这就是我想出的。
我唯一的问题是它不是完全独立的，因为关节必须添加到类之外的物理世界中 - 很简单，你会看到使用两行代码。
编辑我的答案。与通过滑动接头连接车轮相比，悬架需要将车轮连接到滑动体上。做前者可以让轮子旋转。后者没有。
更新：我已取消将此标记为答案。原因是，虽然它在模拟器上运行良好，但当我尝试在我的 iPad（运行 iOS7）上运行它时收到以下错误。当我删除我的车辆类并将使用该 UIColor 方法的车辆组件之一放入我的主场景时，不会引发错误。
UICachedDeviceWhiteColor addObject:]: unrecognized selector sent to instance 0x15e21360
2013-12-14 22:44:19.790 SKTestCase[1401:60b] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[UICachedDeviceWhiteColor addObject:]: unrecognized selector sent to instance
由于某种原因，我不再收到 UICashed... 错误（是的，车辆仍然是一个类）现在我收到：
-[PKPhysicsJointWeld name]: unrecognized selector sent to instance 0x1464f810
2013-12-15 15:28:24.081 MTC[1747:60b] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[PKPhysicsJointWeld name]: unrecognized selector sent to instance 0x1464f810'
*** First throw call stack:
(0x30eaff53 0x3b5186af 0x30eb38e7 0x30eb21d3 0x30e01598 0x3352837d 0x335284d5 0x33527b97 0x33525ca5 0x87385 0x335064f5 0x87ccb 0x33620fe1 0x332aa24b 0x332a5a5b 0x332d4b7d 0x3369e39b 0x3369ca03 0x3369bc53 0x3369bbdb 0x3369bb73 0x33694681 0x3362703f 0x3369b8c1 0x3369b38d 0x3362c21d 0x33629763 0x33694a55 0x33691811 0x3368bd13 0x336266a7 0x336259a9 0x3368b4fd 0x35ab270d 0x35ab22f7 0x30e7a9e7 0x30e7a983 0x30e79157 0x30de3ce7 0x30de3acb 0x3368a799 0x33685a41 0x8a52d 0x3ba20ab7)
libc++abi.dylib: terminating with uncaught exception of type NSException
车辆.h：
#import <SpriteKit/SpriteKit.h>
@interface Vehicle : SKNode
@property (nonatomic,assign) NSMutableArray *joints;
@property (nonatomic) SKSpriteNode *leftWheel;
@property (nonatomic) SKSpriteNode *ctop;
-(id)initWithPosition:(CGPoint)pos;
@end
Vehicle.m
#import "Vehicle.h"
@implementation Vehicle
- (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]) {
_joints = [NSMutableArray array];
int wheelOffsetY = 60;
CGFloat damping = 1;
CGFloat frequency = 4;
SKSpriteNode *chassis = [SKSpriteNode spriteNodeWithColor:[UIColor whiteColor] size:CGSizeMake(120, 8)];
chassis.position = pos;
chassis.physicsBody = [SKPhysicsBody bodyWithRectangleOfSize:chassis.size];
[self addChild:chassis];
_ctop = [SKSpriteNode spriteNodeWithColor:[UIColor greenColor] size:CGSizeMake(70, 16)];
_ctop.position = CGPointMake(chassis.position.x+20, chassis.position.y+12);
_ctop.physicsBody = [SKPhysicsBody bodyWithRectangleOfSize:_ctop.size];
[self addChild:_ctop];
SKPhysicsJointFixed *cJoint = [SKPhysicsJointFixed jointWithBodyA:chassis.physicsBody
bodyB:_ctop.physicsBody
anchor:CGPointMake(_ctop.position.x, _ctop.position.y)];
_leftWheel = [self makeWheel];
_leftWheel.position = CGPointMake(chassis.position.x - chassis.size.width / 2, chassis.position.y - wheelOffsetY); //Always set position before physicsBody
_leftWheel.physicsBody = [SKPhysicsBody bodyWithCircleOfRadius:_leftWheel.size.width/2];
_leftWheel.physicsBody.allowsRotation = YES;
[self addChild:_leftWheel];
SKSpriteNode *rightWheel = [self makeWheel];
rightWheel.position = CGPointMake(chassis.position.x + chassis.size.width / 2, chassis.position.y - wheelOffsetY);
rightWheel.physicsBody = [SKPhysicsBody bodyWithCircleOfRadius:rightWheel.size.width/2];
rightWheel.physicsBody.allowsRotation = YES;
[self addChild:rightWheel];
//------------- LEFT SUSPENSION ----------------------------------------------------------------------------------------------- //
SKSpriteNode *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);
leftShockPost.physicsBody = [SKPhysicsBody bodyWithRectangleOfSize:leftShockPost.size];
[self addChild:leftShockPost];
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];
//------------- RIGHT SUSPENSION ----------------------------------------------------------------------------------------------- //
SKSpriteNode *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);
rightShockPost.physicsBody = [SKPhysicsBody bodyWithRectangleOfSize:rightShockPost.size];
[self addChild:rightShockPost];
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.
[_joints addObject:cJoint];
[_joints addObject:leftSlide];
[_joints addObject:leftSpring];
[_joints addObject:lPin];
[_joints addObject:rightSlide];
[_joints addObject:rightSpring];
[_joints addObject:rPin];
}
return self;
}
@end
MyScene.m：
#import "MyScene.h"
#import "Vehicle.h"
@implementation MyScene {
Vehicle *car;
}
-(id)initWithSize:(CGSize)size {
if (self = [super initWithSize:size]) {
/* Setup your scene here */
self.physicsBody = [SKPhysicsBody bodyWithEdgeLoopFromRect:CGRectMake(0, 0, self.size.width, self.size.height)];
}
return self;
}
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
/* Called when a touch begins */
for (UITouch *touch in touches) {
CGPoint location = [touch locationInNode:self];
car = [[Vehicle alloc] initWithPosition:location];
[self addChild:car];
// Add joints to scene's physics world
for (SKPhysicsJoint *j in car.joints) {
[self.physicsWorld addJoint:j];
}
}
}