Intro to Java Monkey Engine

1. Intro to Java Monkey Engine Download JME SDK @ http://hub.jmonkeyengine.org/downloads/

2. JME Technology • JME stands for the java monkey engine: a game engine written in java and built upon LWJGL (light-weight java GL -- a java binding for OpenGL) • OpenGL is a platform independent library for 2D and 3D graphics. • For our purposes, OpenGL is far too low-level for the kinds of graphics programming we'd like to accomplish • OpenGL concerns itself with fast, often hardware accelerated, rendering of basic geometric primitives) • We appeal to a game engine to provide additional high-level functionality • Note: JME provides audio capability via OpenAL support. JME supports OggVorbis (.ogg) and uncompressed PCM Wave (.wav) formats. • We can use Audicity (http://audacity.sourceforge.net/)to convert other formats to these

3. Game-Level Objects • Main Application (SimpleApplication) - A base class from which the custom game inherits • Provides method hooks (i.e., callbacks) to initialize a game (simpleInitApp) update game (simpleUpdate) objects and re-display (simpleRender) objects. • InputManager- A class to manage all device input (e.g., keyboard, mouse, joystick) and present that input to the application for handling. • Display- A class to insulate the game from the device specific characteristics of platform on which the game is being run. The Display also encapsulates the features of window management. • Renderer- An abstraction of the OpenGL state and rendering pipeline as discussed in class. OpenGL is a state-driven system. That is, you define a graphics state as a set of rendering attributes and then send a sequence of geometric data to the renderer which then is drawn subject to the current attributes. • The three classes above are referred collectively as the JME context.

4. The Main Game Loop

5. Game-Level Objects (cont) • Main Application (SimpleApplication) - A base class from which the custom game inherits • Scene Graph - A class to manage the objects in the scene • Camera - A class to encapsulate the eye position and its attributes (e.g., field of view, depth of field, up vector, etc.). • Math Library for 3D Graphics (functions to handle vectors, matrices, geometric data, collisions, etc.). • Model Importers - A fully featured game engine provides for importing mesh models from any of several different modeling programs.

6. The Scene Graph • A grouping of Nodes in a tree hierarchy according (most of the time) to spatial location. • Spatially because … • Game objects are typically located by location • Allows for fast culling • Tree structure natural for many game objects • Easy to express, create tools for this data structure • Spatial is an abstract class allowing uniform treatment of: • Node (internal, invisible, grouping class, transformable) • Geometry (leaf, visible—mesh and material—transformable).

7. Beginning a Project In the jMonkeyEngine SDK: • Choose File→New Project… from the main menu. • In the New Project wizard, select the template JME3→Basic Game. Click Next. • Specify a project name, e.g. "HelloWorldTutorial" • Specify a path where to store your new project, e.g. a jMonkeyProjects directory in your home directory. • Click Finish.

8. Understanding the JME App Structure public class Main extends SimpleApplication{ public static void main(String[] args) { Main app = new Main(); app.start(); }

9. Understanding the JME App Structure public class Main extends SimpleApplication { . @Override public void simpleInitApp() { Box b = new Box(Vector3f.ZERO, 1, 1, 1); Geometry geom = new Geometry("Box", b); Material mat = new Material(assetManager, “…"); mat.setColor("Color", ColorRGBA.Blue); geom.setMaterial(mat); rootNode.attachChild(geom); }

10. Understanding the JME App Structure public class Main extends SimpleApplication { @Override public void simpleUpdate(float tpf) { //TODO: add update code } @Override public void simpleRender(RenderManagerrm) { //TODO: add render code } }

11. Typical Game Objects • Spatial: Spatials are abstract and exist to allow handling of the Nodes and Geometry uniformly. • Node (internal, i.e. has children) contains transformations and links to children (no Mesh or Material--invisible) • Geometry (leaf) contains transformations and visible characteristics, i.e., Mesh and Material

12. Typical Game Objects • Geometry (leaf) contains transformations and visible characteristics, i.e., Mesh and Material • Mesh • Material • Color (Ambient, Diffuse, Emmisive, Specular) - Base color of an object that is not influenced by a color map • Texture • Color Map • Specular Map • Bump Map (Height Map, Normal Map)

13. Typical Game Objects • Distinguished Spatials • rootNode • Camera

14. Getting Started One of the better ways to learn what you can do in JME is to: • Examine the JME Tests • Complete the JME "Tutorial Series (http://hub.jmonkeyengine.org/wiki/doku.php/jme3:beginner)