Basically i have a circle object which acts as the player, and it can only jump. What I want to do is make the circle object keep rolling while having a constant gravity or force act on the circle object to make it keep rolling to the right on the ground. I have tried making a constant gravity by setting the vector2 x value to 0.5f:
World world = new World(new Vector2(0.5f, -9.8f), true);
When i do this the ball rapidly keeps moving faster as time goes on.
Is there way I can achieve my desired effect?
Play class code:
public class Play implements Screen,ContactListener{
World world = new World(new Vector2(0f, -9.8f), true);
Box2DDebugRenderer debugRenderer;
OrthographicCamera camera;
static final int PPM = 100;
static float height,width;
Body player;
RayHandler handler;
PointLight l1;
Body groundBody;
float tileSize;
boolean playerOnGround = false;
int footContact;
ShapeRenderer shapeRenderer;
PointLight light;
TiledMap tileMap;
OrthogonalTiledMapRenderer tmr;
BallJump game;
int level;
Color lightColor = new Color();
public Play(int level,BallJump game ) {
this.level = level;
this.game = game;
}
#Override
public void show() {
shapeRenderer = new ShapeRenderer();
height = Gdx.graphics.getHeight();
width = Gdx.graphics.getWidth();
//set camera
camera = new OrthographicCamera();
new FitViewport(width/PPM/2, height/PPM/2, camera);
if((height + width) > 1500 && (height + width) < 2000) {
camera.zoom = 0.5f;
} else if ((height + width) > 2000) {
camera.zoom = 0.75f;
}
camera.update();
//player Body
BodyDef bodyDef = new BodyDef();
bodyDef.type = BodyType.DynamicBody;
bodyDef.position.set((width/PPM)/2/2, (height / PPM)/2/2);
player = world.createBody(bodyDef);
CircleShape dynamicCircle = new CircleShape();
dynamicCircle.setRadius(5f/PPM);
FixtureDef fixtureDef = new FixtureDef();
fixtureDef.shape = dynamicCircle;
fixtureDef.density = 0.4f;
fixtureDef.friction = 1f;
fixtureDef.restitution = 0f;
player.createFixture(fixtureDef).setUserData("player");;
debugRenderer = new Box2DDebugRenderer();
//Lighting
handler = new RayHandler(world);
light = new PointLight(handler,500,Color.MAGENTA,4f,width/PPM/2/2/2,height/PPM/2/2);
light.attachToBody(player);
// tile map
tileMap = new TmxMapLoader().load("test2.tmx");
tmr = new OrthogonalTiledMapRenderer(tileMap,0.01f);
TiledMapTileLayer layer = (TiledMapTileLayer) tileMap.getLayers().get("block");
tileSize = layer.getTileHeight()*2;
for(int row = 0; row < layer.getHeight(); row++) {
for(int col = 0; col < layer.getWidth(); col++) {
Cell cell = layer.getCell(col, row);
if(cell == null) { continue;}
if(cell.getTile() == null) { continue;}
BodyDef bdef = new BodyDef();
bdef.type = BodyType.StaticBody;
bdef.position.set((col + 0.5f) * tileSize /PPM/2, (row + 0.5f) * tileSize /PPM/2);
PolygonShape cs = new PolygonShape();
cs.setAsBox(tileSize/2/PPM/2, tileSize/2/PPM/2);
FixtureDef fdef = new FixtureDef();
fdef.friction = 0f;
fdef.shape = cs;
world.createBody(bdef).createFixture(fdef).setUserData("ground");;
world.setContactListener(this);
}
}
}
public void update() {
playerOnGround = footContact > 0;
if(Gdx.input.isKeyJustPressed(Keys.UP) || (Gdx.input.isTouched())) {
if(playerOnGround)
player.applyForceToCenter(0, 0.75f, true);
}
else if (Gdx.input.isKeyPressed(Keys.SPACE)) {
player.setTransform((width/PPM)/2/2, (height / PPM)/2/2, 0);
}
}
#Override
public void pause() {
}
#Override
public void resume() {
}
#Override
public void beginContact(Contact contact) {
Fixture a = contact.getFixtureA();
Fixture b = contact.getFixtureB();
if(b.getUserData().equals("player") && b.getUserData() != null) {
footContact++;
player.setAngularDamping(5f);
}
if(a.getUserData().equals("player") && a.getUserData() != null) {
footContact++;
player.setAngularDamping(5f);
}
}
#Override
public void endContact(Contact contact) {
Fixture a = contact.getFixtureA();
Fixture b = contact.getFixtureB();
if(b.getUserData().equals("player") && b.getUserData() != null) {
footContact--;
}
if(a.getUserData().equals("player") && a.getUserData() != null) {
footContact--;
}
}
#Override
public void preSolve(Contact contact, Manifold oldManifold) {}
#Override
public void postSolve(Contact contact, ContactImpulse impulse) {}
#Override
public void render(float delta) {
camera.position.set(player.getPosition().x, player.getPosition().y, 0);
update();
camera.update();
shapeRenderer.setProjectionMatrix(camera.combined);
Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);
world.step(1/60f, 6, 2);
handler.updateAndRender();
handler.setCombinedMatrix(camera.combined);
debugRenderer.render(world, camera.combined);
}
}
The gravity is a force, which is applied to every (dynamic) body in the world in every step.
That means, that the velocity of those affected object increases every frame.
Thats just the expected result, think about the reality:
If you jump from a high place, you get faster and faster, until you hit the ground (or air resistance limits your speed).
If you want to move with a constant speed (in Box2D), you should do something like that:
Vector2 vel = this.player.body.getLinearVelocity();
if (vel.x < MAX_VELOCITY) {
circle.applyLinearImpulse(impulse.x, impulse.y, pos.x, pos.y, wake);
Where impulse.x is a float, defining the impulse strength applyed in x-direction, impulse.y is the same for y-direction, pos.x and pos.y is the position, to which you want to apply the impulse (if not the center, the body will get some torque-effect) and the boolean wake defines, if the body should wake up.
Related
My sprite moves too slowly. Basically I want to apply less force to move my player. Current this:
getBody().applyForceToCenter(new Vector2(-10000000f,0f), true);
is the force needed to make it move a tiny bit.
I know the reason why I am not able to move it is since I haven't scaled the sprite (64x64) it weights more than 400kg. What should be the correct scale?
This is my game screen.
public class GameScreen implements Screen {
//Reference to our Game, used to set Screens
private Logang game;
//basic playscreen variables
private OrthographicCamera gamecam;
private Viewport gamePort;
//Box2d variables
private World world;
private Box2DDebugRenderer b2dr;
boolean drawn = true;
private Player p;
private int pX = 100, pY = 300;
public GameScreen(Logang game) {
this.game = game;
//create cam used to follow mario through cam world
gamecam = new OrthographicCamera();
gamePort = new ScalingViewport(Scaling.stretch, Logang.GWIDTH, Logang.GHEIGHT, gamecam);
gamePort.apply();
gamecam.position.set(gamecam.viewportWidth / 2, gamecam.viewportHeight / 2, 0);
gamecam.update();
Box2D.init();
//create our Box2D world, setting no gravity in X, -10 gravity in Y, and allow bodies to sleep
world = new World(new Vector2(0, Logang.GRAVITY), true);
//allows for debug lines of our box2d world.
b2dr = new Box2DDebugRenderer();
//create a FitViewport to maintain virtual aspect ratio despite screen size
p = new Player(new Sprite(new Texture("hud_p3.png")), world, pX, pY, 1);
//initially set our gamcam to be centered correctly at the start of of map
line();
}
#Override
public void show() {
}
public void update(float dt) {
//handle user input first
p.update(dt);
//update our gamecam with correct coordinates after changes
}
#Override
public void render(float delta) {
//separate our update logic from render
update(delta);
//Clear the game screen with Black
Gdx.gl.glClearColor(0, 0, 0, 1);
Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);
world.step(1f / 60f, 6, 2);
gamecam.position.set(p.getSprite().getX(),Logang.GHEIGHT / 2, 0); // x and y could be changed by Keyboard input for example
gamecam.update();
game.getBatch().setProjectionMatrix(gamecam.combined);
//renderer our Box2DDebugLines
b2dr.render(world, gamecam.combined);
System.out.println("Player x: " + p.getSprite().getX() + " Camera X: " + gamecam.position.x + " Body X: " + p.getBody().getPosition().x);
//System.out.println("Player y: " + p.getSprite().getY() + " Camera Y: " + gamecam.position.y + " Body Y: " + p.getBody().getPosition().y);
game.getBatch().begin();
if (p.getBody() != null)
p.render(game.getBatch());
EntityManager.renderTerra(game.getBatch(), delta);
game.getBatch().end();
}
public void line() {
Texture tmp = new Texture("hud_p3.png");
tmp.setWrap(Texture.TextureWrap.MirroredRepeat, Texture.TextureWrap.MirroredRepeat);
for (int i = 0; i < 50; i++) {
EntityManager.add(new Ground(new Sprite(tmp), world, (int)(i * Logang.TILE), 1, 2));
}
// EntityManager.changeSize(((Logang.TILE) * 5),Logang.TILE);
}
#Override
public void resize(int width, int height) {
//updated our game viewport
gamePort.update(width, height);
gamecam.position.set(gamecam.viewportWidth / 2, gamecam.viewportHeight / 2, 0);
}
public World getWorld() {
return world;
}
#Override
public void pause() {
}
#Override
public void resume() {
}
#Override
public void hide() {
}
#Override
public void dispose() {
world.dispose();
b2dr.dispose();
}
And this is my entity class
private World world;
private Sprite sprite;
private Body body;
private int tipo;
public Entity(Sprite sprite, World world, int x, int y, int tipo) {
this.sprite = sprite;
this.world = world;
getSprite().setPosition(x, y);
sprite.setSize(Logang.TILE, Logang.TILE);
sprite.setOriginCenter();
define(tipo);
this.tipo = tipo;
}
public void update(float dt){
if(Gdx.input.isKeyPressed(Input.Keys.LEFT)){
getBody().applyForceToCenter(new Vector2(-10000000f,0f), true);
}
if(Gdx.input.isKeyPressed(Input.Keys.RIGHT)){
getBody().applyForceToCenter(new Vector2(10000000f,0f), true);
}
if(Gdx.input.isKeyPressed(Input.Keys.SPACE)){
//getBody().applyLinearImpulse(0f,-Logang.GRAVITY,
getBody().getPosition().x, getBody().getPosition().y, true);
}
}
public void define(int tipo) {
BodyDef bdef = new BodyDef();
bdef.position.set((getSprite().getX() + getSprite().getWidth() / 2),
(getSprite().getY() + getSprite().getHeight() / 2));
switch (tipo) {
case 1: {
bdef.type = BodyDef.BodyType.DynamicBody;
break;
}
case 2: {
bdef.type = BodyDef.BodyType.StaticBody;
break;
}
case 3: {
bdef.type = BodyDef.BodyType.DynamicBody;
break;
}
}
body = world.createBody(bdef);
FixtureDef fdef = new FixtureDef();
fdef.density=0.001f; // (weight: range 0.01 to 1 is good)
PolygonShape shape = new PolygonShape();
shape.setAsBox(getSprite().getWidth() / 2, getSprite().getHeight() / 2);
fdef.shape = shape;
body.createFixture(fdef);
body.setUserData(this);
shape.dispose();
}
public void render(SpriteBatch batch) {
if (tipo != 2) {
float posX = getBody().getPosition().x;
float posY = getBody().getPosition().y;
getSprite().setPosition(posX - getSprite().getWidth() / 2, posY -
getSprite().getHeight() / 2);
}
getSprite().draw(batch);
}
public Sprite getSprite() {
return sprite;
}
public void setSprite(Sprite sprite) {
this.sprite = sprite;
}
public Body getBody() {
return body;
}
public void setBody(Body body) {
this.body = body;
}
And this are the in game variables
public static final int GWIDTH = 800;
public static final int GHEIGHT = (GWIDTH/16)*9;
public static final float PPM = 100f;
public static final float GRAVITY = -10f;
public static final float TILE = 64;
Could you please give me a fix?
I already tried to divide body and gamecam position still no effect
What should be the correct scale?
The right scale would be the scale in real life where 1 unit in LibGDX (Box2D) represents 1 meter in real life. I always advice people to use this scale and zoom the camera properly.
Mind though, if you are using very large objects and zoom the camera all the way back objects appear to be falling slowly. This is obviously because your camera contains a much larger space. Not only would it fall slowly but it won't interact properly with the world if the item is supposed to be smaller.
Adept the camera to your world, not your world to your camera.
More detailed answer I gave
Like my question says can someone tell me, why does my circle texture/sprite are acting like a rectangle ?
Code:
`
#Override
public void create() {
batch = new SpriteBatch();
img = new Texture("ball.png");
sprite = new Sprite(img);
sprite.setPosition(-sprite.getWidth()/2,-sprite.getHeight()/2);
world = new World(new Vector2(0, -1f),true);
BodyDef bodyDef = new BodyDef();
bodyDef.type = BodyDef.BodyType.DynamicBody;
bodyDef.position.set((sprite.getX() + sprite.getWidth()/2) /
PIXELS_TO_METERS,
(sprite.getY() + sprite.getHeight()/2) / PIXELS_TO_METERS);
body = world.createBody(bodyDef);
PolygonShape shape = new PolygonShape();
shape.setAsBox(sprite.getWidth()/2 / PIXELS_TO_METERS, sprite.getHeight()
/2 / PIXELS_TO_METERS);
FixtureDef fixtureDef = new FixtureDef();
fixtureDef.shape = shape;
fixtureDef.density = 0.1f;
fixtureDef.restitution = 0.8f;
body.createFixture(fixtureDef);
shape.dispose();
//CONTINUE
// BOTTOM
BodyDef bodyDefBottom = new BodyDef();
bodyDefBottom.type = BodyDef.BodyType.StaticBody;
float w = Gdx.graphics.getWidth()/PIXELS_TO_METERS;
// Set the height to just 50 pixels above the bottom of the screen so we can see the edge in the
// debug renderer
float h = Gdx.graphics.getHeight()/PIXELS_TO_METERS- 50/PIXELS_TO_METERS;
bodyDefBottom.position.set(0,0);
FixtureDef fixtureDef2 = new FixtureDef();
EdgeShape edgeShape = new EdgeShape();
edgeShape.set(-w/2,-h/2,w/2,-h/2);
fixtureDef2.shape = edgeShape;
bodyEdgeScreenBottom = world.createBody(bodyDefBottom);
bodyEdgeScreenBottom.createFixture(fixtureDef2);
edgeShape.dispose();
// TOP
BodyDef bodyDefTop = new BodyDef();
bodyDefTop.type = BodyDef.BodyType.StaticBody;
w = Gdx.graphics.getWidth()/PIXELS_TO_METERS;
// Set the height to just 50 pixels above the bottom of the screen so we can see the edge in the
// debug renderer
h = Gdx.graphics.getHeight()/PIXELS_TO_METERS;
bodyDefTop.position.set(0,0);
fixtureDef2 = new FixtureDef();
edgeShape = new EdgeShape();
edgeShape.set(-w/2,h/2,w/2,h/2);
fixtureDef2.shape = edgeShape;
bodyEdgeScreenTop = world.createBody(bodyDefTop);
bodyEdgeScreenTop.createFixture(fixtureDef2);
edgeShape.dispose();
// LEFT
BodyDef bodyDefLeft = new BodyDef();
bodyDefLeft.type = BodyDef.BodyType.StaticBody;
w = Gdx.graphics.getWidth()/PIXELS_TO_METERS;
// Set the height to just 50 pixels above the bottom of the screen so we can see the edge in the
// debug renderer
h = Gdx.graphics.getHeight()/PIXELS_TO_METERS;
bodyDefLeft.position.set(0,0);
fixtureDef2 = new FixtureDef();
edgeShape = new EdgeShape();
edgeShape.set(w/2,-h/2,w/2,h/2);
fixtureDef2.shape = edgeShape;
bodyEdgeScreenLeft = world.createBody(bodyDefLeft);
bodyEdgeScreenLeft.createFixture(fixtureDef2);
edgeShape.dispose();
// RIGHT
BodyDef bodyDefRight = new BodyDef();
bodyDefRight.type = BodyDef.BodyType.StaticBody;
w = Gdx.graphics.getWidth()/PIXELS_TO_METERS;
// Set the height to just 50 pixels above the bottom of the screen so we can see the edge in the
// debug renderer
h = Gdx.graphics.getHeight()/PIXELS_TO_METERS;
bodyDefRight.position.set(0,0);
fixtureDef2 = new FixtureDef();
edgeShape = new EdgeShape();
edgeShape.set(-w/2,-h/2,-w/2,h/2);
fixtureDef2.shape = edgeShape;
bodyEdgeScreenRight = world.createBody(bodyDefRight);
bodyEdgeScreenRight.createFixture(fixtureDef2);
edgeShape.dispose();
//CONTINUE
Gdx.input.setInputProcessor(this);
//debugRenderer = new Box2DDebugRenderer();
font = new BitmapFont();
font.setColor(Color.BLACK);
camera = new OrthographicCamera(Gdx.graphics.getWidth(),Gdx.graphics.
getHeight());
}
private float elapsed = 0;
#Override
public void render() {
camera.update();
// Step the physics simulation forward at a rate of 60hz
world.step(1f / 60f, 6, 2);
body.applyTorque(torque, true);
sprite.setPosition((body.getPosition().x * PIXELS_TO_METERS) - sprite.
getWidth() / 2,
(body.getPosition().y * PIXELS_TO_METERS) - sprite.getHeight() / 2)
;
sprite.setRotation((float) Math.toDegrees(body.getAngle()));
Gdx.gl.glClearColor(1, 1, 1, 1);
Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);
batch.setProjectionMatrix(camera.combined);
//debugMatrix = batch.getProjectionMatrix().cpy().scale(PIXELS_TO_METERS,
// PIXELS_TO_METERS, 0);
batch.begin();
if(drawSprite)
batch.draw(sprite, sprite.getX(), sprite.getY(),sprite.getOriginX(),
sprite.getOriginY(),
sprite.getWidth(),sprite.getHeight(),sprite.getScaleX(),sprite.
getScaleY(),sprite.getRotation());
font.draw(batch,
"Restitution: " + body.getFixtureList().first().getRestitution(),
-Gdx.graphics.getWidth()/2,
Gdx.graphics.getHeight()/2 );
batch.end();
//debugRenderer.render(world, debugMatrix);
}
#Override
public void dispose() {
img.dispose();
world.dispose();
}
#Override
public boolean keyDown(int keycode) {
return false;
}
#Override
public boolean keyUp(int keycode) {
return false;
}
#Override
public boolean keyTyped(char character) {
return false;
}
// On touch we apply force from the direction of the users touch.
// This could result in the object "spinning"
#Override
public boolean touchDown(int screenX, int screenY, int pointer, int button) {
body.applyForce(1f,1f,screenX,screenY,true);
//body.applyTorque(0.4f,true);
return true;
}
#Override
public boolean touchUp(int screenX, int screenY, int pointer, int button) {
return false;
}
#Override
public boolean touchDragged(int screenX, int screenY, int pointer) {
return false;
}
#Override
public boolean mouseMoved(int screenX, int screenY) {
return false;
}
#Override
public boolean scrolled(int amount) {
return false;
}
`
I have tried searching for other posts but couldn't find anything that explains to me why it is acting like a rectangle and how to resolve this. I have also tried searching for other methods to draw the texture , even using CircleShape but that cannot put inside texture from image. I'm pretty newbie in libgdx, I'm still learning everyday.
I'm little confused... You are creating PolygonShape and expecting it will behave as circle?
PolygonShape shape = new PolygonShape();
shape.setAsBox(...
All you can achieve this way is polygon with ball sprite inside. If you want to have a circle use mentioned by you CircleShape
CircleShape shape = new CircleShape();
shape.setRadius(1); //or anything you need
...
//assing it to the fixture etc
then update it when drawing with its position and angle - that's all
I am developing an off road game, and I am new to libgdx.
I made a car, with only 3 parts: chassis, rear & front wheel. I got a "Zoomable" camera bind with chassis, chassis connected to wheels with Wheel Joint.
Chassis works fine with texture but not wheels.
Here's the problems:
I can't figure out how to calculate the √(correct) vector2 of wheels to put it in the [Sprite.setPosition] method
How to make my car faster cause it never >94
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 (Screen)
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();
}
}
Can anyone help me understand? many thanks !!!
Box2D has a speed limit, which is about 2.0 units/timestep.
So if you step 60 times / second, you can move 2 * 60 = 120 units/second.
To increase the maximum speed you can decrease the timestep i.e. increase the number of steps/second.
If you, for example, increase it to 30, you can move up to 2 * 120 = 240 units/second.
Also make sure, that you are using meters as your unit. Box2D has been created with kg, meters and seconds in mind, so you should also use those units.
This is my code:
public class Physics3 extends ApplicationAdapter {
SpriteBatch batch;
Sprite sprite, sprite2;
Texture img;
World world;
Body body, body2;
Body bodyEdgeScreen;
Matrix4 debugMatrix;
OrthographicCamera camera;
// final float PIXELS_TO_METERS = 100f;
final short PHYSICS_ENTITY = 0x1; // 0001
final short WORLD_ENTITY = 0x1 << 1; // 0010 or 0x2 in hex
#Override
public void create() {
batch = new SpriteBatch();
img = new Texture("badlogic.jpg");
// Create two identical sprites slightly offset from each other vertically
sprite = new Sprite(img);
sprite.setPosition(-sprite.getWidth()/2,-sprite.getHeight()/2 +200);
sprite2 = new Sprite(img);
sprite2.setPosition(-sprite.getWidth()/2 + 20,-sprite.getHeight()/2 + 800);
world = new World(new Vector2(0, -100f),true);
// Sprite1's Physics body
BodyDef bodyDef = new BodyDef();
bodyDef.type = BodyDef.BodyType.DynamicBody;
bodyDef.position.set(sprite.getX() + sprite.getWidth()/2,
sprite.getY() + sprite.getHeight()/2);
body = world.createBody(bodyDef);
// Sprite2's physics body
BodyDef bodyDef2 = new BodyDef();
bodyDef2.type = BodyDef.BodyType.DynamicBody;
bodyDef2.position.set(sprite2.getX() + sprite2.getWidth()/2,
sprite2.getY() + sprite2.getHeight()/2);
body2 = world.createBody(bodyDef2);
// Both bodies have identical shape
PolygonShape shape = new PolygonShape();
shape.setAsBox(sprite.getWidth()/2, sprite.getHeight()/2);
// Sprite1
FixtureDef fixtureDef = new FixtureDef();
fixtureDef.shape = shape;
fixtureDef.density = 0.1f;
fixtureDef.restitution = 0.5f;
fixtureDef.filter.categoryBits = PHYSICS_ENTITY;
fixtureDef.filter.maskBits = WORLD_ENTITY;
// Sprite2
FixtureDef fixtureDef2 = new FixtureDef();
fixtureDef2.shape = shape;
fixtureDef2.density = 0.1f;
fixtureDef2.restitution = 0.5f;
fixtureDef2.filter.categoryBits = PHYSICS_ENTITY;
fixtureDef2.filter.maskBits = WORLD_ENTITY;
body.createFixture(fixtureDef);
body2.createFixture(fixtureDef2);
shape.dispose();
// Now the physics body of the bottom edge of the screen
BodyDef bodyDef3 = new BodyDef();
bodyDef3.type = BodyDef.BodyType.StaticBody;
float w = Gdx.graphics.getWidth();
float h = Gdx.graphics.getHeight();
bodyDef3.position.set(0, 0);
FixtureDef fixtureDef3 = new FixtureDef();
fixtureDef3.filter.categoryBits = WORLD_ENTITY;
fixtureDef3.filter.maskBits = PHYSICS_ENTITY;
EdgeShape edgeShape = new EdgeShape();
edgeShape.set(-w/2,-h/2,w/2,-h/2);
fixtureDef3.shape = edgeShape;
bodyEdgeScreen = world.createBody(bodyDef3);
bodyEdgeScreen.createFixture(fixtureDef3);
edgeShape.dispose();
camera = new OrthographicCamera(Gdx.graphics.getWidth(),Gdx.graphics.getHeight());
createContactListener();
}
#Override
public void render() {
camera.update();
// Step the physics simulation forward at a rate of 60hz
world.step(1f/60f, 6, 2);
sprite.setPosition((body.getPosition().x) - sprite.getWidth()/2 ,
(body.getPosition().y) -sprite.getHeight()/2 );
sprite.setRotation((float)Math.toDegrees(body2.getAngle()));
sprite2.setPosition((body2.getPosition().x) - sprite2.getWidth()/2 ,
(body2.getPosition().y) -sprite2.getHeight()/2 );
sprite2.setRotation((float)Math.toDegrees(body.getAngle()));
Gdx.gl.glClearColor(1, 1, 1, 1);
Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);
batch.setProjectionMatrix(camera.combined);
batch.begin();
batch.draw(sprite, sprite.getX(), sprite.getY(),sprite.getOriginX(), sprite.getOriginY(),
sprite.getWidth(), sprite.getHeight(), sprite.getScaleX(), sprite.getScaleY(), sprite.getRotation());
batch.draw(sprite2, sprite2.getX(), sprite2.getY(),sprite2.getOriginX(), sprite2.getOriginY(),
sprite2.getWidth(), sprite2.getHeight(), sprite2.getScaleX(), sprite2.getScaleY(), sprite2.getRotation());
batch.end();
}
#Override
public void dispose() {
img.dispose();
world.dispose();
}
private void createContactListener() {
world.setContactListener(new ContactListener() {
#Override
public void beginContact(Contact contact) {
// TODO Auto-generated method stub
Body bodyA = contact.getFixtureA().getBody();
Body bodyB = contact.getFixtureB().getBody();
Gdx.app.log("beginContact", "between " + bodyA.toString() + " and " + bodyB.toString());
}
#Override
public void endContact(Contact contact) {
// TODO Auto-generated method stub
Body bodyA = contact.getFixtureA().getBody();
Body bodyB = contact.getFixtureB().getBody();
Gdx.app.log("endContact", "between " + bodyA.toString() + " and " + bodyB.toString());
}
#Override
public void preSolve(Contact contact, Manifold oldManifold) {
// TODO Auto-generated method stub
}
#Override
public void postSolve(Contact contact, ContactImpulse impulse) {
// TODO Auto-generated method stub
}
});
}
}
And I have a question: Why this code cant detect contact between two dynamic bodies? It just can detect collision between a dynamic and a static body.
This is the expected result, as you are filtering the collision between the dynamic bodies:
fixtureDef2.filter.categoryBits = PHYSICS_ENTITY;
fixtureDef2.filter.maskBits = WORLD_ENTITY;
This says, that the fixtureDef2 is a PHYSICS_ENTITY (categoryBits) and should collide with WORLD_ENTITY (maskBits).
If you want it to collide with the PHYSICS_ENTITY to, you need to set the maskbits to PHYSICS_ENTITY | WORLD_ENTITY.
Basicly the collision filtering is done like this:
boolean collide = (filterA.maskBits & filterB.categoryBits) != 0 && (filterA.categoryBits & filterB.maskBits) != 0;
In your actual case this is:
0010 & 0001 != 0 && 0001 & 0010 != 0
which is false and therefore there is no collision.
Here you can read more about collision filtering.
i'm trying to make a program with Box2D and libgdx that makes the character jump on a static body (here, a circle). But my camera (that is following the dynamic body (the player)) keeps going down, even if my character stays on top of the circle as intended. So my questions are :
1) Why my camera keeps falling down, when it's supposed to follow the "playerBody" that is staying on top of the static body ?
2) Why my camera bounce when I press the Z key, but not my playerbody ?
Thanks in advance. You may try to run it in eclipse, to see better what I mean, here's what I put in my Activity class :
(I got no errors/warnings at all.)
//private SpriteBatch batch;
//private Texture texture;
//private Sprite sprite;
//public Body body;
World world;
Body playerBody;
Body planetBody;
CircleShape planetCircle;
PolygonShape playerBox;
OrthographicCamera camera;
Box2DDebugRenderer debugRenderer;
static final float BOX_STEP=1/60f;
static final int BOX_VELOCITY_ITERATIONS=6;
static final int BOX_POSITION_ITERATIONS=2;
static final float WORLD_TO_BOX=0.01f;
static final float BOX_WORLD_TO=100f;
boolean jump = false;
long lastGroundTime = 0;
#Override
public void create() {
world = new World(new Vector2(0, -50), true);
debugRenderer = new Box2DDebugRenderer();
camera = new OrthographicCamera();
camera.viewportHeight = 320;
camera.viewportWidth = 480;
camera.position.set(camera.viewportWidth * .5f, camera.viewportHeight * .5f, 0f);
camera.update();
//Ground body
/*BodyDef groundBodyDef =new BodyDef();
groundBodyDef.position.set(camera.viewportWidth / 2, camera.viewportHeight / 2 - 100 + 125);
Body groundBody = world.createBody(groundBodyDef);
PolygonShape groundBox = new PolygonShape();
groundBox.setAsBox((camera.viewportWidth) * 2, 10.0f);
groundBody.createFixture(groundBox, 0.0f);
*/
//Planet
BodyDef planetDef = new BodyDef();
planetDef.type = BodyType.StaticBody;
planetDef.position.set(camera.viewportWidth / 2, camera.viewportHeight / 2 - 100);
Body planetBody = world.createBody(planetDef);
CircleShape planetCircle = new CircleShape();
planetCircle.setRadius(125f);
FixtureDef planetFixtureDef = new FixtureDef();
planetFixtureDef.shape = planetCircle;
planetFixtureDef.density = 1.0f;
//planetFixtureDef.friction = 0.0f;
//planetFixtureDef.restitution = 0;
planetBody.createFixture(planetFixtureDef);
//Player
BodyDef playerBodyDef = new BodyDef();
playerBodyDef.type = BodyType.DynamicBody;
playerBodyDef.position.set(camera.viewportWidth / 2, camera.viewportHeight / 2 - 100 + 125 + 50);
playerBody = world.createBody(playerBodyDef);
PolygonShape playerBox = new PolygonShape();
playerBox.setAsBox(5.0f, 15.0f);
FixtureDef playerFixtureDef = new FixtureDef();
playerFixtureDef.shape = playerBox;
playerFixtureDef.density = 1.0f;
//playerFixtureDef.friction = 1.0f;
//playerFixtureDef.restitution = 1;
playerBody.createFixture(playerFixtureDef);
playerBody = world.createBody(playerBodyDef);
//Dynamic Body
/*BodyDef bodyDef = new BodyDef();
bodyDef.type = BodyType.DynamicBody;
bodyDef.position.set(camera.viewportWidth / 2, camera.viewportHeight / 2);
Body body = world.createBody(bodyDef);
CircleShape dynamicCircle = new CircleShape();
dynamicCircle.setRadius(5f);
FixtureDef fixtureDef = new FixtureDef();
fixtureDef.shape = dynamicCircle;
fixtureDef.density = 1.0f;
fixtureDef.friction = 0.0f;
fixtureDef.restitution = 1;
body.createFixture(fixtureDef); */
Gdx.input.setInputProcessor(this);
}
#Override
public void dispose() {
/*batch.dispose();
texture.dispose();*/
/*dynamicCircle.dispose();
groundBox.dispose();*/
playerBox.dispose();
planetCircle.dispose();
}
#Override
public void render() {
//Gdx.gl.glClearColor(1, 1, 1, 1);
update();
Gdx.gl.glClear(GL10.GL_COLOR_BUFFER_BIT);
/*batch.setProjectionMatrix(camera.combined);
batch.begin();
//sprite.draw(batch);
batch.end();*/
camera.position.set(playerBody.getPosition().x, playerBody.getPosition().y, 0);
camera.update();
//camera.apply(Gdx.gl10);
debugRenderer.render(world, camera.combined);
world.step(BOX_STEP, BOX_VELOCITY_ITERATIONS, BOX_POSITION_ITERATIONS);
//playerBody.setAwake(true);
}
#Override
public void resize(int width, int height) {
}
#Override
public void pause() {
}
public void update()
{
if(jump == true /*Gdx.input.isKeyPressed(Gdx.input.)*/ && grounded() == true)
{
playerBody.setLinearVelocity(0, 0);
playerBody.applyLinearImpulse(new Vector2(0,150), new Vector2(playerBody.getPosition().x, playerBody.getPosition().y));
jump = false;
}
//playerBody.setTransform(new Vector2(camera.viewportWidth / 2, playerBody.getPosition().y), playerBody.getAngle());
//planetBody.setTransform(new Vector2(camera.viewportWidth / 2, camera.viewportHeight / 2), 0);
}
#Override
public void resume() {
}
#Override
public boolean keyDown(int keycode) {
//if(keycode == Keys.S)
return false;
}
#Override
public boolean keyUp(int keycode) {
if(keycode == Keys.Z)
jump = true;
return false;
}
public boolean grounded()
{
if(playerBody.getPosition().y <= ((camera.viewportHeight / 2) - 100 + 125))
{
return true;
}
else
{
return false;
}
}
You are creating two playerBody in the world. The second one is assigned but has no fixture. This is the one you are manipulating in your code and your camera is following. Remove the second playerBody = world.createBody(playerBodyDef); and it should work (better).