I am currently working on a 2D endless runner, written in Swift3 and using Spritekit.
Short question:
Is there a way to only check for collisions on the right side of my character's rectangular physics body?
More info:
The platform on which the character runs is made of puzzle pieces and the user builds upon it as the game progresses. The character progresses left to right, in respect to the background (which goes right to left).
I want the character to automatically jump when he collides with a piece on his right side. However, any pieces that the player puts to the right of him (same Y value as the character) is of the same class as the pieces underneath him.
So the same code that checks for collision between the character and pieces to his right, and make him jump, will also make him jump as long as the game detects collision between the character and the pieces under him.
I have not been able to find another problem like mine, since usually others' characters are colliding with objects of different classes from their ground class.
Thanks!
P.S. I have tried to make my character a SKSpriteNode with two physics bodies, but I could not find any helpful documentation. If it helps any, my character also performs a looping running animation--though I can't imagine that would harm anything.
You could achieve that by detecting collisions with your rectangle and then deciding whether the collision was with the side of your interest or not. Here is a discussion about how to do that. Good luck!
Have you tried adding a non visible sub node (e.g. feetNode) to your character's sprite node and giving that sub node the physics body (class) for floor contact ?
Depending on the rest of your logic, it may allow you to use a different physics class for your character have more flexibility in collision detection.
In fact, you could probably use that approach with several sub nodes in your character's sprite node and have multiple collision behaviours for the character depending on what hits it.
Once you obtain the contact point of the 2 bodies that are colliding, determine which body is the one that is colliding by checking the categorymasks and then check its CGPoints x position. This x position can be compared to the other body's x position to know exactly which side it is colliding from.
if Body A's x position > Body B's x position, Body A is on the right and if not, its on the left.
As simple as that.
Hope this helps!
Related
I hope you all can help with this. I'm working on app of a board game. I have hex shaped tiles which are called randomly and laid out at the start of the game. Each of these tiles has four sides with a value of 1 and the other two sides have values of 2 and 3.
Each tile is a SKSpriteNode with transparent rectangle Nodes on the edges. There are 5 different types of tiles and they need to be separate Sprites with child nodes because in addition to being randomly laid out they area also randomly rotated. So I need to know programmatically which tile edges are touching which edges of other tiles.
Like this:
https://app.box.com/s/nnym97st3xmrsx979zchowdq1qwsmpoo
(I tried to post an image of what I'm trying to accomplish, but apparently I don't have a high enough of a rating.) ;-)
For example: If a "2" is touching a "3", etc.
I first tried Collision detection, but of course that only works with dynamic, moving objects.
I tried an IF statement to compare if the other nodes were touching and then remembered that the coordinates where specific to the Parent Node, so that didn't work.
I then tried intersectsNode, but that seems to only work with nodes under the same parent.
I am currently working with convertPoint in order to get the coordinates to match the scene and thus be comparable. But I can't seem to get it work the way I need.
There must be something simple that I am not seeing. Any ideas?
Certainly not simple.
One solution would be to start all your shapes slightly spaced out from each other. Add invisible child nodes with physics bodies to all six sides and give each physics body an appropriate category based on their rating (1, 2 or 3).
When you start the game, move all the outer nodes into their proper position (sides touching) by using whatever movement method your prefer. This will give you contact messages as each hex side touches another. The contact messages will tell you what side number is touching its neighbor.
The exact coding of this idea depends on your current code, game play, etc...
I am trying to make a game with SpriteKit where the main character shoots a 'rope' and swings through the level (Think spiderman-ish). I have no problem making the rope and having it attached to the player and different sprites but I don't really know how to go about the 'shooting' part.
My current rope is built similar to this (https://www.youtube.com/watch?v=7jWdcbmnmKQ&hd=1) where I have several separate parts connected using SKPhysicsJointPin. I have tried several different approaches to shoot the rope, both with applyImpulse/Force and SKActions, but none works smoothly.
To sum it up:
- What is best practice for creating a rope that can extend in a specific direction?
I'm fine with just general pointers in the right direction since this is all to learn and I don't think I really need completed code for it.
General pointer:
Shoot a physics body in the way you need it to "fly" (the bullet)
In didSimulatePhysics assign the bullet's position to the rope's first node
In theory this should extend the rope while shooting, without affecting the trajectory of the bullet.
You may need to add more rope segments as the distance between the bullet and the weapon/player increases, otherwise the rope may be huddled too tightly together at the start of the bullet's flight path, causing physics to behave unexpectedly. Though adding rope segments in-flight may cause issues in its own right.
One solution could be to disable physics for the rope until a certain distance has been reached or the bullet "hit" something. Until then the rope could be considered a straight line and rope segment nodes positioned accordingly along a straight line between bullet and weapon.
Instead of using the physics engine to move your extending rope (applyImpulse), try moving the rope's end in a straight line at a fixed speed until it hits a target. Just a thought!
I have a ship that everything is centered around and everything moves relative to it. It is a first person shooter. Right now when I fire, and the ship speeds up, it catches up to the bullets. I would like the physics world to move relative to the ship's speed so that the bullet is essentially unaffected by ship speed.
The physics engine is doing the right thing, but not the right thing for my game.
I have other elements that move relative to the ship as it moves, which move correctly now, so don't want make ship stationary and move everything else in world around it. I don't see a direct way to do this maybe there is an indirect way? Perhaps I can manually take over the positioning of the bullets. I would like to use the other parts of the physics engine for doing collisions etc so don't want to completely manually do it, but will if that is the only option.
Anyone else have any suggestions?
It sounds like your bullets are receiving air friction. This is controlled by the physics bodies "damping" property. A value of 1.0 will make it static without movement. A value of 0 will allow it to move continuously without ever stoping. The default value is 0.1 as per the Apple documents. Assign your node like so to remove the damping(air friction)...
yourNode.physicsBody.damping = 0
I'm working on a game in which the user should be able to trigger 'rods' that come out from the edge of the screen to displace elements on screen (balls). These projectiles roughly resemble pool-cues. Or perhaps pinball plungers, except that they start from the 'loaded' position (mostly offscreen), and when triggered, they eject out, then quickly retreat.
I'm unclear how I should build these with Sprite Kit.
The game uses the PhysicsEngine, and the onscreen balls should be effected both by gravity AND they should be displaced when they collide with the rods. However the rods should neither be effected by gravity, not displaced when they collide with the balls -- they should simply retreat regardless of whether they've made contact with the balls.
I realize I can set the affectedByGravity property for the rods. However because they will still displace slightly when they collide with the balls. How can I 'fix' or 'peg' them in place? Do I need to use an SKPhysicsSlidingJoint? If so, has anyone encountered any examples online? Is there a simpler way to do this?
A related physics engine, Box2D distinguishes static, kinematic, and dynamic bodies.
Kinematic bodies can move and will collide with other objects, but they are themselves not affected by dynamic bodies or forces like gravity. Thus, consider setting rod.dynamic = NO; but animate it with actions. See also here in the reference for SKPhysicsBody.
i'm creating simple iOS game with Cocos2D and Box2D. In my game user has to create full word by shooting to squares with letters. If shooted letter is correct the square should explode, otherwise the square should fall down. I have created simple contact listener and I can detect collision between bullet and square but the problem is how to avoid collision force when letter is incorrect? I that situation (incorrect letter) i want square to simply fall down without applying collision force to the square.
Maybe I can delete the square and create new one at the position of deleted, but i think it's not the best idea :)
One suggestion I would make would be on collision, if the letter is incorrect, set the bodies x and z velocities to 0. This way when they collide with incorrect squares they will simply fall.
Another thing you could do would be to set the target square's body as fixed ( or rigid, I can't remember what it's called in Box2d off the top of my head). So even if an incorrect letter collides with it, it will not budge but the letter will bounce off it. And it the letter is correct, you can explode it as normal.
The solution I would advice is to set the velocity of the bullet to 0 in both directions in the PreSolve callback of the contact listener. Obviously you do a check in the PreSolve function. This way as the function is called PreSolve, the collision calculation have not happened yet. so setting velocity to 0 will make the bullet to have no effect on the square in terms of force.