Box2d和LibGDX sprite与fixture不同步

Question

问题是当身体开始移动时，精灵会偏移。

我正在使用RUBE编辑器加载资产。

这是汽车的源代码：

public class Vehicle {

// Vehicle settings
public DriveMode driveMode = DriveMode.ALL_WHEEL_DIVE;
public SuspensionSetting suspensionSetting = SuspensionSetting.LOW;

private float suspensionFrequency = 5;
private float torque = 10f;
private float speedLimit = 6f;
private float SPIN_FACTOR = 0.8f;

public enum DriveMode {
    ALL_WHEEL_DIVE,
    REAR_WHEEL_DRIVE,
    FRONT_WHEEL_DRIVE
}

public enum SuspensionSetting {
    HIGH,
    NORMAL,
    LOW
}

// The body
public Body body;
private Sprite bodySprite;

// Wheels
public Body frontWheel;
public Body rearWheel;
private Sprite frontWheelSprite;
private Sprite rearWheelSprite;

// Temporary
private Vector2 tempPosition = new Vector2();

public Vehicle(RubeScene scene) {
    // Images
    RubeImage bodyImage = scene.getNamed(RubeImage.class, "body-image").first();
    RubeImage fwImage = scene.getNamed(RubeImage.class, "front-wheel-image").first();
    RubeImage rwImage = scene.getNamed(RubeImage.class, "rear-wheel-image").first();

    // Body
    Texture tempTexture;
    tempTexture = new Texture(bodyImage.file);
    bodySprite = new Sprite(tempTexture, tempTexture.getWidth(), tempTexture.getHeight());

    float tempWidth = bodyImage.width * PPM;
    float tempHeight = bodyImage.height * PPM;
    bodySprite.setSize(tempWidth, tempHeight);
    bodySprite.setOrigin(tempWidth / 2, tempHeight / 2);

    // Front wheel
    tempTexture = new Texture(fwImage.file);
    frontWheelSprite = new Sprite(tempTexture, tempTexture.getWidth(), tempTexture.getHeight());

    tempWidth = fwImage.width * PPM;
    tempHeight = fwImage.height * PPM;
    frontWheelSprite.setSize(tempWidth, tempHeight);
    frontWheelSprite.setOrigin(tempWidth / 2, tempHeight / 2);

    // Rear wheel
    tempTexture = new Texture(rwImage.file);
    rearWheelSprite = new Sprite(tempTexture, tempTexture.getWidth(), tempTexture.getHeight());

    tempWidth = rwImage.width * PPM;
    tempHeight = rwImage.height * PPM;
    rearWheelSprite.setSize(tempWidth, tempHeight);
    rearWheelSprite.setOrigin(tempWidth / 2, tempHeight / 2);

    body = bodyImage.body;
    rearWheel = rwImage.body;
    frontWheel = fwImage.body;
}

/**
 * Updates the positions and orientation of the sprites
 * @param delta elapsed time
 */
public void update(float delta) {
    // Update body
    tempPosition.set(body.getWorldCenter().scl(PPM).sub(bodySprite.getWidth() / 2, bodySprite.getHeight() / 2));
    bodySprite.setPosition(tempPosition.x, tempPosition.y);
    bodySprite.setRotation(body.getAngle() * MathUtils.radiansToDegrees);

    // Update front wheel
    tempPosition.set(frontWheel.getWorldCenter()).scl(PPM).sub(frontWheelSprite.getWidth() / 2, frontWheelSprite.getHeight() / 2);
    frontWheelSprite.setPosition(tempPosition.x, tempPosition.y);
    frontWheelSprite.setRotation(frontWheel.getAngle() * MathUtils.radiansToDegrees);

    // Update rear wheel
    tempPosition.set(rearWheel.getWorldCenter()).scl(PPM).sub(rearWheelSprite.getWidth() / 2, rearWheelSprite.getHeight() / 2);
    rearWheelSprite.setPosition(tempPosition.x, tempPosition.y);
    rearWheelSprite.setRotation(rearWheel.getAngle() * MathUtils.radiansToDegrees);

    // Limit the speed to 4 meters per second
    if (body.getLinearVelocity().x > speedLimit) {
        body.setLinearVelocity(speedLimit, body.getLinearVelocity().y);
    }
}

/**
 * Renders the graphics to the screen
 * @param sb initialized sprite batch
 */
public void render(SpriteBatch sb) {
    bodySprite.draw(sb);
    frontWheelSprite.draw(sb);
    rearWheelSprite.draw(sb);
}

public void driveForward(float delta) {

    // Rotate counter-clockwise
    body.applyTorque(SPIN_FACTOR, true);

    switch (driveMode) {
        case ALL_WHEEL_DIVE:
            frontWheel.applyTorque(-torque * delta, true);
            rearWheel.applyTorque(-torque * delta, true);
            break;
        case REAR_WHEEL_DRIVE:
            rearWheel.applyTorque(-torque * delta, true);
            break;
        case FRONT_WHEEL_DRIVE:
            frontWheel.applyTorque(-torque * delta, true);
            break;
    }
}

public void driveBackward(float delta) {

    // Rotate clockwise
    body.applyTorque(-SPIN_FACTOR, true);

    switch (driveMode) {
        case ALL_WHEEL_DIVE:
            frontWheel.applyTorque(torque * delta, true);
            rearWheel.applyTorque(torque * delta, true);
            break;
        case REAR_WHEEL_DRIVE:
            rearWheel.applyTorque(torque * delta, true);
            break;
        case FRONT_WHEEL_DRIVE:
            frontWheel.applyTorque(torque * delta, true);
            break;
    }
}

public void toggleDriveMode() {
    switch (driveMode) {
        case ALL_WHEEL_DIVE:
            driveMode = DriveMode.FRONT_WHEEL_DRIVE;
            break;
        case FRONT_WHEEL_DRIVE:
            driveMode = DriveMode.REAR_WHEEL_DRIVE;
            break;
        case REAR_WHEEL_DRIVE:
            driveMode = DriveMode.ALL_WHEEL_DIVE;
            break;
    }
}

public void toggleSuspensionSettings () {
    switch (suspensionSetting) {
        case HIGH:
            suspensionSetting = SuspensionSetting.LOW;
            suspensionFrequency = 6;
            break;
        case NORMAL:
            suspensionSetting = SuspensionSetting.HIGH;
            suspensionFrequency = 10;
            break;
        case LOW:
            suspensionSetting = SuspensionSetting.NORMAL;
            suspensionFrequency = 8;
            break;
    }
    this.setSuspensionFrequency();
}

private void setSuspensionFrequency() {
    Array<JointEdge> joints = body.getJointList();
    for (int i = 0; i < joints.size; i++) {
        Joint joint = joints.get(i).joint;
        if(joint.getType() == JointDef.JointType.WheelJoint) {
            ((WheelJoint)joint).setSpringFrequencyHz(suspensionFrequency);
        }
    }
}

}

我不知道为什么会这样。我尝试了不同类型车辆的相同代码，并且都产生相同的结果。夹具移动到图像之前。

Answer 1

事实证明渲染代码与更新代码混合在一起。