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apps: add the HelloNewHinge tutorial app
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apps/src/main/java/com/github/stephengold/lbjexamples/apps/HelloNewHinge.java
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| /* | ||
| Copyright (c) 2020-2024 Stephen Gold and Yanis Boudiaf | ||
| All rights reserved. | ||
| Redistribution and use in source and binary forms, with or without | ||
| modification, are permitted provided that the following conditions are met: | ||
| 1. Redistributions of source code must retain the above copyright notice, this | ||
| list of conditions and the following disclaimer. | ||
| 2. Redistributions in binary form must reproduce the above copyright notice, | ||
| this list of conditions and the following disclaimer in the documentation | ||
| and/or other materials provided with the distribution. | ||
| 3. Neither the name of the copyright holder nor the names of its | ||
| contributors may be used to endorse or promote products derived from | ||
| this software without specific prior written permission. | ||
| THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND | ||
| ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED | ||
| WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE | ||
| DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE | ||
| FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL | ||
| DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR | ||
| SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER | ||
| CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, | ||
| OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE | ||
| OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | ||
| */ | ||
| package com.github.stephengold.lbjexamples.apps; | ||
|
|
||
| import com.github.stephengold.sport.Constants; | ||
| import com.github.stephengold.sport.TextureKey; | ||
| import com.github.stephengold.sport.input.RotateMode; | ||
| import com.github.stephengold.sport.physics.BasePhysicsApp; | ||
| import com.jme3.bullet.PhysicsSpace; | ||
| import com.jme3.bullet.PhysicsTickListener; | ||
| import com.jme3.bullet.collision.shapes.CylinderCollisionShape; | ||
| import com.jme3.bullet.collision.shapes.HullCollisionShape; | ||
| import com.jme3.bullet.collision.shapes.PlaneCollisionShape; | ||
| import com.jme3.bullet.joints.NewHinge; | ||
| import com.jme3.bullet.joints.motors.MotorParam; | ||
| import com.jme3.bullet.joints.motors.RotationMotor; | ||
| import com.jme3.bullet.objects.PhysicsBody; | ||
| import com.jme3.bullet.objects.PhysicsRigidBody; | ||
| import com.jme3.math.FastMath; | ||
| import com.jme3.math.Plane; | ||
| import com.jme3.math.Vector3f; | ||
| import java.util.ArrayList; | ||
| import java.util.Collection; | ||
| import java.util.List; | ||
| import jme3utilities.math.MyQuaternion; | ||
|
|
||
| /** | ||
| * An example of vehicle physics using NewHinge. | ||
| * <p> | ||
| * Builds upon HelloVehicle. | ||
| * | ||
| * @author Stephen Gold [email protected] | ||
| */ | ||
| public class HelloNewHinge | ||
| extends BasePhysicsApp<PhysicsSpace> | ||
| implements PhysicsTickListener { | ||
| // ************************************************************************* | ||
| // fields | ||
|
|
||
| /** | ||
| * wheels for steering | ||
| */ | ||
| final private static List<RotationMotor> steer = new ArrayList<>(2); | ||
| /** | ||
| * drive wheels | ||
| */ | ||
| final private static List<PhysicsRigidBody> drive = new ArrayList<>(2); | ||
| private static PhysicsRigidBody chassis; | ||
| // ************************************************************************* | ||
| // new methods exposed | ||
|
|
||
| /** | ||
| * Main entry point for the HelloNewHinge application. | ||
| * | ||
| * @param arguments array of command-line arguments (not null) | ||
| */ | ||
| public static void main(String[] arguments) { | ||
| HelloNewHinge application = new HelloNewHinge(); | ||
| application.start(); | ||
| } | ||
| // ************************************************************************* | ||
| // BasePhysicsApp methods | ||
|
|
||
| /** | ||
| * Create the PhysicsSpace. Invoked once during initialization. | ||
| * | ||
| * @return a new instance | ||
| */ | ||
| @Override | ||
| public PhysicsSpace createSpace() { | ||
| PhysicsSpace result | ||
| = new PhysicsSpace(PhysicsSpace.BroadphaseType.DBVT); | ||
|
|
||
| // To enable the callbacks, register the application as a tick listener. | ||
| result.addTickListener(this); | ||
|
|
||
| return result; | ||
| } | ||
|
|
||
| /** | ||
| * Initialize the application. | ||
| */ | ||
| @Override | ||
| public void initialize() { | ||
| super.initialize(); | ||
|
|
||
| getCameraInputProcessor().setRotationMode(RotateMode.DragLMB); | ||
| setBackgroundColor(Constants.SKY_BLUE); | ||
| } | ||
|
|
||
| /** | ||
| * Populate the PhysicsSpace. Invoked once during initialization. | ||
| */ | ||
| @Override | ||
| public void populateSpace() { | ||
| // Create a wedge-shaped vehicle with a low center of gravity. | ||
| // The local forward direction is +Z. | ||
| float noseZ = 1.4f; // offset from chassis center | ||
| float spoilerY = 0.5f; // offset from chassis center | ||
| float tailZ = -0.7f; // offset from chassis center | ||
| float undercarriageY = -0.1f; // offset from chassis center | ||
| float halfWidth = 0.4f; | ||
| Collection<Vector3f> cornerLocations = new ArrayList<>(6); | ||
| cornerLocations.add(new Vector3f(+halfWidth, undercarriageY, noseZ)); | ||
| cornerLocations.add(new Vector3f(-halfWidth, undercarriageY, noseZ)); | ||
| cornerLocations.add(new Vector3f(+halfWidth, undercarriageY, tailZ)); | ||
| cornerLocations.add(new Vector3f(-halfWidth, undercarriageY, tailZ)); | ||
| cornerLocations.add(new Vector3f(+halfWidth, spoilerY, tailZ)); | ||
| cornerLocations.add(new Vector3f(-halfWidth, spoilerY, tailZ)); | ||
| HullCollisionShape wedgeShape | ||
| = new HullCollisionShape(cornerLocations); | ||
| float mass = 5f; | ||
| chassis = new PhysicsRigidBody(wedgeShape, mass); | ||
| chassis.setEnableSleep(false); | ||
| physicsSpace.addCollisionObject(chassis); | ||
|
|
||
| // Add 4 wheels, 2 in the front (for steering) and 2 in the rear. | ||
| boolean front = true; | ||
| boolean rear = false; | ||
| float frontAxisZ = 0.7f * noseZ; // offset from chassis center | ||
| float rearAxisZ = 0.8f * tailZ; // offset from chassis center | ||
| float radius = 0.3f; // of each tire | ||
| float restLength = 0.2f; // of the suspension | ||
| float xOffset = 0.9f * halfWidth; | ||
| Vector3f axleDirection = new Vector3f(-1f, 0f, 0f); | ||
| Vector3f suspensionDirection = new Vector3f(0f, -1f, 0f); | ||
| addWheel(new Vector3f(-xOffset, 0f, frontAxisZ), | ||
| suspensionDirection, axleDirection, restLength, radius, front); | ||
| addWheel(new Vector3f(xOffset, 0f, frontAxisZ), | ||
| suspensionDirection, axleDirection, restLength, radius, front); | ||
| addWheel(new Vector3f(-xOffset, 0f, rearAxisZ), | ||
| suspensionDirection, axleDirection, restLength, radius, rear); | ||
| addWheel(new Vector3f(xOffset, 0f, rearAxisZ), | ||
| suspensionDirection, axleDirection, restLength, radius, rear); | ||
|
|
||
| // Visualize the chassis. | ||
| visualizeShape(chassis); | ||
|
|
||
| // Apply a steering angle of 6 degrees left (to the front wheels). | ||
| for (RotationMotor motor : steer) { | ||
| motor.set(MotorParam.ServoTarget, FastMath.PI / 30f); | ||
| } | ||
|
|
||
| // Add a static plane to represent the ground. | ||
| float planeY = -radius - 0.35f; | ||
| addPlane(planeY); | ||
| } | ||
| // ************************************************************************* | ||
| // PhysicsTickListener methods | ||
|
|
||
| /** | ||
| * Callback from Bullet, invoked just before each simulation step. | ||
| * | ||
| * @param space the space that's about to be stepped (not null) | ||
| * @param timeStep the time per simulation step (in seconds, ≥0) | ||
| */ | ||
| @Override | ||
| public void prePhysicsTick(PhysicsSpace space, float timeStep) { | ||
| // Apply a constant torque (to the rear wheels). | ||
| for (PhysicsRigidBody wheel : drive) { | ||
| Vector3f torque = new Vector3f(1f, 0f, 0f); | ||
| MyQuaternion.rotate(wheel.getPhysicsRotation(null), torque, torque); | ||
| wheel.applyTorque(torque); | ||
| } | ||
| } | ||
|
|
||
| /** | ||
| * Callback from Bullet, invoked just after each simulation step. | ||
| * | ||
| * @param space the space that was just stepped (not null) | ||
| * @param timeStep the time per simulation step (in seconds, ≥0) | ||
| */ | ||
| @Override | ||
| public void physicsTick(PhysicsSpace space, float timeStep) { | ||
| // do nothing | ||
| } | ||
|
|
||
| /** | ||
| * Update the window title. Invoked during each update. | ||
| */ | ||
| @Override | ||
| public void updateWindowTitle() { | ||
| // do nothing | ||
| } | ||
| // ************************************************************************* | ||
| // private methods | ||
|
|
||
| /** | ||
| * Add a horizontal plane body to the space. | ||
| * | ||
| * @param y (the desired elevation, in physics-space coordinates) | ||
| */ | ||
| private void addPlane(float y) { | ||
| Plane plane = new Plane(Vector3f.UNIT_Y, y); | ||
| PlaneCollisionShape shape = new PlaneCollisionShape(plane); | ||
| PhysicsRigidBody body | ||
| = new PhysicsRigidBody(shape, PhysicsBody.massForStatic); | ||
|
|
||
| physicsSpace.addCollisionObject(body); | ||
|
|
||
| String resourceName = "/Textures/greenTile.png"; | ||
| float maxAniso = 16f; | ||
| TextureKey textureKey | ||
| = new TextureKey("classpath://" + resourceName, maxAniso); | ||
| visualizeShape(body) | ||
| .setSpecularColor(Constants.DARK_GRAY) | ||
| .setTexture(textureKey); | ||
| } | ||
|
|
||
| /** | ||
| * Add a cylindrical wheel, joined to the chassis by a NewHinge. | ||
| * | ||
| * @param connectionPoint the location of the connection point (not null) | ||
| * @param suspensionDirection the direction of suspension motion (not null, | ||
| * not zero, unaffected) | ||
| * @param axle the direction of the axle's axis (not null, not zero, | ||
| * unaffected) | ||
| * @param restLength the rest length | ||
| * @param wheelRadius the desired radius of the wheel | ||
| * @param isFrontWheel true for a front/steer wheel, false for a rear/drive | ||
| * wheel | ||
| */ | ||
| private void addWheel(Vector3f connectionPoint, | ||
| Vector3f suspensionDirection, Vector3f axle, float restLength, | ||
| float wheelRadius, boolean isFrontWheel) { | ||
| float thickness = 0.5f * wheelRadius; | ||
| CylinderCollisionShape shape = new CylinderCollisionShape( | ||
| wheelRadius, thickness, PhysicsSpace.AXIS_X); | ||
| float mass = 0.5f; | ||
| PhysicsRigidBody body = new PhysicsRigidBody(shape, mass); | ||
| body.setEnableSleep(false); | ||
| Vector3f center = connectionPoint.add(0f, -restLength, 0f); | ||
| body.setPhysicsLocation(center); | ||
| physicsSpace.addCollisionObject(body); | ||
|
|
||
| // Visualize the shape of the wheel: | ||
| visualizeShape(body); | ||
|
|
||
| NewHinge joint = new NewHinge( | ||
| chassis, body, center, suspensionDirection, axle); | ||
| if (isFrontWheel) { | ||
| RotationMotor motor = joint.getRotationMotor(PhysicsSpace.AXIS_Z); | ||
| motor.setMotorEnabled(true); | ||
| motor.setServoEnabled(true); | ||
| motor.set(MotorParam.TargetVelocity, 1f); | ||
| steer.add(motor); | ||
| } else { | ||
| joint.set(MotorParam.LowerLimit, 3 + PhysicsSpace.AXIS_Z, 0f); | ||
| joint.set(MotorParam.UpperLimit, 3 + PhysicsSpace.AXIS_Z, 0f); | ||
| drive.add(body); | ||
| } | ||
| joint.set(MotorParam.Damping, PhysicsSpace.AXIS_Z, 30f); | ||
| joint.set(MotorParam.Stiffness, PhysicsSpace.AXIS_Z, 90f); | ||
| joint.setCollisionBetweenLinkedBodies(false); | ||
| physicsSpace.addJoint(joint); | ||
| } | ||
| } |