Physics game with cocos2d for iphone v3.0.0

Question

I'm new to cocos2d-iphone, I'm creating demo app about physics with cocos2d-iphone

I want to create an outline of the basic physics node (node #1), to keep some node "in door"

And I add some node (nodes #2) into node #1

But when I rotate node #1, all nodes #2 fall down. I can not keep them inside node #1.

I'm using Cocos2D-iPhone version 3.0.0

My demo is here : https://github.com/ditimtriky/DemoCocos2d

Can you help me to fix it?

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

You can take a quick look at here https://plus.google.com/photos/105576008720153830534/albums/6020993675161389681/6020993675419257554

or

https://lh6.googleusercontent.com/-F3WIN7j8_nE/U47d2OI9CtI/AAAAAAAAGVI/eAzccfAPZds/w180-h240-no/1401870652451id172912.gif

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

#import "MyScene.h"

@implementation MyScene {
    CCPhysicsNode *_physicsNode;
}

+ (instancetype)scene {
    return [[self alloc] init];
}

- (void)onEnter {
    [super onEnter];
    glClearColor(0.1, 0.1, 0.1, 1.0);

    [[CCSpriteFrameCache sharedSpriteFrameCache] addSpriteFramesWithFile:@"newton.plist"];

    _physicsNode = [CCPhysicsNode node];
    _physicsNode.gravity = ccp(0, 3*-980.665);
    _physicsNode.debugDraw = YES;
    [self addChild:_physicsNode];

    // create an outline of the basic physics node, to keep physics "in door"
    CCNode *outline = [CCNode node];
    outline.contentSize = CGSizeMake(280, 300);
    outline.anchorPoint = ccp(0.5, 0.5);
    outline.position = ccp(160, 284);

    outline.physicsBody = [CCPhysicsBody bodyWithPolylineFromRect:CGRectMake(0, 0, 280, 300) cornerRadius:3];
    outline.physicsBody.friction = 1.f;
    outline.physicsBody.elasticity = 0.5f;
    outline.physicsBody.collisionCategories = @[@"outline"];
    outline.physicsBody.collisionMask = @[@"sphere", @"rope"];
    [_physicsNode addChild:outline];

    for (int i = 0; i < 20; i++) {
        CCSprite *sprite = [CCSprite spriteWithImageNamed:@"letter.o.png"];
        sprite.anchorPoint = ccp(0.5,0.5);
        sprite.position = ccp(160, 284);

        CCPhysicsBody *body =
        [CCPhysicsBody bodyWithCircleOfRadius:25
                                    andCenter:ccp(sprite.contentSize.width/2,sprite.contentSize.height/2)];
        sprite.physicsBody = body;

        body.friction = 0.5;
        body.elasticity = 1.0;
        body.collisionCategories = @[@"sphere"];
        body.collisionMask = @[@"sphere", @"outline"];

        [_physicsNode addChild:sprite];
    }

    //rotate
    [outline runAction:
     [CCActionRepeatForever actionWithAction:
      [CCActionSequence actionWithArray:@[[CCActionRotateTo actionWithDuration:1 angle:180],
                                          [CCActionRotateTo actionWithDuration:1 angle:360]]]]];

    // add a reset button
    CCButton *resetButton = [CCButton buttonWithTitle:@"" spriteFrame:[CCSpriteFrame frameWithImageNamed:@"reset.png"]];
    resetButton.positionType = CCPositionTypeNormalized;
    resetButton.position = (CGPoint){0.90f, 0.80f};;
    [resetButton setTarget:self selector:@selector(onResetClicked:)];
    [self addChild:resetButton];
}

- (void)onResetClicked:(id)sender
{
    // recreate the scene
    [[CCDirector sharedDirector] replaceScene:[self.class scene]];
}

@end

Answer 1

The problem is mixing actions and physics together in 3.0. The action only sets the position, causing the physics body to "teleport" along with it. This is fixed in 3.1 for static bodies with actions.

If you want to stay on 3.0 you need to update the body's angle and angular velocity manually.