Build a simple seesaw with Sprite Kit physics

Building a simple element for your game with SKPhysics and SKPhysicsJointPin. Here is the class code for a simple physical seesaw like in this video

//
//  WWSeesaw.m
//  PoBo
//
//  Created by zinne on 18.07.14.
//  Copyright (c) 2014 waveworks. All rights reserved.
//
#import "WWSeesaw.h"
@implementation WWSeesaw
+(void)addSeesaw: (CGPoint)pos game:(SKScene*)game {
SKSpriteNode * anchor = [SKSpriteNode spriteNodeWithColor:[UIColor clearColor] size:CGSizeMake(1, 1)];
anchor.position = pos;
anchor.name = @"whip_anchor";
anchor.physicsBody = [SKPhysicsBody bodyWithCircleOfRadius:1];
anchor.physicsBody.affectedByGravity = false;
anchor.physicsBody.dynamic = false;
[game addChild:anchor];
SKSpriteNode * whip = [SKSpriteNode spriteNodeWithImageNamed:@"seesaw.png"];
whip.name = @"whip";
whip.size = CGSizeMake(200, 15);
whip.physicsBody = [SKPhysicsBody bodyWithRectangleOfSize:CGSizeMake(200, 15)];
[anchor addChild:whip];
SKSpriteNode * gear = [SKSpriteNode spriteNodeWithImageNamed:@"gear_1.png"];
gear.size = CGSizeMake(20, 20);
gear.name = @"gear";
[anchor addChild:gear];
SKPhysicsJointPin* jointPin = [SKPhysicsJointPin jointWithBodyA:anchor.physicsBody
bodyB:whip.physicsBody
anchor:anchor.position];
[game.physicsWorld addJoint:jointPin];
}
@end

// WWSeesaw.m

// PoBo

// Created by zinne on 18.07.14.

#import "WWSeesaw.h"

@implementation WWSeesaw

+(void)addSeesaw: (CGPoint)pos game:(SKScene*)game {

SKSpriteNode * anchor = [SKSpriteNode spriteNodeWithColor:[UIColor clearColor] size:CGSizeMake(1, 1)];

anchor.position = pos;

anchor.name = @"whip_anchor";

anchor.physicsBody = [SKPhysicsBody bodyWithCircleOfRadius:1];

anchor.physicsBody.affectedByGravity = false;

anchor.physicsBody.dynamic = false;

[game addChild:anchor];

SKSpriteNode * whip = [SKSpriteNode spriteNodeWithImageNamed:@"seesaw.png"];

whip.name = @"whip";

whip.size = CGSizeMake(200, 15);

whip.physicsBody = [SKPhysicsBody bodyWithRectangleOfSize:CGSizeMake(200, 15)];

[anchor addChild:whip];

SKSpriteNode * gear = [SKSpriteNode spriteNodeWithImageNamed:@"gear_1.png"];

gear.size = CGSizeMake(20, 20);

gear.name = @"gear";

[anchor addChild:gear];

SKPhysicsJointPin* jointPin = [SKPhysicsJointPin jointWithBodyA:anchor.physicsBody

bodyB:whip.physicsBody

anchor:anchor.position];

[game.physicsWorld addJoint:jointPin];

}

@end

4 thoughts on “Build a simple seesaw with Sprite Kit physics”

new2objectivec on 17. August 2014

Thanks for the very helpful post. Can you please also show example of making a „cross“ – with 2 whips connected to the same anchor point in the middle rather than just a seesaw? I tried to add a second whip to the same anchor point but it doesn’t work…
Thanks

Antworten
- new2objectivec on 3. September 2014
  
  Got the „cross“ working by joining 2nd rectangle to the first one using fixed joint (SKPhysicsJointFixed). Code available on my blog as below. Thanks.
  
  http://new2objectivec.blogspot.com.au/2014/08/how-to-create-cross-or-plus-shape.html
  
  Antworten
- zinne on 22. September 2014
  
  Hi,
  I added a new tutorial for this crosses you asked:
  http://www.free-pobo.com/build-a-rotating-mill-with-sprite-kit-physics/
  
  Antworten
new2objectivec on 25. April 2015

Thanks you!

Antworten

WaveWorks – GameStudios

Build a simple seesaw with Sprite Kit physics

4 thoughts on “Build a simple seesaw with Sprite Kit physics”

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