模拟水/使精灵“浮动”。在spritekit中的水 [英] Simulate water/ make sprite "float" on water in spritekit
问题描述
我正在尝试为我的游戏加水。除了不同的背景颜色，它没有多少。
但是，我希望 player-sprite 浮在它上面（或者在其中间）。如果玩家只是从下面走进水里，我希望他漂浮到顶端。如果他摔倒了，我希望他慢慢改变方向然后再回来。
I'm trying to add water to my game. Except for a different background color, there isn't much to it.
However, I'd like the player-sprite to float on top of it (or halfway in it). If the player just walks into the water from below, I'd like him to float to the top. If he falls down, I'd like him to slowly change direction and float back up.
我尝试在水中时使重力为负，但这给了我一些略微不受欢迎的效果。例如，当他（玩家）浮出水面时，正常的重力会将他推倒，水将推动他，等等。最终，玩家将在水中弹跳，从一端推到另一端。当他浮出水面时，我希望他能够平静地留在水面上。我怎样才能实现这个目标？
I tried making the gravity negative when he's in the water, but this gives me some slightly unwanted effects. For example as he (the player) surfaces, the normal gravity will push him back down, the water will push him up, and so on. Ultimately the player will be "bouncing" in the water, being pushed from one end to another. I'd like him to calmly remain on top of the water when he surfaces. How can I achieve this?
这是我在 update-loop 中的代码：
SKNode *backgroundNodeAtPoint = [_bgLayer nodeAtPoint:_ball.position];
if ([backgroundNodeAtPoint.name isEqualToString:@"WATER"]) {
self.physicsWorld.gravity = CGVectorMake(self.physicsWorld.gravity.dx, 2);
} else {
if (self.physicsWorld.gravity.dy != -4) {
self.physicsWorld.gravity = CGVectorMake(self.physicsWorld.gravity.dx, -4);
}
}
基本上这会将我的引力改为 -4 ，除非它已经 -4 。
Basically this changes my gravity to 2 when the player is in the water, and otherwise changes it to -4 unless it's already -4.
谢谢！
推荐答案
我相信你有三种可能的选择有关模拟水的问题。
There are three possible options I believe you have with regards to simulating water.
1）如评论中所述，您可以尝试使用SKFieldNode（iOS 8+）。但是从个人经验来看，现场节点对我来说并没有真正做到这一点，因为除非你对其进行大量定制，否则你无法用它来控制你的模拟，在这种情况下你也可以从头开始自己进行计算并减少复杂性。
1) As mentioned in the comments you could try to use SKFieldNode (iOS 8+). But from personal experience the field node didn't really do it for me because you don't get much control over your simulation with it unless you heavily customize it, in which case you might as well just do your own calculations from scratch and reduce complexity.
2）你可以在水中调整精灵的线性和旋转阻尼。事实上，甚至苹果在他们的文档引用中都提到了这一点。然而，这不会给你带来浮力。
2) You could adjust the linear and rotational damping of your sprite when inside the water. In fact, even apple mentions this in the quote from their documentation. However this won't give you buoyancy.
linearDamping和angularDamping属性用于计算身体上的
摩擦力，因为它穿越世界。例如，这个
可能用于模拟空气或水的摩擦。
The linearDamping and angularDamping properties are used to calculate friction on the body as it moves through the world. For example, this might be used to simulate air or water friction.
3）自己进行计算。在更新方法中，检查身体何时进入水，何时进入，您可以计算粘度和/或浮力，并相应地调整节点的速度。在我看来，这是最好的选择，但也更难。
3) Perform the calculations yourself. In the update method, check when the body enters you "water" and when it does you can calculate viscosity and/or buoyancy and adjust the velocity of your node accordingly. This in my opinion is the best option but also the more difficult.
编辑：我刚刚在Swift中写了一个选项3的快速示例。我认为这就是你要找的东西。我在顶部添加了因子常数，因此您可以调整它以获得您想要的结果。动作是动态应用的，因此它不会干扰你当前的速度（即你可以在水中控制你的角色）。下面是场景的代码和gif。请记住，增量时间假设为每秒60帧（1/60）并且没有速度钳制。根据您的游戏，这些是您可能想要或不想要的功能。
Edit: I just wrote a quick example of option 3 in Swift. I think it's what you are looking for. I added factor constants on the top so you can adjust it to get exactly what you want. The motion is applied dynamically so it won't interfere with you current velocity (i.e. you can control your character while in the water). Below is the code for the scene and a gif as well. Keep in mind that the delta time is assumed to be 60 frames a second (1/60) and there is no velocity clamping. These are features you may or may not want depending on your game.
Swift
class GameScene: SKScene {
//MARK: Factors
let VISCOSITY: CGFloat = 6 //Increase to make the water "thicker/stickier," creating more friction.
let BUOYANCY: CGFloat = 0.4 //Slightly increase to make the object "float up faster," more buoyant.
let OFFSET: CGFloat = 70 //Increase to make the object float to the surface higher.
//MARK: -
var object: SKSpriteNode!
var water: SKSpriteNode!
override func didMoveToView(view: SKView) {
object = SKSpriteNode(color: UIColor.whiteColor(), size: CGSize(width: 25, height: 50))
object.physicsBody = SKPhysicsBody(rectangleOfSize: object.size)
object.position = CGPoint(x: self.size.width/2.0, y: self.size.height-50)
self.addChild(object)
water = SKSpriteNode(color: UIColor.cyanColor(), size: CGSize(width: self.size.width, height: 300))
water.position = CGPoint(x: self.size.width/2.0, y: water.size.height/2.0)
water.alpha = 0.5
self.addChild(water)
self.physicsBody = SKPhysicsBody(edgeLoopFromRect: self.frame)
}
override func update(currentTime: CFTimeInterval) {
if water.frame.contains(CGPoint(x:object.position.x, y:object.position.y-object.size.height/2.0)) {
let rate: CGFloat = 0.01; //Controls rate of applied motion. You shouldn't really need to touch this.
let disp = (((water.position.y+OFFSET)+water.size.height/2.0)-((object.position.y)-object.size.height/2.0)) * BUOYANCY
let targetPos = CGPoint(x: object.position.x, y: object.position.y+disp)
let targetVel = CGPoint(x: (targetPos.x-object.position.x)/(1.0/60.0), y: (targetPos.y-object.position.y)/(1.0/60.0))
let relVel: CGVector = CGVector(dx:targetVel.x-object.physicsBody.velocity.dx*VISCOSITY, dy:targetVel.y-object.physicsBody.velocity.dy*VISCOSITY);
object.physicsBody.velocity=CGVector(dx:object.physicsBody.velocity.dx+relVel.dx*rate, dy:object.physicsBody.velocity.dy+relVel.dy*rate);
}
}
override func touchesEnded(touches: NSSet!, withEvent event: UIEvent!) {object.position = (touches.anyObject() as UITouch).locationInNode(self);object.physicsBody.velocity = CGVectorMake(0, 0)}
}
目标-C
#import "GameScene.h"
#define VISCOSITY 6.0 //Increase to make the water "thicker/stickier," creating more friction.
#define BUOYANCY 0.4 //Slightly increase to make the object "float up faster," more buoyant.
#define OFFSET 70.0 //Increase to make the object float to the surface higher.
@interface GameScene ()
@property (nonatomic, strong) SKSpriteNode* object;
@property (nonatomic, strong) SKSpriteNode* water;
@end
@implementation GameScene
-(void)didMoveToView:(SKView *)view {
_object = [[SKSpriteNode alloc] initWithColor:[UIColor whiteColor] size:CGSizeMake(25, 50)];
self.object.physicsBody = [SKPhysicsBody bodyWithRectangleOfSize:self.object.size];
self.object.position = CGPointMake(self.size.width/2.0, self.size.height-50);
[self addChild:self.object];
_water = [[SKSpriteNode alloc] initWithColor:[UIColor cyanColor] size:CGSizeMake(self.size.width, 300)];
self.water.position = CGPointMake(self.size.width/2.0, self.water.size.height/2.0);
self.water.alpha = 0.5;
[self addChild:self.water];
self.physicsBody = [SKPhysicsBody bodyWithEdgeLoopFromRect:self.frame];
}
-(void)update:(NSTimeInterval)currentTime {
if (CGRectContainsPoint(self.water.frame, CGPointMake(self.object.position.x,self.object.position.y-self.object.size.height/2.0))) {
const CGFloat rate = 0.01; //Controls rate of applied motion. You shouldn't really need to touch this.
const CGFloat disp = (((self.water.position.y+OFFSET)+self.water.size.height/2.0)-((self.object.position.y)-self.object.size.height/2.0)) * BUOYANCY;
const CGPoint targetPos = CGPointMake(self.object.position.x, self.object.position.y+disp);
const CGPoint targetVel = CGPointMake((targetPos.x-self.object.position.x)/(1.0/60.0), (targetPos.y-self.object.position.y)/(1.0/60.0));
const CGVector relVel = CGVectorMake(targetVel.x-self.object.physicsBody.velocity.dx*VISCOSITY, targetVel.y-self.object.physicsBody.velocity.dy*VISCOSITY);
self.object.physicsBody.velocity=CGVectorMake(self.object.physicsBody.velocity.dx+relVel.dx*rate, self.object.physicsBody.velocity.dy+relVel.dy*rate);
}
}
-(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
self.object.position = [(UITouch*)[touches anyObject] locationInNode:self];
self.object.physicsBody.velocity = CGVectorMake(0, 0);
}
@end
这篇关于模拟水/使精灵“浮动”。在spritekit中的水的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
