Hey so I am looking for something similar to in tennis when players challenge a point and the video shows whether the ball was in or out by zooming in really really close to the moment when the ball lands to see whether a fraction was on the line.
I have experimented with using transitions with xScale and yScale but the results I get is strange, almost as if the objects have moved during zooming in. If there was a way to lock in position and then zoom, that would work. The second method I tried is putting the graphics into a display group and then scaling the group. This also results in weird behaviour where the whole group begins moving diagonally across the screen.
Please help as this is confusing me
cheers.
Objects which will scale:
cloud = display.newImageRect("cloud.png", 419,273)
cloud.anchorY = 0
cloud.anchorX = 0.5
cloud.alpha = 1
cloud.x = display.contentCenterX
cloud.y = display.contentCenterY + 250
physics.addBody(cloud, {isSensor=true})
star = display.newImageRect("Star.png", 78,72)
star.anchorY = 0
star.anchorX = 0.5
star.alpha = 1
star.name = "Star"
physics.addBody(star, {isSensor=true})
star.x = display.contentCenterX
star.y = display.actualContentHeight - display.actualContentHeight - 100
Scale Function
function scale( event )
transition.to(star, {time=2000, xScale=1.5, yScale = 1.5})
transition.to(cloud, {time=2000, xScale=1.5, yScale=1.5})
end
When you scale an object, it may "move" due to its anchor position, which is the position of the object that is used to position it and also works as its 'anchor' during rotation or scale.
So, you have 2 options:
1) Set the anchor position (obj.anchorX = value , obj.anchorY = value ) to the one that will make your object stays in the position that you want;
2) During the transition, also change its x and y to compensate the moving.
Related
I'm trying to make a game where the sprite will always move to the right when hit by an object. However since the Sprite rotates constantly and the zero radians rotates with the Sprite causes my calculated magnitude to go the opposite direction if the sprite is facing left and hits the object. Is there a way to keep the direction of the magnitude always pointing to the right even if the zero is facing left?
// referencePoint = upper right corner of the frame
let rightTriangleFinalPoint:CGPoint = CGPoint(x: referencePoint.x, y: theSprite.position.y)
let theSpriteToReferenceDistance = distanceBetweenCGPoints(theSprite.position, b: referencePoint)
let theSpriteToFinalPointDistance = distanceBetweenCGPoints(theSprite.position, b: rightTriangleFinalPoint)
let arcCosineValue = theSpriteToFinalPointDistance / theSpriteToReferenceDistance
let angle = Double(acos(arcCosineValue))
let xMagnitude = magnitude * cos(angle)
let yMagnitude = (magnitude * sin(angle)) / 1.5
Not sure if this works for you:
I would use an orientation constraint to rotate the sprite. The movement can be done independent from the orientation in that case.
I made an tutorial some time ago: http://stefansdevplayground.blogspot.de/2014/09/howto-implement-targeting-or-follow.html
So I figured out what was going on.
It seems like the angle doesn't rotate with the Sprite like I originally thought and the vector that I am making is working with the code above. THE problem that I had was that I also set the collision bit for the objects which is wrong. If I only set the contact bit for the objects against the sprite the my desired outcome comes true.
I've been struggling with this problem for a while, which appears to be buried deep inside the spritekit physics engine.
My first question would be: Does Spritekit process its physics updates in a different thread than the main thread?
I have a "world" node in the scene which I move around to simulate a "camera" view. As such, I can center the "camera" on my player character node. Since the player jumps up and down a lot, I want to smooth the camera. Without camera smoothing, there's no problems. But when I add camera smoothing, as such: (this code is called from didFinishUpdate)
CGPoint ptPosition = self.position;
float fSmoothY = m_fLastCameraY + (ptPosition.y - m_fLastCameraY) * 0.1;
CGPoint pointCamera = [self.scene convertPoint:CGPointMake(ptPosition.x, fSmoothY) fromNode:self.parent];
[gameScene centerOnPoint:pointCamera];
m_fLastCameraY = fSmoothY;
If I call the above code from didSimulatePhysics, it does the exact same thing. It stutters whenever it falls down (due to the Y camera smoothing).
When plotting it out, you can see that the player Y (the red line) is stuttering over the course of the frames.
How can I fix this, or work around it if it can't be truly "fixed"?
I suggest you apply an infinite impulse response (IIR) filter to smooth the camera. You can do that by...
First, declare the instance variables
CGFloat alpha;
CGFloat fSmoothY;
and then Initialize alpha and fSmoothY
// alpha should be in [0, 1], where a larger value = less smoothing
alpha = 0.5;
fSmoothY = ptPosition.y;
Lastly, apply the filter with
fSmoothY = fSmoothY * (1-alpha) + ptPosition.y * alpha;
I'm developing a game on Iphone and Ipad like a space invaders.
Balloons to destroy are falling from the top of the screen in a straight line.
Here my codes to add them :
func addBalloonv(){
var balloonv:SKSpriteNode = SKSpriteNode (imageNamed: "ballonvert.png")
balloonv.physicsBody = SKPhysicsBody (circleOfRadius: balloonv.size.width/2)
balloonv.physicsBody.dynamic = true
balloonv.physicsBody.categoryBitMask = balloonCategory | greenCategory
balloonv.physicsBody.contactTestBitMask = flechetteCategory
balloonv.physicsBody.collisionBitMask = balloonCategory
balloonv.physicsBody.mass = 1
balloonv.physicsBody.restitution = 1
balloonv.physicsBody.allowsRotation = true
let minX = balloonv.size.width/2
let maxX = self.frame.size.width - balloonv.size.width/2
let rangeX = maxX - minX
let position:CGFloat = CGFloat(arc4random()) % CGFloat(rangeX) + CGFloat(minX)
balloonv.position = CGPointMake(position, self.frame.size.height+balloonv.size.height)
self.addChild(balloonv)
I have one func by balloon color.
So for the moment they move in straight line and I'm looking for random movements (with turbulences like balloon in air) from the top and both sides.
How can I do that?
Thank you very much !!
This is exactly what the new Physics Fields feature in SpriteKit (as of iOS 8 / OS X Yosemite) is for. These let you apply different kinds of forces to all physics bodies in region, like gravity, drag, and turbulence. See the SKFieldNode class docs for details.
Fields are a kind of node, so to get what you're after, you'd add one noise (or turbulence) field to your scene, covering the area that the balloons fall through, and it'll perturb the path of each balloon that passes. The simplest way to do it goes something like this:
let field = SKFieldNode.noiseFieldWithSmoothness(0.5, animationSpeed: 0.1)
scene.addChild(field)
You'll want to tweak the smoothness, animation speed, and field.strength till you get just the level of noise you want. You might also look into whether you want just a noise field, which applies random forces in random directions, or a turbulence field, which does the same thing, but with forces that get stronger when bodies are moving faster.
The above code gets you a field whose region of effect is infinite. You might want to limit it to a specific area (for example, so it doesn't keep knocking your balloons around after they land). I did this to make a field that covers only the top 3/4 of a 300x200 scene:
field.region = SKRegion(size: CGSize(width: 300, height: 100))
field.position = CGPoint(x: 150, y: 150)
What I want is that the images fall from the top side of the screen and start falling down accelerating, they would only be falling straight down, alternating positions around the width of the screen, meaning one on the right, then another one in the middle, and then another one on the left side and so on in the different positions, until they disappear at the bottom of the screen.
I tried this
function moveMeteors()
for i = 1, math.random(1, 2) do
meteors = display.newImage("meteor.png")
screenGroup:insert(meteors)
meteors.x = (math.random(display.contentWidth))
meteors.y = centerY - 340
transition.to(meteors, {time = math.random(3500 - speedMeteor, 4500 - speedMeteor),
y = 1000 + speedMeteor, onComplete = clear })
speedMeteor = speedMeteor + 10
end
end
But, sometimes the images appear one over the other and I do not want that, I mean, each image appear and go from the top to the bottom of the screen in his own line. I hope that I've explained this well.
You should look into utilizing the built in physics of Coronasdk. CoronaDocs:Physics.
As an example this code should easily simulate the effect you a trying to get, you will have to add functions to take care of removing objects as they leave the screen etc.
local physics = require("physics")
physics.start()
function SpawnMeteor()
local meteor = display.newImage( "meteor.png", math.random(display.contentWidth), centerY - 340)
physics.addBody( meteor)
end
timer.performWithDelay( 2000, SpawnMeteor)
I have an endless runner game, my main character has a physics body, I use it to handle jumping.
Everything is great before he collides with obstacles. He starts shifting back, and I want him to stay on his x position at all times.
I tried setting the body dynamic to NO, but this stops jumping.
How do I go about this? I don't want character to move on the x axis.
do this on the update method
- (void)didSimulatePhysics {
CGPoint fixedXPos = myCharacter.position;
fixedXPos.x = fixedX;
[myCharacter setPosition:fixedXPos];
}
you can also use constraints
let range = SKRange(lowerLimit: 300, upperLimit: 340)
let lockToCenter = SKConstraint.positionX(range, y: range)
node.constraints = [ lockToCenter ]
and set the lower and upper limits to the same value for it to be locked in position.