首先，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
我正在尝试在车轮(左轮)和底盘之间添加一个滑动接头，以及一个 Spring 接头，以产生减震效果。
使用下面的代码，我没有压缩。我意识到文档显示了一个 Spring 接头将两个预兆拉在一起 - 与我想要的相反。这在SK有可能吗？
我认为销接头可能是罪魁祸首？当我注释掉销钉接头时，汽车零件就会乱七八糟 - 一切都在屏幕上飞来飞去。最初，销接头将车轮固定在底盘上，但显然我想将车轮固定在“减震器”上。
此外，SKPhysicsJointSliding 的“轴”参数让我有点困惑。它需要一个向量。相对于 ?
先感谢您。
- (SKShapeNode*) makeWheel
{
SKShapeNode *wheel = [[SKShapeNode alloc] init];
CGMutablePathRef myPath = CGPathCreateMutable();
CGPathAddArc(myPath, NULL, 0,0, 16, 0, M_PI*2, YES);
wheel.path = myPath;
wheel.physicsBody.mass = 0.5;
return wheel;
}
- (void) createCar{
// 1. car body
SKSpriteNode *carBody = [SKSpriteNode spriteNodeWithColor:[UIColor whiteColor] size:CGSizeMake(120, 8)];
carBody.position = CGPointMake(200, 700);
carBody.physicsBody = [SKPhysicsBody bodyWithRectangleOfSize:carBody.size];
carBody.physicsBody.mass = 1.0;
[self addChild:carBody];
// 2. wheels
SKShapeNode *leftWheel = [self makeWheel];
leftWheel.position = CGPointMake(carBody.position.x - carBody.size.width / 2, carBody.position.y-40);
leftWheel.physicsBody = [SKPhysicsBody bodyWithCircleOfRadius:16];
[self addChild:leftWheel];
SKShapeNode *rightWheel = [self makeWheel];
rightWheel.position = CGPointMake(carBody.position.x + carBody.size.width / 2, carBody.position.y);
rightWheel.physicsBody = [SKPhysicsBody bodyWithCircleOfRadius:16];
[self addChild:rightWheel];
/* Build left shock absorber and attach wheel */
CGVector av =CGVectorMake(0.0, 5.0);
SKPhysicsJointSliding *leftSlide = [SKPhysicsJointSliding jointWithBodyA:carBody.physicsBody
bodyB:leftWheel.physicsBody
anchor:leftWheel.position
axis:av];
SKPhysicsJointSpring *leftSpring = [SKPhysicsJointSpring jointWithBodyA:carBody.physicsBody bodyB:leftWheel.physicsBody
anchorA:CGPointMake(carBody.position.x - carBody.size.width / 2, carBody.position.y)
anchorB:leftWheel.position];
SKPhysicsJointPin *leftPin = [SKPhysicsJointPin jointWithBodyA:leftSpring.bodyA
bodyB:leftSpring.bodyB
anchor:leftWheel.position];
[self.physicsWorld addJoint:leftSlide];
[self.physicsWorld addJoint:leftSpring];
[self.physicsWorld addJoint:leftPin];
[self.physicsWorld addJoint:[SKPhysicsJointPin jointWithBodyA:carBody.physicsBody bodyB:rightWheel.physicsBody anchor:rightWheel.position]];
}
最佳答案
编辑我的答案。悬架需要将车轮连接到滑动体上，而不是通过滑动接头连接车轮。做前者可以让轮子旋转。后者没有。
车辆.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
关于ios - SpriteKit - Spring 接头(减震器)，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/20257015/