libGdx с разъемом для велосипеда колес Box2D

Question

Я использую фреймворк libGdx с редактором физики Box2D. Я не могу понять, что не так. Почему я не могу правильно совместить колеса с шасси. Колеса не удерживают шасси. Извини за ошибку. Здесь рис. то, что я получаю:

<img src='http://s4.postimg.org/a0d6ujpjt/test.jpg' border='0' alt="test" />

Код для моего приложения:

package com.ernestyno.test; 

import com.ernestyno.text.bodyeditorloader.BodyEditorLoader; 
import com.badlogic.gdx.Gdx; 
import com.badlogic.gdx.InputAdapter; 
import com.badlogic.gdx.graphics.Texture; 
import com.badlogic.gdx.graphics.Texture.TextureFilter; 
import com.badlogic.gdx.graphics.g2d.Sprite; 
import com.badlogic.gdx.graphics.g2d.SpriteBatch; 
import com.badlogic.gdx.math.MathUtils; 
import com.badlogic.gdx.math.Vector2; 
import com.badlogic.gdx.physics.box2d.Body; 
import com.badlogic.gdx.physics.box2d.BodyDef; 
import com.badlogic.gdx.physics.box2d.CircleShape; 
import com.badlogic.gdx.physics.box2d.BodyDef.BodyType; 
import com.badlogic.gdx.physics.box2d.FixtureDef; 
import com.badlogic.gdx.physics.box2d.World; 
import com.badlogic.gdx.physics.box2d.joints.WheelJoint; 
import com.badlogic.gdx.physics.box2d.joints.WheelJointDef; 

public class Dviratis extends InputAdapter { 
private World world; 
private float x, y, width; 

private Body dviracioRemasBody, kairysRatasBody, desinysRatasBody; 
private WheelJoint kairysRatasJoint, desinysRatasJoint; 
private Vector2 dviracioRemasOrigin, ratasOrigin; 
private Sprite remasSprite, kairysRatasSprite, desinysRatasSprite; 
private Texture remasTexture, ratasTexture; 

//FIXTURES 
private FixtureDef dviracioRemasFixture, dviracioRatoFixture; 

private float 
//REMAS FIXTURE DUOMENYS 
REMAS_DENSITY  = 5f, 
REMAS_FRICTION  = .4f, 
REMAS_RESTITUTION = .3f, 

//RATU FIXTURE DUOMENYS 
RATAS_DENSITY  = REMAS_DENSITY * 1.5f, 
RATAS_FRICTION  = 50f, 
RATAS_RESTITUTION = .4f; 

private String 
BODY_EDITOR_FILE  = "json/dviratis.json", 
BODY_EDITOR_REMAS_NAME = "DviracioRemas", 
BODY_EDITOR_RATAS_NAME = "ratas"; 

public Dviratis(World world, float x, float y, float width) { 
    this.world = world; 
    this.x = x; 
    this.y = y; 
    this.width = width; 

    this.setFixture(); 
    this.setSprite(); 
    this.setBody(); 
} 

public void setFixture() { 
    this.dviracioRemasFixture    = new FixtureDef(); 
    this.dviracioRatoFixture    = new FixtureDef(); 

    this.dviracioRemasFixture.density  = this.REMAS_DENSITY; 
    this.dviracioRemasFixture.friction  = this.REMAS_FRICTION; 
    this.dviracioRemasFixture.restitution = this.REMAS_RESTITUTION; 

    this.dviracioRatoFixture.density  = this.RATAS_DENSITY; 
    this.dviracioRatoFixture.friction  = this.RATAS_FRICTION; 
    this.dviracioRatoFixture.restitution = this.RATAS_RESTITUTION; 
} 

public void setSprite() { 
    this.remasTexture = new Texture(Gdx.files.internal("json/dviracio_remas.png")); 
    this.remasTexture.setFilter(TextureFilter.Linear, TextureFilter.Linear); 
    this.remasSprite = new Sprite(this.remasTexture); 
    this.remasSprite.setSize(this.width, this.width * this.remasSprite.getHeight()/this.remasSprite.getWidth()); 

    this.ratasTexture = new Texture(Gdx.files.internal("json/dviracio_ratas.png")); 
    this.ratasTexture.setFilter(TextureFilter.Linear, TextureFilter.Linear); 
    this.desinysRatasSprite = new Sprite(this.ratasTexture); 
    this.desinysRatasSprite.setSize(this.width/3, this.width/3); 

    this.kairysRatasSprite = new Sprite(this.ratasTexture); 
    this.kairysRatasSprite.setSize(this.width/3, this.width/3); 
} 

public void setBody() { 
    BodyDef bodyDef = new BodyDef(); 
    BodyEditorLoader loader = new BodyEditorLoader(Gdx.files.internal(this.BODY_EDITOR_FILE)); 

    bodyDef.type = BodyType.DynamicBody; 
    bodyDef.position.set(this.x, this.y); 

    this.dviracioRemasBody = this.world.createBody(bodyDef); 
    loader.attachFixture(this.dviracioRemasBody, this.BODY_EDITOR_REMAS_NAME, this.dviracioRemasFixture, this.width); 
    this.dviracioRemasOrigin = loader.getOrigin(this.BODY_EDITOR_REMAS_NAME, this.width).cpy(); 

    this.desinysRatasBody = this.world.createBody(bodyDef); 
    loader.attachFixture(this.desinysRatasBody, this.BODY_EDITOR_RATAS_NAME, this.dviracioRatoFixture, this.width/3); 

    this.kairysRatasBody = this.world.createBody(bodyDef); 
    loader.attachFixture(this.kairysRatasBody, this.BODY_EDITOR_RATAS_NAME, this.dviracioRatoFixture, this.width/3); 

    this.ratasOrigin = loader.getOrigin(this.BODY_EDITOR_RATAS_NAME, this.width).cpy(); 

    //masinos kairio rato susiejimas prie masinos kuno 
    WheelJointDef axisDef = new WheelJointDef(); 
    axisDef.bodyA = this.dviracioRemasBody; 
    axisDef.bodyB = this.desinysRatasBody; 
    //nuo centro ratu susiejimo atittraukimas i x ir y pozicija 
    axisDef.localAnchorA.set(0.73f, -0.45f); 
    axisDef.localAnchorB.set(0f, 0f); 
    axisDef.localAxisA.set(Vector2.Y); //Vector2.Y = new Vector2(0, 1); - ratu amortizacija y asije, o ne x asije 

    this.desinysRatasJoint = (WheelJoint) world.createJoint(axisDef); 

    axisDef.bodyB = this.kairysRatasBody; 
    axisDef.localAnchorA.set(-1f, -0.45f); 
    axisDef.frequencyHz = this.dviracioRemasFixture.density; //amortizatoriaus galia 
    axisDef.maxMotorTorque = this.dviracioRemasFixture.density * 10; //variklio galia 

    this.kairysRatasJoint = (WheelJoint) world.createJoint(axisDef); 
} 

public void render() { 
    Vector2 pozicija = this.dviracioRemasBody.getPosition().sub(this.dviracioRemasOrigin); 

    this.remasSprite.setPosition(pozicija.x, pozicija.y); 
    this.remasSprite.setOrigin(this.dviracioRemasOrigin.x, this.dviracioRemasOrigin.y); 
    this.remasSprite.setRotation(this.dviracioRemasBody.getAngle() * MathUtils.radiansToDegrees); 

    pozicija = this.desinysRatasBody.getPosition().sub(this.ratasOrigin); 

    this.desinysRatasSprite.setPosition(pozicija.x, pozicija.y); 
    this.desinysRatasSprite.setOrigin(this.ratasOrigin.x, this.ratasOrigin.y); 
    this.desinysRatasSprite.setRotation(this.desinysRatasBody.getAngle() * MathUtils.radiansToDegrees); 

    pozicija = this.kairysRatasBody.getPosition().sub(this.ratasOrigin); 

    this.kairysRatasSprite.setPosition(pozicija.x, pozicija.y); 
    this.kairysRatasSprite.setOrigin(this.ratasOrigin.x, this.ratasOrigin.y); 
    this.kairysRatasSprite.setRotation(this.kairysRatasBody.getAngle() * MathUtils.radiansToDegrees); 
} 

public void draw(SpriteBatch batch) { 
    this.remasSprite.draw(batch); 
    this.desinysRatasSprite.draw(batch); 
    this.kairysRatasSprite.draw(batch); 
} 

public Body getRemas() { 
    return dviracioRemasBody; 
} 

public Body getDviracioRemasBody() { 
    return dviracioRemasBody; 
} 
} 

Answer 1

Ха ... Я нашел, что это неправильно. Программа «физика-тело-редактор» генерирует неправильную центральную позицию круга в файле .json. Координаты - cx и cy. Поэтому я заменил файл BodyEditorLoader.java. Создал еще один метод attachFixture(), который позволяет описывать другие координаты круга.

Вместо для кругов:

loader.attachFixture(this.desinysRatasBody, this.BODY_EDITOR_RATAS_NAME, this.dviracioRatoFixture, this.width/3); 

Использование:

loader.attachFixture(this.desinysRatasBody, this.BODY_EDITOR_RATAS_NAME, this.dviracioRatoFixture, this.width/3, new Vector2(0,0)); 

Если вы хотите, вы можете скачать BodyEditorLoader file

Теперь мои колеса находится в правильном положении. Result image