I have to create a simulation in landscape which displays a sine function and a node which moves on the given path (the sine wave). So far I've created the sine wave with a simple sine wave with it's period (2*PI).
The question is how do I create the simulation of an infinite wave and the node moving up and down ?
My code so far is:
(CGMutablePathRef)sineWithAmplitude:(CGFloat)amp frequency:(CGFloat)freq
width:(CGFloat)width centered:(BOOL)centered
andNumPoints:(NSInteger)numPoints {
CGFloat offsetX = 0;
CGFloat offsetY = amp;
// Center the sinusoid within the shape node
if (centered) {
offsetX = -width/2.0;
offsetY = 0;
}
CGMutablePathRef path = CGPathCreateMutable();
// Move to the starting point
CGPathMoveToPoint(path, nil, offsetX, offsetY);
CGFloat xIncr = width / (numPoints-1);
// Construct the sinusoid
for (int i=1;i<numPoints;i++) {
CGFloat y = (amp * sin(2*M_PI*freq*i/(numPoints-1))*multiplier);
CGPathAddLineToPoint(path, nil, i*xIncr+offsetX, y+offsetY);
}
return path;
And the update method:
/* Called before each frame is rendered */
self.scaleMode = SKSceneScaleModeResizeFill;
// Create an SKShapeNode
SKShapeNode *node = [SKShapeNode node];
node.position = CGPointMake(x, y);
// Assign to the path attribute
node.path = [self sineWithAmplitude:20.0 frequency:frequency1 width:400.0 centered:YES andNumPoints:70];
//node.frame.size.height
node.strokeColor = [SKColor blackColor];
[self addChild:node];
x = x+400;
Until now I only display a wave, but the result should move right and look like the image.
The circle is the node that goes up and down while the wave simulates too. Any help will be greatly appreciated.
Related
Could you please help me with the problem I have?
define CC_RADIANS_TO_DEGREES(ANGLE) ((ANGLE) * 57.29577951f) // PI
-(void)didMoveToView:(SKView )view {
/ Setup your scene here */
_skyColor = [SKColor colorWithRed:113.0/255.0 green:197.0/255.0 blue:207.0/255.0 alpha:1.0];
[self setBackgroundColor:_skyColor];
//Setup the array to hold the walking frames
NSMutableArray *padlingFrames = [NSMutableArray array];
//Load the TextureAtlas for the bear
SKTextureAtlas *kajakAnimatedAtlas = [SKTextureAtlas atlasNamed:#"KajakImages"];
//Load the animation frames from the TextureAtlas
long numImages = kajakAnimatedAtlas.textureNames.count;
for (int i=1; i <= numImages; i++) {
NSString *textureName = [NSString stringWithFormat:#"kajak_0%d", i];
SKTexture *temp = [kajakAnimatedAtlas textureNamed:textureName];
[padlingFrames addObject:temp];
}
_kajakPadlingFrames = padlingFrames;
//Create kajak sprite, setup position in middle of the screen, and add to Scene
SKTexture *temp = _kajakPadlingFrames[0];
_kajak = [SKSpriteNode spriteNodeWithTexture:temp];
_kajak.position = CGPointMake(CGRectGetMidX(self.frame), CGRectGetMidY(self.frame));
[_kajak setScale:0.2];
[self addChild:_kajak];
}
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent )event {
/ Called when a touch begins */
CGPoint touchLocation = [[touches anyObject] locationInNode:self];
[self updateRotate:touchLocation];
}
(void)updateRotate:(CGPoint)touchLocation
{
float deltaX = touchLocation.x - _kajak.position.x;
float deltaY = touchLocation.y - _kajak.position.y;
float angle = atan2f(deltaY, deltaX);
SKAction *action = [SKAction rotateByAngle: CC_RADIANS_TO_DEGREES(angle) duration: 5.0];
[_kajak runAction:action];
}
The kayak is not rotate in the direction the I touch. It is some thing I missing? Please help me. Tank you in advance
The zero angle for SKSpriteNodes is pointing up (as opposed to standard trig functions that treat zero angle as pointing right). I had to create a special angle calculation function to take that into account in my game (see below, in Swift).
You may also need to make sure that the coordinate system you are using for the positions is the same for the sprite and the touch location. From your code (i'm not very comfortable with Obj-C) I believe they are both base on the scene's bounds but I'm not certain.
// angle between two points
// ------------------------
// SpriteKit's zero angle is pointing up
// atan2 returns an angle pointing right
// we're usung sprite kit's conventions so removing 90° from the result
//
func spriteAngleFrom(start:CGPoint, to finish:CGPoint) -> CGFloat
{
let deltaX = finish.x - start.x
let deltaY = finish.y - start.y
return atan2(deltaY,deltaX) - CGFloat.pi/2
}
You also need to use rotateToAngle, not rotateByAngle. And I would suggest you also specify shortestUnitArc : true.
I am new to SpriteKit but not to iOS. I'm having a great deal of difficulty figuring out the conversions from UIKit coordinates to SKScene coordinates. In addition, their relations to the units used for the SpriteKit physics engine evades me.
Here's what I'm trying to do: I am launching a sprite with an initial velocity in both x and y directions. The sprite should start near the screen's bottom left corner (portrait mode) and leave near the bottom right corner. Another sprite should appear somewhere on the previous sprite's trajectory. This sprite is static.
The blue frame is the screen boundary, the black curve is the first sprite's trajectory and the red circle is the static sprite.
Now using the screen as 640 x 960. In my SKScene's didMoveToView: method I set the gravity as such:
self.physicsWorld.gravity = CGVectorMake(0.0f, -2.0f);
Then I make the necessary calculations for velocity and position:
"t" is time from left corner to right;
"y" is the maximum height of the trajectory;
"a" is the acceleration;
"vx" is velocity in the x direction;
"vy" is velocity in the y direction;
and
"Tstatic" is the time at which the dynamic sprite will be at the static sprite's position;
"Xstatic" is the static sprite's x-position;
"Ystatic" is the static sprite's y-position;
-(void)addSpritePair {
float vx, vy, t, Tstatic, a, Xstatic, Ystatic, y;
a = -2.0;
t = 5.0;
y = 800.0;
vx = 640.0/t;
vy = (y/t) - (1/8)*a*t;
Tstatic = 1.0;
Xstatic = vx*Tstatic;
Ystatic = vy*Tmark + 0.5*a*Tstatic*Tstatic;
[self spriteWithVel:CGVectorMake(vx, vy) andPoint:CGPointMake(xmark, ymark)];
}
-(void)spriteWithVel:(CGVector)velocity andPoint:(CGPoint)point{
SKSpriteNode *staticSprite = [SKSpriteNode spriteNodeWithImageNamed:#"ball1"];
staticSprite.anchorPoint = CGPointMake(.5, .5);
staticSprite.position = point;
staticSprite.name = #"markerNode";
staticSprite.zPosition = 1.0;
SKSpriteNode *dynamicSprite = [SKSpriteNode spriteNodeWithImageNamed:#"ball2"];
dynamicSprite.anchorPoint = CGPointMake(.5, .5);
dynamicSprite.position = CGPointMake(1 ,1);
dynamicSprite.zPosition = 2.0;
dynamicSprite.physicsBody = [SKPhysicsBody bodyWithCircleOfRadius:hoop.size.width/2];
dynamicSprite.physicsBody.allowsRotation = NO;
dynamicSprite.physicsBody.velocity = velocity;
dynamicSprite.physicsBody.affectedByGravity = YES;
dynamicSprite.physicsBody.dynamic = YES;
dynamicSprite.physicsBody.mass = 1.0f;
dynamicSprite.markerPoint = point;
dynamicSprite.physicsBody.restitution = 1.0f;
dynamicSprite.physicsBody.friction = 0.0f;
dynamicSprite.physicsBody.angularDamping = 0.0f;
dynamicSprite.physicsBody.linearDamping = 0.0f;
[self addChild:hoop];
[self addChild:marker];
}
When I execute the code, the following happens:
Can someone please help me out?
I'm building a game using spriteKit.
I created a spriteNode called 'planet' and set a velocity. It drops down from the top of the screen with constant speed to the bottom of the screen. However, it slows down towards the middle of the screen and stops moving entirely. I added the method 'moveTowardPosition' as an attempt to fix this issue by forcing the objects to move offscreen. Does anyone have an idea of what the issue might be?
Thanks!
Here is the setup of the object:
-(void)physicsBodySetup
{
//initializes the physicsBody
self.physicsBody = [SKPhysicsBody bodyWithCircleOfRadius:40];
self.physicsBody.affectedByGravity = NO;
//sets its category mask
self.physicsBody.categoryBitMask = TKCollisionCategoryPlanet;
//planet doesn't collide with anything
self.physicsBody.collisionBitMask = 0;
//the planet can get into contact with an astranaut
self.physicsBody.contactTestBitMask = TKCollisionCategoryAstronaut |
}
//adds 'planet' to the screen at random position
//#param frame: the frame of the main view
-(void)addPosition:(CGRect)frame
{
//specifies a random position to add the planet on the screen
float randomPositionY = frame.size.height + self.size.height;
float randomPositionX = [TKUtil randomWithMin:10+self.size.width max:frame.size.width-10 - self.frame.size.width];
self.position = CGPointMake(randomPositionX, randomPositionY);
[self velocitySetup];
}
-(void)velocitySetup
{
//initializes the speed to be a constant
self.planetSpeed = TKPlanetSpeed;
self.physicsBody.velocity = CGVectorMake(0, self.planetSpeed);
}
//#param position: the point of planet on the screen
-(void)moveTowardsPosition:(CGPoint)position
{
float offScreenX = position.x;
float offScreenY = position.y - 2000;
CGPoint pointOffScreen = CGPointMake(offScreenX, offScreenY);
float Distance = pointOffScreen.y - position.y;
float time = Distance / self.planetSpeed;
SKAction *movePlanet = [SKAction moveTo:pointOffScreen duration:time];
NSArray *sequence = #[movePlanet, [SKAction removeFromParent]];
[self runAction:[SKAction sequence:sequence]];
}
The default value of friction is 0.2. So you can try:
self.physicsBody.friction = 0.0
now it won't be affected by surface anymore.
i've created a code that creates a line of unlimited size by touch and i'm wondering how to restrict the size such that the beginning and end of the line can be a small distance to a maximum set distance apart?
The code i used was:
pathToDraw = CGPathCreateMutable();
CGPathMoveToPoint(pathToDraw, NULL, positionInScene.x, positionInScene.y);
lineNode = [SKShapeNode node];
lineNode.path = pathToDraw;
lineNode.zPosition = 1000;
lineNode.strokeColor = [SKColor blueColor];
lineNode.physicsBody = [SKPhysicsBody bodyWithEdgeLoopFromPath:pathToDraw];
lineNode.physicsBody.categoryBitMask = ballCategory;
lineNode.physicsBody.contactTestBitMask = ballCategory;
[self addChild:lineNode];
in the touch Began Method and
CGPathAddLineToPoint(pathToDraw, NULL, location.x, location.y);
lineNode.path = pathToDraw;
lineNode.zPosition = 1000;
lineNode.physicsBody = [SKPhysicsBody bodyWithEdgeLoopFromPath:pathToDraw];
lineNode.physicsBody.categoryBitMask = boundaryCategory;
lineNode.physicsBody.contactTestBitMask = ballCategory;
lineNode.name = #"boundary";
lineNode.physicsBody.restitution=1;
in the touchMoved method.
Thank you
First add this function...
// Computes the distance between two points
static inline CGFloat distance(CGPoint p1, CGPoint p2)
{
CGFloat dx = p1.x - p2.x;
CGFloat dy = p1.y - p2.y
return sqrt(dx*dx+dy*dy);
}
then add this to your touches moved function...
CGFloat lineLength = distance(location, positionInScene);
if (distance < kMaxDistance) {
// Draw line here
}
Also, I suggest you wait until you know the line is valid before creating the SKShapeNode. Perhaps you should create a placeholder node, such as a circle, and then create the shape node line after you verified that the line is valid.
I have created my SKScene subclass which sets the anchorpoint and then adds one SKSpriteNode for the world, the world has multiple SKSpriteNodes for the obstacles, player etc. I am also centering on the
The problem I am having is that as I have set the anchorpoint of the scene to (0.5, 0.5), the position of any child node that I add to the world starts at the center of the world. How do I fix the postion of the nodes so that position = (0,0) will be at the bottom left of the world node and any child nodes added to it, instead of the center?
#implementation LevelScene
-(id)initWithSize:(CGSize)size {
if (self = [super initWithSize:size]) {
NSLog(#"width:%f height:%f", self.view.bounds.size.width, self.view.bounds.size.height);
// set the physics body
self.physicsWorld.gravity = CGVectorMake(0,-5);
self.physicsWorld.contactDelegate = self;
self.anchorPoint = CGPointMake(0.5, 0.5);
NSMutableDictionary *plistDict = [[NSMutableDictionary alloc] initWithContentsOfFile:[[NSBundle mainBundle] pathForResource:#"LevelScene" ofType:#"plist"]];
NSString *backgroundImage = [plistDict objectForKey:#"background"];
// add a node that holds the background
background = [SKSpriteNode spriteNodeWithTexture:[SKTexture textureWithImageNamed:backgroundImage] size:CGSizeMake(1024, 768)];
background.position = CGPointMake(0, 0);
[self addChild:background];
world = [SKSpriteNode spriteNodeWithColor:[SKColor brownColor] size:CGSizeMake(1024, 768)];
world.position = CGPointMake(0, 0); // this should be bottom-left
world.size = CGSizeMake(1024, 768);
world.physicsBody = [SKPhysicsBody bodyWithEdgeLoopFromRect:world.frame];
world.physicsBody.categoryBitMask = worldCategory;
[self addChild:world];
// load in the game tiles (these are non-dynamic tiles the player can use)
[self loadInTiles];
// add in game object to the world skspritenode - this just creates a subclass of skspritenode and sets position to 0,0
[self addGameObject:CGPointMake(0, 0)];
...
}
// ...setup functions, input handling, etc
-(void)didSimulatePhysics {
// setup the player to move depending on their direction
[player updatePosition];
[self centreOnNode:player];
}
-(void)centreOnNode: (SKSpriteNode *)node {
CGPoint cameraPositionInScene = [node.scene convertPoint:node.position fromNode:node.parent];
CGFloat x = node.parent.position.x - cameraPositionInScene.x;
CGFloat y = node.parent.position.y - cameraPositionInScene.y;
NSLog(#"camera x:%f y:%f", x, y);
NSLog(#"world frame origin x:%f y:%f", world.frame.origin.x, world.frame.origin.y);
node.parent.position = CGPointMake(x, y);
}
If you want to set the world sprite's origin to the bottom left side, just set it's anchor point.
world.anchorPoint = CGPointMake(0,0);
With this, the world sprite's coordinate system will be just like that of the scene's default.
Make sure to remove the line:
self.anchorPoint = CGPointMake(0.5, 0.5);
Replace this row:
world.position = CGPointMake(0, 0);
by this:
world.position = CGPointMake(-CGRectGetMidX(self.frame), -CGRectGetMidY(self.frame));
(0,0) is the center of the scene, since you set anchor point of the SKScene to (0.5,0.5)