All collisions working except for one. What do I do? - swift

Question

I have a square consisting of four different colors in the middle of my scene. At the same time, I have smaller squares of the same color randomly generated from each sides of the scene with the intention of colliding with the square in the middle. (Blue to blue, yellow to yellow, etc).
With that being said, 3 out of four of my collisions are working just fine. Red hits red fine, blue hits blue fine and yellow hits yellow fine but my green square just doesn't want to do what it should. This is how I have my collisions set up:
struct PhysicsCatagory {
static let FirstPerson : UInt32 = 0x1 << 1
static let SecondPerson : UInt32 = 0x1 << 2
static let ThirdPerson : UInt32 = 0x1 << 4
static let FourthPerson : UInt32 = 0x1 << 8
}
smallBlue.physicsBody?.categoryBitMask = PhysicsCatagory.FirstPerson
smallBlue.physicsBody?.contactTestBitMask = PhysicsCatagory.SecondPerson
smallRed.physicsBody?.categoryBitMask = PhysicsCatagory.ThirdPerson
smallRed.physicsBody?.contactTestBitMask = PhysicsCatagory.FourthPerson
smallRed.physicsBody?.collisionBitMask = 0
smallGreen.physicsBody?.categoryBitMask = PhysicsCatagory.ThirdPerson
smallGreen.physicsBody?.contactTestBitMask = PhysicsCatagory.FourthPerson
smallGreen.physicsBody?.collisionBitMask = 0
bigRed.physicsBody?.contactTestBitMask = PhysicsCatagory.FourthPerson
bigRed.physicsBody?.categoryBitMask = PhysicsCatagory.ThirdPerson
bigRed.physicsBody?.collisionBitMask = 0
bigGreen.physicsBody?.categoryBitMask = PhysicsCatagory.ThirdPerson
bigGreen.physicsBody?.contactTestBitMask = PhysicsCatagory.FourthPerson
bigGreen.physicsBody?.collisionBitMask = 0
bigBlue.physicsBody?.categoryBitMask = PhysicsCatagory.FirstPerson
bigBlue.physicsBody?.contactTestBitMask = PhysicsCatagory.SecondPerson
bigBlue.physicsBody?.collisionBitMask = 0
bigYellow.physicsBody?.categoryBitMask = PhysicsCatagory.FirstPerson
bigYellow.physicsBody?.collisionBitMask = 0
bigYellow.physicsBody?.contactTestBitMask = PhysicsCatagory.SecondPerson
func didBeginContact() {
let firstBody = contact.bodyA.node as! SKSpriteNode // registering as big blue square
let secondBody = contact.bodyB.node as! SKSpriteNode // register ing as little blue square
if firstBody.color == secondBody.color { //if the colors collide, remove small one from the scene
//firstBody.removeFromParent()
label.text = "\(numPoints)" // points label increment
numPoints++ //points label increment
secondBody.removeFromParent()
}
if firstBody.color != secondBody.color { // if colors don't match, call gameOver scene
//gameOver()
}
let thirdBody = contact.bodyA.node as! SKSpriteNode
let fourthBody = contact.bodyB.node as! SKSpriteNode
if thirdBody.color == fourthBody.color {
label.text = "\(numPoints)"
numPoints++
fourthBody.removeFromParent()
}
if thirdBody.color != fourthBody.color {
//gameOver()
}
let fifthBody = contact.bodyA.node as! SKSpriteNode
let sixthBody = contact.bodyB.node as! SKSpriteNode
if fifthBody.color == sixthBody.color {
label.text = "\(numPoints)"
numPoints++
secondBody.removeFromParent()
}
let seventhBody = contact.bodyA.node as! SKSpriteNode
let eighthBody = contact.bodyB.node as! SKSpriteNode
if seventhBody.color == eighthBody.color {
label.text = "\(numPoints)"
numPoints++
eighthBody.removeFromParent()
print("green removed")
}
}
Is there something I'm missing? Will post more code if necessary.
Here is an english representation of what I am looking for
if small red equals big red then gain a point, update the label, and remove small red
if small blue equals big blue then gain a point, update the labelm and remove small blue
if small yellow equals big yellow then gain a point, update points label and remove little yellow.
if small green equals big green, gain point and update label and remove little yellow from scene
if little blue does not equal big blue, call game over scene
if little yellow does not equal big yellow, call game over scene
if little red does not equal big red, call game over scene
if little green does not equal big green, call game over scene

Answer 1

How the contact bodies work, is didBeginContact will be called everytime 2 nodes collide, that is, in 1 update cycle, if red hits blue, and red hits green, 2 calls to didBeginContact will take place. This means that your creation of thirdBody and so fourth have no meaning, because it ends up being the same as firstBody every time. This means that we can delete all that code entirely, and have it like this:
func didBeginContact() {
let firstBody = contact.bodyA.node as! SKSpriteNode // registering as big blue square
let secondBody = contact.bodyB.node as! SKSpriteNode // register ing as little blue square
if firstBody.color == secondBody.color { //if the colors collide, remove small one from the scene
label.text = "\(numPoints)" // points label increment
numPoints++ //points label increment
secondBody.removeFromParent()
}
if firstBody.color != secondBody.color { // if colors don't match, call gameOver scene
//gameOver()
}
}
What this code says is I do not care what the 2 objects are, if a red object hits a red object, lets remove the second object.
Ok, but now we have a problem, what if the second object is the big red.
We need to program our code so that second object is always small red. This is where the categories come in. The category is an integer representation of what this object should be.
If we make our bigger object category masks lower than our smaller object category masks, we could write a formula like this:
let firstBody = ((contact.bodyA.categoryBitMask <= contact.bodyB.categoryBitMask) ? contact.bodyA.node : contactBodyB.node) as! SKSpriteNode // registering as big blue square
let secondBody = ((contact.bodyA.categoryBitMask <= contact.bodyB.categoryBitMask) ? contact.bodyB.node : contactBodyA.node) as! SKSpriteNode // registering as little blue square
which says let firstBody be the node of bodyA if A <= B or else bodyB if A > B and let secondBody be the node of bodyB if A <= B or else bodyA if A > B.
The way you have categoryBitMasks done now, it is not possible. You will have to create bitmasks so that your larger objects and smaller objects do not share the same mask.
Now we have our order preserved, so our code says exactly what we are looking for.
If you want to add a print out of what color was removed, then we just do a condition afterwards to check the color. See below for the final result.
func didBeginContact() {
let firstBody = ((contact.bodyA.categoryBitMask <= contact.bodyB.categoryBitMask) ? contact.bodyA.node : contactBodyB.node) as! SKSpriteNode // registering as big blue square
let secondBody = ((contact.bodyA.categoryBitMask <= contact.bodyB.categoryBitMask) ? contact.bodyB.node : contactBodyA.node) as! SKSpriteNode // registering as little blue square
if firstBody.color == secondBody.color { //if the colors collide, remove small one from the scene
label.text = "\(numPoints)" // points label increment
numPoints++ //points label increment
if(secondBody.color == UIColor.greenColor())
{
print("Green was removed")
}
if(secondBody.color == UIColor.redColor())
{
print("Red was removed")
}
if(secondBody.color == UIColor.blueColor())
{
print("Blue was removed")
}
if(secondBody.color == UIColor.yellowColor())
{
print("Yellow was removed")
}
secondBody.removeFromParent()
}
if firstBody.color != secondBody.color { // if colors don't match, call gameOver scene
//gameOver()
}
}
Now keep in mind, you never bother checking the type of collision that is happening, so if you decide in the future to add medium red that kills you on a color match, this will cause problems. Because in its current state, we only care that red hits red, we do not care if it was medium or small. So you need to use that switch method we talked about in your other question to first check what type of collision happened, before doing any processing:
func didBeginContact() {
let firstBody = ((contact.bodyA.categoryBitMask <= contact.bodyB.categoryBitMask) ? contact.bodyA.node : contactBodyB.node) as! SKSpriteNode // registering as big blue square
let secondBody = ((contact.bodyA.categoryBitMask <= contact.bodyB.categoryBitMask) ? contact.bodyB.node : contactBodyA.node) as! SKSpriteNode // registering as little blue square
switch(firstBody.categoryBitMask | secondBody.categoryBitMask)
{
case BigObject | SmallObject:
if firstBody.color == secondBody.color { //if the colors collide, remove small one from the scene
label.text = "\(numPoints)" // points label increment
numPoints++ //points label increment
if(secondBody.color == UIColor.greenColor())
{
print("Green was removed")
}
if(secondBody.color == UIColor.redColor())
{
print("Red was removed")
}
if(secondBody.color == UIColor.blueColor())
{
print("Blue was removed")
}
if(secondBody.color == UIColor.yellowColor())
{
print("Yellow was removed")
}
secondBody.removeFromParent()
}
if firstBody.color != secondBody.color { // if colors don't match, call gameOver scene
//gameOver()
}
default:()
}
}