I am making an app in which balls roll on tracks.
So when we touch and drag the balls around the screen, they should move along the tracks. If the drag goes out too distant from the track, it should stop. The tracks can be any shape.
What is the best appraoch..?
It depends on how the track is defined programatically, but it you've got a CGPath that represents it, or can make one, use can use CGPathContainsPoint in the touchesMoved method and refuse to update the position of the ball if it is outside the path.
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I want to create a circular room in a 2D level. How can I handle this problem?
My thought process was to break the level into chunks and move their position depending on where the player currently is. This would allow the level to wrap around depending on where the player travels. I can do this manually with each part but i'm looking for a better solution that can handle this programatically. I'm open to better ways to solve this problem as well.
Is the space 2D? if so, you could place two invisible colliders at the extremities of the room (one at the beginning and one at the end), and change the player's position when he collides with them. To ensure that the transition is smooth, place them a little outside of the camera space: the player won't be rendered during transition, and you would obtain a teleport effect from side to side.
As another suggestion, you can lock the player to being in the center chunk with a camera just showing that chunk. Everytime he gets through a collider on the end or the start of the middle platform you delete the opposite side platform and place it in the far end of the platform the player is now seeing, effectively making the new platform as the middle one.
I need help implementing controls to move a SceneKit sphere. I want to have the user touch on the screen and when they move their finger around, the ball will move relative to the position of the user's finger. I don't want the y to increase or decrease I just want x and z, almost like a hula hoop.
I think you can use the GameController Framework seen Apple have released the WWDC Demo 'Fox', and it use GameController to control the character.
I am trying to build a game using cocos2d where the user is able to drag an object along a path to a end goal. I have gotten the drag and drop to work but I am not sure how to implement the path so that when the user goes off the path it dies.
Any idea how to implement this so that I can have multiple levels?
From my understanding of your problem you don't want to do drag and drop at all.
Instead make the movement along the path an action and use the user's touch to set how far along that action they are. That way (like you would scrub backwards and forwards with a video) the user can scrub the object's action along its path.
I would first of all get your object moving along the path you desire using CCBezierTo or whatever. When you are happy with the results start the touch actions.
When the user touches the object you want to know how far along the path they are where 0 is the start and 1 the end. Then move the number closer to 1 the closer to the endpoint the touch moves and closer to 0 as it moves closer to the start point.
If you path is fairly straightish you can probably just do a simple calculation of where the touch is on a straight line between the start and end point. If its a complicated curve say going in circles you will have some hard work/trig to do!
Then as the touch moves you will need to update the object's position to the new location on the path. Say you have worked out the the touch is now at .75 along your path you will now need to workout the position the object should be at .75 * duration. You may need to extend or add a category to your action to allow you to set the position your given elapsed value.
Hope this steers you in a possible direction!
I'm trying to create a top down car game where the camera follows both the player and the player's rotation. I can get CCFollow to work easily, but I have had no success with CCCamera. I assume that I need the camera in order to make rotation follow the player (i.e. have the player facing up at all times) but I have had no luck on google.
Can anyone either provide a code snippet or a tutorial on how to create a rotation-following top down camera?
Cheers!
My suggestion: don't use the CCCamera.
Your game design requires the car to move over a track. In programming terms this is often much easier accomplished by keeping the car static, and instead moving the background underneath.
Assume your car is at the center of the screen. It's supposed to move from left to right. Instead of moving the car or the camera, move the background layer - just in reverse: move the background layer from right to left to make it seem like the car is moving from left to right.
The same is true for rotation. If you want the car to turn left, rotate the background in clockwise direction.
This is a lot easier and can be accomplished simply by changing the position and direction properties of the background layer. Note that you do not need to do this for each object in the background layer, it's sufficient to add all objects to the background layer in the appropriate positions and then just change the background layer properties. The layer's children will follow accordingly.
I have a simple project built with Cocos2D and Chipmunk. So far it's just a Ball (body, shape & sprite) bouncing on the Ground (a static line segment at the bottom of the screen).
I implemented the ccTouchesBegan/Moved/Ended methods to drag the ball around.
I've tried both:
cpBodySlew(ballBody, touchPoint, 1.0/60.0f);
and
ballBody->p = cgPointMake(touchPoint.x,touchPoint.y);
and while the Ball does follow my dragging, it's still being affected by gravity and it tries to go down (which causes velocity problems and others).
Does anyone know of the preferred way to Drag an active Body while the physics simulation is going on?
Do I need somehow to stop the simulation and turn it back on afterwards?
Thanks!
Temporarily remove the body from the space.
If you want the object to have inertia when you release it, that's a different story. The cleanest way is to attach a fairly stiff spring between the ball and a temporary sensor body that moves under the control of your finger. When you let go with your finger, the ball will retain whatever kinematics it had while you were dragging it. Be sure not to remove the ball from the space in this case.
You aren't updating the velocity of the object when you aren't using cpBodySlew(). That is why it falls straight down.
A better way to do it is to use a force clamped pivot joint like the official demos do to implement mouse control. http://code.google.com/p/chipmunk-physics/source/browse/trunk/Demo/ChipmunkDemo.c#296