I'm currently trying to spawn aliens for a space invaders game I'm creating in class. I'm using a while loop with a counter to adjust an array to a given variable value. This way I can increase the number of aliens without any re-writing. The problem is, although my aliens spawn, the x position is not increasing as I would like it to. I only see one Alien on the screen so I've concluded that they are all spawning, but only with a 1-pixel difference, therefore unnoticeable. Here's what I have so far, any help would be greatly appreciated!
//Add and display given amount of aliens...
while (alienAmount > displayLoopCounter) {
aliens.append(SKSpriteNode(texture: SKTexture(imageNamed: "ClassicAlien")))
self.addChild(aliens[displayLoopCounter])
//Location
aliens[displayLoopCounter].position.y = CGFloat(-15)
aliens[displayLoopCounter].position.x = CGFloat(displayLoopCounter + 25)
print(aliens[displayLoopCounter].position.x)
displayLoopCounter += 1
print(displayLoopCounter)
//Have we run out of aliens yet?
if displayLoopCounter > alienAmount {
displayAliens = false
}
You just need to change the spacing you're setting between aliens. In other terms, you need to set the x position of each alien sprite to have more spacing between them. Currently, you are just adding displayLoopCounter to the x position of each alien. Since displayLoopCounter only increases one at a time, the aliens are all spawned with a 1-pixel difference to each other. If we want a bigger difference, we will need to multiply displayLoopCounter by our intended spacing so that we get that spacing between each alien.
You can just set a spacingBetweenAliens variable with a numeric type (such as Int or CGFLoat or Double) and change this line:
aliens[displayLoopCounter].position.x = CGFloat(displayLoopCounter + 25)
To this:
let basePosition = displayLoopCounter * spacingBetweenAliens
aliens[displayLoopCounter].position.x = CGFloat(basePosition + 25)
This way, the aliens will be spawned with the value of spacingBetweenAliens in pixels between them.
Related
This is an example view:
I want to calculate a frame with a CGPoint where I can spawn another card(UIView) without touching any existing card. Ofcourse it is optional since the view can be full of cards, therefore there is no free spot.
This is how I can see any card on the screen and my function how it is now:
func freeSpotCalculator() -> CGPoint?{
var takenSpots = [CGPoint]()
for card in playableCards{
takenSpots.append(card.center)
}
}
I have no idea where to start and how to calculate a random CGPoint on the screen. The random frame has the same width and height as a card in on the screen.
The naive approach to this is very simple, but could be problematic once the screen fills up. Generate a random CGPoint with x coordinate between 0 and the screen width and a y coordinate between 0 and the screen height. Check if a rectangle with a center at that point intersects any existing view. If it does not, you have your random position.
Where this gets problematic is when the screen starts to fill up. At that point you could be trying many many random points before finding a place to put the card. You could also reach a situation where no more cards will fit. How do you know that you have reached that? Will your loop generating the random points just run forever?
A smarter solution is to keep track of the free spaces on the screen. Always generate your random points roughly within these free spaces. You could do this using a grid if approximate is close enough. Is there a card occupying each grid location? Then when the largest free space is smaller than the size of your card rectangle, you know you're done. It's a lot more work than the naive approach, but it's faster when the screen starts to fill up and you'll know for sure when you're done.
If you know that you will always have more screen space than the cards can possibly take up, the naive approach is fine.
The idea
You know the width and height of your container UIView. And, each card has the same width and height. I would go about this by calculating a grid.
Even though you want to display cards randomly, relying on a grid will give you a standardized array of centers that you can use to generate the appearance of randomness (place a card at any random center that is a part of the grid, for example).
If you were to place a card at truly any random location, you might just want to use CGRectIntersectsRect(card1.frame, card2.frame) to detect collisions.
The pattern
First, let's store the card width and height as constants.
let cardWidth = card.bounds.size.width
let cardHeight = card.bounds.size.height
As a basic proof of concept, let's say your container view width is 250 points. Let's say the card width is 5 points. That means you can fit 250 / 5 = 50 cards in one row, where one row has the height of one card.
The number of centers in a row = the number of cards in that row. Each center is the same distance apart. In the following diagram (if I can even call it that), the [ and ] represent edges of a row. The -|- represents a card, where | is the center of the card.
[ - | - - | - - | - - | - - | - ]
Notice how every center is two dashes away from the next center. The only consideration is that the center next to the edge is one dash away from the edge. In terms of cards, each center is one whole card away from the next, and the centers next to the edges are one half card away from the edges.
The key to the pattern
This pattern means that the x position of any card center in a specific row = (cardWidth / 2) + (the card index * cardWidth). In fact, this pseudo-equation works for y positions as well.
The code
Here's some Swift that creates an array of centers using this method.
var centers = [CGPoint]()
let numberOfRows: CGFloat = containerView.bounds.size.height / cardHeight
let numberOfCardsPerRow: CGFloat = containerView.bounds.size.width / cardWidth
for row in 0 ..< Int(numberOfRows) {
for card in 0 ..< Int(numberOfCardsPerRow) {
// The row we are on affects the y values of all the centers
let yBasedOnRow = (cardHeight / 2) + (CGFloat(row) * cardHeight)
// The xBasedOnCard formula is effectively the same as the yBasedOnRow one
let xBasedOnCard = (cardWidth / 2) + (CGFloat(card) * cardWidth)
// Each possible center for this row gets appended to the centers array
centers.append(CGPoint(x: xBasedOnCard, y: yBasedOnRow))
}
}
This code should create a grid of centers for your cards. You could build a function around it that returns a random center for a card to be placed and keeps track of used centers.
Potential improvements
First, I think that the centers array could be made a matrix ([[CGPoint]]()) for more logical storage of points.
Second, this code currently makes the assumption that the width and height of the container view are divisible by the card width and height. For example, a container width of 177 and a card width of 5 would result in some problems. The code could be fixed a number of different ways to account for this.
Best solution simplest/performance is to display card randomly BUT inside a grid. The trick is to have the grid bigger than the card size, so the card position inside the grid will be random.
Easy to check which position is occupy and cards will be on "random" frames.
1- Create a Collection View Controller with the total number of card u want to display (lets say.. max card that enter in the screen?)
2- Set the prototype cell size bigger than the card. If the card is 50x80 then the cell should be 70x110.
3- Add a UIImageView to the cell with constraints, this will be your card image
4- Create a UICollectionViewCell, with a method that set the card frames randomly inside the cell (modify the constraints)
Done!
Cells with no card will have no image or an empty cell as you wish. So to add a new card, just do a random between the empty cells and add the card with its random coordinates inside the cell.
Your UICollectionViewCell would like like this
class CardCollectionViewCell: UICollectionViewCell {
#IBOutlet weak var card: UIImageView!
override func awakeFromNib() {
super.awakeFromNib()
let newX = CGFloat(arc4random_uniform(UInt32(bounds.size.width-card.bounds.size.width+1)))
let newY = CGFloat(arc4random_uniform(UInt32(bounds.size.height-card.bounds.size.height+1)))
card.leftAnchor.constraintEqualToAnchor(leftAnchor, constant: newX).active = true
card.topAnchor.constraintEqualToAnchor(rightAnchor, constant: newY).active = true
}
}
And your Collections View Controller should like like this
Collection View Image
As I can see in the picture all your cards are aligned at the bottom of the View. so if you generate a random y position from 0 to origin of your cards row - one card height you can simply get a CGPoint based on the frame of your view and size of the cards.
If you want to randomly place cards along the screen, you could do something like this:
func random() -> CGFloat {
return CGFloat(Float(arc4random()) / 0xFFFFFFFF)
}
func random(min: CGFloat, max: CGFloat) -> CGFloat {
return random() * (max - min) + min
}
let actualX = random(min: *whatever amount*, max: *whatever amount* )
let actualY = random(min: *Height of the first card*, max: *whatever amount* )
card.position = CGPoint(x: actualX, y: actualY )
The cards will then be positioned randomly above the existing cards.
I am not sure if you are planning to place all the cards in an orderly way. But if you do, you could do it like this.
Once the view is loaded, get all the possible card positions and store them in a map together with a number used as the key. Then you could generate a random number from 0 to the total number of possible card positions that you stored in the map. Then every time you occupy a position, clear a value from the map.
You can try with CAShapeLayer and UIBezierPath.
Create a CAShapeLayer for your main view where you will be adding sub views. Let's call it as main shape layer. This will be helpful to check the new view estimated is within the main view.
Create a UIBezierPath instance. Whenever a valid new sub view is found, add the edges to this path.
Create a random point within the main view.
Create a CGRect based on random point as center of your sub view. Let’s call it as estimated view frame.
Check the estimated view frame is completely visible in your main view. Else go to step 3.
Check your 4 edges of your estimated view frame with path object. If any one of the edge is inside the path, go to step 3.
If 4 edges are not inside the path, the estimated view frame is the new view’s frame.
Create a new subview and add it to your main view.
Add the edges of new view to path.
I have created a sample project in swift with the above logic.
https://github.com/mcabasheer/find-free-space-in-uiview
You can change the width and height of new view. I have added a condition to stop looking for next free space after trying 50 times. This will help to avoid infinite loop.
As #davecom highlighted, taking a random number to add new view will waste the space and you will run out of space quickly. If you are able to maintain the free available space, you can add more sub views.
So I am developing a game using Spritekit that uses a pyramid of Sprites (let's say circles for a simple instance). The user can choose the amount of rows of sprites they would like to have in the game. The sprites are to form a pyramid, so if you have 1 row, you have 1 sprite node. It increases by 2 the farther down you go (the more rows you choose) - creating the pyramid shape. So if a user picked 3 rows, the game board would look like this:
O
O O O
O O O O O
However, when it gets to 5 rows, it loses its pyramid shape because the screen is only so wide and it has to fit all the elements onto the screen (elements are more smushed together in rows further down).
My question is, to fix this issue, what would I have to do to make the pyramid resize and change its spacing between elements depending on how many rows are chosen? Would I have to multiply the spacing by a certain factor? I have also heard of people adding layers onto the screen - maybe drawing the sprites in some sort of container so that it always resizes the pyramid to fit the screen without skewing the pyramid shape?
Your idea is correct! Make a SKNode container, then update it's .size property, or do .setScale.
(not at xcode right now, pardon if not 100%)
// Say that our scene's size is 400x400:
let bkg = SKShapeNode(rectangleOfSize: self.size)
bkg.addChild(firstSprite)
bkg.addChild(secondSprite) // And so on...
// Find the farthest point in bkg:
var farthestX = CGFloat(0)
for node in bkg.children {
if node.position.x + node.frame.size.width / 2 > farthestX {
farthestX = node.position.x + node.frame.size.width / 2
}
}
// Do math to resize the bkg:
if self.size.width < farthestX {
let scaler = self.size.width / farthestX
bkg.setScale(scaler)
}
This should work, or at least the general idea should work... You would want to check for Y values and Height as well.
You can easily compute a symmetrical size proportional to the number of rows and resize your sprites accordingly. This is my idea in pseudocode:
let computedSize = deviceWidth/(2*(rows-1) + 1)
for sprite in sprites {
sprite.size.width = computedSize
sprite.size.height = computedSize
}
I know scene coordinates are (0,0) at center so how can i distribute 4 SKNodes along the width using a for loop
for index 1...4 {
let node = SKNode()
node.postion = evenly distribute along the scene width. who can i do it?
}
You could use the width of the scene divided by the number of nodes minus 1. This would then be multiplied by the index minus 1, then added to the minimum x value of your scene.
let widthRange = scene.frame.maxX - scene.frame.minX
for index 1...4 {
let node = SKNode()
node.postion = scene.frame.minX + widthRange/(4-1) * (index-1)
}
This should place each node an equal distance away from each other along the width of the scene, starting from each edge.
If your index for the for loop doesn't start at 1, the code would need to be modified to something like this:
let widthRange = scene.frame.maxX - scene.frame.minX
var counter = 0
for index 352...356 {
let node = SKNode()
node.postion = scene.frame.minX + widthRange/(4-1) * counter
counter+=1
}
If you're unsure of which version to use, use the second version, as it's less reliant on the format of the for loop (as long as you reset counter to 0 before every time you use this).
If you need any clarifications as to what does what, feel free to ask.
Edit
This should clarify what the code actually does.
let widthRange = scene.frame.maxX - scene.frame.minX is used to get the size of the scene, then set it to a variable that is used later. Making this a variable is sort of optional as you could just use the scene size, however I put it this way so it's less messy.
var counter = 0 simply makes a counter variable, that's used in the for-loop, to place the nodes. Make sure to set it to 0 before every time you run the loop. counter+=1 is then used later so each node is multiplied by an increasing value, which creates the different x-positions. (I'll get into that later)
node.postion = scene.frame.minX + widthRange/(4-1) * counter is the complicated line. First, I use scene.frame.minX to start placement from the lowest width/x-position. widthRange/(4-1) is a little harder to understand. It uses the scenes width (from earlier), then divides by one less than the amount of nodes. The best way to understand this, is that to cut a rectangle (only in a single direction) so it has 2 cuts through it (2 of the nodes), and 2 edges (the other 2 nodes), you would need 3 sections. (The rectangle would be cut into 3). This gets the distance between each node. The pattern of #ofNodes-1 follows for every amount of nodes. The * counter part is the part that makes the node's x-position actually change. Since every time the loop is gone through, counter increases by 1 (starting at 0) the amount of "sections" from before (widthRange/(4-1)) is increased by 1.
Now i have a working Joystick, but I want to increase the characters speed.
I´m using this one at the moment: http://roadtonerdvana.wordpress.com/2013/09/20/jcinput-a-simple-joystick-for-sprite-kit/
I attached an Imagefile as the moving object, but it´s way too slow for my purpose.
Where and how can I change the speed?
If you read the post you'll know that the joystick returns a x and y value, each ranging from -1 to 1.
Every time you move the joystick, the properties x and y of it change accordingly, the maximum value is 1 and the minimum is -1.
In the update method, you could do something like this to adjust the speed :
-(void)update:(CFTimeInterval)currentTime {
// I'm using the magic number of 5 as an example of how to magnify the speed x5
float speedX = 5 * self.joystick.x;
float speedY = 5 * self.joystick.y;
[self.myLabel setPosition:CGPointMake(self.myLabel.position.x+speedX, self.myLabel.position.y+speedY)];
}
I'm currently trying to make a basic platformer with XNA and I'm wondering how to create a "jumping effect." I currently have basic keyboard input which allows for sideways movement, but I would like my sprite to slowly progress into a jump rather than instantly teleporting there (right now I have something like Rectangle.Y += 40 every time I jump, making the sprite instantly appear there). Does anyone have any insight?
I'm not totally across how to implement this in XNA/C#, but in Flash games I've made I just added a vertical velocity property. I'll try write everything as C# as I can..
Example; create the velocity property:
float verticalVelocity = 0;
Vertical velocity should be constantly reduced (by gravity). Set up a gravity property somewhere accessible from your player:
float Gravity = 2.5;
And in your update() method for the player, increment the verticalVelocity by Gravity. Also increment the Y position of your player by the verticalVelocity. This will simulate falling:
verticalVelocity += Gravity;
Position.Y += verticalVelocity; // this may be -= in XNA, not sure where the y axis beings
When you hit a surface, the velocity should be reset to 0.
And finally, to jump, simply subtract a given value from verticalVelocity:
public void Jump(float height)
{
// Only jump if standing on a surface.
if(verticalVelocity == 0)
verticalVelocity -= height;
}
You'll eventually want to add gravity and possibly other forces to your game, so I highly recommend you save yourself a lot of pain and implement some kind of basic force system. This can be done using Vector2s, as you can just add them to the speed of your character. Then just apply an instantaneous force to your character to push it up.
If you really don't want to use a physics engine, you can make a Vector2 with the high point of the jump for the Y and the characters X, and then use the Vector2.Lerp method to interpolate between the characters position and the end point of the jump.
This is generally a very bad system to use, and I highly recommend you either use an existing physics engine, or make your own simple one.
use a sinusoidcode should look something like this:
float ground = 0.0f;
float angle = 330.0f;
jump(){
if(ground == 0.0f)ground = Rectangle.Y;
if(Rectangle.Y <= ground)
{
Rectangle.Y+=Math.Sin(angle/(Math.Pi*180));
angle++;
}
}
You can accurately create a gravity effect if you modify the ySpeed dynamically, as opposed to just adding 40.
You want to declare a ySpeed
ySpeed = 0;
Then you want to use an acceleration variable
acceleration = 0.25;
Okay, now that we've done that, let's add gravity, provided that our player isn't touching the floor.
if(playerLocationY + playerHeight > floorLocationY)
{
gravity = false;
}
else
{
gravity = true;
}
if(gravity)
{
ySpeed += acceleration;
}
Now that we've got that down, we want to include something that allows us to jump.
if(KeyPressed == UP)
{
ySpeed -= acceleration;
}
This will move our player in the upward direction
We now want to make sure we actually move, so let's add one last line and we're done.
playerLocationY += ySpeed;
Congratulations, you made it.