I've an explosion in my SKScene and I want this Explosion even effect another objects close to its , Object are in all sides .I want to give them force to run away with this explosion .
It sounds like you need an SKFieldNode implementing a vortexField():
https://developer.apple.com/reference/spritekit/skfieldnode#1654415
SKFieldNode:
A node that applies physics effects to a portion of the scene.
vortextField()
Creates a field node that applies a perpendicular force to physics bodies.
Related
I am attempting to move a SKEmitterNode to follow a bullet in my game to give it a trailing effect however, no matter which way I attempt to implement this, it doesn't seem to work how I want it to and I'm at a loss for how to make this.
I have attempted to add the emitter to my main scene and manually moved the node a few times per second but it ends up not leaving a trail and keeping all the particles in one place like this:
Next I attempted to set the target node, however when I do this the trail goes for a bit then stops rather than following the bullet like it's supposed to. It also rotates and distorts from the rotation of the projectile like shown here:
For reference of the type of effect I'm looking for:
You should populate the targetNode property of your emitter with a node that is not moving like the scene.
emitterNode.targetNode = self // where self is the current scene
So I am playing around with SceneKit (in Swift), and for pure fun, creating an endless runner style game. In the game scene, I have a character moving forward on the z-axis. I have setup a few objects that are repeatedly created when the last expires. Most of these objects are under a node hierarchy. So, I have attempted these two methods for memory management:
Method 1: I have an invisible plane. Only 'special' parent node bodies can collide with this plane. So when the parent node's physics body collides with it, I remove it from the parent, which in result the node removes all of its children.
Method 2: Again I have an invisible plane. Except in this method everything I would potentially like to remove, can and does collide with the invisible plane on it's own accord. So in plain, everything collides with the invisible plane and removes itself from it's parent.
Now. Everything runs and works well. Except when it comes to removing nodes from their parents, I see a noticeable jolt in the framerate or speed of the game. Just for a second or so. With method 1, the jolt happens once for every time a parent node collides with my invisible plane. With method 2, the jolts are continuous and framerate is continuously low and jumpy.
I would be interested in hearing knowledge on ways of achieving something like this smoothly!
A big thanks in advance.
I am creating a 2D autoscroller and when my player (with a circle physicsBody) collides with an SKAction moveTo-powered obstacle which is moving towards it, it makes small, almost unnoticable lags. I tried lowering the friction and the density of the objects, but nothing helped. Any ideas?
You have chosen to use a circle with phycsicsBody. An SKPhysicsBody object is used to add physics simulation to a node. When a scene processes a new frame, it performs physics calculations on physics bodies attached to nodes in the scene. These calculations include gravity, friction, and collisions with other bodies. After the scene completes these calculations, it updates the positions and orientations of the node objects.
You have also chosen to use SKActions, when using the actions to move a body such changes don't go through the physics engine, indeed usually you could add unwanted actions and unexpected events as "bouncy lags".
So, if you're using physics to move a body, you shouldn't use move actions, apply an impulse or force, or set it's velocity directly
Setting restitution to zero may help. This controls the elasticity, or bounciness of a sprite.
What is an effective method to perform instantaneous hit detection in SpriteKit? Using SpriteKit's built in physics engine I want to collect affected objects during a single frame for situations such as an explosion's blast radius.
I have considered adding an SKNode with SKPhysicsBody to the explosive object and accessing its allContactedBodies property when it explodes but this would add unnecessary collision detection to other frames.
I have also considered adding an SKNode with SKPhysicsBody to the scene or altering an existing one at the time of explosion and using an action to remove or restore the node after a short duration but this feels unnecessarily complex and may delay the hit detection until the next frame.
I have wondered if there is a means to extend SKPhysicsWorld to allow for enumerating bodies with a circle in addition to a rectangle - or to extend SKPhysicsBody to allow manual collision detection with another test body.
However, I do not see how to access an SKPhysicsBody's shape data to do either of these.
If I were to tackle this problem I would do it by creating a node with a physics body and then messing with its dynamic, categoryBitMask, and collisionBitMask properties. I would set dynamic to false since theoretically the collision/explosion doesn't move because it hits other objects. I would set its categoryBitMask so that every object generated a "didBeginContact" report when colliding with it. And I would set its collisionBitMask so that it never caused impulses because of collision. This way the physicsBody is more of a probe then an actual physics object, just being what is their.
At the end of that the physics body should cause collision reports but not repel any objects. Obviously you can create this body and just not have it added to the scene until it is actually time to detect things. Then after that frame is over and you know all the physics bodies it touched you can remove it again.
Then I would set the scene as a physicsContactDelegate and impliment the did begin contact method.
class GameScene: Scene, SKPhysicsContactDelegate {
func didBeginContact(contact: SKPhysicsContact)
{
var AName:NSString = NSString(string: contact.bodyA.node!.name!)
var BName:NSString = NSString(string: contact.bodyB.node!.name!)
}
}
Then I would have if statements checking if either AName or BName were the name of your "probing" node/physicBody. Then after that you can add code to do whatever you want as a result of that collision.
Good luck! If you are having troubles with the bit mask properties I would strongly suggest checking out this.
I am new to Objective-C. I am currently working on a game using Cocos2D and Box2D. My problem is that when 3 objects collide together, the game crashes. Now let me describe my game in details:
In my game I have a main character standing on top of a building. Below the building there's this the road. Enemies pass by the road at various random speeds entering the screen from right and exiting from the left. I have created the enemies as b2_kinematicBodies and set a random velocity for each of them using SetLinearVelocity(). The main character shoots the enemies. The projectile (the object being shot) is a b2_dynamicBody. When the projectile hits the enemies, both the projectile and the enemy are destroyed. During gameplay sometimes an enemy moving at a slow speed is crossed by one which is moving at a higher speed. If a projectile hits the two enemies just at the point when they are overlapping and one is about to pass the other one, the game crashes! Please help me with this.
I have detected collision using b2contactListener class.
One thing I didn't mention before is that I am not creating the enemies as individual distinct bodies. Instead, I am creating it once and making it move and I am calling this method (which creates the enemies and makes them move) inside init as below:
[self schedule:#selector(addRightTarget) interval:2.0];
I believe the issue is that the collisions are calculated before your handler gets any calls. Meaning that when your handler gets called, the bullet has hit 2 objects. So you get 2 call-backs as shown below.
Collision Detected: Bullet + Enemy1
Destroy Enemy1
Destroy Bullet
Collision Detected: Bullet + Enemy2
Destroy Enemy2
Destroy Bullet [CRAAAASH!!! You just tried to delete a non-existent object]
1st: You should not be removing anything except in your step function (as someone mentioned in another answer)
2nd: Pick one of these:
Make your list/array of objects-to-delete be a 'set' or implemented in such a way that duplicates are avoided.
Check for existence of your object in the world
The collision only happens between 2 objects in Box2D. So in your mentioned scenario your will get multiple collision events which could be,
Enemy-1 and Enemy-2
Enemy-1 and Bullet
Enemy-2 and Bullet
So one possible reason of crash could be that you are not expecting (Enemy-1 and Enemy-2) collision and you are handling it like you have collision between (Enemy-1 and Bullet) so you might be casting it into wrong class. Make sure you are checking the kind of class "isKindOf" before casting it.
Also you may want to use Contact Filtering and or assign category masks to your enemies so that they don't collide with each other and only collide with bullet.
But it will be more help full if you tell something about how and where you destroy your bodies (I hope its not inside your Collision Detection Functions) and also if you can share the exception text when your application crash, that will be helpful.
I used a rather cheap workaround. I alternately created enemy fixtures of different sizes(differing by few pixels). So now if i shoot them even when they overlap, the app doesn't crash(because only the bigger object collides and gets destroyed). This serves my purpose. Thanx a llot for your help. I really appreciate it! :)