I use physicsBodies that are made from an image, I put an image file in the Assets.xcassets file and create the spriteNode using the image name as the imageNamed argument, I then use the spriteNodes texture as the texture argument of the physicsBody and the same size value from the spriteNode as the size argument. This works like a charm below 13.0 (13.0 has some issues with this). However, if I try to do this same thing with the same image files but in a Texture Atlas the spriteNode() still looks perfectly fine but the physicsBody is massively out of proportion, I would be able to get them to line up by dividing the width and height of the physicsBody by different values but the fact that I'm gonna have to brute force something means I've probably done something wrong
Image of result when using spriteAtlas, keep in mind the wings aren't part of the spriteNode and the rectangle around the eagle is a different body: oh no no no
How I create physicsBodies:
func createPigeon(size: CGSize, position: CGPoint) {
//W/o texture atlas
sprite = SKSpriteNode(imageNamed: "pigeonHitBox")
//with textureAtlas
sprite = SKSpriteNode(texture: gameScene.spriteAtlas.textureNamed("pigeonHitBox"))
sprite!.size = size
sprite!.position = position
sprite!.name = "Pigeon"
sprite!.physicsBody = SKPhysicsBody(texture: sprite!.texture!, size: size)
sprite!.zPosition = 1
sprite!.physicsBody!.isDynamic = true
defaultCollisions()
gameScene.addChild(sprite!)
}
So I figured out that the problem was due to the way SpriteKit overlaps and deletes alpha in order to squeeze more images into one atlas. The only fix I could find for this was putting the images I used for hitboxes into the Assets.xcassets file and making sure the animation action had resize set to false.
I get why this is done but this has just resulted in me not being able to put a good 13 images inside a textureAtlas, there should be an option to not axe alpha
Related
I have a SKSpriteNode which has a PNG texture, partly transparent.
I want to make a logical split line on this sprite and then measure the volume or opaque pixel count in each part. The object of the exercise is to tell what percentage total sprite volume exists in each part.
I have done some research and came empty. Seems there are no built in methods to do so. Can you guide me in the right direction here?
you could create a "pixel perfect" SKPhysicsBody like this:
let sprite = SKSpriteNode(imageNamed: "Spaceship")
sprite.physicsBody = SKPhysicsBody(texture: sprite.texture!,
size: sprite.texture!.size())
And then access the property sprite.physicsBody.area which gives you the area of the body in square meters (you can convert it to points, here is the documentation)
The sprite I use for my character looks something like this (pink = transparent part):
After I set physicsBody to my node with self.physicsBody = SKPhysicsBody(texture: self.texture!, size: self.size), and set my SKView to show physics, I get an outline like this:
Which is, basically, the right mask, stretched to fit the size of the image.
Is there any way to get a physicsBody exactly around my character?
After playing around for quite a while, I've found the solution:
It's weird, but giving the SKPhysicsBody initializer a new SKTexture made from the same image, used for creating the SKTexture of SKSpriteNode initializer, worked perfectly well for me.
It should work. It works in my code with this line:
self.physicsBody = SKPhysicsBody.init(texture: self.texture!, size: self.frame.size)
Are you sure you do not scale the sprite after the creation of the physics body?
I want to animate an SKSpriteNode using textures from an SKTextureAtlas, using SKAction.animateWithTextures(textures,timePerFrame,resize,restore). However, the textures in the atlas have a size that is slightly larger than the original texture (it's basically a character moving). When the action is run, the textures are either compressed to fit the original size of the sprite, or recentered when I set resize to false, which changes the position of the character. What I want, though, is for the textures to be anchored at the lower-left corner (or lower-right, depending on the direction) so that the position of the character doesn't change apart from the extra part of the texture.
I've tried changing the anchor point of the sprite prior to running the action, but obviously that applies to the original texture as well. Also, I guess changing the size of the original texture would have an impact on the physics behaviour, which I want to avoid.
Does anyone have a suggestion about how to do this?
Thanks!
David
This would work
Edit all the textures to match the size of the largest sized texture.
Just give the smaller textures some padding using an alpha channel to give you a transparent background.
E.g. Notice how the first texture has lots of negative space
(From CartoonSmart.com)
Create the physics body with a certain size in mind. E.g. You can load the texture without the padding and get the size. Then position it as needed onto the new and improved texture with padding. So after you create the Sprite as normal with the new resized textures you can then
/// load a texture to be a template for the size
let imageTextureSizeTemplate = SKTexture(imageNamed: textureWithoutPadding)
let bodySize = imageTextureSizeTemplate.size()
/// position template texture physics body on texture that will be used
let bodyCenter = CGPointMake(0.5, 0.5)
// create physics body
let body:SKPhysicsBody = SKPhysicsBody(rectangleOfSize: bodySize, center: bodyCeneter)
self.physicsBody = body
Set resize: false when you animate the textures.
A little bit stuck on how to paint/draw an effect like an alpha Chanel onto an SKSpriteNode node i've started off with setting up the two images I need (ps if there is another way to do this is sprite-kit id love to know how to paint the masks
1)The hidden picture - SKSpriteNode *hiddenimageNode
2)The overlay that gets scratched away SKSpriteNode *myOverlay
3)And finally a mask node comprising of
UIImage *image;
SKTexture *maskTexture= [SKTexture textureWithImage:image];
maskNode = [SKSpriteNode spriteNodeWithTexture:maskTexture];
all of these are placed inside of a node "cropNode" [SKCropNode node];
this works more like a static image (that of a circle moving at touch location and not quite what I'm after, I'm hoping to be able to scratch away the entire image)
this works fine but its Not quite the look I'm after
Pictures: Dragging finger from pos1 to pos02, while "erasing purple layer to reveal a smileyface"
is there a way to make it look like I'm erasing the sprite?
nubie coder
//Updating project...
So since then I have tried using this code
https://github.com/oyiptong/CGScratch
and have added it to my SkScene by creating a subview then placing the UIView (Scratchview into it)the erasing is working however the erasing is not happening where the touches are occurring, any ideas why this might be happening?
If you are doing this in iOS 8, then your best bet is to just use SKSpriteNodes as your masking nodes, there is a weird bug with other kinds of nodes that causes distortion.
If you are doing this with iOS9 +, then SKShapeNodes are fixed.
I am going to explain the concept for iOS 9. To get this to work in iOS 8 is a real pain, since subtraction does not subtract alpha in iOS 8.
Now for your mask nodes, you only have 2 options for drawing, On and Off based on the alpha level of the pixels in your mask image. So what you want to do is incorporate subtraction alpha blending to create your desired effect.
let bigcircle = SKShapeNode(circleOfRadius: 80)
bigcircle = .whiteColor()
let littlecircle = SKShapeNode(circleOfRadius: 40)
littlecircle.position = CGPoint(x: 10, y: 10)
littlecircle.fillColor = .whiteColor()
littlecircle.blendMode = .Subtract
bigcircle.addChild(littlecircle)
maskNode = bigcircle
What this code is doing is making a big white circle with a radius of 80 points, and drawing a white circle inside of it at 40 points. Since we are using subtraction blending, it is going to take the new color and subtract it from the old (in our case white(1,1,1,1) - white(1,1,1,10 = transparent(0,0,0,0)) and get us a nice hole in our mask that will end up being cropped out of the layer over your smiley face.
I'm using an SKTexture with an image and set the SKPhysicsBody. Like that:
var moleTexture = SKTexture(imageNamed: "moleTop1")
leftPlayer = SKSpriteNode(texture: moleTexture)
leftPlayer.physicsBody = SKPhysicsBody(texture: moleTexture, size: leftPlayer.texture!.size())
Now after I start my game, I noticed that the physicsBody is set wrong. I've activated the showPhysics property and my image looks like that:
As you see, the only thing which is used by SKPhysicsBody is the little part on the middle left(blue border).
How can I change that so that the whole image will be used?
That looks interesting. I believe it will only create an outline (or one shape) and it appears to be starting from the left and because there are no other pixels near enough it calls it done.
I wonder if you get a different result if those pixels are touching. I would try and validate that first. If that is the case you may have to change the texture or use a different variation of the texture for the physical body.
I hope that helps =)