Example usage for com.badlogic.gdx.physics.box2d Body getInertia

Introduction

In this page you can find the example usage for com.badlogic.gdx.physics.box2d Body getInertia.

Prototype

public float getInertia() 

Source Link

Document

Get the rotational inertia of the body about the local origin.

Usage

From source file:com.agateau.pixelwheels.racer.SpinningComponent.java

License:Open Source License

@Override
public void act(float delta) {
    if (!mActive) {
        return;// w w w. ja v  a  2 s .c  o m
    }
    Body body = mVehicle.getBody();

    // Slow down
    body.applyLinearImpulse(body.getLinearVelocity().nor().scl(-body.getMass()), body.getWorldCenter(), true);

    // Spin
    float nextAngle = body.getAngle() + body.getAngularVelocity() * GameWorld.BOX2D_TIME_STEP;
    if (nextAngle > mTargetBodyAngle) {
        stopSpinning();
        return;
    }

    float totalRotation = mTargetBodyAngle - nextAngle;
    float desiredAngularVelocity = totalRotation / GameWorld.BOX2D_TIME_STEP;
    if (desiredAngularVelocity < 0) {
        desiredAngularVelocity = MathUtils.clamp(desiredAngularVelocity, -MAX_ANGULAR_VELOCITY,
                -MIN_ANGULAR_VELOCITY);
    } else {
        desiredAngularVelocity = MathUtils.clamp(desiredAngularVelocity, MIN_ANGULAR_VELOCITY,
                MAX_ANGULAR_VELOCITY);
    }
    float impulse = body.getInertia() * (desiredAngularVelocity - body.getAngularVelocity());
    body.applyAngularImpulse(impulse, true);
}

---

From source file:com.badlogic.gdx.tests.box2d.ApplyForce.java

License:Apache License

@Override
protected void createWorld(World world) {
    world.setGravity(new Vector2(0, 0));

    float k_restitution = 0.4f;
    Body ground;//from   w  w w.j a  va2 s .  co  m

    {
        BodyDef bd = new BodyDef();
        bd.position.set(0, 20);
        ground = world.createBody(bd);

        EdgeShape shape = new EdgeShape();

        FixtureDef sd = new FixtureDef();
        sd.shape = shape;
        sd.density = 0;
        sd.restitution = k_restitution;

        shape.set(new Vector2(-20, -20), new Vector2(-20, 20));
        ground.createFixture(sd);

        shape.set(new Vector2(20, -20), new Vector2(20, 20));
        ground.createFixture(sd);

        shape.set(new Vector2(-20, 20), new Vector2(20, 20));
        ground.createFixture(sd);

        shape.set(new Vector2(-20, -20), new Vector2(20, -20));
        ground.createFixture(sd);

        shape.dispose();
    }

    {
        Transform xf1 = new Transform(new Vector2(), 0.3524f * (float) Math.PI);
        xf1.setPosition(xf1.mul(new Vector2(1, 0)));

        Vector2[] vertices = new Vector2[3];
        vertices[0] = xf1.mul(new Vector2(-1, 0));
        vertices[1] = xf1.mul(new Vector2(1, 0));
        vertices[2] = xf1.mul(new Vector2(0, 0.5f));

        PolygonShape poly1 = new PolygonShape();
        poly1.set(vertices);

        FixtureDef sd1 = new FixtureDef();
        sd1.shape = poly1;
        sd1.density = 4.0f;

        Transform xf2 = new Transform(new Vector2(), -0.3524f * (float) Math.PI);
        xf2.setPosition(xf2.mul(new Vector2(-1, 0)));

        vertices[0] = xf2.mul(new Vector2(-1, 0));
        vertices[1] = xf2.mul(new Vector2(1, 0));
        vertices[2] = xf2.mul(new Vector2(0, 0.5f));

        PolygonShape poly2 = new PolygonShape();
        poly2.set(vertices);

        FixtureDef sd2 = new FixtureDef();
        sd2.shape = poly2;
        sd2.density = 2.0f;

        BodyDef bd = new BodyDef();
        bd.type = BodyType.DynamicBody;
        bd.angularDamping = 5.0f;
        bd.linearDamping = 0.1f;

        bd.position.set(0, 2);
        bd.angle = (float) Math.PI;
        bd.allowSleep = false;
        m_body = world.createBody(bd);
        m_body.createFixture(sd1);
        m_body.createFixture(sd2);
        poly1.dispose();
        poly2.dispose();
    }

    {
        PolygonShape shape = new PolygonShape();
        shape.setAsBox(0.5f, 0.5f);

        FixtureDef fd = new FixtureDef();
        fd.shape = shape;
        fd.density = 1.0f;
        fd.friction = 0.3f;

        for (int i = 0; i < 10; i++) {
            BodyDef bd = new BodyDef();
            bd.type = BodyType.DynamicBody;

            bd.position.set(0, 5 + 1.54f * i);
            Body body = world.createBody(bd);

            body.createFixture(fd);

            float gravity = 10.0f;
            float I = body.getInertia();
            float mass = body.getMass();

            float radius = (float) Math.sqrt(2 * I / mass);

            FrictionJointDef jd = new FrictionJointDef();
            jd.localAnchorA.set(0, 0);
            jd.localAnchorB.set(0, 0);
            jd.bodyA = ground;
            jd.bodyB = body;
            jd.collideConnected = true;
            jd.maxForce = mass * gravity;
            jd.maxTorque = mass * radius * gravity;

            world.createJoint(jd);
        }

        shape.dispose();
    }
}

---

From source file:com.stercore.code.net.dermetfan.utils.libgdx.box2d.Autopilot.java

License:Apache License

/** @param wake if the body should be woken up if its sleeping
 *  @see #calculateTorque(Vector2, float, float, float, float, float) */
public void rotate(Body body, Vector2 target, float angle, float force, float delta, boolean wake) {
    body.applyTorque(/*w  w w . j a  va  2s  .  c om*/
            calculateTorque(rotateRelative ? target : vec2_0.set(positionAccessor.apply(body)).sub(target),
                    body.getTransform().getRotation() + angle, body.getAngularVelocity(), body.getInertia(),
                    adaptForceToMass ? force * body.getMass() : force, delta),
            wake);
}

---

From source file:net.dermetfan.utils.libgdx.box2d.Autopilot.java

License:Apache License

/** @param wake if the body should be woken up if its sleeping
 *  @see #calculateTorque(Vector2, float, float, float, float, float) */
public void rotate(Body body, Vector2 target, float angle, float force, float delta, boolean wake) {
    body.applyTorque(//from  ww w. j a  v  a  2 s.com
            calculateTorque(rotateRelative ? target : vec2_0.set(positionAccessor.access(body)).sub(target),
                    body.getTransform().getRotation() + angle, body.getAngularVelocity(), body.getInertia(),
                    adaptForceToMass ? force * body.getMass() : force, delta),
            wake);
}

---

From source file:zzz.box2dtest.ApplyForce.java

License:Apache License

@Override
protected void createWorld(World world) {
    world.setGravity(new Vector2(0, 0));
    Gdx.input.setInputProcessor(this);

    float k_restitution = 0.4f;
    Body ground;/*from   ww  w . j  av  a2  s. co  m*/

    {
        BodyDef bd = new BodyDef();
        bd.position.set(0, 20);
        ground = world.createBody(bd);

        EdgeShape shape = new EdgeShape();

        FixtureDef sd = new FixtureDef();
        sd.shape = shape;
        sd.density = 0;
        sd.restitution = k_restitution;

        shape.set(new Vector2(-20, -20), new Vector2(-20, 20));
        ground.createFixture(sd);

        shape.set(new Vector2(20, -20), new Vector2(20, 20));
        ground.createFixture(sd);

        shape.set(new Vector2(-20, 20), new Vector2(20, 20));
        ground.createFixture(sd);

        shape.set(new Vector2(-20, -20), new Vector2(20, -20));
        ground.createFixture(sd);

        shape.dispose();
    }

    {
        Transform xf1 = new Transform(new Vector2(), 0.3524f * (float) Math.PI);
        xf1.setPosition(xf1.mul(new Vector2(1, 0)));

        Vector2[] vertices = new Vector2[3];
        vertices[0] = xf1.mul(new Vector2(-1, 0));
        vertices[1] = xf1.mul(new Vector2(1, 0));
        vertices[2] = xf1.mul(new Vector2(0, 0.5f));

        PolygonShape poly1 = new PolygonShape();
        poly1.set(vertices);

        FixtureDef sd1 = new FixtureDef();
        sd1.shape = poly1;
        sd1.density = 4.0f;

        Transform xf2 = new Transform(new Vector2(), -0.3524f * (float) Math.PI);
        xf2.setPosition(xf2.mul(new Vector2(-1, 0)));

        vertices[0] = xf2.mul(new Vector2(-1, 0));
        vertices[1] = xf2.mul(new Vector2(1, 0));
        vertices[2] = xf2.mul(new Vector2(0, 0.5f));

        PolygonShape poly2 = new PolygonShape();
        poly2.set(vertices);

        FixtureDef sd2 = new FixtureDef();
        sd2.shape = poly2;
        sd2.density = 2.0f;

        BodyDef bd = new BodyDef();
        bd.type = BodyType.DynamicBody;
        bd.angularDamping = 5.0f;
        bd.linearDamping = 0.1f;

        bd.position.set(0, 2);
        bd.angle = (float) Math.PI;
        bd.allowSleep = false;
        m_body = world.createBody(bd);
        m_body.createFixture(sd1);
        m_body.createFixture(sd2);
        poly1.dispose();
        poly2.dispose();
    }

    {
        PolygonShape shape = new PolygonShape();
        shape.setAsBox(0.5f, 0.5f);

        FixtureDef fd = new FixtureDef();
        fd.shape = shape;
        fd.density = 1.0f;
        fd.friction = 0.3f;

        for (int i = 0; i < 10; i++) {
            BodyDef bd = new BodyDef();
            bd.type = BodyType.DynamicBody;

            bd.position.set(0, 5 + 1.54f * i);
            Body body = world.createBody(bd);

            body.createFixture(fd);

            float gravity = 10.0f;
            float I = body.getInertia();
            float mass = body.getMass();

            float radius = (float) Math.sqrt(2 * I / mass);

            FrictionJointDef jd = new FrictionJointDef();
            jd.localAnchorA.set(0, 0);
            jd.localAnchorB.set(0, 0);
            jd.bodyA = ground;
            jd.bodyB = body;
            jd.collideConnected = true;
            jd.maxForce = mass * gravity;
            jd.maxTorque = mass * radius * gravity;

            world.createJoint(jd);
        }

        shape.dispose();
    }
}

---