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In this tutorial we will learn to load 3-D models and text into the scene graph, using the jME asset manager. You also learn how to arrive at the correct paths, and which file formats to use.
package jme3test.helloworld;
import com.jme3.app.SimpleApplication;
import com.jme3.font.BitmapText;
import com.jme3.light.DirectionalLight;
import com.jme3.material.Material;
import com.jme3.math.Vector3f;
import com.jme3.scene.Geometry;
import com.jme3.scene.Spatial;
import com.jme3.scene.shape.Box;
/** Sample 3 - how to load an OBJ model, and OgreXML model,
* a material/texture, or text. */
public class HelloAssets extends SimpleApplication {
public static void main(String[] args) {
HelloAssets app = new HelloAssets();
app.start();
}
@Override
public void simpleInitApp() {
Spatial teapot = assetManager.loadModel("Models/Teapot/Teapot.obj");
Material mat_default = new Material(
assetManager, "Common/MatDefs/Misc/ShowNormals.j3md");
teapot.setMaterial(mat_default);
rootNode.attachChild(teapot);
// Create a wall with a simple texture from test_data
Box(Vector3f.ZERO, 2.5f,2.5f,1.0f);
Spatial wall = new Geometry("Box", box );
Material mat_brick = new Material(
assetManager, "Common/MatDefs/Misc/Unshaded.j3md");
mat_brick.setTexture("ColorMap",
assetManager.loadTexture("Textures/Terrain/BrickWall/BrickWall.jpg"));
wall.setMaterial(mat_brick);
wall.setLocalTranslation(2.0f,-2.5f,0.0f);
rootNode.attachChild(wall);
// Display a line of text with a default font
guiNode.detachAllChildren();
guiFont = assetManager.loadFont("Interface/Fonts/Default.fnt");
BitmapText helloText = new BitmapText(guiFont, false);
helloText.setSize(guiFont.getCharSet().getRenderedSize());
helloText.setText("Hello World");
helloText.setLocalTranslation(300, helloText.getLineHeight(), 0);
guiNode.attachChild(helloText);
// Load a model from test_data (OgreXML + material + texture)
Spatial ninja = assetManager.loadModel("Models/Ninja/Ninja.mesh.xml");
ninja.scale(0.05f, 0.05f, 0.05f);
ninja.rotate(0.0f, -3.0f, 0.0f);
ninja.setLocalTranslation(0.0f, -5.0f, -2.0f);
rootNode.attachChild(ninja);
// You must add a light to make the model visible
DirectionalLight sun = new DirectionalLight();
sun.setDirection(new Vector3f(-0.1f, -0.7f, -1.0f));
rootNode.addLight(sun);
}
}
Build and run the code sample. You should see a green Ninja with a colorful teapot standing behind a wall. The text on the screen should say "Hello World".
JME3 comes with a handy asset manager that helps you keep your assets organized. Project assets are media files such as models, materials, textures, scenes, shaders, sounds, and fonts. The Asset manager can load files from:
assets
directory of your project, andThis is our recommended directory structure for storing assets:
MyGame/assets/Interface/ MyGame/assets/MatDefs/ MyGame/assets/Materials/ MyGame/assets/Models/ MyGame/assets/Scenes/ MyGame/assets/Shaders/ MyGame/assets/Sounds/ MyGame/assets/Textures/ MyGame/build.xml MyGame/src/... MyGame/...
This is just a suggested best practice, you can name the directories in the assets directory what ever you like.
Place your textures in a subdirectory of assets/Textures/
. Load the texture into the material before you set the Material. The following code sample is from the simpleInitApp()
method and loads a simple wall model:
// Create a wall with a simple texture from test_data Box(Vector3f.ZERO, 2.5f,2.5f,1.0f); Spatial wall = new Geometry("Box", box ); Material mat_brick = new Material( assetManager, "Common/MatDefs/Misc/Unshaded.j3md"); mat_brick.setTexture("ColorMap", assetManager.loadTexture("Textures/Terrain/BrickWall/BrickWall.jpg")); wall.setMaterial(mat_brick); wall.setLocalTranslation(2.0f,-2.5f,0.0f); rootNode.attachChild(wall);
In this case, you create your own Material and apply it to a Geometry. You base Materials on default material descriptions (such as "Unshaded.j3md"), as shown in this example.
This example displays the text "Hello World" in the default font at the bottom edge of the window. You attach text to the guiNode
– this is a special node for flat (orthogonal) display elements. You display text to show the game score, player health, etc.
The following code sample goes into the simpleInitApp()
method.
// Display a line of text with a default font guiNode.detachAllChildren(); guiFont = assetManager.loadFont("Interface/Fonts/Default.fnt"); BitmapText helloText = new BitmapText(guiFont, false); helloText.setSize(guiFont.getCharSet().getRenderedSize()); helloText.setText("Hello World"); helloText.setLocalTranslation(300, helloText.getLineHeight(), 0); guiNode.attachChild(helloText);
Tip: Clear existing text in the guiNode by detaching all its children.
Export your 3D model in OgreXML format (.mesh.xml, .scene, .material, .skeleton.xml) and place it in a subdirectory of assets/Models/
. The following code sample goes into the simpleInitApp()
method.
// Load a model from test_data (OgreXML + material + texture) Spatial ninja = assetManager.loadModel("Models/Ninja/Ninja.mesh.xml"); ninja.scale(0.05f, 0.05f, 0.05f); ninja.rotate(0.0f, -3.0f, 0.0f); ninja.setLocalTranslation(0.0f, -5.0f, -2.0f); rootNode.attachChild(ninja); // You must add a directional light to make the model visible! DirectionalLight sun = new DirectionalLight(); sun.setDirection(new Vector3f(-0.1f, -0.7f, -1.0f).normalizeLocal()); rootNode.addLight(sun);
Note that you do no need to create a Material if you exported the model with a material. Remember to add a light source, as shown, otherwise the material (and the whole model) is not visible!
What if your game relies on user supplied model files, that are not included in the distribution? If a file is not located in the default location (e.g. assets directory), you can register a custom Locator and load it from any path.
Here is a usage example of a ZipLocator that is registered to a file town.zip
in the top level of your project directory:
assetManager.registerLocator("town.zip", ZipLocator.class.getName()); Spatial scene = assetManager.loadModel("main.scene"); rootNode.attachChild(scene);
Here is a HttpZipLocator that can download zipped models and load them:
assetManager.registerLocator( "http://jmonkeyengine.googlecode.com/files/wildhouse.zip", HttpZipLocator.class.getName()); Spatial scene = assetManager.loadModel("main.scene"); rootNode.attachChild(scene);
JME3 offers ClasspathLocator, ZipLocator, FileLocator, HttpZipLocator, and UrlLocator (see com.jme3.asset.plugins
).
To create 3D models and scenes, you need a 3D Mesh Editor with an OgreXML Exporter plugin. For example, you can . You use the jMonkeyPlatform to load models, convert models and create scenes from them.
If you use Blender, export your models as Ogre XML meshes with materials as follows:
something.mesh.xml
goes with something.material
, plus (optionally) something.skeleton.xml
and some JPG texture files.assets/Models/
directory. E.g. assets/Models/something/
.JME3 can load Ogre XML models + materials, Ogre DotScenes, as well as Wavefront OBJ+MTL models. The loadModel() code works with these files when you run the code directly from the jMonkeyPlatform.
If you build the executables using the default build script, then the original model files (XML, OBJ, etc) are not included. When you run the executable, you get an error message if you try to load any models directly:
com.jme3.asset.DesktopAssetManager loadAsset WARNING: Cannot locate resource: Models/Ninja/Ninja.mesh.xml com.jme3.app.Application handleError SEVERE: Uncaught exception thrown in Thread[LWJGL Renderer Thread,5,main] java.lang.NullPointerException
Loading the XML/OBJ files directly is only acceptable during the development phase. If your graphic designer pushes updated files to the asset directory, you can quickly review the latest version in your development environment.
For testing and for the final release build, you use .j3o files exclusively. J3o is an optimized binary format for jME3 applications, and .j3o files are automatically included in the distributable JAR file by the build script. When you do QA test builds or are ready to release, use the jMonkeyPlatform to convert all .obj/.scene/.xml/.blend files to .j3o files, and only load the .j3o versions.
Open your JME3 Project in the jMonkeyplatform.
Spatial ninja = assetManager.loadModel("Models/Ninja/Ninja.j3o");
If your executable gets a runtime exception, make sure you have converted all models to .j3o!
Task? | Solution! |
---|---|
Load a model with materials | Use the asset manager's loadModel() method and attach the Spatial to the rootNode. Spatial elephant = assetManager.loadModel("Models/Elephant/Elephant.mesh.xml"); rootNode.attachChild(elephant); Spatial elephant = assetManager.loadModel("Models/Elephant/Elephant.j3o"); rootNode.attachChild(elephant); |
Load a model without materials | If you have a model without materials, you have to give it a material to make it visible. Spatial teapot = assetManager.loadModel("Models/Teapot/Teapot.j3o"); Material mat = new Material(assetManager, "Common/MatDefs/Misc/ShowNormals.j3md"); // default material teapot.setMaterial(mat); rootNode.attachChild(teapot); |
Load a scene | You load scenes just like you load models: Spatial scene = assetManager.loadModel("Scenes/town/main.scene"); rootNode.attachChild(scene); Spatial scene = assetManager.loadModel("Scenes/town/main.j3o"); rootNode.attachChild(scene); |
As an exercise, let's try different ways of loading a scene. You will learn how to load the scene directly, or from a zip file.
town
. It contains XML and texture files, and file called main.scene. (This is just for your information, you do not need to do anything with it.)jMonkeyProjects/MyGameProject/assets/ jMonkeyProjects/MyGameProject/build.xml jMonkeyProjects/MyGameProject/src/ jMonkeyProjects/MyGameProject/town.zip ...
Use the following method to load models from a zip file:
town.zip
is in the project directory.simpleInitApp() {
assetManager.registerLocator("town.zip", ZipLocator.class.getName()); Spatial gameLevel = assetManager.loadModel("main.scene"); gameLevel.setLocalTranslation(0, -5.2f, 0); gameLevel.setLocalScale(2); rootNode.attachChild(gameLevel);
The loadModel() method now searches this zip directly for the files to load.
(This means, do not write loadModel(town.zip/main.scene)
or similar!)
Tip: If you register new locators, make sure you do not get any file name conflicts: Don't name all scenes main.scene
but give each scene a unique name.
Earlier in this tutorial, you loaded scenes and models from the asset directory. This is the most common way you will be loading scenes and models. Here is the typical procedure:
town/
directory into the assets/Scenes/
directory of your project.simpleInitApp() {
Spatial gameLevel = assetManager.loadModel("Scenes/town/main.scene"); gameLevel.setLocalTranslation(0, -5.2f, 0); gameLevel.setLocalScale(2); rootNode.attachChild(gameLevel);
Note that the path is relative to the assets/…
directory.
Here is a third method you must know, loading a scene/model from a .j3o file:
assets/Scenes/town
directory. main.scene
and convert the scene to binary: The jMoneyPlatform generates a main.j3o file.simpleInitApp() {
Spatial gameLevel = assetManager.loadModel("Scenes/town/main.j3o"); gameLevel.setLocalTranslation(0, -5.2f, 0); gameLevel.setLocalScale(2); rootNode.attachChild(gameLevel);
Again, note that the path is relative to the assets/…
directory.
Now you know how to populate the scenegraph with static shapes and models, and how to build scenes. You have learned how to load assets using the assetManager
and you have seen that the paths start relative to your project directory. Another important thing you have learned is to convert models to .j3o format for the executable JARs etc.
Let's add some action to the scene and continue with the Update Loop!
See also: