I'm using a SpriteKit game engine within XCode while developing a game that bounces a ball and platforms come from the sky and the objective is to bounce on the platforms to get higher. I need to add a velocity to the ball when it falls down + comes in contact with a platform. I'm having trouble trying to detect the balls Y position. I had something like this in the update method but nothing happens... I'm open to suggestions.
//The value of the _number instance variable is the Y position of the ball.
if (_number++) {
NSLog(#"UP");
}
if (_number--) {
NSLog(#"DOWN");
}
You can see a node's position by using code like this:
if(myNode.position.y > 0)
NSLog(#"y is greater than 0");
If you want to check a node's current speed (vector) you can do it like this:
if(myNode.physicsBody.velocity.dy > 0)
NSLog(#"Moving up");
if(myNode.physicsBody.velocity.dy < 0)
NSLog(#"Moving down");
Remember that position and speed (vector) are not the same thing.
You need to read the SKPhysicsBody docs to understand about CGVector and other important issues.
Alright, this:
if (_number++) {
NSLog(#"UP");
}
if (_number--) {
NSLog(#"DOWN");
}
doesn't work to do anything. It shouldn't even run. I don't why it doesn't give an error.
number++; is a simplified form of
number = number + 1;
You can't place it in an if statement.
First make the variable #property int ypos in your header.
Then every update compare the current y to the ypos.
After comparing, save the current y to ypos.
Place this in your Update method.
if (ball.position.y > _ypos)
{
//going up
}
else if (ball.position.y < _ypos)
{
//going down
}
_ypos = ball.position.y;
P.S. I haven't had access to a computer so the formatting might suck from my phone
Related
I'm making a simple game in Spritekit where I roll a ball around the screen. Right now it works fine and the ball moves around how I want it to. I want to change it though so that the neutral position is something like 45 degrees instead of flat. This is the code I have now.
- (void)startMonitoringAcceleration {
if (_motionManager.accelerometerAvailable) {
[_motionManager startAccelerometerUpdates];
}
}
- (void)moveBallFromMotionManager {
CMAccelerometerData* data = _motionManager.accelerometerData;
if (fabs(data.acceleration.x) > 0.05) {
[_ball.physicsBody applyForce:CGVectorMake(25.0 * data.acceleration.y, -25.0 * data.acceleration.x)];
}
if (fabs(data.acceleration.y) > 0.05) {
[_ball.physicsBody applyForce:CGVectorMake(25.0 * data.acceleration.y, -25.0 * data.acceleration.x)];
}
}
-(void)update:(CFTimeInterval)currentTime {
[self moveBallFromMotionManager];
}
I'm new to this, so I don't really know how I should go about doing it. Thanks for any help.
Create a baseline for your pitch and roll. For example, at the init method (or anytime you want) set 2 variables with the current value for pitch and roll. Once done, you can use those variables as an offset against current values.
For example, the pitch offset is set at 0.3. If your current pitch reading is 0.45, subtract the offset from the current reading.
I'm writing a 2D ball game with sprite kit on iOS 7 and currently struggling on one physic simulation.
To explain the expected behavior: if a ball is dropped into a tea cup, it will circle around, loosing speed and finally stand still in the center of the cup.
I've tried to archive this with gravity, but gravity in sprite kit only applies to vertical X and Y axis, not Z-axis. I also tried to use level gravity by switching gravity values with small physic bodies on beginContact depending on the current ball position in the tea cup. But some contacts are dropped and the result is far away to look realistic.
I think I need to solve this in the update: method, but I have no idea which way to go.
Any advice greatly welcome and I need to mention that I'm not an expert on math, please explain your path to go. :-)
Since there's no built-in support for this kind of behavior in SpriteKit, rather than trying to hack existing functions to get what you want, you're probably better off integrating some published 2D physics formulas in your x,y 2D world. I would think that something like simulating magnetic or a homing behavior might be right for this.
A simple example would be something like (in the scene's -update: method):
CGFloat strength = 0.5; //(some scaling value)
CGPoint ballLocation = ball.position;
CGPoint cupLocation = cup.position;
[ball.physicsBody applyForce:CGVectorMake((cupLocation.x - ballLocation.x) * strength,
(cupLocation.y - ballLocation.y) * strength)];
following Joshd great idea, I have created an NSArray with like explained in my comment above. Hope this snippets does help some others...
The result could be found on youtube: http://youtu.be/Uephg94UH30
Sorry for the bad Airplay frame rate, it runs perfectly smooth on my iPad
The -update: functions does the work but only triggered if _meditationIsActive. This bool is set in -didBeginContact: when any ball gets in contact with a hole.
if (_lastCheck > 0.005)
{
if (_meditationIsActive)
{
CGFloat strength = 0.1; //(some scaling value)
CGPoint ballLocation;
CGPoint holeLocation;
for (MeditationHole * holeObj in _meditationHoles)
{
if (holeObj.connectedMeditationBall != nil)
{
ballLocation = holeObj.connectedMeditationBall.position;
holeLocation = holeObj.position;
[holeObj.connectedMeditationBall.physicsBody applyForce:CGVectorMake(
(holeLocation.x - ballLocation.x) * strength, (holeLocation.y - ballLocation.y) * strength)];
}
}
_meditationIsActive = [self doesMeditationApplies];
}
_lastCheck = 0;
}
At the end I'm checking if there is a valid ball out of the array in contact with a hole to avoid checking during every update. This is done with the following function where position check +/- 48 detects a ball close to a hole and +/-1 ball stands still
- (bool)doesMeditationApplies
{
bool isInArea = NO;
int perfectMatchCount = 0;
for (MeditationHole * holeObj in _meditationHoles)
{
if (holeObj)
{
if (holeObj.connectedMeditationBall != nil)
{
MeditationBall * ballObj = holeObj.connectedMeditationBall;
if ((ballObj.position.x >= holeObj.position.x - 48) &&
(ballObj.position.x <= holeObj.position.x + 48) &&
(ballObj.position.y >= holeObj.position.y - 48) &&
(ballObj.position.y <= holeObj.position.y + 48))
{
isInArea = YES;
}
else
{
holeObj.connectedMeditationBall = nil;
}
if ((ballObj.position.x >= holeObj.position.x - 1) &&
(ballObj.position.x <= holeObj.position.x + 1) &&
(ballObj.position.y >= holeObj.position.y - 1) &&
(ballObj.position.y <= holeObj.position.y + 1))
{
perfectMatchCount++;
isInArea = YES;
}
}
}
}
if (perfectMatchCount == _oxydStonesMax)
{
if (_sound)
{
self.pauseMusicPlaybackBlock(YES);
NSLog(#"PlaySound Meditation");
[OxydScene PlaySystemSound:#"Win2"];
}
isInArea = NO;
[self showPauseScreenWithWin:YES andPauseOnly:NO];
}
return isInArea;
}
I already know how to check for collisions with the doesintersectNode-method in Cocos3d, but in my case, I want to avoid obstacles, before I get in touch with them. In example, I want to stop in front of a wall, before I crash against it.
For this reasons I wrote the methods getNodeAtLocation in my subclass of CC3Scene and -(BOOL)shouldMoveDirectionallywithDistance:(float)distance in the class of my person, which should move around.
Unfortunately, I have some problems with the algorithm of the last method. Here the code:
-(BOOL)shouldMoveDirectionallywithDistance:(float)distance
{
BOOL shouldMove = NO;
float x = self.person.globalLocation.x;
float z = self.person.globalLocation.z;
int times = 5;
for (int i = 0; i < times; i++) {
CC3Vector newPos = cc3v(x, 0.5, z);
CC3PODResourceNode *obstacle = (CC3PODResourceNode *)[myScene getNodeAtLocation:newPos];
if (obstacle) {
return NO;
}else{
shouldMove = YES;
}
x += self.person.globalForwardDirection.x * distance / times;
z += self.person.globalForwardDirection.z * distance / times;
}
return shouldMove;
}
In this method, I get the important parts of the coordinates (for my proposal just the x- and z-values) and increase them by a fifth of the forwardDirection. I decided, that this makes sense, when the obstacle is i.e. a thin wall. But for reasons I don't know, this method doesn't work, and the person is able to walk through this wall. So where is the problem in my code?
I strongly believe, that the getNodeAtLocation-method works correctly, as I tested it multiple times, but maybe there are my mistakes:
-(CC3Node *)getNodeAtLocation:(CC3Vector )position
{
CC3Node *node = nil;
for (CC3PODResourceNode *aNode in self.children) {
if ([aNode isKindOfClass:[CC3PODResourceNode class]] ) {
for (CC3PODResourceNode *child in aNode.children) {
if (CC3BoundingBoxContainsLocation(child.globalBoundingBox, position)) {
node = aNode;
}
}
}
}
return node;
}
To conclude, in my view the mistake is in the -(BOOL)shouldMoveDirectionallywithDistance:(float)distance-method. I suppose, that something is wrong with the increase of the x- and z-values, but I couldn't figure out, what exactly is incorrect.
If you are still interested in finding an answer to this problem. I may be able to provide you with an alternative solution. I am about to release free source for a 3d collision engine I ported to cocos3d, and it will give you more flexibility than simply stoping an object in front of another.
I am currently polishing out the code a little for easy use, but if you are interested you can email me to: waywardson07#aol.com
you could also get a little preview of the engine in action here: http://www.youtube.com/watch?v=QpYZlF7EktU
Note: the video is a little dated.
After several attempts, it appears to be easier as I thought:
Just using the doesIntersectNode method has the right effect for me.
But please notice, that this is not a real solution to the problem of stopping in front of obstacles.
I'm trying to make some moving tiles from a Tiled map editor tmx file.
I have the moving tiles in their own layer, and I just want to simply have them move up, and then when they reach a certain y, move back down, and etc.
I have been looking around for a bit on a clear way of accomplishing this, but my efforts have been unsuccessful.
I tried using some of the methods here.
I'm still really new to cocos2d development in general, so I wold appreciate any insight on this. Thank you very much for your time. If you have any questions, please ask! :)
Also if it helps, the tiles I'm trying to move are in a big T shape.
FINAL UPDATE:
(Removed more irrelevant code so anyone in the future can easily find my solution (the full answer is below), you can find where I got my layer iterate method at the link above).
Okay, so I have finally got it working close to how I want.. I don't think this is exactly the most ideal way of doing it, but this is what I've got.
Note: In order for this to work for you, you have to run your app out of debug mode or it will lag/make the player fall through the ground (at least it did for me..).
I have an update function that calls certain functions every frame. (Checking collisions, moving platforms, etc).
That update function calls my move platforms function..
like this:
[self movePlatforms:0.1];
this is my movePlatforms function..
-(void)movePlatforms: (ccTime) dt{
if(goingDown){
moveCount++;
}else{
moveCount--;
}
CGSize s = [movingTiles layerSize];
for( int x=0; x<s.width;x++) {
for( int y=0; y< s.height; y++ ) {
CCSprite *tile = [movingTiles tileAt:ccp(x,y)];
if(goingDown){
CGPoint newPosition = ccp(tile.position.x, tile.position.y - 1);
tile.position = newPosition;
if(moveCount >= 100){
goingDown = false;
}
}else{
CGPoint newPosition = ccp(tile.position.x, tile.position.y + 1);
tile.position = newPosition;
if(moveCount <= 0){
goingDown = true;
}
}
}
}
}
So basically, I created a int moveCount and a BOOL goingDown to keep track of how many times my movePlatform function has been called. So after 100 calls, it switches direction.
(This works fine for me, you might need something else like a collision detecter if that is the case use this).
if (CGRectIntersectsRect([someSprite boundingBox], [someSprite boundingBox])) {
//Do something
}
Hopefully this works for someone in the future, I know this was quite the headache for me, and it probably isn't even done correctly or there is a much better way to do it, but if this helps you, that is awesome!
Creating and removing tiles will effect your performance.
Instead of it, try to move the tile changing their position:
CCSprite *tile = [movingTiles tileAt:ccp(92,platformY)];
[movingTiles removeTileAt:ccp(92,platformY)];
CGPoint newTilePosition = tile.position;
if (goingDown){
newTilePosition.y ++;
if(newTilePosition.y >= 20){
goingDown = false;
}
}else{
newTilePosition.y --;
if(newTilePosition.y <= 10){
goingDown = true;
}
}
tile.position = newTilePosition;
Here is the (kind of) step by step of how I got my moving tiles working, this is only related to the moving tiles, and nothing else.
Note: You will need to run this as a release (not debug) in order to get everything running smoothly, and not having your character fall through the ground.
In the interface I created these variables:
#interface HelloWorldLayer(){
CCTMXTiledMap *map;
BOOL goingDown;
int moveCount;
}
The CCTMXTiledMap is the instance of my map.
The BOOL and int are two variables I use to keep track of my moving tiles.
-(id) init {
if( (self=[super init]) ) {
// add our map
map = [[CCTMXTiledMap alloc] initWithTMXFile:#"level1-1.tmx"];
map.position = ccp(0,0);
[self addChild:map];
//add our moving platforms layer
movingTiles = [map layerNamed:#"moving_platforms"];
//set the variables I use to keep track of the moving platforms
goingDown = true;
moveCount = 0;
//schedule my update method
[self schedule:#selector(update:)];
}
return self;
}
After the init method, I then create my move platforms method:
-(void)movePlatforms: (ccTime) dt{
if(goingDown){
moveCount++;
}else{
moveCount--;
}
CGSize s = [movingTiles layerSize];
for( int x=0; x<s.width;x++) {
for( int y=0; y< s.height; y++ ) {
CCSprite *tile = [movingTiles tileAt:ccp(x,y)];
if(goingDown){
CGPoint newPosition = ccp(tile.position.x, tile.position.y - 1);
tile.position = newPosition;
if(moveCount >= 100){
goingDown = false;
}
}else{
CGPoint newPosition = ccp(tile.position.x, tile.position.y + 1);
tile.position = newPosition;
if(moveCount <= 0){
goingDown = true;
}
}
}
}
}
So this is where the magic happens, I use methods I got from here, and the gentleman Mauricio Tollin told me I could update a tile position rather than destroy and recreate them.
So I iterate through every tile in my moving platforms layer, and tell them to go down 1 every call, until moveCount >= 100, then it says goingDown is now false, and it switches its direction. From there it just goes back and forth, counting to 100, and then back down.
If you want it to move longer, just increase 100 to 200 or whatever you want. (Or you can use a check to detect collision, and when it collides with a specified sprite, you can have it change then. If that is more of what you want, use this).
if (CGRectIntersectsRect([someSprite boundingBox], [someSprite boundingBox])) {
//Do something
}
After all of that, I create my update method:
-(void)update:(ccTime)dt{
[self movePlatforms:0.1];
}
In the init method it schedules the update method to be called every frame, and then the update method will run the movePlatforms method (or any other function that needs to be checked frequently, such as hazard detection, etc).
You can also make the platforms move slower by changing the time passed into movePlatforms, or you can schedule a slower update interval in the init method.
I hope this helps someone out in the future, I just wanted to create this answer with a more in depth process of how I got this working, since my question post was really unorganized and heavily edited while I was learning.
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.