subclass - SpriteKit : How To Subclass SKNode to create a Vehicle class (complex object with joints)

Question

有没有人(本地)弄清楚如何对 SKNode 进行子类化以包含通过关节连接的多个物体 - 例如汽车？

似乎没有办法将子类的关节添加到父场景的物理世界属性中。

此外，当尝试编译并运行下面的对象时，即使没有关节，我也会收到 BAD_EXC_ACCESS 错误。

感谢@Smick 提供此处发布的初始车辆代码:Sprite Kit pin joints appear to have an incorrect anchor

卡车类别:

#import "Truck.h"

@implementation Truck


-(id)initWithPosition:(CGPoint)pos {


SKSpriteNode *carBody = [SKSpriteNode spriteNodeWithColor:[UIColor whiteColor] size:CGSizeMake(120, 8)];
carBody.physicsBody = [SKPhysicsBody bodyWithRectangleOfSize:carBody.size];
carBody.position = pos;
carBody.physicsBody.mass = 1.0;


SKSpriteNode *carTop = [SKSpriteNode spriteNodeWithColor:[UIColor whiteColor] size:CGSizeMake(50, 8)];
carTop.position = CGPointMake(230, 708);
carTop.physicsBody = [SKPhysicsBody bodyWithRectangleOfSize:carTop.size];
carTop.physicsBody.mass = 0;

SKPhysicsJointFixed *carBodyJoint = [SKPhysicsJointFixed jointWithBodyA:carBody.physicsBody
                                                                  bodyB:carTop.physicsBody
                                                                 anchor:CGPointMake(0, 0)];



return self;
}

+(Truck*)initWithPosition:(CGPoint)pos {
return [[self alloc] initWithPosition:pos];
}


@end

我的场景:

Answer 1

抱歉发帖晚了，但我自己就点击了这个。

除非附加的节点已添加到 SKScene 的场景图中，否则物理关节不起作用。

在上面的 initWithPosition 期间，情况并非如此。传递 SKScene 对我来说也不起作用，我怀疑是因为车辆节点仍未添加到场景图中。

您仍然可以将物理关节封装在类中，但必须在

之后调用另一个方法

[self addChild:car]

这是我对您已有的内容的改进:

车辆.h

@interface Vehicle : SKNode

@property (nonatomic) SKSpriteNode *leftWheel;
@property (nonatomic) SKSpriteNode *ctop;

-(id)initWithPosition:(CGPoint)pos;
-(void)initPhysics;

@end

车辆.m

//

#import "Vehicle.h"

@implementation Vehicle {
    SKSpriteNode *chassis;
    SKSpriteNode *rightWheel;
    SKSpriteNode *leftShockPost;
    SKSpriteNode *rightShockPost;
    int wheelOffsetY;
    CGFloat damping;
    CGFloat frequency;
}

- (SKSpriteNode*) makeWheel
{
    SKSpriteNode *wheel = [SKSpriteNode spriteNodeWithImageNamed:@"Wheel.png"];
    //    wheel.physicsBody = [SKPhysicsBody bodyWithCircleOfRadius:wheel.size.width/2];
    return wheel;
}

-(id)initWithPosition:(CGPoint)pos {

    if (self = [super init]) {

        wheelOffsetY    =   60;
        damping         =   1;
        frequency       =   4;

        chassis = [SKSpriteNode spriteNodeWithColor:[UIColor whiteColor] size:CGSizeMake(120, 8)];
        chassis.position = pos;
        [self addChild:chassis];

        _ctop = [SKSpriteNode spriteNodeWithColor:[UIColor greenColor] size:CGSizeMake(70, 16)];
        _ctop.position = CGPointMake(chassis.position.x+20, chassis.position.y+12);

        [self addChild:_ctop];

        _leftWheel = [self makeWheel];
        _leftWheel.position = CGPointMake(chassis.position.x - chassis.size.width / 2, chassis.position.y - wheelOffsetY);  //Always set position before physicsBody

        [self addChild:_leftWheel];

        rightWheel = [self makeWheel];
        rightWheel.position = CGPointMake(chassis.position.x + chassis.size.width / 2, chassis.position.y - wheelOffsetY);
        [self addChild:rightWheel];

        //------------- LEFT SUSPENSION ----------------------------------------------------------------------------------------------- //

        leftShockPost = [SKSpriteNode spriteNodeWithColor:[UIColor blueColor] size:CGSizeMake(7, wheelOffsetY)];
        leftShockPost.position = CGPointMake(chassis.position.x - chassis.size.width / 2, chassis.position.y - leftShockPost.size.height/2);
        [self addChild:leftShockPost];


        //------------- RIGHT SUSPENSION ----------------------------------------------------------------------------------------------- //

        rightShockPost = [SKSpriteNode spriteNodeWithColor:[UIColor blueColor] size:CGSizeMake(7, wheelOffsetY)];
        rightShockPost.position = CGPointMake(chassis.position.x + chassis.size.width / 2, chassis.position.y - rightShockPost.size.height/2);
        [self addChild:rightShockPost];

    }

    return self;
}

-(void) initPhysics {

    chassis.physicsBody = [SKPhysicsBody bodyWithRectangleOfSize:chassis.size];
    _ctop.physicsBody = [SKPhysicsBody bodyWithRectangleOfSize:_ctop.size];

    SKPhysicsJointFixed *cJoint = [SKPhysicsJointFixed jointWithBodyA:chassis.physicsBody
                                                                bodyB:_ctop.physicsBody
                                                               anchor:CGPointMake(_ctop.position.x, _ctop.position.y)];

    _leftWheel.physicsBody = [SKPhysicsBody bodyWithCircleOfRadius:_leftWheel.size.width/2];
    _leftWheel.physicsBody.allowsRotation = YES;

    rightWheel.physicsBody = [SKPhysicsBody bodyWithCircleOfRadius:rightWheel.size.width/2];
    rightWheel.physicsBody.allowsRotation = YES;

    leftShockPost.physicsBody = [SKPhysicsBody bodyWithRectangleOfSize:leftShockPost.size];
    SKPhysicsJointSliding  *leftSlide = [SKPhysicsJointSliding jointWithBodyA:chassis.physicsBody
                                                                        bodyB:leftShockPost.physicsBody
                                                                       anchor:CGPointMake(leftShockPost.position.x, leftShockPost.position.y)
                                                                         axis:CGVectorMake(0, 1)];

    leftSlide.shouldEnableLimits = TRUE;
    leftSlide.lowerDistanceLimit = 5;
    leftSlide.upperDistanceLimit = wheelOffsetY;


    SKPhysicsJointSpring *leftSpring = [SKPhysicsJointSpring jointWithBodyA:chassis.physicsBody bodyB:_leftWheel.physicsBody
                                                                    anchorA:CGPointMake(chassis.position.x - chassis.size.width / 2, chassis.position.y)
                                                                    anchorB:_leftWheel.position];
    leftSpring.damping = damping;
    leftSpring.frequency = frequency;

    SKPhysicsJointPin *lPin = [SKPhysicsJointPin jointWithBodyA:leftShockPost.physicsBody bodyB:_leftWheel.physicsBody anchor:_leftWheel.position];

    rightShockPost.physicsBody = [SKPhysicsBody bodyWithRectangleOfSize:rightShockPost.size];
    SKPhysicsJointSliding  *rightSlide = [SKPhysicsJointSliding jointWithBodyA:chassis.physicsBody
                                                                         bodyB:rightShockPost.physicsBody
                                                                        anchor:CGPointMake(rightShockPost.position.x, rightShockPost.position.y)
                                                                          axis:CGVectorMake(0, 1)];

    rightSlide.shouldEnableLimits = TRUE;
    rightSlide.lowerDistanceLimit = 5;
    rightSlide.upperDistanceLimit = wheelOffsetY;


    SKPhysicsJointSpring *rightSpring = [SKPhysicsJointSpring jointWithBodyA:chassis.physicsBody bodyB:rightWheel.physicsBody
                                                                     anchorA:CGPointMake(chassis.position.x + chassis.size.width / 2, chassis.position.y)
                                                                     anchorB:rightWheel.position];
    rightSpring.damping = damping;
    rightSpring.frequency = frequency;

    SKPhysicsJointPin *rPin = [SKPhysicsJointPin jointWithBodyA:rightShockPost.physicsBody bodyB:rightWheel.physicsBody anchor:rightWheel.position];

    // Add all joints to the array.
    // Add joints to scene's physics world

    [self.scene.physicsWorld addJoint: cJoint];
    [self.scene.physicsWorld addJoint: leftSlide];
    [self.scene.physicsWorld addJoint: leftSpring];
    [self.scene.physicsWorld addJoint: lPin];
    [self.scene.physicsWorld addJoint: rightSlide];
    [self.scene.physicsWorld addJoint: rightSpring];
    [self.scene.physicsWorld addJoint: rPin];

}
@end

并从 MyScene.m 调用它

_car = [[DMVehicle alloc] initWithPosition:location];
[self addChild:_car];
[_car initPhysics];

希望有所帮助，我知道它对我的工作有所帮助