TL;DR : I want to find a method to give an impulse to an object so that the speed of this object is precisely proportional to the scene size.
I am currently building a SpriteKit game that will be available on many different screen sizes, my scene resizes itself to be the same size in points as its view (scene.scaleMode = .ResizeFill), when I launched my game on other devices than the one which I had developed it, I noticed that :
The size of nodes was too small
The speed of the objects was too low (the way I give speed to my objects is by calling applyImpulse(:_) on their physics body).
I think I fixed the size issue with a simple proportionality operation : I looked at the objectArea/sceneArea ratio of the scene that had the correct object size and than, instead of giving fixed dimensions to my objects, I simply gave them dimensions so that the ratio is always the same regardless of the scene area.
For the object speed, it was trickier...
I first thought it was due to the physics body mass being higher since the object itself was bigger, but since I attributed to objects their mass directly via their mass property, the objects would have the exact same mass regardless of their size.
I finally figured out that it was just due to the screen size being different therefore, an object, even by moving at the same speed, would seem to move slower on a bigger screen.
My problem is that I don't know exactly how to tune the strength of my impulse so that it is consistent across different scene sizes, my current approach is this one :
force = sqrt(area) * k
Where k is also a proportionality coefficient, I couldn't do the proportionality on the area, otherwise, speed would have grown exponentially (so I did it with the square root of the area instead).
While this approach works, I only found this way of calculating it with my intuition. While I know that objects areas are correctly proportional to the scene size, I can't really know if the speed can be considered as equivalent on all screen sizes
Do you know what I should do to ensure that the speed will always be equivalent on all devices ?
Don't do it
Changing the physics world in relation of the screen of the device is wrong.
The physics world should be absolutely agnostic about its graphics representation. And definitively it should have the same properties (size, mass, distance, ...) regardless of the screen.
I understand you don't want the scene to be smaller of the screen when the game runs on a iPad Pro instead of an iPhone 5 but you need to solve this problem in another way.
I suggest you to try another scaleMode like aspectFill (capitalized if you're on Xcode 7: AspectFill). This way the scene is zoomed and all your sprites will appear bigger.
Another point of view
In the comments below #Knight0fDragon pointed out some scenarios where you might actually want to make some properties of the Physics World depending on the UI. I suggest the reader of this answer to take a look at the comments below for a point of view different from mine.
Related
I have this simple domino scene where you can click a domino and apply a force to knock it.
At first I had this dominoes in a scale of (x=0.1), (y=0.6), (z=0.3) 1 is supposed to be 1 meter, they fell without a problem but too slow. According to unity documentation on Rigidbody this made total sense.
Use the right size.
The size of the your GameObject’s mesh is much more important than the mass of the Rigidbody. If you find that your Rigidbody is not behaving exactly how you expect - it moves slowly, floats, or doesn’t collide correctly - consider adjusting the scale of your mesh asset. Unity’s default unit scale is 1 unit = 1 meter, so the scale of your imported mesh is maintained, and applied to physics calculations. For example, a crumbling skyscraper is going to fall apart very differently than a tower made of toy blocks, so objects of different sizes should be modeled to accurate scale.
So I just re sized the dominoes to (x=0.01), (y=0.06), (z=0.03), this time they fell to the desired speed but for some reason they stop falling and don't knock the next domino.
example GIF
I don't know why this is happening but i can guess that this is because at the time of calculating physics the engine doesn't waste so much resources in calculating small objects that are probably not even going to be seen by the user.
Modifying mass doesn't seem to do anything, also draw and angular draw are both 0 and already tried every collision detection mode.
Is there any solution or workaround for this?
In my experience, Unity physics doesn't like too small objects since it introduces rounding errors. A game simulation usually does not need the same accuracy as when you try to land on Mars. Therefore, I usually avoid scales less than 0.1f.
In your case, I would keep the scales at 1.0f and instead experiment with either increasing the world gravitation, changing it from the default -9.81f to -98.1f (Edit - Project Settings - Physics). Or changing the default Time Scale from 1f to 5f (Edit - Project Settings - Time).
Try not to make too big changes in the beginning since it might introduce strange effects on other parts of the gameplay.
I have a sphere with bounciness set to 1
The ball has no drag and uses gravity
It hits a platform, which has bounciness set to 1 and no friction
Yet, the ball bounces higher on every bounce, going to infinity. How is such a thing possible, when I have not given it any extra momentum?
The issue comes from the fact that physics in games happens in discrete frames, and that a moving object will be "inside" another at the frame where there is a collision. The physics engine then has to separate the objects before the next frame, and figure out how much energy to "bounce" with.
One of the steps to do this involves figuring out how much the objects overlap, and that's where this phantom extra energy is comin from. Less error in the overlap equals less error in the energy.
Don't fiddle with the bounciness; those are naive solutions, not to mention they sidestep the issue rather than solving it.
What you should do is to fix what's wrong with your collisions. That can be done a number of ways, the most appropriate/performant of which depends on each specific game:
Increase your physics frame rate (decrease fixed delta time). This reduces overlaps and makes physics frames "smoother". It doesn't really solve phantom energy though; only makes it's causes and effects smaller (maybe so small they become unnoticeable, which is all you need).
Set your sphere's collision detection method to Continuous Dynamic,
and set your ground to static. If you need the sphere to collide with
other stuff, those other stuff present similar issues, and those need
to be non-static, set their rigidbodies' collision detection method
to Continuous. (This is the method I most often find to be the best, but I've had projects where others were better for various reasons)
Increase your Default Solver Velocity Iterations
Change your solver type to Temporal Gauss Seidel
I have had a similar issue with javascript/html/css canvas animations. I have no explanation for this. Use a number like 0.99999 or 0.969399 and that should do the trick. I do get what you mean though it's weird. Just get close to 1. That's all I can say. I hope this helps anyway.
How can I scale up the size of my world/level to include more gameobjects without causing lag for the player?
I am creating an asset for the asset store. It is a random procedural world generator. There is only one major problem: world size.
I can't figure out how to scale up the worlds to have more objects/tiles.
I have generated worlds up to 2000x500 tiles, but it lags very badly.
The maximum sized world that will not affect the speed of the game is
around 500x200 tiles.
I have generated worlds of the same size with smaller blocks: 1/4th the size (it doesn't affect how many tiles you can spawn)
I would like to create a world at least the size of 4200x1200 blocks without lag spikes.
I have looked at object pooling (it doesn't seem like it can help me
that much)
I have looked at LoadLevelAsync (don't really know how to use this,
and rumor is that you need Unity Pro which I do not have)
I have tried setting chunks Active or Deactive based on player
position (This caused more lag than just leaving the blocks alone).
Additional Information:
The terrain is split up into chunks. It is 2d, and I have box colliders on all solid tiles/blocks. Players can dig/place blocks. I am not worried about the amount of time it takes for the level to load initially, but rather about the smoothness of the game while playing it -no lag spikes while playing.
question on Unity Forums
If you're storing each tile as an individual GameObject, don't. Use a texture atlas and 'tile data' to generate the look of each chunk whenever it is dug into or a tile placed on it.
Also make sure to disable, potentially even delete any chunks not within the visible range of the player. Object pooling will help significantly here if you can work out the maximum number of chunks that will ever be needed at once, and just recycle chunks as they go off the screen.
DETAILS:
There is a lot to talk about for the optimal generation, so I'm going to post this link (http://studentgamedev.blogspot.co.uk/2013/08/unity-voxel-tutorial-part-1-generating.html) It shows you how to do it in a 3D space, but the principales are essentially the same if not a little easier for 2D space. The following is just a rough outline of what might be involved, and going down this path will result in huge benefits, but will require a lot of work to get there. I've included all the benefits at the bottom of the answer.
Each tile can be made to be a simple struct with fields like int id, vector2d texturePos, bool visible in it's simplest form. You can then store these tiles in a 2 dimensional array within each chunk, though to make them even more memory efficient you could store the texturePos once elsewhere in the program and write a method to get a texturePos by id.
When you make changes to this 2 dimensional array which represents either the addition or removal of a tile, you update the chunk, which is the actual GameObject used to represent the tiles. By iterating over the tile data stored in the chunk, it will be possible to generate a mesh of vertices based on the position of each tile in the 2 dimensional array. If visible is false, simply don't generate any vertices for it.
This mesh alone could be used as a collider, but won't look like anything. It will also be necessary to generate UV co-ords which happen to be the texturePos. When Unity then displays the mesh, it will display specific points of the texture atlas as defined by the UV co-ords of the mesh.
This has the benefit of resulting in significantly fewer GameObjects, better texture batching for Unity, less memory usage, faster random access for any tile as it's not got any MonoBehaviour overhead, and a genuine plethora of additional benefits.
UPDATE: the problem was in floor size. I just made it smaller and problem is solved.
Hello there, I spent almost 1 week already googling... hope that you can help me with that. I baked my shadows, result and all needed settings are shown on the picture. The problem is that quality of shadow on the tree is much much better than of shadow on the ground. Do you have any guesses why?
I just made this one tree bigger than others so that it's easy to see the problem...
(shadow quality is set as the highest, rendering path is Deffered lightning)
Reducing the size of the ground object solved the issue.
The likely reason this works is that texel budget per object is limited by the lightmap size regardless of user-defined texels per unit. For example, if lightmaps are 2048x2048 and the ground is 2x2 km, there is ~1 pixel per square meter, assuming 1 unit is 1 meter.
Although it was not the case here, inconsistencies between shadows may be observed when dynamic and static shadows use inconsistent resolutions.
I'm trying to create a chain in unity3d. A player should be capable of grabing one side of it and pull it to different location. So i created some grids and connect them together. It all works fine, the problem is only when user pulls a bit faster, then I got some spaces bettwen seperate grids. Is there anyway to set max distance on that?
Btw. I'm doing these in 2d so i have 2d Rigidbody and 2d Hinge joint.
Thanks!
The solverIterationCount of rigidbodies affects the smoothness of physics when they are moving fast. You should try increasing it or dynamically adjusting it according to the speed of the rigidbodies to increase stabilty
http://docs.unity3d.com/Documentation/ScriptReference/Physics-solverIterationCount.html
There a number of ways to tackle this issue, all with the up sides and down sides:
increasing accuracy:: this is usually the first place new game designers go, and crank up accuracy to the max. But then end up playing the price later when performance plummets. So be gentle, try to find a good balance, and if it does not cut it make up the rest with other tricks.
The main ways to increase accuracy are, increasing fixed times interval, and increasing ridged body Iteration count
.
Increasing restrictions::This often requires the most time, but cutting corners allows for smoother more predictable physics and can increase performance
small example:: the top link of the chain only needs to simulate rotation on the ridged body
.
Cheating:: find any way to make things easier, fake it
for example:: does the image really need to match the physics? Why not make sure the sprites stick together, but alow the physics to have small gaps
playing with the same concept more or less this week, experimented some with 2D Unity joints, I think the issue you are having is identical to one I had yesterday, the force you are applying 'breaks' joints for some frames, hence that almost 'spring' joint effect, make sure the mass and/or force applied are not too heavy, also maybe increase the chain parts mass, makes the joints more solid too.
In Editor, Hinge Joint -> Use Spring = true; Spring/Damper/Target Position = 0.