我正在开发越野游戏，我是libgdx的新手。
我开了一辆车，只有3个零件：底盘，后轮和后轮。前轮。我有一个“Zoomable”相机与底盘绑定，底盘连接到带轮接头的车轮。
底盘可以很好地处理纹理而不是车轮。
以下是问题：
Focus.java
public class Focus extends InputAdapter {
private Body chassis, rearWheel, frontWheel;
private WheelJoint leftAxis, rightAxis;
private float speed = 90f;
private Sprite spriteChassis, spriteRearWheel, spriteFrontWheel;
private float xOffSet = 5f;
private float yOffSet = -2f;
private float rwOffSet = 0;
private float fwOffSet = 0;
private float rwOffSetY = 0;
private float fwOffSetY = 0;
public float getOffSetX(){ return xOffSet; }
public float getOffSetY(){ return yOffSet; }
public Focus(World world, FixtureDef chassisFixtureDef, FixtureDef wheelFixtureDef, float x, float y) {
BodyDef bodyDef = new BodyDef();
bodyDef.type = BodyDef.BodyType.DynamicBody;
bodyDef.position.set(x,y);
bodyDef.gravityScale = 1;
float width = 5.333f;
float height = 1.933f;
BodyEditorLoader loader = new BodyEditorLoader(Gdx.files.internal("data/focus.json"));
chassis = world.createBody(bodyDef);
loader.attachFixture(chassis, "focus", chassisFixtureDef, width);
String imgpath = loader.getImagePath("focus");
chassis.createFixture(chassisFixtureDef);
chassis.setGravityScale(1.2f);
spriteChassis = new Sprite(new Texture(imgpath));
spriteRearWheel = new Sprite(new Texture("tires.png"));
spriteFrontWheel = new Sprite(new Texture("tires.png"));
// Wheels
CircleShape wheelShape = new CircleShape();
wheelShape.setRadius(height / 6f);
wheelFixtureDef.shape = wheelShape;
rearWheel = world.createBody(bodyDef);
rearWheel.createFixture(wheelFixtureDef);
frontWheel = world.createBody(bodyDef);
frontWheel.createFixture(wheelFixtureDef);
// Axels
WheelJointDef axisDef = new WheelJointDef();
axisDef.bodyA = chassis;
axisDef.bodyB = rearWheel;
rwOffSet = wheelShape.getRadius()*3.3f;
axisDef.localAnchorA.x = rwOffSet;
rwOffSetY = height/10.5f;
axisDef.localAnchorA.y = rwOffSetY;
axisDef.frequencyHz = chassisFixtureDef.density;
axisDef.localAxisA.set(Vector2.Y);
axisDef.maxMotorTorque = chassisFixtureDef.density * 24.5f;
leftAxis = (WheelJoint) world.createJoint(axisDef);
// right
// Axels
WheelJointDef axisDef2 = new WheelJointDef();
axisDef2.bodyA = chassis;
axisDef2.bodyB = frontWheel;
axisDef2.localAnchorA.set(width, 0);
axisDef2.frequencyHz = chassisFixtureDef.density;
axisDef2.localAxisA.set(Vector2.Y);
fwOffSet = width-wheelShape.getRadius()*3.f;
axisDef2.localAnchorA.x = fwOffSet;
fwOffSetY = height/9f;
axisDef.localAnchorA.y = fwOffSetY;
axisDef2.maxMotorTorque = chassisFixtureDef.density * 24.5f;
rightAxis = (WheelJoint) world.createJoint(axisDef2);
}
@Override
public boolean keyDown(int keycode) {
switch(keycode) {
case Input.Keys.W:
leftAxis.enableMotor(false);
rightAxis.enableMotor(true);
rightAxis.setMotorSpeed(-speed);
break;
case Input.Keys.S:
leftAxis.enableMotor(false);
rightAxis.enableMotor(true);
rightAxis.setMotorSpeed(speed);
break;
case Input.Keys.SPACE:
leftAxis.enableMotor(true);
leftAxis.setMotorSpeed(0);
rightAxis.enableMotor(true);
rightAxis.setMotorSpeed(0);
break;
}
return true;
}
@Override
public boolean keyUp(int keycode) {
switch(keycode) {
case Input.Keys.SPACE:
case Input.Keys.W:
case Input.Keys.S:
leftAxis.enableMotor(false);
rightAxis.enableMotor(false);
break;
}
return true;
}
public Sprite getSpriteChassis(){ return spriteChassis; }
public Sprite getSpriteRearWheel() { return spriteRearWheel; }
public Sprite getSpriteFrontWheel() { return spriteFrontWheel; }
public Body getChassis() { return chassis; }
public Body getFrontWheel() { return frontWheel; }
public Body getRearWheel() { return rearWheel; }
}
SmallHill.java（屏幕）
public class SmallHill implements Screen {
private final float PIXELS_PER_METER = 15f; // how many pixels to a meter
private final float TIME_STEP = 1 / 60f; // 60 fps
private final float SPEED = 1 / 60f; // speed constant
private final float MIN_ZOOM = .25f; // How far in should we be able to zoom
private final float ANGULAR_MOMENTUM = .5f;
private final int VELOCITY_ITERATIONS = 8; // copied from box2d example
private final int POSITION_ITERATIONS = 3; // copied from box2d example
private World world;
private Box2DDebugRenderer debugRenderer;
private OrthographicCamera camera;
private Body ball;
private Focus focus;
private BitmapFont font;
private SpriteBatch batch;
private Texture texture;
@Override
public void show() {
batch = new SpriteBatch();
font = new BitmapFont();
font.setColor(Color.RED);
world = new World(new Vector2(0, -9.81f), true);
debugRenderer = new Box2DDebugRenderer();
camera = new OrthographicCamera();
camera.zoom = 1f;
BodyDef bodyDef = new BodyDef();
// Shape
ChainShape groundShape = new ChainShape();
groundShape.createChain(new Vector2[] {new Vector2(-1,24),new Vector2(0,14),new Vector2(25,14),new Vector2(50,10),new Vector2(100,5),new Vector2(150,12),new Vector2(155,10), new Vector2(200,22),new Vector2(225,22),new Vector2(226,22.15f),new Vector2(227,22),new Vector2(229,22.25f),new Vector2(350,22),new Vector2(385,24),new Vector2(389,25),new Vector2(390,24),new Vector2(395,25),new Vector2(398,24),new Vector2(400,25),new Vector2(401,48) });
CircleShape ballShape = new CircleShape();
ballShape.setRadius(1f);
ballShape.setPosition(new Vector2(-10, 16));
// Fixture
FixtureDef fixtureDef = new FixtureDef();
fixtureDef.shape = groundShape;
fixtureDef.friction = .8f;
fixtureDef.restitution = 0;
world.createBody(bodyDef).createFixture(fixtureDef);
fixtureDef.shape = ballShape;
fixtureDef.friction = 0.9f;
fixtureDef.restitution = .3f;
fixtureDef.density = 3;
bodyDef.type = BodyType.DynamicBody;
fixtureDef.density = 5;
fixtureDef.friction = .4f;
fixtureDef.restitution = .1f;
FixtureDef wheelFixtureDef = new FixtureDef();
wheelFixtureDef.density = fixtureDef.density ;
wheelFixtureDef.friction = 2;
wheelFixtureDef.restitution = .7f;
focus = new Focus(world, fixtureDef, wheelFixtureDef, 50, 14);
wheelFixtureDef.shape.dispose();
fixtureDef.shape.dispose();
Gdx.input.setInputProcessor(new InputMultiplexer(new InputController() {
@Override
public boolean keyDown(int keycode) {
switch(keycode) {
case Input.Keys.ESCAPE:
dispose();
break;
case Input.Keys.R:
camera.zoom = 1;
break;
case Input.Keys.PLUS:
camera.zoom = 10;
break;
case Input.Keys.MINUS:
camera.zoom = 1;
break;
}
return false;
}
@Override
public boolean scrolled(int amount) {
if(amount == -1 && camera.zoom <= MIN_ZOOM) {
camera.zoom = MIN_ZOOM;
} else {
camera.zoom += amount / PIXELS_PER_METER;
}
return false;
}
},focus));
}
@Override
public void render(float delta) {
Gdx.gl.glClearColor(0, 0, 0, 1);
Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);
world.step(TIME_STEP, VELOCITY_ITERATIONS, POSITION_ITERATIONS);
camera.position.set(focus.getChassis().getWorldCenter().x,focus.getChassis().getWorldCenter().y,0);
camera.update();
String x;
WheelJoint wj = (WheelJoint) focus.getChassis().getJointList().get(0).joint;
x = (int)Math.abs(wj.getJointSpeed())+"";
batch.begin();
font.draw(batch, x, 20, 20);
focus.getSpriteChassis().setPosition((Gdx.graphics.getWidth() / 2 - focus.getSpriteChassis().getWidth() / 2) + focus.getOffSetX(), (Gdx.graphics.getHeight() / 2 - focus.getSpriteChassis().getHeight() / 2) + focus.getOffSetY());
focus.getSpriteChassis().setRotation(focus.getChassis().getAngle() * MathUtils.radiansToDegrees);
focus.getSpriteChassis().setScale(1/camera.zoom);
focus.getSpriteChassis().draw(batch);
focus.getSpriteRearWheel().setPosition((Gdx.graphics.getWidth() / 2 - focus.getSpriteChassis().getWidth() / 2) , (Gdx.graphics.getHeight() / 2 - focus.getSpriteChassis().getHeight() / 2) );
focus.getSpriteFrontWheel().setPosition((Gdx.graphics.getWidth() / 2 - focus.getSpriteChassis().getWidth() / 2) , (Gdx.graphics.getHeight() / 2 - focus.getSpriteChassis().getHeight() / 2) );
//focus.getSpriteRearWheel().setPosition((Gdx.graphics.getWidth() / 2 - focus.getSpriteChassis().getWidth() / 2) + focus.getRwOffSet()*PIXELS_PER_METER*(1/camera.zoom), (Gdx.graphics.getHeight() / 2 - focus.getSpriteChassis().getHeight() / 2) + focus.getRwOffSetY()*PIXELS_PER_METER*(1/camera.zoom) );
//focus.getSpriteFrontWheel().setPosition((Gdx.graphics.getWidth() / 2 - focus.getSpriteChassis().getWidth() / 2)+ focus.getFwOffSet()*PIXELS_PER_METER*(1/camera.zoom) , (Gdx.graphics.getHeight() / 2 - focus.getSpriteChassis().getHeight() / 2) + focus.getFwOffSetY()*PIXELS_PER_METER*(1/camera.zoom));
focus.getSpriteRearWheel().setRotation(focus.getRearWheel().getAngle() * MathUtils.radiansToDegrees);
focus.getSpriteFrontWheel().setRotation(focus.getFrontWheel().getAngle() * MathUtils.radiansToDegrees);
focus.getSpriteRearWheel().setScale(1 / camera.zoom);
focus.getSpriteRearWheel().draw(batch);
focus.getSpriteFrontWheel().setScale(1 / camera.zoom);
focus.getSpriteFrontWheel().draw(batch);
batch.end();
debugRenderer.render(world, camera.combined);
}
@Override
public void resize(int width, int height) {
camera.viewportWidth = width / PIXELS_PER_METER;
camera.viewportHeight = height / PIXELS_PER_METER;
}
@Override
public void hide() { dispose(); }
@Override
public void pause() { }
@Override
public void resume() { }
@Override
public void dispose() {
world.dispose();
debugRenderer.dispose();
batch.dispose();
font.dispose();
}
}
任何人都可以帮助我理解吗？非常感谢!!!
答案 0 :(得分：0)
Box2D有一个速度限制，约为2.0单位/时间步 因此，如果你步进60次/秒，你可以移动2 * 60 = 120单位/秒 为了增加最大速度，你可以减少时间步长，即增加步数/秒 例如，如果您将其增加到30，则可以移动到2 * 120 = 240单位/秒。
另外请确保您使用仪表作为您的单位。 Box2D的创建时考虑了千克，米和秒，所以你也应该使用这些单位。