I have created a SCNNode object on a SCNPlane object. Both objects are added to the scene view root node, like below:
scView.scene.rootNode.addChildNode(ballNode)
scView.scene.rootNode.addChildNode(planeNode)
Now, my issue is that the ball node is moving out of the plane node boundary.
When I tried to add ballNode as planeNode's child then, the ball node is not getting added to a plane as expected. It behaves very strangely.
Basically, I need to restrict the movement of ballNode within planeNode area. How can I do it?
Great question!
When adding a child node to another node, there are no constraints being implicitly applied to the child, aside from existing within the infinite coordinate space of the parent node.
While changing the transform (eg position) of the parent node will directly apply to all child nodes, each child node can still freely transform within the parent nodes local coordinate space.
It'd be a good idea to read the SCNNode docs if you haven't already, as it covers the foundational aspects.
To do what you want, when moving the ball in your gameloop, you will need to manually check whether or not that ball is outside the boundary you are trying to enforce, and change its position accordingly.
Depending on your desired outcome, you may want to also check out SCNPhysicsBody as a way to construct your scene with implied physical boundaries.
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
I am working on a basic racing game using Apple's SceneKit and am running into issues simulating a car. Using the SCNPhysicsVehicle behavior, I am able to properly set up the car and drive it using the documented methods.
However, I am unable to get the car's position. It seems logical that the SCNPhysicsVehicle would move the SCNNodes that contain the chassis and the wheels as the car moves but the SCNNodes remain at their original position and orientation. Strangely enough, the chassis' SCNPhysicsBody's velocity remains accurate throughout the simulation so I can assume that the car's position is based off of the SCNPhysicsBody and not the SCNNode. Unfortunately, there is no documented method that I have found to get an SCNPhysicsBody's position.
Getting a car's position should be trivial and is essential to create a racing game but I can't seem to find any way of getting it. Any thoughts or suggestions would be appreciated.
Scene Kit automatically updates the position of the node that owns an SCNPhysicsBody based on the physics simulation, so SCNNode.position is the right property to look for.
The catch is that there are actually two versions of that node in play. The one you typically access is called the "model" node. It reflects the target values for properties you set, even if you set those properties through an animation. The presentationNode reflects the state of the node currently being rendered — if an animation is in progress, the node's properties have intermediate values, not the target values of the animation.
Actions, physics, constraints, and any scene graph changes you make inside update/render loop methods directly target the "presentation" version of your scene graph. So, to read node properties that have been set by the physics simulation, get the presentationNode for the node you're interested in (the node that owns the vehicle's chassisBody physics body), then read the presentation node's position (or other properties).
I have the same problem with my player node.
I move it with applyForce (to manage collision detection).
But when i check node position after some movement, the node position has not move (presentation node is the actual position as rickster write in his answer)
I manage to update the scnNode.position with renderer loop
You have to set position of your node with the presentationNode position.
node.position = node.presentationNode.position
Set this into renderer(_: updateAtTime) and your node position will sync with any animation you made to the physicsBody
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 have a parent SKSpriteNode which contains a number of child SKShapeNodes, SKSpriteNodes and SKLabelNodes arranged in specific X,Y position relative to the parent.
When I flip the parent by running an SKAction on it:
SKAction.scaleXTo(-1, duration: duration)
It flips the parent including the children (which I want) but the horizontal alignment of all the children nodes is randomized.
I must mention that I have
parent.anchorPoint = CGPoint(x: 0,y: 0)
The reason this is happening is because of your anchor point. Scaling (And all transformations) happens on this point. To test, take a piece of paper, put a pencil on the top left corner, then try moving the right side over to the left. leaving the pencil where it is. You will notice that the right side is now -width of the paper
What you need to do in this case, is add the width back in to keep the paper at the same location.
Same rule with the sprites. You have to add the width in when doing a negative scale, then remove the width when going back to a positive scale
(or just put your anchor in the center)
Geometrical transformation you apply to a node are automatically applied to its descendants.
This is why when you move/rotate/scale a node the children (and the grandchildren...) are updated as well.
If you want apply a transformation to your sprite without involving other nodes simply change the structure of you scene moving the children of your sprite like shown below.
As it is now
In this image the green circle is your sprite. In the left scenario when you change the green node, it's children are updated accordingly. And you don't want that.
As it should be
So move to the right scenario. Create a new SKNode (the orange one) and place it as shown below.
Now the green node has no children so you can apply geometrical transformation to it without any side effect.
Hi im pretty new to programming and I have encountered a small issue. I am creating a simple game which has a score label. However, the score label is covered whenever a downward scrolling obstacle passes. I would like for the score label to not be covered by the obstacles.Is there a way i can change the sprite hierarchy in spritekit? Thanks
I would recommend creating a node for the static stuff that should be fixed on screen (like a game HUD). Then you set this node's zPosition to be higher then the game play node (where all game objects are placed and manipulated).
This makes it also easier implementing a camera or moving the game play node if needed without the score label or any other fixed hud element moving as well.
So you will have something like this :
SKNode *hudNode = [SKNode node];
hudNode.zPosition = 1000;
[hudNode addChild:scoreLabel];
SKNode *gamePlayNode = [SKNode node];
gamePlayNode.zPosition = 0; // Not mandatory as it defaults to 0 but I put this here for clarification
[self addChild:hudNode]; // self is your scene instance
[self addChild:gamePlayNode];
You can change the zPosition property of your label node, by making it 100 it will be above all other nodes (default value is 0.0):
labelNode.zPosition = 100;
Nodes are drawn in the order they are added to the scene (or parent node). You can change the order in which nodes are drawn by setting their zPosition property.
From Apple's documentation...
...The z position is the node’s height relative to its parent node, much as a node’s position
property represents its x and y position relative to parent’s
position. So you use the z position to place a node above or below the
parent’s position.
When you take z positions into account, here is how the node tree is
rendered:
Each node’s global z position is calculated.
Nodes are drawn in order from smallest z value to largest z value.
If two nodes share the same z value, ancestors are rendered first, and siblings are rendered in child order.
You can also use zPosition to optimize rendering performance...
...it might be better if Sprite Kit could gather all of the nodes that share the same texture and drawing mode and and draw them with a single drawing pass. To enable these sorts of optimizations, you set the view’s ignoresSiblingOrder property to YES.