Smart pursue for enemy shipsHEADmaster

3 files changed, 122 insertions, 0 deletions

diff --git a/core/src/org/snoopdesigns/endless/world/steering/ChaseSteering.java b/core/src/org/snoopdesigns/endless/world/steering/ChaseSteering.java
new file mode 100644
index 0000000..3ac3ac7
--- /dev/null
+++ b/core/src/org/snoopdesigns/endless/world/steering/ChaseSteering.java
@@ -0,0 +1,108 @@
+package org.snoopdesigns.endless.world.steering;
+
+import java.util.List;
+
+import com.badlogic.gdx.Gdx;
+import com.badlogic.gdx.ai.steer.SteeringAcceleration;
+import com.badlogic.gdx.ai.steer.SteeringBehavior;
+import com.badlogic.gdx.ai.steer.behaviors.Arrive;
+import com.badlogic.gdx.ai.steer.behaviors.BlendedSteering;
+import com.badlogic.gdx.ai.steer.behaviors.Face;
+import com.badlogic.gdx.ai.utils.Location;
+import com.badlogic.gdx.math.MathUtils;
+import com.badlogic.gdx.math.Vector2;
+import org.snoopdesigns.endless.context.Context;
+import org.snoopdesigns.endless.physics.Box2DLocation;
+import org.snoopdesigns.endless.physics.SteerablePhysicalBody;
+
+public class ChaseSteering implements Steering {
+
+    private final SteeringAcceleration<Vector2> steeringOutput = new SteeringAcceleration<>(new Vector2());
+    private final BlendedSteering<Vector2> steeringCombination;
+    private final Location<Vector2> positionTarget;
+    private final Location<Vector2> faceTarget;
+    private final SteeringApplicator steeringApplicator;
+    private final SteerablePhysicalBody steerablePhysicalBody;
+    private final Vector2 lastVelocity = new Vector2(0f, 0f);
+    private final float maxDistance;
+    private final float minDistance;
+    private float targetDirection;
+
+    public ChaseSteering(final SteerablePhysicalBody steerablePhysicalBody,
+                         final float maxDistance,
+                         final float minDistance,
+                         final SteeringApplicator steeringApplicator) {
+        this.steerablePhysicalBody = steerablePhysicalBody;
+        this.maxDistance = maxDistance;
+        this.minDistance = minDistance;
+        this.steeringApplicator = steeringApplicator;
+
+        positionTarget = new Box2DLocation();
+        faceTarget = new Box2DLocation();
+
+        steeringCombination = new BlendedSteering<>(steerablePhysicalBody);
+        getSteeringBehaviours().forEach(steeringBehaviour ->
+                steeringCombination.add(steeringBehaviour, 0.5f));
+
+        targetDirection = MathUtils.random(MathUtils.PI2);
+    }
+
+    @Override
+    public void calculate() {
+        final Vector2 targetDisplacement = new Vector2(maxDistance, 0f).rotateRad(targetDirection);
+        final float distanceToPlayer = new Vector2(
+                steerablePhysicalBody.getBody().getPosition().x -
+                        Context.getInstance().getPlayerShip().getBody().getPosition().x,
+                steerablePhysicalBody.getBody().getPosition().y -
+                        Context.getInstance().getPlayerShip().getBody().getPosition().y)
+                .len();
+        if (distanceToPlayer > maxDistance + 10f) {
+            // Rotate target rotation point only of player is far away
+            targetDirection += Gdx.graphics.getDeltaTime() / 1f;
+        }
+        final Vector2 displacement = targetDisplacement.limit(Math.max(0, (distanceToPlayer - minDistance)));
+        final Vector2 targetPos = new Vector2(
+                Context.getInstance().getPlayerShip().getBody().getPosition().x + displacement.x,
+                Context.getInstance().getPlayerShip().getBody().getPosition().y + displacement.y);
+
+        positionTarget.getPosition().set(targetPos);
+        faceTarget.getPosition().set(positionTarget.getPosition());
+
+        steeringCombination.calculateSteering(steeringOutput);
+        if (distanceToPlayer <= minDistance) { // do not move, if close to player, only rotate
+            steeringOutput.linear.setZero();
+        }
+
+        applySteering();
+    }
+
+    private void applySteering() {
+        // Update position and linear velocity.
+        if (steeringOutput.angular != 0) {
+            // this method internally scales the torque by deltaTime
+            steeringApplicator.applyAngularVelocity(steeringOutput.angular);
+        }
+
+        if (!steeringOutput.linear.isZero()) {
+            if (steeringOutput.linear.len() >= lastVelocity.len() - 10) {
+                steeringApplicator.applyLinearVelocity(steeringOutput.linear);
+            } else {
+                steeringApplicator.stopLinearVelocity();
+            }
+            lastVelocity.x = steeringOutput.linear.x;
+            lastVelocity.y = steeringOutput.linear.y;
+        } else {
+            steeringApplicator.stopLinearVelocity();
+        }
+    }
+
+    private List<SteeringBehavior<Vector2>> getSteeringBehaviours() {
+        return List.of(
+                new Face<>(steerablePhysicalBody, faceTarget),
+                new Arrive<>(steerablePhysicalBody, positionTarget)
+                        .setTimeToTarget(0.1f)
+                        .setArrivalTolerance(10f)
+                        .setDecelerationRadius(100f)
+        );
+    }
+}
diff --git a/core/src/org/snoopdesigns/endless/world/steering/Steering.java b/core/src/org/snoopdesigns/endless/world/steering/Steering.java
new file mode 100644
index 0000000..c13b575
--- /dev/null
+++ b/core/src/org/snoopdesigns/endless/world/steering/Steering.java
@@ -0,0 +1,5 @@
+package org.snoopdesigns.endless.world.steering;
+
+public interface Steering {
+    void calculate();
+}
diff --git a/core/src/org/snoopdesigns/endless/world/steering/SteeringApplicator.java b/core/src/org/snoopdesigns/endless/world/steering/SteeringApplicator.java
new file mode 100644
index 0000000..d683465
--- /dev/null
+++ b/core/src/org/snoopdesigns/endless/world/steering/SteeringApplicator.java
@@ -0,0 +1,9 @@
+package org.snoopdesigns.endless.world.steering;
+
+import com.badlogic.gdx.math.Vector2;
+
+public interface SteeringApplicator {
+    void applyAngularVelocity(float angular);
+    void applyLinearVelocity(Vector2 linear);
+    void stopLinearVelocity();
+}