I have a SKSpriteNode that moves with the accelerometer by using the following code:
-(void)processUserMotionForUpdate:(NSTimeInterval)currentTime {
SKSpriteNode* ship = (SKSpriteNode*)[self childNodeWithName:#"fishderp"];
CMAccelerometerData* data = self.motionManager.accelerometerData;
if (fabs(data.acceleration.y) > 0.2) {
[gameFish.physicsBody applyForce:CGVectorMake(0, data.acceleration.y)];
}
}
This works well however, the node (gamefish) moves off the screen. How can I prevent this and have it stay on the screen?
Try using an SKConstraint which was designed exactly for this purpose and introduced in iOS8:
Just add this to the setup method of the gameFish node. The game engine will apply the constraint after the physics has run. You won't have to worry about it. Cool huh?
// get the screensize
CGSize scr = self.scene.frame.size;
// setup a position constraint
SKConstraint *c = [SKConstraint
positionX:[SKRange rangeWithLowerLimit:0 upperLimit:scr.width]
Y:[SKRange rangeWithLowerLimit:0 upperLimit:scr.width]];
gameFish.constraints = #[c]; // can take an array of constraints
The code depends on whether you have added the gameFish node to self or to another node (something like a "worldNode"). If you have added it to self, look at the code below:
// get the screen height as you are only changing your node's y
float myHeight = self.view.frame.size.height;
// next check your node's y coordinate against the screen y range
// and adjust y if required
if(gameFish.position.y > myHeight) {
gameFish.position = CGPointMake(gameFish.position.x, myHeight);
}
For the bottom you can do a check of < 0 or whatever value you need.
Related
the rect should be alpha=0.1 once the circle touches the rect . but if statement not working . it becomes 0.1 opacity without hitting
/* js
var circle = new lib.mycircle();
stage.addChild(circle);
var rect = new lib.myrect();
stage.addChild(rect);
rect.x=200;
rect.y=300;
circle.addEventListener('mousedown', downF);
function downF(e) {
stage.addEventListener('stagemousemove', moveF);
stage.addEventListener('stagemouseup', upF);
};
function upF(e) {
stage.removeAllEventListeners();
}
function moveF(e) {
circle.x = stage.mouseX;
circle.y = stage.mouseY;
}
if(circle.hitTest(rect))
{
rect.alpha = 0.1;
}
stage.update();
*/
The way you have used hitTest is incorrect. The hitTest method does not check object to object. It takes an x and y coordinate, and determines if that point in its own coordinate system has a filled pixel.
I modified your example to make it more correct, though it doesn't actually do what you are expecting:
circle.addEventListener('pressmove', moveF);
function moveF(e) {
circle.x = stage.mouseX;
circle.y = stage.mouseY;
if (rect.hitTest(circle.x, circle.y)) {
rect.alpha = 0.1;
} else {
rect.alpha = 1;
}
stage.update();
}
Key points:
Reintroduced the pressmove. It works fine.
Moved the circle update above the hitTest check. Otherwise you are checking where it was last time
Moved the stage update to last. It should be the last thing you update. Note however that you can remove it completely, because you have a Ticker listener on the stage in your HTML file, which constantly updates the stage.
Added the else statement to turn the alpha back to 1 if the hitTest fails.
Then, the most important point is that I changed the hitTest to be on the rectangle instead. This essentially says: "Is there a filled pixel at the supplied x and y position inside the rectangle?" Since the rectangle bounds are -49.4, -37.9, 99, 76, this will be true when the circle's coordinates are within those ranges - which is just when it is at the top left of the canvas. If you replace your code with mine, you can see this behaviour.
So, to get it working more like you want, you can do a few things.
Transform your coordinates. Use localToGlobal, or just cheat and use localToLocal. This takes [0,0] in the circle, and converts that coordinate to the rectangle's coordinate space.
Example:
var p = rect.localToLocal(0, 0, circle);
if (rect.hitTest(p.x, p.y)) {
rect.alpha = 0.1;
} else {
rect.alpha = 1;
}
Don't use hitTest. Use getObjectsUnderPoint, pass the circle's x/y coordinate, and check if the rectangle is in the returned list.
Hope that helps. As I mentioned in a comment above, you can not do full shape collision, just point collision (a single point on an object).
I would like to have my camera follow the first-person view of a moving entity. I do not believe that trackedEntity will work for this use case because I don't want to look at the entity, but I want to look out from it. I would also like the user to be able to use the mouse to turn the camera with respect to the moving entity (for example, to look out the left window of a moving plane).
In a traditional game engine, I would do this by attaching the camera to the entity, so it would move with it, but retain its own local transform with respect to the entity so that it was free to move with respect to the entity.
The only way I can think of right now is to keep track of the "user-controlled" transform separately and multiply it with the entity transform at every clock tick. Is there a better way?
Have a look at Cesium's Cardboard sandcastle example. Here you are on board of a hot-air balloon and perceive the world from there. After scrolling out, you can pan with the mouse to look around. Since the calculations are quite complicated, I cannot give any details how it works, but it seems that the camera view is aligned to the moving direction of the entity. The essential part of the script is:
// Set initial camera position and orientation to be when in the model's reference frame.
var camera = viewer.camera;
camera.position = new Cesium.Cartesian3(0.25, 0.0, 0.0);
camera.direction = new Cesium.Cartesian3(1.0, 0.0, 0.0);
camera.up = new Cesium.Cartesian3(0.0, 0.0, 1.0);
camera.right = new Cesium.Cartesian3(0.0, -1.0, 0.0);
viewer.scene.postUpdate.addEventListener(function (scene, time) {
var position = entity.position.getValue(time);
if (!Cesium.defined(position)) {
return;
}
var transform;
if (!Cesium.defined(entity.orientation)) {
transform = Cesium.Transforms.eastNorthUpToFixedFrame(position);
} else {
var orientation = entity.orientation.getValue(time);
if (!Cesium.defined(orientation)) {
return;
}
transform = Cesium.Matrix4.fromRotationTranslation(
Cesium.Matrix3.fromQuaternion(orientation),
position
);
}
// Save camera state
var offset = Cesium.Cartesian3.clone(camera.position);
var direction = Cesium.Cartesian3.clone(camera.direction);
var up = Cesium.Cartesian3.clone(camera.up);
// Set camera to be in model's reference frame.
camera.lookAtTransform(transform);
// Reset the camera state to the saved state so it appears fixed in the model's frame.
Cesium.Cartesian3.clone(offset, camera.position);
Cesium.Cartesian3.clone(direction, camera.direction);
Cesium.Cartesian3.clone(up, camera.up);
Cesium.Cartesian3.cross(direction, up, camera.right);
});
Maybe you can try to modify the camera vectors or multiply the transform with another rotation matrix to simulate turning one's head (to look left/right/back) while being in the initial perspective. For instance, you can try to combine the example above with code from a repository called Cesium First Person Camera Controller.
Had to figure this out myself as well.
Camera.setView and self-defined utility functions are your friend.
E.g. Here is a naive implementation of rotation (does not work well when the pitch of the camera is too "birds-eye-view" like):
Cesium.Camera.prototype.rotateView = function(rotation) {
let { heading, pitch, roll } = rotation;
heading = this.heading + (heading || 0);
pitch = this.pitch + (pitch || 0);
roll = this.roll + (roll || 0);
const destination = this.position;
this.setView({
destination,
orientation: {
heading,
pitch,
roll
}
});
};
Similarly you can update the position with the position of the entity by providing destination.
I'm trying to write a basic game using Apple's Sprite Kit framework. So far, I have a ship flying around the screen, using SKPhysicsBody. I want to keep the ship from flying off the screen, so I edited my update method to make the ship's velocity zero. This works most of the time, but every now and then, the ship will fly off the screen.
Here's my update method.
// const int X_MIN = 60;
// const int X_MAX = 853;
// const int Y_MAX = 660;
// const int Y_MIN = 60;
// const float SHIP_SPEED = 50.0;
- (void)update:(CFTimeInterval)currentTime {
if (self.keysPressed & DOWN_ARROW_PRESSED) {
if (self.ship.position.y > Y_MIN) {
[self.ship.physicsBody applyForce:CGVectorMake(0, -SHIP_SPEED)];
} else {
self.ship.physicsBody.velocity = CGVectorMake(self.ship.physicsBody.velocity.dx, 0);
}
}
if (self.keysPressed & UP_ARROW_PRESSED) {
if (self.ship.position.y < Y_MAX) {
[self.ship.physicsBody applyForce:CGVectorMake(0, SHIP_SPEED)];
} else {
self.ship.physicsBody.velocity = CGVectorMake(self.ship.physicsBody.velocity.dx, 0);
}
}
if (self.keysPressed & RIGHT_ARROW_PRESSED) {
if (self.ship.position.x < X_MAX) {
[self.ship.physicsBody applyForce:CGVectorMake(SHIP_SPEED, 0)];
} else {
self.ship.physicsBody.velocity = CGVectorMake(0, self.ship.physicsBody.velocity.dy);
}
}
if (self.keysPressed & LEFT_ARROW_PRESSED) {
if (self.ship.position.x > X_MIN) {
[self.ship.physicsBody applyForce:CGVectorMake(-SHIP_SPEED, 0)];
} else {
self.ship.physicsBody.velocity = CGVectorMake(0, self.ship.physicsBody.velocity.dy);
}
}
}
At first, I used applyImpulse in didBeginContact to push the ship back. This made the ship bounce, but I don't want the ship to bounce. I just want it to stop at the edge.
What is the right way to make the ship stop once it reaches the edge? The code above works most of the time, but every now and then the ship shoots off screen. This is for OS X—not iOS—in case that matters.
Check out this link...
iOS7 SKScene how to make a sprite bounce off the edge of the screen?
[self setPhysicsBody:[SKPhysicsBody bodyWithEdgeLoopFromRect:self.frame]]; //Physics body of Scene
This should set up a barrier around the edge of your scene.
EDIT:
This example project from Apple might also be useful
https://developer.apple.com/library/mac/samplecode/SpriteKit_Physics_Collisions/Introduction/Intro.html
Your code is not clear in what the velocity variables represent. Keep in mind that if the velocity is too high your ship will have travelled multiple points between updates. For example, your ship's X/Y is at (500,500) at the current update. Given a high enough velocity, your ship could be at (500,700) at the very next update. If you had your boundary set at (500,650) your ship would already be past it.
I suggest you do a max check on velocity BEFORE applying it to your ship. This should avoid the problem I outlined above.
As for bouncy, bouncy... did you try setting your ship's self.physicsBody.restitution = 0; ? The restitution is the bounciness of the physics body. If you use your own screen boundaries, then I would recommend setting those to restitution = 0 as well.
Your best bet would be to add a rectangle physics body around the screen (boundary). Set the collision and contact categories of the boundary and player to interact with each other. In the didBeginContact method you can check if the bodies have touched and, if they have, you can call a method to redirect the ship.
Your problem is that your update method may not be checking the location frequently enough before the ship gets off screen.
This will help you to define you screen edges in Swift.
self.physicsBody = SKPhysicsBody ( edgeLoopFromRect: self.frame )
I've put together a custom top-down camera logic script based on Unity3D's ThirdPersonCamera.js script. Everything appears to be working properly, the camera follows the target player on the XZ plane and even moves along the Y-axis as appropriate when the player jumps.
Only the camera isn't looking at the player. So I tried using Transform.LookAt() on the cameraTransform to have the camera looking directly down on the player. This does cause the camera to correctly look directly down on the player, but then movement via WASD no longer works. The player just sits there. Using Spacebar for jumping does still work though.
This doesn't make sense to me, how should the orientation of the camera's transform be affecting the movement of the player object?
The code for my script is below:
// The transform of the camera that we're manipulating
var cameraTransform : Transform;
// The postion that the camera is currently focused on
var focusPosition = Vector3.zero;
// The idle height we are aiming to be above the target when the target isn't moving
var idleHeight = 7.0;
// How long should it take the camera to focus on the target on the XZ plane
var xzSmoothLag = 0.3;
// How long should it take the camera to focus on the target vertically
var heightSmoothLag = 0.3;
private var _target : Transform;
private var _controller : ThirdPersonController;
private var _centerOffset = Vector3.zero;
private var _headOffset = Vector3.zero;
private var _footOffset = Vector3.zero;
private var _xzVelocity = 0.0;
private var _yVelocity = 0.0;
private var _cameraHeightVelocity = 0.0;
// ===== UTILITY FUNCTIONS =====
// Apply the camera logic to the camera with respect for the target
function process()
{
// Early out if we don't have a target
if ( !_controller )
return;
var targetCenter = _target.position + _centerOffset;
var targetHead = _target.position + _headOffset;
var targetFoot = _target.position + _footOffset;
// Determine the XZ offset of the focus position from the target foot
var xzOffset = Vector2(focusPosition.x, focusPosition.z) - Vector2(targetFoot.x, targetFoot.z);
// Determine the distance of the XZ offset
var xzDistance = xzOffset.magnitude;
// Determine the Y distance of the focus position from the target foot
var yDistance = focusPosition.y - targetFoot.y;
// Damp the XZ distance
xzDistance = Mathf.SmoothDamp(xzDistance, 0.0, _xzVelocity, xzSmoothLag);
// Damp the XZ offset
xzOffset *= xzDistance;
// Damp the Y distance
yDistance = Mathf.SmoothDamp(yDistance, 0.0, _yVelocity, heightSmoothLag);
// Reposition the focus position by the dampened distances
focusPosition.x = targetFoot.x + xzOffset.x;
focusPosition.y = targetFoot.y + yDistance;
focusPosition.z = targetFoot.z + xzOffset.y;
var minCameraHeight = targetHead.y;
var targetCameraHeight = minCameraHeight + idleHeight;
// Determine the current camera height with respect to the minimum camera height
var currentCameraHeight = Mathf.Max(cameraTransform.position.y, minCameraHeight);
// Damp the camera height
currentCameraHeight = Mathf.SmoothDamp( currentCameraHeight, targetCameraHeight, _cameraHeightVelocity, heightSmoothLag );
// Position the camera over the focus position
cameraTransform.position = focusPosition;
cameraTransform.position.y = currentCameraHeight;
// PROBLEM CODE - BEGIN
// Have the camera look at the focus position
cameraTransform.LookAt(focusPosition, Vector3.forward);
// PROBLEM CODE - END
Debug.Log("Camera Focus Position: " + focusPosition);
Debug.Log("Camera Transform Position: " + cameraTransform.position);
}
// ===== END UTILITY FUNCTIONS =====
// ===== UNITY FUNCTIONS =====
// Initialize the script
function Awake( )
{
// If the camera transform is unassigned and we have a main camera,
// set the camera transform to the main camera's transform
if ( !cameraTransform && Camera.main )
cameraTransform = Camera.main.transform;
// If we don't have a camera transform, report an error
if ( !cameraTransform )
{
Debug.Log( "Please assign a camera to the TopDownThirdPersonCamera script." );
enabled = false;
}
// Set the target to the game object transform
_target = transform;
// If we have a target set the controller to the target's third person controller
if ( _target )
{
_controller = _target.GetComponent( ThirdPersonController );
}
// If we have a controller, calculate the center offset and head offset
if ( _controller )
{
var characterController : CharacterController = _target.collider;
_centerOffset = characterController.bounds.center - _target.position;
_headOffset = _centerOffset;
_headOffset.y = characterController.bounds.max.y - _target.position.y;
_footOffset = _centerOffset;
_footOffset.y = characterController.bounds.min.y - _target.position.y;
}
// If we don't have a controller, report an error
else
Debug.Log( "Please assign a target to the camera that has a ThirdPersonController script attached." );
// Apply the camera logic to the camera
process();
}
function LateUpdate( )
{
// Apply the camera logic to the camera
process();
}
// ===== END UNITY FUNCTIONS =====
I've marked the problem code section with PROBLEM CODE comments. If the problem code is removed, it allows WASD movement to work again, but then the camera is no longer looking at the target.
Any insight into this issue is very much appreciated.
I figured it out, the issue was with the ThirdPersonController.js script that I was using. In the function UpdateSmoothedMovementDirection(), the ThirdPersonController uses the cameraTransform to determine the forward direction along the XZ plane based on where the camera is looking at. In doing so, it zeros out the Y axis and normalizes what's left.
The cameraTransform.LookAt() call I perform in my custom TopDownCamera.js script has the camera looking directly down the Y-axis. So when the ThirdPersonController gets a hold of it and zeros out the Y-axis, I end up with zero forward direction, which causes the XZ movement to go nowhere.
Copying ThirdPersonController.js and altering the code so that:
var forward = cameraTransform.TransformDirection(Vector3.forward);
forward.y = 0;
forward = forward.normalized;
becomes:
forward = Vector3.forward;
fixed the issue.
I am trying to imitate what Apple has when showing the search result in the App Store. (reference: http://searchengineland.com/apple-app-search-shows-only-one-result-at-a-time-133818)
It shows like the detailed-application-info in a cards and it is paged. I am stuck at how to make the previous-and-next card shows when one active card in the middle and the scroll view's paging behaviour is still intact.
I have tried using the UICollectionView and set the clipSubviews to NO, hoping that it will show the previous page and the next page, but as soon as the cell goes off-screen, the cell gets hidden (removed from the view hierarchy) and not displayed. I think thats the flyweight pattern of the UICollectionView (the behavior of UICollectionView). Any ideas of what would be possible?
Cheers,
Rendy Pranata
The problem: UICollectionView as a subclass of UIScrollView essentially animates its bounds by a stride of bounds.size. Although this could mean that all you had to do is decrease the bounds while keeping the frame bigger, unfortunately UICollectionView will not render any cells outside its current bounds... destroying your preview effect.
The Solution:
Create a UICollectionView with paging set to NO and with the desired frame.
Create UICollectionViewCells that are smaller than the UICollectionView's frame/bounds. At this stage, a part of the next cell should show in the frame. This should be visible before implementing the other steps below.
Add a collectionView.contentInset.left and right (I assume your layout is horizontal) equal to the contentOffsetValue method (as shown below for simplicity) so as to align the first and last cells to the middle.
Create a UICollectionViewFlowLayout which overrides the method that gives the stopping point like so:
Like so:
-(CGFloat)contentOffsetValue
{
return self.collectionView.bounds.size.width * 0.5f - self.itemSize.width * 0.5f;
}
- (CGPoint)targetContentOffsetForProposedContentOffset:(CGPoint)proposedContentOffset withScrollingVelocity:(CGPoint)velocity
{
static float EscapeVelocity = 0.5f; // otherwise snap back to the middle
NSArray* layoutAttributesArray = [self layoutAttributesForElementsInRect:self.collectionView.bounds];
if(layoutAttributesArray.count == 0)
return proposedContentOffset;
CGFloat currentBoundsCenterX = self.collectionView.contentOffset.x + self.collectionView.bounds.size.width * 0.5f;
UICollectionViewLayoutAttributes* candidateNextLayoutAttributes = layoutAttributesArray.firstObject;
for (UICollectionViewLayoutAttributes* layoutAttributes in layoutAttributesArray)
{
if ((layoutAttributes.representedElementCategory != UICollectionElementCategoryCell) ||
(layoutAttributes == candidateNextLayoutAttributes)) // skip the first comparison
continue;
if(velocity.x > EscapeVelocity || velocity.x < -(EscapeVelocity))
{
if(velocity.x > EscapeVelocity && layoutAttributes.center.x > candidateNextLayoutAttributes.center.x)
{
candidateNextLayoutAttributes = layoutAttributes;
}
else if (velocity.x < -(EscapeVelocity) && layoutAttributes.center.x < candidateNextLayoutAttributes.center.x)
{
candidateNextLayoutAttributes = layoutAttributes;
}
}
else
{
if(fabsf(currentBoundsCenterX - layoutAttributes.center.x) < fabsf(currentBoundsCenterX - candidateNextLayoutAttributes.center.x))
{
candidateNextLayoutAttributes = layoutAttributes;
}
}
}
return CGPointMake(candidateNextLayoutAttributes.center.x - self.collectionView.bounds.size.width * 0.5f, proposedContentOffset.y);
}
I just put together a sample project which shows how you could do this. I created a container view which is 100 points wider than the 320 points for the screen. Then I put a UICollectionView into that container. This offsets everything by 50 points on both sides of the screen.
Then there is a content cell which simply has a background and a label so you can visually identify what is happening. On the left and right there are empty cells. In the viewDidLoad method the content inset is set to negative values on the left and right to make the empty cells now scroll into view. You can adjust the inset to your preference.
This mimics the behavior fairly closely. To get the label below, like in the example you can simply check the contentOffset value to determine which cell is in focus. To do that you'd use the UIScrollViewDelegate which is a part of UICollectionView.
https://github.com/brennanMKE/Interfaces/tree/master/ListView
You'll notice this sample project has 2 collection views. One is a normal horizontal flow layout while the other one which has larger cells is the one which mimics the example you mentioned.