How to end a game when hitting an object from below? - swift

Question

Hey so I am making this project in which the player has to jump platforms all the way to the top. Some monsters spawn randomly throughout the game. So the idea is to lose the game when you hit them from below, but can go on if you jump on them. I already did the part in which the player jumps on it and you destroy the monster but I am still stuck on that part to lose the game when you hit it from below. Any ideas on how I can manage to do this? For this project I followed Ray Wenderlich's tutorial on How To Make a Game Like Mega Jump.
So on my GameScene, I have the didBeginContact method:
func didBeginContact(contact: SKPhysicsContact) {
var updateHUD = false
let whichNode = (contact.bodyA.node != player) ? contact.bodyA.node : contact.bodyB.node
let other = whichNode as GameObjectNode
updateHUD = other.collisionWithPlayer(player)
if updateHUD {
lblStars.text = String(format: "X %d", GameState.sharedInstance.stars)
lblScore.text = String(format: "%d", GameState.sharedInstance.score)
}
}
Which then calls the method from the GameObjectNode Scene.
class MonsterNode: GameObjectNode {
var monsterType: MonsterType!
override func collisionWithPlayer(player: SKNode) -> Bool {
if player.physicsBody?.velocity.dy < 0 {
player.physicsBody?.velocity = CGVector(dx: player.physicsBody!.velocity.dx, dy: 450.0)
if monsterType == .Normal {
self.removeFromParent()
}
}
When the player jumps on top of the monster, the monster is removed from the parent. I was trying to set that if the player's velocity is greater than 0 when colliding with the monster, then the player is removed from parent. Then when I go back to my GameScene, I could declare something in my update method so that when the player is removed from the parent call the endGame() method.
override func update(currentTime: NSTimeInterval) {
if gameOver {
return
}
if Int(player.position.y) > endLevelY {
endGame()
}
if Int(player.position.y) < maxPlayerY - 500 {
endGame()
}
}
Of course I wasn't able to make that work, and I still can't. So if anyone could help me out on how I can manage to do this, or probably some tutorial which could guide me into doing this I would really appreciate it! Thank you in advance.

Answer 1

First you use the didBeginContact method to establish if a contact between player and monster has been made. Next you compare the y positions of the player and monster. If the monster's y position is greater than than the player's... BANG, player dies.
The code sample assumes you have multiple monsters, each with a unique name, and have them all stored in an array.
- (void)didBeginContact:(SKPhysicsContact *)contact {
uint32_t collision = (contact.bodyA.categoryBitMask | contact.bodyB.categoryBitMask);
if (collision == (CategoryMonster | CategoryPlayer)) {
for(SKSpriteNode *object in monsterArray) {
if(([object.name isEqualToString:contact.bodyB.node.name]) || ([object.name isEqualToString:contact.bodyA.node.name])) {
if(object.position.y > player.position.y) {
// moster is above player
}
}
}
}
Couple of notes... If you have more than one monster active at any one time, you will need to have a unique name for each one. Reason being that you will need to know which monster contacted the player and that can only happen if you can differentiate between monsters. Hence the unique name for each one.
The if check for the y position is a simple one and only needs +1 y to be fulfilled. If it is possible for your player to make side contact with a monster and not die, you can change the if condition to be something like if(object.position.y > player.position.y+50) to make sure that the contact was actually from the bottom.
(I am not all too proficient in Swift yet so code sample is in Obj-C.)