I have a series of (flat plane) nodes in my scene that I need to have constantly facing the camera.
How can I adjust the transform/rotation to get this working?
Also, where do I make this calculation?
Currently I am trying to make it happen on user interaction in the SCNSceneRendererDelegate renderer:updateAtTime: delegate method.
How about an SCNBillboardConstraint? That restricts you to iOS 9/El Capitan/tvOS. Add the constraint to each of your flat plane (billboard) nodes.
From the SceneKit Framework Reference: https://developer.apple.com/library/ios/documentation/SceneKit/Reference/SCNBillboardConstraint_Class/index.html
An SCNBillboardConstraint object automatically adjusts a node’s orientation so that it always points toward the pointOfView node currently being used to render the scene.
In the more general case, SCNLookAtConstraint will keep any node's minus-Z axis pointed toward any other node.
Related
I'm using SceneKit with ARKit, and right now have a simple app where I tap on the screen and it adds an ARAnchor and a SCNNode to my scene.
At some point, I'm going to want to move the entire scene, so I tried changing sceneView.scene.rootNode.position.x += 10 to test this out. If I call this on any particular node, that node does move appropriately. But calling this on rootNode, nothing happens, where I'd expect every child node (which is every node in the scene) to move along with it.
Why are my other nodes not moving appropriately, and is there something I can do to fix this? Or am I thinking about this wrong?
Per the docs for SCNScene.rootNode:
You should not modify the transform property of the root node.
The root node defines the origin of the world coordinate system — all other measurements are relative to it. Hence, it's not meaningful (and is often problematic) to change its position, orientation, scale, or any other aspect of its transform.
If you want to move all the content in your SceneKit scene, create a new node to contain all of the others, and change that node's transform. (You can't do this for nodes added by ARSCNView, because ARKit makes those direct children of the root node, but the whole point of those is positioning them in world space.)
SKNode has a position property which represents the node's position in parent. Whereas GKAgent2D also has a position property which according to the documentation is its position in 2D space. How are these two related? And how do we convert between each other and is a conversion necessary?
You can use GameplayKit without SpriteKit. The Agent's position is internal to GameplayKit and then you synchronize your sprite's position to your agent's position. It means you can also have agents with other frameworks.
GKAgent2D position is arbitrary to whatever system you are using it for, you so there is no exact need to convert it. Now to keep your game simple and easy to understand, you are probably going to want to keep everything based on the scene coordinates, so you are going to want to convert your SKNode position to the position it is at on the scene, this way you can keep all of your GKAgent values based on scene position as well.
I have a SCNNode, and an SCNCamera. The camera is located up and in front of the node, and looks down on the node via an SCNLookAtConstraint that I have setup. However when the node moves laterally, the camera only rotates, instead of moving with the it. Is there any way to get the camera to move with the node?
You are only using SCNLookAtConstraint, which as its name says, make the camera Look At the object only. (You only need to rotate your head to look at something)
To make the Camera move with it, you will need either a SCNTransformConstraint (documentation here), or simply make the Camera Node a child of the object you want it to follow.
In case you want the Camera to smoothly follow the object, and be constrained only by a distance (as if it was dragged by a rope), the SCNTransformConstraint is the way to go.
If the transform between your node and the camera is always the same, you should consider making the camera a child node of your node. This is way more efficient and simpler than using constraints.
I made my camera node a child of the SCNNode I wanted to follow. That's another way to achieve this.
I currently have a scene which contains a central node at the root of the scene with earth-like geometry and a node representing a flying vehicle.
However I cannot find the right approach to control the movement of the vehicle. I need the ability to turn left and right while orbiting at a static altitude and speed.
I have tried many combinations of animations and physics body forces all leading to undesirable results.
The closest I've come is:
Setting the pivot property of the vehicle to the centre of the scene
Then setting an Action like below to control moving forward
[_vehicleNode runAction:[SCNAction repeatActionForever:[SCNAction rotateByX:-1 y:0 z:0 duration:10.0]]];
Then finally applying forces for turning left and right with
[_vehicleNode.physicsBody applyTorque:SCNVector4Make(0, 1, 0, 1) impulse:YES];
However I cannot seem to set the pivot and/or position to the right value to get the desired result.
Edit: It appears as the above method would be the solution I'm looking for, however for some reason when I add geometry to the vehicle node, it's position in the scene graph gets changed dramatically. When I add hardcoded buttons to change it's position to where it belongs it appears correct for only that single frame then straight back to being in the middle of nowhere.
Edit 2: After replacing all geometry with a primitive sphere for testing the node is now rotating as intended but is now unaffected by physics forces appearing to ignore it's declaration as a dynamicBody.
If I understand what you are trying to achieve correctly, you can try this:
add a first node to your scene, positioned at (0,0,0) and make it rotate forever along the Y axis using an SCNAction
add your ship node as a child of the first node. Position it at (X,0,0) so that it orbits around the earth
rotate your ship node along the X axis with an action or an animation
I have a SpriteKit Scene in which I want to have the effect as if a camera zoom and scale. Does anyone know of any libraries or some easy methods of doing this?
It was very easy to do in other 2D engines but does not seem simple.
I was thinking of doing it from the app delegate, and using the window to zoom since my character does stay around the same position.
The desired effect I would like to accomplish is like that of the start of an Angry Bird level when the camera pans into the level and then the launch doc.
http://www.youtube.com/watch?v=_iQbZ3KNGWQ This is an example of the camera zoom and pans I am talking about.
Thanks for the help.
If you add an SKNode to the SKScene, and make your scene content children of that node instead of direct children of the scene, then you can zoom and pan all of the contained content just by adjusting the xScale, yScale and position properties of the added node. (Any content you did not want scrolled e.g. scores or whatever could then be added to a different SKNode or added directly to the scene).
The adjustment could be done by overriding one of update:, didEvaluateActions, or didSimulatePhysics in your SKScene subclass. The choice would depend on if you are just moving your character around by yourself in update:, or if it also gets moved around by running SKActions or by simulated physics.