Использование SKPhysicsBody для создания автомобиля

Question

Я пытаюсь сделать транспортное средство (в данном случае поездом) перемещаться на основе ввода проигрывателя. Если я двигаю поезд через SKAction, колеса не вращаются. Я мог бы использовать метод applyForce на физическом теле, но мне нужно больше контроля. Мне нужно сделать это на определенное расстояние за определенное время. Как это можно сделать?

-(void)didMoveToView:(SKView *)view { 
    SKTexture *trainBodyTexture = [SKTexture textureWithImageNamed:@"levelselect_trainbody"]; 
    SKSpriteNode *trainBody = [[SKSpriteNode alloc] initWithTexture:trainBodyTexture]; 
    trainBody.zPosition = 0; 
    trainBody.position = CGPointMake(300, 500); 
    trainBody.physicsBody = [SKPhysicsBody bodyWithRectangleOfSize:trainBody.size]; 
    [self addChild:trainBody]; 

    SKTexture *trainWheelTexture = [SKTexture textureWithImageNamed:@"levelselect_trainwheel"]; 
    SKSpriteNode *trainWheel1 = [[SKSpriteNode alloc] initWithTexture:trainWheelTexture]; 
    trainWheel1.zPosition = 1; 
    trainWheel1.physicsBody = [SKPhysicsBody bodyWithCircleOfRadius:trainWheel1.size.width/2]; 
    trainWheel1.physicsBody.allowsRotation = YES; 
    trainWheel1.position = CGPointMake(220, 400); 
    [self addChild:trainWheel1]; 

    SKSpriteNode *trainWheel2 = [[SKSpriteNode alloc] initWithTexture:trainWheelTexture]; 
    trainWheel2.zPosition = 1; 
    trainWheel2.physicsBody = [SKPhysicsBody bodyWithCircleOfRadius:trainWheel2.size.width/2]; 
    trainWheel2.physicsBody.allowsRotation = YES; 
    trainWheel2.position = CGPointMake(380, 400); 
    [self addChild:trainWheel2]; 

    SKShapeNode *dot = [SKShapeNode shapeNodeWithCircleOfRadius:10]; 
    dot.zPosition = 2; 
    dot.fillColor = [NSColor redColor]; 
    dot.position = CGPointMake(0, -20); 
    [trainWheel1 addChild:dot]; 

    SKPhysicsJointPin *pin = [SKPhysicsJointPin jointWithBodyA:trainBody.physicsBody bodyB:trainWheel1.physicsBody anchor:trainWheel1.position]; 
    SKPhysicsJointPin *pin2 = [SKPhysicsJointPin jointWithBodyA:trainBody.physicsBody bodyB:trainWheel2.physicsBody anchor:trainWheel2.position]; 

    [self.scene.physicsWorld addJoint:pin]; 
    [self.scene.physicsWorld addJoint:pin2]; 

    //[trainWheel1 runAction:[SKAction moveByX:300 y:0 duration:3]]; 
    [trainBody.physicsBody applyForce:CGVectorMake(3000, 0)]; 

} 

UPDATE: Реализован с поездом класса (предложенный Джафар Sheriff)

Train.h

#import <SpriteKit/SpriteKit.h> 

@interface Train : SKSpriteNode 

-(void) createPhysics; 
-(void) moveLeft; 
-(void) moveRight; 

@end 

Train.m

#import "Train.h" 

@interface Train() 

@property SKSpriteNode *trainBody, *trainWheelFront, *trainWheelRear; 
@property SKPhysicsWorld *physicsWorld; 

@end 

@implementation Train 

-(instancetype) init { 
    if (self = [super init]) { 
     [self initTrainBody]; 
     [self initWheels]; 
    } 
    return self; 
} 

-(void) initTrainBody { 
    SKTexture *trainBodyTexture = [SKTexture textureWithImageNamed:@"levelselect_trainbody"]; 
    _trainBody = [[SKSpriteNode alloc] initWithTexture:trainBodyTexture]; 
    _trainBody.zPosition = 0; 
    _trainBody.physicsBody = [SKPhysicsBody bodyWithRectangleOfSize:_trainBody.size]; 
    [self addChild:_trainBody]; 
} 

-(void) initWheels { 
    SKTexture *_trainWheelTexture = [SKTexture textureWithImageNamed:@"levelselect_trainwheel"]; 
    _trainWheelFront = [[SKSpriteNode alloc] initWithTexture:_trainWheelTexture]; 
    _trainWheelFront.zPosition = 1; 
    _trainWheelFront.physicsBody = [SKPhysicsBody bodyWithCircleOfRadius:_trainWheelFront.size.width/2]; 
    _trainWheelFront.physicsBody.allowsRotation = YES; 
    _trainWheelFront.position = CGPointMake(-80, -82); 
    [self addChild:_trainWheelFront]; 

    _trainWheelRear = [[SKSpriteNode alloc] initWithTexture:_trainWheelTexture]; 
    _trainWheelRear.zPosition = 1; 
    _trainWheelRear.physicsBody = [SKPhysicsBody bodyWithCircleOfRadius:_trainWheelRear.size.width/2]; 
    _trainWheelRear.physicsBody.allowsRotation = YES; 
    _trainWheelRear.position = CGPointMake(80, -82); 
    [self addChild:_trainWheelRear]; 

    //dot used to see if wheels are rotating, no other point 
    SKShapeNode *dot = [SKShapeNode shapeNodeWithCircleOfRadius:10]; 
    dot.zPosition = 2; 
    dot.fillColor = [NSColor redColor]; 
    dot.position = CGPointMake(0, -20); 
    [_trainWheelFront addChild:dot]; 
} 

//this method is called after the train node is added to the scene in GameScene otherwise will get error adding joints before node is in scene 
-(void) createPhysics { 
    SKPhysicsJointPin *pin = [SKPhysicsJointPin jointWithBodyA:_trainBody.physicsBody bodyB:_trainWheelFront.physicsBody anchor:_trainWheelFront.position]; 
    SKPhysicsJointPin *pin2 = [SKPhysicsJointPin jointWithBodyA:_trainBody.physicsBody bodyB:_trainWheelRear.physicsBody anchor:_trainWheelRear.position]; 

    [self.scene.physicsWorld addJoint:pin]; 
    [self.scene.physicsWorld addJoint:pin2]; 
} 

-(void) moveLeft { 
    SKAction *rotateLeft = [SKAction rotateByAngle:6*M_PI duration:0.2]; 
    [_trainWheelFront runAction:rotateLeft]; 
    [_trainWheelRear runAction:rotateLeft]; 
} 

-(void) moveRight { 
    SKAction *rotateRight = [SKAction rotateByAngle:-6*M_PI duration:0.2]; 
    [_trainWheelFront runAction:rotateRight]; 
    [_trainWheelRear runAction:rotateRight]; 
} 


@end 

GameScene.m

#import "GameScene.h" 
#import "Train.h" 

@interface GameScene() 

@property Train *train; 

@end 

@implementation GameScene 

-(void)didMoveToView:(SKView *)view { 
    [self initTrain]; 

    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyPressed:) name:@"KeyPressedNotificationKey" object:nil]; //using notifications and custom view class to handle key presses 

} 

-(void) initTrain { 
    _train = [[Train alloc] init]; 
    _train.position = CGPointMake(500, 300); 
    [self addChild:_train]; 
    [_train createPhysics]; 
} 

-(void)update:(CFTimeInterval)currentTime { 
    /* Called before each frame is rendered */ 
} 

-(void) keyPressed:(NSNotification*)notification { 
    NSNumber *keyCodeObject = notification.userInfo[@"keyCode"]; 
    NSInteger keyCode = keyCodeObject.integerValue; 
    NSLog(@"keycode = %lu", keyCode); 
    switch (keyCode) { 
     case 123: 
      [self leftArrowPressed]; 
      break; 
     case 124: 
      [self rightArrowPressed]; 
      break; 
    } 
} 

-(void) leftArrowPressed { 
    SKAction *moveLeft = [SKAction moveByX:-200 y:0 duration:0.2]; 
    [_train runAction:moveLeft]; 
    [_train moveLeft]; 
} 

-(void) rightArrowPressed { 
    SKAction *moveRight = [SKAction moveByX:200 y:0 duration:0.2]; 
    [_train runAction:moveRight]; 
    [_train moveRight]; 
} 

@end 

Примечание: Это решение приводит к тому, весь поезд, чтобы перевернуть и урод, когда левая/правая клавиши нажаты. Похоже, что мои контактные штыри неправильны, но они кажутся мне верными:/

Answer 1

По умолчанию Initializer of SkSpriteNode - - (instancetype)initWithTexture:(SKTexture *)texture color:(SKColor *)color size:(CGSize)size; Попробуйте это,

@interface Train : SKSpriteNode 
- (instancetype)initTrainWithColor:(UIColor *) color andSize:(CGSize) size; 
-(void) animateWheelsWithTime:(float) time; 
@end 


@interface Train() 
{ 
    SKSpriteNode *wheel1; 
    SKSpriteNode *wheel2; 
    NSMutableArray *wheelsArray; 
} 
@end 

@implementation Train 
- (instancetype)initTrainWithColor:(UIColor *) color andSize:(CGSize) size 
{ 
self = [super initWithTexture:nil color:color size:size]; 
if (self) 
{ 
    [self addWheels]; 
} 
return self; 
} 
    -(void)addWheels 
    { 
    wheelsArray = [[NSMutableArray alloc]init]; 
    wheel1 = [SKSpriteNode spriteNodeWithImageNamed:@"wheel"]; 
    [wheel1 setPosition:CGPointMake(-(self.frame.size.width/2.0f-wheel1.frame.size.width/2.0f), - (self.frame.size.height/2.0f - wheel1.frame.size.height/2.0f))]; 
[self addChild:wheel1]; 

wheel2 = [SKSpriteNode spriteNodeWithImageNamed:@"wheel"]; 
[wheel2 setPosition:CGPointMake((self.frame.size.width/2.0f-wheel2.frame.size.width/2.0f), - (self.frame.size.height/2.0f - wheel2.frame.size.height/2.0f))]; 
[self addChild:wheel2]; 

[wheelsArray addObject:wheel1]; 
[wheelsArray addObject:wheel2]; 
} 

-(void) animateWheelsWithTime:(float) time 
{ 
    for (SKSpriteNode *wheel in wheelsArray) 
     { 
     SKAction *act = [SKAction rotateByAngle:3*M_PI duration:time]; 
     [wheel runAction:act]; 
    } 
} 
@end 

В GameScene.m добавить поезд, как это,

-(void) addTrain 
    { 
     Train *train1 = [[Train alloc]initTrainWithColor:[UIColor yellowColor] andSize:CGSizeMake(150, 100)]; 
     [train1 setPosition:CGPointMake(self.size.width/2.0f, self.size.height/2.0f)]; 
    [self addChild:train1]; 

    SKAction *act = [SKAction moveTo:CGPointMake(self.size.width/2.0f, self.size.height - 50) duration:2]; 
    [train1 runAction:act]; 
    [train1 animateWheelsWithTime:2]; 
} 

Я попробовал, и это работает.