How implement 3d person tank?

lamao · March 21, 2013, 1:09pm

I read manuals about collision and physics but don’t understand how to reach my goal. Here is code of simple scene:
[java]
package mygame;

import com.jme3.app.SimpleApplication;
import com.jme3.app.StatsAppState;
import com.jme3.bullet.BulletAppState;
import com.jme3.bullet.collision.shapes.CollisionShape;
import com.jme3.bullet.control.CharacterControl;
import com.jme3.bullet.control.RigidBodyControl;
import com.jme3.bullet.util.CollisionShapeFactory;
import com.jme3.cursors.plugins.JmeCursor;
import com.jme3.input.KeyInput;
import com.jme3.input.RawInputListener;
import com.jme3.input.controls.ActionListener;
import com.jme3.input.controls.KeyTrigger;
import com.jme3.input.controls.MouseAxisTrigger;
import com.jme3.input.event.JoyAxisEvent;
import com.jme3.input.event.JoyButtonEvent;
import com.jme3.input.event.KeyInputEvent;
import com.jme3.input.event.MouseButtonEvent;
import com.jme3.input.event.MouseMotionEvent;
import com.jme3.input.event.TouchEvent;
import com.jme3.light.AmbientLight;
import com.jme3.light.Light;
import com.jme3.light.PointLight;
import com.jme3.material.Material;
import com.jme3.material.MaterialDef;
import com.jme3.math.ColorRGBA;
import com.jme3.math.FastMath;
import com.jme3.math.Quaternion;
import com.jme3.math.Vector3f;
import com.jme3.renderer.RenderManager;
import com.jme3.scene.CameraNode;
import com.jme3.scene.Geometry;
import com.jme3.scene.Node;
import com.jme3.scene.Spatial;
import com.jme3.scene.control.CameraControl;
import com.jme3.scene.shape.Box;
import com.jme3.scene.shape.Quad;

/**

test

@author normenhansen
*/
public class Main extends SimpleApplication implements ActionListener {
private static final String ACTION_FORWARD = “Forward”;
private static final String ACTION_BACK = “Back”;
private static final String ACTION_LEFT = “Left”;
private static final String ACTION_RIGHT = “Right”;
private static final float PLAYER_MOVE_SPEED = 4f;
private static final float PLAYER_ROTATION_SPEED = FastMath.HALF_PI;

private BulletAppState bulletAppState;

private Node scene;
private Entity player;
private RigidBodyControl playerControl;
private boolean left = false;
private boolean right = false;
private boolean forward = false;
private boolean back = false;

public static void main(String[] args) {
Main app = new Main();
app.start();
}

public Main() {
super(new StatsAppState());
}

@Override
public void simpleInitApp() {

 bulletAppState = new BulletAppState();
 stateManager.attach(bulletAppState);
 
 //scene = (Node)assetManager.loadModel("Scenes/scene.mesh.j3o");
 scene = initScene();
 rootNode.attachChild(scene);
 CollisionShape sceneShape = CollisionShapeFactory.createMeshShape(scene);
 RigidBodyControl sceneControl = new RigidBodyControl(sceneShape, 0);
 sceneControl.setKinematic(true);
 scene.addControl(sceneControl);
 bulletAppState.getPhysicsSpace().add(sceneControl);
 
 //Spatial playerMesh = assetManager.loadModel("Textures/units/player/player.obj");
 Spatial playerMesh = new Geometry("player", new Box(0.5f, 0.5f, 1f));
 Material playerMaterial = new Material(assetManager, "Common/MatDefs/Misc/Unshaded.j3md");
 playerMaterial.setColor("Color", ColorRGBA.Blue);
 playerMesh.setMaterial(playerMaterial);
 player = new Entity("Player", playerMesh);
 player.setSpeed(PLAYER_MOVE_SPEED);
 player.setRotationSpeed(PLAYER_ROTATION_SPEED);
 player.setLocalTranslation(0, 0.1f, 0);
 scene.attachChild(player);
 CollisionShape playerShape = CollisionShapeFactory.createBoxShape(player);
 playerControl = new RigidBodyControl(playerShape, 1f);
 player.addControl(playerControl);
 bulletAppState.getPhysicsSpace().add(playerControl);
         
 
 Light light = new AmbientLight();
 rootNode.addLight(light);
 
 PointLight pointLight = new PointLight();
 pointLight.setPosition(new Vector3f(15, 10, 15));
 rootNode.addLight(pointLight);
 
 cam.setLocation(new Vector3f(0, 15, 15));
 cam.lookAt(player.getLocalTranslation(), Vector3f.UNIT_Y);
 setupKeys();

}

private Node initScene() {
Geometry floor = new Geometry(“floor”, new Box(10, 0.1f, 10f));
Material floorMaterial = new Material(assetManager, “Common/MatDefs/Misc/Unshaded.j3md”);
floorMaterial.setColor(“Color”, ColorRGBA.Gray);
floor.setMaterial(floorMaterial);

 Geometry box1 = new Geometry("box1", new Box(1, 1, 1));
 box1.setLocalTranslation(2, 0.5f, 1);        
 Geometry box2 = new Geometry("box2", new Box(1, 1, 1));
 box2.setLocalTranslation(-2, 0.5f, 1);
 Material boxMaterial = new Material(assetManager, "Common/MatDefs/Misc/Unshaded.j3md");
 boxMaterial.setColor("Color", ColorRGBA.Brown);
 box1.setMaterial(boxMaterial);
 box2.setMaterial(boxMaterial);
 
 Node scene = new Node("scene");
 scene.attachChild(floor);
 scene.attachChild(box1);
 scene.attachChild(box2);
 
 return scene;

}

private void setupKeys() {
inputManager.addMapping(ACTION_FORWARD, new KeyTrigger(KeyInput.KEY_W));
inputManager.addMapping(ACTION_BACK, new KeyTrigger(KeyInput.KEY_S));
inputManager.addMapping(ACTION_LEFT, new KeyTrigger(KeyInput.KEY_A));
inputManager.addMapping(ACTION_RIGHT, new KeyTrigger(KeyInput.KEY_D));

 inputManager.addListener(this, ACTION_FORWARD);
 inputManager.addListener(this, ACTION_BACK);
 inputManager.addListener(this, ACTION_LEFT);
 inputManager.addListener(this, ACTION_RIGHT);

 mouseInput.setCursorVisible(true);

}

@Override
public void simpleUpdate(float tpf) {
if (left) {
Quaternion rotation = new Quaternion().fromAngleAxis(
player.getRotationSpeed() * tpf, Vector3f.UNIT_Y);
player.setDirection(rotation.mult(player.getDirection()));
player.rotate(rotation);
} else if (right) {
Quaternion rotation = new Quaternion().fromAngleAxis(
-player.getRotationSpeed() * tpf, Vector3f.UNIT_Y);
player.setDirection(rotation.mult(player.getDirection()));
player.rotate(rotation);
}

player.setMoveDirection(Vector3f.ZERO);
if (forward) {
    player.setMoveDirection(player.getDirection().mult(player.getSpeed()));
} else if (back) {
    player.setMoveDirection(player.getDirection().negate().multLocal(player.getSpeed()));
}

playerControl.setLinearVelocity(player.getMoveDirection());
//player.move(player.getMoveDirection().mult(tpf));

cam.lookAt(player.getLocalTranslation(), Vector3f.UNIT_Y);

}

@Override
public void simpleRender(RenderManager rm) {
//TODO: add render code
}

@Override
public void onAction(String name, boolean isPressed, float tpf) {
if (ACTION_FORWARD.equals(name)) {
if (isPressed) {
forward = true;
} else {
forward = false;
}
} else if (ACTION_BACK.equals(name)) {
if (isPressed) {
back = true;
} else {
back = false;
}
} else if (ACTION_LEFT.equals(name)) {
if (isPressed) {
left = true;
} else {
left = false;
}
} else if (ACTION_RIGHT.equals(name)) {
if (isPressed) {
right = true;
} else {
right = false;
}
}
}

}

[/java]

Say we have something like a tank (can rotate and move). Move by W&S and rotate by A&D.

Why my character is not rotated? If I remove RigidBodyControl from it I can rotate model by A&D.
Why it sometimes rotates when I move it forward or backward?
How make next behaviour - when characters hit with obstacle it just stops and not begins rotation?
I tried implement collision detection via Spatial.collideWith but I found that in JME3 collisions between spaitals are not supported.

lamao · March 21, 2013, 1:11pm

Entity is simple subclass of Node.
[java]
public class Entity extends Node {

private static final String SPATIAL_GROUP_MODEL = "model";

private Vector3f direction = Vector3f.UNIT_Z.negate();

private Vector3f moveDirection = Vector3f.ZERO;

private float speed;

private float rotationSpeed;

private EntityAction moveAction;

public Entity(String name, Spatial model) {
    setName(name);
    model.setName(SPATIAL_GROUP_MODEL);
    attachChild(model);
}

[/java]