SpriteKit-RadialGravity

Simple planet gravity in Spritekit

This adds a easy way to implement planet gravity in your game

How to use it

1. Import the Planet.h class to the scene.

2. Disable world gravity.

3. Set a spritenode with a the circular PhysicsBody as you normally would.

4. Set the gravity range of the planet. [planet setGravityRange: (float)];

5. Set the gravity strength. [planet setGravityMultiplier: (float)]; //(start with 0.2f)

6. Add the planet gravity update to the update method. [planet doGravityUpdate];

=======================

    -(id)initWithSize:(CGSize)size {    
        if (self = [super initWithSize:size])
        {
            [self setPhysicsBody: [SKPhysicsBody bodyWithEdgeLoopFromRect: self.frame]];
            [self.physicsWorld setGravity: CGVectorMake( 0, 0)];
            
            planet = [Planet spriteNodeWithImageNamed:@"planet.png"];
            [planet setSize: CGSizeMake(100, 100)];
            [planet setPosition: CGPointMake( self.size.width/2, self.size.height/2)];
            [planet setPhysicsBody: [SKPhysicsBody bodyWithCircleOfRadius: 50]];
            [planet.physicsBody setDynamic: false];
            [planet setGravityRange: 120];
            [planet setGravityMultiplier: 0.1f];
            [self addChild: planet];
        }
        return self;
    }

    -(void)update:(CFTimeInterval)currentTime
    {
        [planet doGravityUpdate: self.children];
    }

========================

[planet setGravityRange: (float)];

• how far the gravity will reach

[planet setGravityMultiplier: (float)];

• how powerful the gravity is (is already really strong, so start with 0.2f)

[objectToAffect.physicsbody setAffectedByGravity: (true || false) ];

• planets will only affect if affectedByGravity

[planet doGravityUpdate: (array of children)];

• Does the magic to calculate the radial force

example: https://dl.dropboxusercontent.com/u/102932241/RadialGravity.zip