I have a SpriteKit game in which there are balls that bounce around. Despite using a texture atlas (a .spriteatlas folder located in my .xcassets folder), I'm getting 2 draw calls for each ball.
Some facts:
The balls are SKSpriteNode's.
Each ball is a parent node that has a child node (an overlay with the opposite rotation of the ball to provide the illusion of lighting/shadow). So, we're talking about 2 nodes for each ball.
The balls' textures are preloaded up front and stored in memory via textureNamed(_:).
I have set view.ignoresSiblingOrder = true.
There is no SpriteKit background image that would make the balls render on top of another node; the background is transparent. So, the balls do not overlap other content.
zPosition is not set -- not on the parent and not on the child.
Based on what I've learned about how the scene is rendered, I would expect to see all the parent nodes rendered in a single pass, with additional passes for the child nodes (though, even that is suspicious since I have ignoresSiblingOrder set to true).
What am I not understanding, here? Why does my draw count increase so drastically as more balls are added to the scene?
Thank you!
UPDATE:
If I don't add the child nodes to the balls, the draw count for the balls is 1 regardless of how many balls there are. So, it's definitely an issue with the child nodes, not the parents.
I solved the problem by setting zPosition to the same value on both the parent and child.
parentNode.zPosition = 1.0
childNode.zPosition = 1.0
There are now a total of 2 draws for the balls regardless of how many balls there are.
Related
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.
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
I've coded some cannonballs in a 2d game which has a 45 degree vertical to horizontal viewpoint. They are spawned using a prefab, and then spawn an explosion prefab upon their destruction. They then are spawn on top of each other in a random order. Is there a way to set further forwards object (In my case lower in the y axis) to be further forwards in the same layer, without creating individual prefabs for each explosion with different sorting layers?
I don't know of any built-in way to do that, but how about attaching a script to the cannonballs that will assign the sprite renderer's "order in layer" to -transform.y * 10 (adjust the *10 as needed to accomodate your scale)?
I am having an issue with the zPosition undesirably changing when a node is touched.
I can't give a simple code example because currently my scene and rendering is quite complex. Everything is drawn correctly when the scene is presented and for the most part besides as described below it works.
So the issue explained - we have a base image node correctly rendered below a tower node (tower defence game). The tower is circular and the base image is square, so the corners stick out. If you manage to touch the corners, for some reason beyond my knowledge, the zPosition changes to above the tower.
There is no particular code on touches to change any zPositions of anything in the game.
I know this is a shot in the dark, but any insight would be great and much appreciated.
If your view's ignoreSiblingOrder property is set, you should set the zPosition of each node, appropriately, to ensure that they are drawn in the correct order.
From Apple's documentation...
The default value (of SKView's ignoreSiblingOrder property) is NO,
which means that when multiple nodes share the same z position, those
nodes are sorted and rendered in a deterministic order. Parents are
rendered before their children, and siblings are rendered from eldest
to youngest. When this property is set to YES, the position of the
nodes in the tree is ignored when determining the rendering order.
The rendering order of nodes at the same z position is arbitrary and may change every time a new frame is rendered [emphasis added].
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.