Hi I'm making a game where you tap to give an upward impulse to the ball of lets for example say a cgvector (4,0).
This if for both 4inch and 3.5 inch retina displays.
Will the impulse move the ball the same amount in pixels or same amount relative to the screen size different. I need the ball to move the same amount relative to the size or else the game will become easier on i5's . I have an idea of how to achieve it.
Could someone with knowledge of how impulse works clear this up?
Only asking because i recently played it on a i5 and got higher scores than usually on the i4
Thanks
physics simulation does not depend on screen size, however the scene may be scaled (see scaleMode) which can affect how much of the scene you can see on each device.
Related
How does sceneKit deal with various screen sizes? Do geometries become bigger on larger screens? Does camera angle become bigger and wider? Do physics simulations look exactly the same on various phones? Thanks for help.
Do geometries become bigger on larger screens?
Nope, geometry size will be the same size, in the arbitrary unit you use (Meters by default). They will however appear bigger/smaller on screen but the size is the same (see next answer).
Does camera angle become bigger and wider?
Slightly. The FOV adapts on an axis to fit the aspect of the screen. You can try that out by running your app on the resizable simulator and see how it reacts.
Do physics simulations look exactly the same on various phones?
Yes and no. Overall, the simulation will feel the same (weight, speed, behaviour), but in details the randomness of the physics engine and the differences in hardware will make the simulations slightly different and random every time.
As I am porting an iPhone app that uses SpriteKit to iPad, I have been able to scale all the screen elements and font sizes using the height ratio of the iPhone 5 to iPad screen.
Everything looks proportional, except for the physics since there is more area.
So the question is, how do I scale the physics along with the screen using that height ratio?
Perhaps changing density or mass of all the nodes? How would I do it, mathematically using the ratio so that it is perfect?
You can configure the SKPhysicsWorld object attached to the SKScene.
It changes:
The gravity property that applies an acceleration to volume-based bodies in the simulation.
The speed property determines the rate at which the simulation runs.
You can set those properties to values that seems good to you on an iPad. Changing the Physic World changes physics for all SKObjects.
How do you simulate sliding, image a circle on screen and its sliding across the screen background. Or a puck sliding in an air hockey game.
This app shows exactly what I want if you care to see an example in action!
https://itunes.apple.com/gb/app/puck-puck/id463455207?mt=8
The app is free and put it there in case someone wanted to download it to exactly see what I was talking about. My current method is using physics.start() and setLinearVelocity(200, -300), then when the object is returning "falling" down screen i physics.pause() this gives appearance of fast - gradual stop. Wondering if another way so I could use friction to change things up.
Sliding friction is a force with a constant magnitude and a direction opposite to the direction of motion.
The magnitude is a free variable you can adjust to get the motion you like. In real life it's proportional to the normal force (the force perpendicular to the surface, related to the weight) and a coefficient of kinetic friction (which is a measure of how "frictiony" the interface is -- ice or sandpaper).
Kinetic friction stops when the motion stops. Then static friction takes over, which is similir to kinetic but a little stronger, and applies as long as the object stands still. A common mistake is to botch this transition, so that the object winds up oscillating at low speed.
I am looking to create a similar tunnel effect in COCOS2D (iOS). Could anyone suggest any pointers?
ref Video 1
ref Video 2
Till now I have tried with several ring shape sprites with decreasing scale and positioned center to a same point and keeping Z decreasing as well for each smaller sprite.
With that, animating it with CCScaleTo and changing the size to 2.0 with animation duration but it does not come anyway near to the tunnel effect shown in the reference.
Thanks,
sam
I found the implementation description from the author of this effect:
"It surely was a lot of work to create the depth illusion in a 2D plane.
The principle is very easy though: circles start in the middle of the screen with scale 0. Then the first circle of the tunnel starts scaling proportionally to the time elapsed (linear scaling doesn't work) and after some time the second circle starts scaling, then the 3rd, and 4th and so on.
You then lower proportionally the alpha value for the circles (the ones in the far back have alpha value lower than the ones in front to give the illusion of blur), you define a path that every circle has to follow, moving the X and Y coordinates of it, then you put a spaceship in the middle of the screen. Tilting the device makes the tunnel to shift left and right, up and down (but that gives the impression that the spaceship is moving instead!).
Once the circles go out of the screen, they are quickly faded and put back into initial position (to save memory so I don't need to create new circles but I reuse the same ones).
Sorry about my english, but I hope that explained the general idea :)"
this is what i'm trying to do, 2 balls will drop at different height, their bounce is set to 1.0, which means after bounce they will go back to their original position. But the higher ball will drop and bounce faster than the lower ball, so when the higher ball bounces and goes back to it's original position once, the lower ball finishes its first bounce too.
is ok that they don't bounce once at the same time? i just want to know how i can change their speed.
so far what i have found is that we can't change their mass, density won't effect drop speed, set gravity will effect both. any solution please?
and i'm trying to change the mass of those ball, so the ball that higher from the ground can drop faster
Heavier things do not fall faster. Either in reality or a proper simulation thereof. The reason why we think of heavy things falling faster is because of air resistance. Objects moving through the air have resistance from that air, and this slows down light objects more than heavier ones.
So you would either have to break the physics system or implement air resistance.