A Goal Oriented Action Planning (GOAP) example, implemented with FXGL (JavaFX game library)

FXGLGoapExample.java

///usr/bin/env jbang "$0" "$@" ; exit $?

// The GOAP functionality is not fully integrated in FXGL yet, so we need to grab it 
// from the Snapshots Maven Central repository.
//REPOS mavencentralsnapshots,acme=https://oss.sonatype.org/content/repositories/snapshots

// This is the FXGL version we need for this demo. 
// 21+dev-SNAPSHOT has a first implementation of the GOAP functionality.
//DEPS com.github.almasb:fxgl:21+dev-SNAPSHOT

package com.almasb.fxglgames.geowars;

import com.almasb.fxgl.ai.goap.GoapAction;
import com.almasb.fxgl.ai.goap.GoapPlanner;
import com.almasb.fxgl.app.GameApplication;
import com.almasb.fxgl.app.GameSettings;
import com.almasb.fxgl.core.collection.PropertyMap;
import com.almasb.fxgl.core.math.FXGLMath;
import com.almasb.fxgl.dsl.components.WaypointMoveComponent;
import com.almasb.fxgl.entity.Entity;
import javafx.geometry.Point2D;
import javafx.geometry.Rectangle2D;
import javafx.scene.paint.Color;
import javafx.scene.shape.Rectangle;

import java.util.*;

import static com.almasb.fxgl.dsl.FXGL.*;

/**
 * This is a Goal Oriented Action Planning (GOAP) example, 
 * implemented with FXGL (JavaFX game library).
 * The full info is available in a JFX In Action interview with Almas Baim.
 * 
 * Make sure you have JBang installed, see https://www.jbang.dev/download/.
 * 
 * Run it with: 
 * jbang FXGLGoapExample.java
 *
 * While the application is running, you can press `CTRL + R` to restart it.
 */
public class FXGLGoapExample extends GameApplication {

    private Map<GoapAction, Entity> actionMap = new HashMap<>();

    @Override
    protected void initSettings(GameSettings settings) {
        settings.setWidth(1280);
        settings.setHeight(720);
    }

    @Override
    protected void initGame() {
        // Initialize the player, buildings, and GOAP actions
        var player = spawnPlayer();

        var allActions = new ArrayList<GoapAction>();

        for (int i = 1; i <= 3; i++) {
            var building = spawnBuilding(i);

            GoapAction action = new GoapAction();

            if (i > 1) {
                action.addPrecondition("visit" + (i - 1), true);
            }

            action.addEffect("visit" + i, true);

            allActions.add(action);
            actionMap.put(action, building);
        }

        // Use GOAP AI to plan the move
        var goal = new PropertyMap();
        goal.setValue("visit3", true);

        var actions = GoapPlanner.INSTANCE
                .plan(new HashSet<>(allActions),
                        new PropertyMap(),
                        goal);

        var points = actions.stream()
                .map(a -> actionMap.get(a).getPosition())
                .toList();

        // Move the player to the goals according to the preconditions
        player.getComponent(WaypointMoveComponent.class)
                .move(points);
    }

    private Entity spawnPlayer() {
        return entityBuilder()
                .at(150, 150)
                .viewWithBBox(new Rectangle(40, 40, Color.BLUE))
                .with(new WaypointMoveComponent(200, Collections.emptyList()))
                .buildAndAttach();
    }

    private Entity spawnBuilding(int i) {
        return entityBuilder()
                .at(FXGLMath.randomPoint(
                        new Rectangle2D(0, 0, getAppWidth() - 100, getAppHeight() - 100)
                ))
                .view(new Rectangle(100, 100, FXGLMath.randomColor()))
                .view(getUIFactoryService().newText("Building " + i, Color.RED, 18.0))
                .buildAndAttach();
    }

    public static void main(String[] args) {
        launch(args);
    }
}