	}
+}

src/main/java/nl/andrewl/starship_arena/model/Camera.java

@@ -3,19 +3,19 @@ package nl.andrewl.starship_arena.model;
 import java.awt.geom.Point2D;
 
 public class Camera {
-	public static final double SCALE_INTERVAL = 50.0;
+	private static final float[] SCALE_FACTORS = {500, 200, 100, 50, 25, 10, 5, 1, 0.5f, 0.25f, 0.1f, 0.05f, 0.01f};
+	public static final byte DEFAULT_SCALE_FACTOR_INDEX = 5;
 
-	private Object focus;
+	private PhysicsObject focus;
+	private final Point2D.Float position = new Point2D.Float();
+	private float rotation;
+	private byte scaleIndex = DEFAULT_SCALE_FACTOR_INDEX;
 
-	private Point2D.Float position = new Point2D.Float();
-
-	private int scaleIncrement = 1;
-
-	public Object getFocus() {
+	public PhysicsObject getFocus() {
 		return focus;
 	}
 
-	public void setFocus(Object focus) {
+	public void setFocus(PhysicsObject focus) {
 		this.focus = focus;
 	}
 
@@ -23,15 +23,32 @@ public class Camera {
 		return position;
 	}
 
-	public void setPosition(Point2D.Float position) {
-		this.position = position;
+	public void setPosition(float x, float y) {
+		this.position.x = x;
+		this.position.y = y;
 	}
 
-	public int getScaleIncrement() {
-		return scaleIncrement;
+	public float getRotation() {
+		return rotation;
 	}
 
-	public void setScaleIncrement(int scaleIncrement) {
-		this.scaleIncrement = scaleIncrement;
+	public void setRotation(float rotation) {
+		this.rotation = rotation;
+	}
+
+	public float getScaleFactor() {
+		return SCALE_FACTORS[scaleIndex];
+	}
+
+	public void zoomOut() {
+		if (scaleIndex < SCALE_FACTORS.length - 1) scaleIndex++;
+	}
+
+	public void zoomIn() {
+		if (scaleIndex > 0) scaleIndex--;
+	}
+
+	public void resetScale() {
+		scaleIndex = DEFAULT_SCALE_FACTOR_INDEX;
 	}
 }

src/main/java/nl/andrewl/starship_arena/model/PhysicsObject.java

@@ -2,7 +2,7 @@ package nl.andrewl.starship_arena.model;
 
 import java.awt.geom.Point2D;
 
-public class PhysicsObject {
+public abstract class PhysicsObject {
 	/**
 	 * The position of this object in the scene, in meters from the origin.
 	 * Positive x-axis goes to the right, and positive y-axis goes down.
@@ -28,6 +28,11 @@ public class PhysicsObject {
 		return position;
 	}
 
+	public void setPosition(float x, float y) {
+		this.position.x = x;
+		this.position.y = y;
+	}
+
 	public float getRotation() {
 		return rotation;
 	}
@@ -42,6 +47,11 @@ public class PhysicsObject {
 		return velocity;
 	}
 
+	public void setVelocity(float x, float y) {
+		this.velocity.x = x;
+		this.velocity.y = y;
+	}
+
 	public float getRotationSpeed() {
 		return rotationSpeed;
 	}

src/main/java/nl/andrewl/starship_arena/model/Ship.java

@@ -1,5 +1,6 @@
 package nl.andrewl.starship_arena.model;
 
+import nl.andrewl.starship_arena.model.ship.Cockpit;
 import nl.andrewl.starship_arena.model.ship.Gun;
 import nl.andrewl.starship_arena.model.ship.Panel;
 import nl.andrewl.starship_arena.model.ship.ShipComponent;
@@ -15,18 +16,21 @@ public class Ship extends PhysicsObject {
 
 	private final Collection<Panel> panels;
 	private final Collection<Gun> guns;
+	private final Collection<Cockpit> cockpits;
 
 	private Color primaryColor = Color.GRAY;
 
-	public Ship(ShipModel model) {
+	private Ship(ShipModel model) {
 		this.modelName = model.getName();
 		this.components = model.getComponents();
 		this.panels = new ArrayList<>();
 		this.guns = new ArrayList<>();
+		this.cockpits = new ArrayList<>();
 		for (var c : components) {
 			c.setShip(this);
 			if (c instanceof Panel p) panels.add(p);
 			if (c instanceof Gun g) guns.add(g);
+			if (c instanceof Cockpit cp) cockpits.add(cp);
 		}
 	}
 
@@ -42,6 +46,18 @@ public class Ship extends PhysicsObject {
 		return components;
 	}
 
+	public Collection<Panel> getPanels() {
+		return panels;
+	}
+
+	public Collection<Gun> getGuns() {
+		return guns;
+	}
+
+	public Collection<Cockpit> getCockpits() {
+		return cockpits;
+	}
+
 	public Color getPrimaryColor() {
 		return primaryColor;
 	}

src/main/java/nl/andrewl/starship_arena/model/ShipModel.java

@@ -2,10 +2,7 @@ package nl.andrewl.starship_arena.model;
 
 import com.google.gson.Gson;
 import com.google.gson.GsonBuilder;
-import nl.andrewl.starship_arena.model.ship.ComponentDeserializer;
-import nl.andrewl.starship_arena.model.ship.GeometricComponent;
-import nl.andrewl.starship_arena.model.ship.Gun;
-import nl.andrewl.starship_arena.model.ship.ShipComponent;
+import nl.andrewl.starship_arena.model.ship.*;
 
 import java.util.Collection;
 
@@ -62,6 +59,7 @@ public class ShipModel {
 	public static ShipModel load(String json) {
 		Gson gson = new GsonBuilder()
 				.registerTypeAdapter(ShipComponent.class, new ComponentDeserializer())
+				.registerTypeAdapter(Gun.class, new GunDeserializer())
 				.create();
 		ShipModel model = gson.fromJson(json, ShipModel.class);
 		model.normalizeComponents();

src/main/java/nl/andrewl/starship_arena/model/ship/Gun.java

@@ -5,6 +5,23 @@ import java.awt.geom.Point2D;
 public class Gun extends ShipComponent {
 	private String name;
 	private Point2D.Float location;
+	private float rotation;
+	private float maxRotation;
+	private float minRotation;
+	private float barrelWidth;
+	private float barrelLength;
+
+	public Gun() {}
+
+	public Gun(String name, Point2D.Float location, float rotation, float maxRotation, float minRotation, float barrelWidth, float barrelLength) {
+		this.name = name;
+		this.location = location;
+		this.rotation = rotation;
+		this.maxRotation = maxRotation;
+		this.minRotation = minRotation;
+		this.barrelWidth = barrelWidth;
+		this.barrelLength = barrelLength;
+	}
 
 	public String getName() {
 		return name;
@@ -13,4 +30,24 @@ public class Gun extends ShipComponent {
 	public Point2D.Float getLocation() {
 		return location;
 	}
+
+	public float getRotation() {
+		return rotation;
+	}
+
+	public float getMaxRotation() {
+		return maxRotation;
+	}
+
+	public float getMinRotation() {
+		return minRotation;
+	}
+
+	public float getBarrelWidth() {
+		return barrelWidth;
+	}
+
+	public float getBarrelLength() {
+		return barrelLength;
+	}
 }

src/main/java/nl/andrewl/starship_arena/model/ship/GunDeserializer.java

@@ -0,0 +1,22 @@
+package nl.andrewl.starship_arena.model.ship;
+
+import com.google.gson.*;
+
+import java.awt.geom.Point2D;
+import java.lang.reflect.Type;
+
+public class GunDeserializer implements JsonDeserializer<Gun> {
+	@Override
+	public Gun deserialize(JsonElement jsonElement, Type type, JsonDeserializationContext ctx) throws JsonParseException {
+		JsonObject obj = jsonElement.getAsJsonObject();
+		return new Gun(
+				obj.get("name").getAsString(),
+				ctx.deserialize(obj.get("location"), Point2D.Float.class),
+				(float) Math.toRadians(obj.get("rotation").getAsFloat()),
+				(float) Math.toRadians(obj.get("maxRotation").getAsDouble()),
+				(float) Math.toRadians(obj.get("minRotation").getAsFloat()),
+				obj.get("barrelWidth").getAsFloat(),
+				obj.get("barrelLength").getAsFloat()
+		);
+	}
+}

src/main/java/nl/andrewl/starship_arena/view/ArenaPanel.java

@@ -1,7 +1,9 @@
 package nl.andrewl.starship_arena.view;
 
+import nl.andrewl.starship_arena.control.CameraController;
 import nl.andrewl.starship_arena.model.Arena;
 import nl.andrewl.starship_arena.model.Camera;
+import nl.andrewl.starship_arena.model.PhysicsObject;
 
 import javax.swing.*;
 import java.awt.*;
@@ -9,15 +11,10 @@ import java.awt.geom.AffineTransform;
 
 public class ArenaPanel extends JPanel {
 	private final Arena arena;
-
 	private final ShipRenderer shipRenderer = new ShipRenderer();
 
 	public ArenaPanel(Arena arena) {
 		this.arena = arena;
-		this.addMouseWheelListener(e -> {
-			arena.getCamera().setScaleIncrement(arena.getCamera().getScaleIncrement() + e.getWheelRotation());
-			repaint();
-		});
 	}
 
 	@Override
@@ -28,37 +25,44 @@ public class ArenaPanel extends JPanel {
 		g2.fillRect(0, 0, getWidth(), getHeight());
 
 		AffineTransform originalTx = g2.getTransform();
-		AffineTransform tx = new AffineTransform();
-
-		Camera cam = arena.getCamera();
-
-		double translateX = (double) getWidth() / 2;
-		double translateY = (double) getHeight() / 2;
-		if (cam.getFocus() == null) {
-			translateX += cam.getPosition().x;
-			translateY += cam.getPosition().y;
-		}
-
-		double scale = 1 * Camera.SCALE_INTERVAL;
-		if (cam.getScaleIncrement() > 0) {
-			scale = cam.getScaleIncrement() * Camera.SCALE_INTERVAL;
-		} else if (cam.getScaleIncrement() < 0) {
-			scale = 1.0 / Math.abs(cam.getScaleIncrement() * Camera.SCALE_INTERVAL);
-		}
-
-		tx.translate(translateX, translateY);
-		tx.scale(scale, scale);
-		g2.setTransform(tx);
-
+		AffineTransform camTx = getCameraTransform();
 		for (var s : arena.getShips()) {
+			AffineTransform shipTx = new AffineTransform(camTx);
+			shipTx.translate(s.getPosition().x, s.getPosition().y);
+			shipTx.rotate(s.getRotation());
+			g2.setTransform(shipTx);
 			shipRenderer.render(s, g2);
 		}
-
 		g2.setTransform(originalTx);
 
+		// Testing indicators.
 		g2.setColor(Color.GREEN);
 		g2.fillRect(0, 0, 20, 20);
 		g2.setColor(Color.BLUE);
 		g2.fillRect(getWidth() - 20, getHeight() - 20, 20, 20);
+		g2.setColor(Color.MAGENTA);
+		g2.fillOval(getWidth() / 2 - 5, getHeight() / 2 - 5, 10, 10);
+	}
+
+	private AffineTransform getCameraTransform() {
+		AffineTransform tx = new AffineTransform();
+		Camera cam = arena.getCamera();
+		// Start by translating such that 0, 0 is in the center of the screen instead of top-left.
+		tx.translate((double) getWidth() / 2, (double) getHeight() / 2);
+		tx.scale(cam.getScaleFactor(), cam.getScaleFactor());
+
+		double rotation = -cam.getRotation();
+		double x = -cam.getPosition().x;
+		double y = -cam.getPosition().y;
+		if (cam.getFocus() != null) {
+			PhysicsObject f = cam.getFocus();
+			rotation -= f.getRotation();
+			x -= f.getPosition().x;
+			y -= f.getPosition().y;
+		}
+
+		tx.rotate(rotation);
+		tx.translate(x, y);
+		return tx;
 	}
 }

src/main/java/nl/andrewl/starship_arena/view/ArenaWindow.java

@@ -1,5 +1,7 @@
 package nl.andrewl.starship_arena.view;
 
+import nl.andrewl.starship_arena.control.CameraController;
+import nl.andrewl.starship_arena.control.GameUpdater;
 import nl.andrewl.starship_arena.model.Arena;
 import nl.andrewl.starship_arena.util.ResourceUtils;
 
@@ -11,6 +13,7 @@ import java.io.InputStream;
 
 public class ArenaWindow extends JFrame {
 	private final ArenaPanel arenaPanel;
+	private final GameUpdater updater;
 
 	public ArenaWindow(Arena arena) {
 		super("Starship Arena");
@@ -33,7 +36,13 @@ public class ArenaWindow extends JFrame {
 		}
 
 		arenaPanel = new ArenaPanel(arena);
-		add(arenaPanel);
+		setContentPane(arenaPanel);
 		pack();
+
+		var camCtl = new CameraController(arena.getCamera());
+		addKeyListener(camCtl);
+		addMouseWheelListener(camCtl);
+		updater = new GameUpdater(arena, arenaPanel);
+		updater.start();
 	}
 }

src/main/java/nl/andrewl/starship_arena/view/ShipRenderer.java

@@ -3,15 +3,21 @@ package nl.andrewl.starship_arena.view;
 import nl.andrewl.starship_arena.model.Ship;
 import nl.andrewl.starship_arena.model.ship.Cockpit;
 import nl.andrewl.starship_arena.model.ship.GeometricComponent;
+import nl.andrewl.starship_arena.model.ship.Gun;
 
 import java.awt.*;
+import java.awt.geom.AffineTransform;
 import java.awt.geom.Path2D;
 
 public class ShipRenderer implements Renderer<Ship> {
 	@Override
 	public void render(Ship ship, Graphics2D g) {
-		for (var c : ship.getComponents()) {
-			if (c instanceof GeometricComponent geo) {
+		for (var p : ship.getPanels()) renderGeometricComponent(p, g);
+		for (var c : ship.getCockpits()) renderGeometricComponent(c, g);
+		for (var gun : ship.getGuns()) renderGun(gun, g);
+	}
+
+	private void renderGeometricComponent(GeometricComponent geo, Graphics2D g) {
 		Path2D.Float path = new Path2D.Float();
 		var first = geo.getPoints().get(0);
 		path.moveTo(first.x, first.y);
@@ -22,10 +28,24 @@ public class ShipRenderer implements Renderer<Ship> {
 		if (geo instanceof Cockpit) {
 			g.setColor(new Color(0f, 0f, 0.5f, 0.5f));
 		} else {
-					g.setColor(ship.getPrimaryColor());
+			g.setColor(geo.getShip().getPrimaryColor());
 		}
 		g.fill(path);
 	}
-		}
+
+	private void renderGun(Gun gun, Graphics2D g) {
+		AffineTransform originalTx = g.getTransform();
+		AffineTransform tx = new AffineTransform(originalTx);
+		tx.rotate(gun.getRotation() + Math.PI, gun.getLocation().x, gun.getLocation().y);
+		tx.translate(gun.getLocation().x, gun.getLocation().y);
+		g.setTransform(tx);
+		Path2D.Float path = new Path2D.Float();
+		path.moveTo(-gun.getBarrelWidth() / 2, 0);
+		path.lineTo(gun.getBarrelWidth() / 2, 0);
+		path.lineTo(gun.getBarrelWidth() / 2, gun.getBarrelLength());
+		path.lineTo(-gun.getBarrelWidth() / 2, gun.getBarrelLength());
+		g.setColor(Color.DARK_GRAY);
+		g.fill(path);
+		g.setTransform(originalTx);
 	}
 }

src/main/resources/ships/corvette.json

@@ -40,13 +40,23 @@
       "type": "gun",
       "name": "Port-Side Machine Gun",
       "mass": 500,
-      "location": {"x": 0.15, "y": 0.4}
+      "location": {"x": 0.15, "y": 0.35},
+      "rotation": 0,
+      "minRotation": -160,
+      "maxRotation": 5,
+      "barrelWidth": 0.02,
+      "barrelLength": 0.2
     },
     {
       "type": "gun",
       "name": "Starboard-Side Machine Gun",
       "mass": 500,
-      "location": {"x": 0.85, "y": 0.4}
+      "location": {"x": 0.85, "y": 0.35},
+      "rotation": 0,
+      "minRotation": -5,
+      "maxRotation": 160,
+      "barrelWidth": 0.02,
+      "barrelLength": 0.2
     }
   ]
 }