Edges - Cocos2d/Box2D - iphone

I have two sprites, a ball and a wooden plank. If the ball falls off of the wooden plank the ball is supposed to simulate falling.
My problem is, how do I determine if the ball isn't touching the wooden plank? Should I just created edges around the plank and if the ball collides with them then it scales the ball?
There are multiple planks that are attached together.
Does anyone have an idea on how to accomplish this?

Edges around the plank would work but a simpler way would be to use the collision callback's EndContact to determine when the ball and plank separate. However if the ball is allowed to bounce a bit while still over the plank and not be considered to have fallen off, you will need to check the position of the ball as well. If that is the case then placing some other sensors in the fall region might be more reliable.

Related

It is impossible to implement accurate collisions in 3D SpriteRenderers? Is Billboard incompatible with rigidbodies?

I've been having difficulty implementing enemies with a billboarding system for a while:
For a new project I'm reusing some animated sprites from an old static camera shooter game I made. It consisted of shooting projectiles and hitting enemies advancing towards your position. The enemies were capsules which had an animated plane in front of them.
I wanted to go a step further and make a raycast system that would detect if the impact on a plane is on the alpha part of its texture. I achieved it using a SpriteRenderer and a plane that matched the size of the sprite which receives the impact of the Raycast.
The problem comes with the movement of the enemies. If I use Rigidbodies this conflicts with the plane which detects the impact, since I have to use a non-convex Mesh Collider for RaycastHit.textureCoord (With Convex colliders it doesn't return the correct position). I need Rigidbody based movement for the enemies to push each other when colliding.
I tried using Transform Movement, since the error does not occur, but this allows enemies to pass through each other and occupy the same space.
I started investigating navMesh but I'm not sure if it is possible to avoid collisions.
I started to place a group of trigger colliders on the enemy mimicking the shape of the sprite. But this makes it difficult for me to detect collisions when enemies do certain animations (Some enemies jump diagonally or their animations are a bit jittery).
I would like to keep the impact detection system for the sprite, but maybe there is another way to check the texture at the impact location.
I think my options are:
With rigidbody based movement: separate the animation and hit detection system from the enemy movement. And make the billboarding effect teleport to the object constantly.
With Transform movement: Detect if they are overlapping and move them in opposite direction to the overlapping to simulate the collision.
With motion based navMesh: I'm not sure if it will be useful to me, since the characters jump and I also believe that a Mesh Agent ship cannot simultaneously be an obstacle. I understand that the navMesh cannot be generated in runtime.
Leaving texture based detection and using the trigger colliders group: Animate the colliders to also follow the animations. Or simplify everything to a large collider, losing precision on impact.
-Find an alternative method to detect the impact coordinates in the texture, avoiding using RaycastHit.textureCoord and therefore Mesh Collider. (Although I would like to keep the impact detection system as it is, maybe there is a similar approach for the same result).
The reason I have not yet delved into these solutions is because I would like to keep the system simple. I'm trying to avoid separating the enemy into 2 gameobjects, simulating collisions or animating collider positions. I honestly don't know which way to go in order to move forward with the project.

Two Colliders overlap a little bit each other in Unity

After coding left and right movement of player which had BoxCollider and Rigidbody, An serious problem happened. when player moved toward an cube which had BoxCollider, player's collider overlapped with the cube by 0.02. Please tell me how to fix this problem.
For your information, the movement that I made was by rigidbody.MovePosition in FixedUpdate. And I already set collision detection to continuous. Also, I set the friction to zero with Physics Material.
When player don't move, the x Position is 2.525 enter image description here
But when player move, the x Position is 2.545 enter image description here
Colliders overlap - it's how collision detection works. If the overlap is too great, you can make one or both of them bigger, make the physics settings tighter, or some combination of these. Note that the amount of overlap is also affected by the speed of the objects - the more speed, the more potential overlap. What you can't do is expect PhysX to work with no collider overlap.

Unity Brick Breaker: Ball hitting in-between two bricks

I am making a 2D Brick Breaker game in Unity.
I have an issue with the scenario when ball hits in between two bricks. I have BoxCollider2D attached to all bricks and a CircleCollider2D attached to the ball. When the ball hits between 2 adjacent bricks, it bounces back in the same direction as if it hit the edge of the brick. There is no edge in between, but two adjacent bricks form a continuous surface. So, the ball should bounce off of the surface (in other direction) instead of bouncing back.
Anyone knows of any solution to tackle this problem? I asked this in the Unity Physics forums but didn't get any answer, so checking if anywhere here might have had this issue.
Thanks,
Mukul
I am guessing this could be the problem:
When your ball is hitting the bricks with a strong force, There is a chance it might move one of the bricks by a very very slight distance, even if the mass of the brick is much heavier.
This movement might cause an uneven surface, which is why the ball bounces back in the same direction.
Try adding a Rigidbody Component on every brick (if you have not done it already), and set its isKinematic property to true.
Let me know if this solves it.
Way 1:
Use one box collider for the wall, but not for every single brick.
This will fix your issue + will optimize your project.
Way 2:
You need to build wall programmaly and colliders in this case must be without spaces between them. This must fix the issue.
Way 3:
Make your own hitting wall logic.
OnColliderEnter you need to get balls velocity.
OnColliderEnd you need to set manually velocity.

Side scroller style scene with gravity

I've started learning sprite kit and I think I've got the basics but now I'm struggling with something.
I want to create a game that has a 'Streets of rage' type feel to it whereby the user can move up and down, but isn't jumping, they're still on a 2D plane. But I also want them to be effected by gravity e.g stairs etc. like the following picture.
Am I right in assuming that I should have my background image with colliders around the blue and brown edges, and then create a physicsbody collider located at the feet of my player/players so that it looks like they can move against the background, but when their feet reach the top it would stop?
Could I then place other obstacles like rocks etc on that path that they would be able to collide into, but that could also sit over the path and the sky? How would I handle the fact that these could be constantly colliding depending on the position?
I appreciate there isn't any code here, but I'm trying to understand the concept around this before I jump in coding a solution.
Thanks
I would use a categoryBitMask to separate the different planes of objects.
And I would play with collisionBitMask/contactTestBitMask depending from the plane the player is in, in addition to the z-order.
Thus you can have a rock that collides your player if they are both in the same line else the player would walk behind/front.

Sprite Kit physicsBody loses consistency during rotation - zrotation

I have this classic situation of a pinball game
All objects are physicsBody with rights collision masks and so on.. they collide perfectly.
The problem is that they only work when they are static...If I try to rotate a paddle on its anchorpoint, there is no collision with the ball and the ball falls down, passing through the paddle.
I thought it was a problem of speed but I think that during the rotation the physicsBody simply doesn't work.
Do you have suggestions?
Thank you so much.
That's exactly the problem you get when rotating a static body, it's not going to act physically correct.
For example static bodies have no force, no velocity - if you move or rotate it, it will just be there at the new position and new rotation without pushing any dynamic bodies around. Only if a dynamic body now happens to be intersecting with the static body will the physics engine try to resolve the collision, usually in a brute-force manner (aka "get me outta here").
Therefore the paddle has to be dynamic if you want it to move, accelerate and spin the ball. Both paddle and ball may need to have continuous collision detection enabled as to not lose any precision in the paddle motion applied to the ball, and vice versa.