I try to draw rain and snow as particle system using Core Graphics.
In simulator rendering proceeded fine but when I run my app on real device rendering is slow down.
So, advise me please approaches to increase particle system drawing performance on iPhone.
May be I should use OpenGL for this or CoreAnimation?
OpenGL would be the lowest level to drop to for the rendering, so should offer the best performance (if done right). CoreAnimation would be close enough if there are not too many particles (the exact figure depends on other factors, but upto about 50 should be ok).
When you say you're using CoreGraphics at the moment do you mean you're redrawing based on a timer? If so then CoreAnimation will definitely help you out - as long as you can seperate out each particle into a view. You could still use CoreGraphics to render the individual particles.
Are you using a physics engine to calculate the positions?
If you are simply drawing a view with Core Graphics, then redrawing it every frame to reflect the movement of the particles, you will see terrible performance (for more, see this answer). You will want to go to OpenGL ES or Core Animation for the particle system animation.
My recommendation would be to look at CAReplicatorLayer, a new Core Animation layer type added in iPhone OS 3.0 and Snow Leopard. I've seen some impressive particle systems created just using this one layer type, without using much code. See the ReplicatorDemo sample application (for the Mac, but the core concepts are the same), or Joe Ricioppo's "To 1e100f And Beyond with CAReplicatorLayer" article.
It's hard to give advice with little to no information about your implementation. One thing that is a major bottleneck on the iPhone from my experience are memory allocations. So if you're allocating new objects for each particle spawned, that would be the first thing you might want to fix. (Allocate a pool of objects and reuse them.)
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I have been building a game for VR using Unity3d. It has only low poly models and the file size is less then 40 mb still the game lags when played on mobile.. Please suggest how to improve the performance..
Thank you in advance..
In order to improve performance in VR for mobile you have to optimize everything as best as you can, you should keep some of these variables in mind:
Graphics Side
- Number of polygons in the scene
- How many source of lighting do you have
Programming Side
- How much work is taking your code, is doing it efficiently?
The programming part can include problems within the physics system, also some logic problems that can probably decrease the overall performance because of higher computation.
My advice is to learn about the Profiler that unity offers, actually you can observe how much work is taking your code and where exactly it is your bottle-neck. This video also can be useful.
Of course a solution could be implement your code following design standards, like design patterns and software architecture (depending on the size of the project).
I hope it can be useful for you!
What I found from developing and launching a vr game is some of the issues below
Number of polygons is usually your first to check even though your models are low poly. For example, I looked at Synty models in the unity store and some of them were over 1k for a bag and 7k for a character model. This seriously reduce the amount of objects you can if you want to target a max of 50000 per eyes.
With some models, you can use blender and the decimate tool to reduce the polygon count pretty easily. From there I would use LOD's to reduce their count further based on distance.
Use occlusion culling (pro version only)
Set your camera distance to maybe a 100 instead of the default
Use mobile shaders and careful using some of the standard shaders as they are expensive. Also transparent shaders will becomes expensive cause overdraw.
Batch your textures and make them static if possible
Don't use dynamic shadows on lighting but instead bake your lights
Try to avoid using physics as this becomes expensive and instead raycast to trigger events or shooting weapons.
Run profiler often and check for any bottlenecks (pro version only)
Reduce the count of Particles effects and their values
Character bones can also cause issue so remove as many as possible
There is also your code to look at as mentioned by Manujamming
Set quality setting to low in the inspector to gain best performance.
Could you provide a screenshot of your game scene?
I hope this makes sense.
Best of luck!
I had an idea for an app that would require me to implement these little sprites that would require basic physics features like gravity, acceleration, etc... so naturally I looked into a game loop for the iPhone, there were plenty of threads on this, but what I am trying to understand is that I want to be able to create these sprites and have them behave naturally using a game loop, but still have full "standard" iPhone interaction, i.e. touches, pinching, swiping, core animation, core data, etc...
Is this just as simple as implementing a game loop on a background thread and updating sprites on that thread then doing the standard operations on the main UI thread (except of course for obvious background tasks)?
I would like some general overview of this type of thing if thats possible.
I wanted the same thing, but the iPhone SDK is all about async and callbacks and it's better to roll with the framework rather than fight it. If Cocos2d does not satisfy you, you could look into hooking into NSRunLoop.
With regards to CADisplayLink: I noticed a drop in performance (decreased triangle throughput) when using CADisplayLink with OpenGL ES (which you have stated you are not using so I will not elaborate further).
In Xcode try creating a iPhone OpenGL ES project. Just build and run with the default code. You should see a box moving up and down. This simple example should give you an insight into animating objects and how the OS version of the device matters. The OpenGL view is based off a normal view that you can attach gesture watchers to.
Check out one of the available game physics engines. Cocos2D is a good place to start: http://www.cocos2d-iphone.org/ -- free and lots of resouRces to get started with.
I want to create an iPhone/iPod game. I want it to be 3d, but I want to use sprites instead of OpenGL to do this (I assume this would be easier since I don't know OpenGL).
I was thinking of simply layering sprites over top of each other and changing their size to give an illusion of 3d. It doesn't need to be too convincing since the game will be somewhat cartoony.
How can I use sprites as an alternative to OpenGL on the iPhone platform?
You can use CoreAnimation for this. Either using UIImageViews (or plain UIViews) or CALayers.
It's usually the best choice for some types of 2d games (board games, for example), since animation, rotation and scaling are really easy. Just keep in mind that if performance is your concern, OpenGL will always be better.
Depending on how much 3d, I'd recommend taking a look at cocos2d. It supports multiple layers, sprites, animations, etc, but is pretty straightforward to pick up & learn. (Much easier than OpenGL to me) The example code is very comprehensive.
http://code.google.com/p/cocos2d-iphone/
I have built a game using core animation with upto about 17 - 20 objects floating about the screen scaling and rotating and performance was fine on the iPhone (make sure you check regularly on the iPhone as the simulator doesnt simulate iPhone memory or CPU speed).
CoreAnimation is pretty simple and really powerful. Use PNG's for images and I don't think you will have to many issues. The real killer of this will be alpha's in your images, this is hard work for the iPhone. So the less transparency you have the better you app will go.
In addition to Marco's answer I want to add: Not using OpenGL may also tax the device battery a little more. As I understand it, OpenGL ES can be more efficient on a device power supply (if implemented properly). Of course, this depends on how much animation is going to be used with UIImageView, UIView or CALayers, etc.
I'm sure there is a tipping point.
On an iPhone:
If I am writing a game that has multiple levels, with multiple animations (image sequences), jpg and png (transparent), some full screen and some not, some looped and some played once only. What is the best way of doing it? Each level might have up to 10MB of images. Add on to this music, and video (cut scenes). All 2D graphics, no 3D models.
Is OpenGL required? Or can this be achieved with Quartz or Core Animation?
I do similar using UIViews and a bit of Core Graphics (Quartz 2D) and it works fine. I've found the custom drawing in Core Graphics pushes it a bit further, tho - UIViews work best when given images rather than having to draw themselves. Also watch out for lots of transparencies. You'll probably find that large or long (many frame) animations will be the killer, though. There are some techniques for minimising the impact of the animations which involves allowing it to purge images from memory if not being immediately displayed (I forget the setting). This may result in your animations not being as smooth as you they would otherwise be (not sure if Open GL ES would help here, though).
You should probably prototype using UIViews, and decide then if it's worth doing the extra work for OpenGL ES. Also, if you're not already familiar with OpenGL/ Open GL ES it's a steep learning curve.
I've used both Quartz and OpenGL to do graphics on the iPhone, and while OpenGL has a much higher learning curve, it gives much better performance than Quartz. Let's say you have a scene that involves drawing 6 large, semi-transparent images on top of each other. Quartz will do it, but you'll probably get 15fps at best. OpenGL takes advantage of the iPhone's PowerVR chip and the drawing is hardware accelerated - so you can load those images into OpenGL textures and render at 25-30fps no problem.
I would agree with Phil though - try doing it using Quartz and see if it meets your needs. OpenGL is extremely powerful but it's API lacks some of the convenience features of Quartz (such as saving/restoring graphics state).
One another note entirely, you might want to take a look at Unity's iPhone development tools (http://unity3d.com/#iphone). They leverage OpenGL but provide you with an IDE to create your game. It abstracts away all of the graphics-level code, so you can focus on the high-level gameplay. My brother uses it to write iPhone games, and it's extremely cool.
I recommend having a look at Cocos2D iPhone.
cocos2d for iPhone is a framework for building 2D games, demos, and other graphical/interactive applications. It is based on the cocos2d design: it uses the same API, but instead of using python it uses objective-c.
Most likely OpenGl.
One advantage of using OpenGL ES would be that the investment of time for learning the technology could be applied to other platforms/contexts and your game is potentially more port-friendly. These may not be important to you.
I would suggest using Quartz. OpenGL ES is really best for 3d stuff. However both work fairly well, so if you already know OpenGL ES, it's fine to use that.
You should consider using a lot of less resources in your game, Apple recommends not to use more than 10 mb in texture for openGL apps.
Try texture atlas, reuse graphics, tile based graphics...but avoid to use to much graphic assets.
I've seen a lot of bandying about what's better, Quartz or OpenGL ES for 2D gaming. Neverminding libraries like Cocos2D, I'm curious if anyone can point to resources that teach using OpenGL ES as a 2D platform. I mean, are we really stating that learning 3D programming is worth a slight speed increase...or can it be learned from a 2D perspective?
GL is likely to give you better performance, with less CPU usage, battery drain, and so on. 2D drawing with GL is just like 3D drawing with GL, you just don't change the Z coordinate.
That being said, it's easier to write 2D drawing code with Quartz, so you have to decide the trade-off.
Cribbed from a similar answer I provided here:
You probably mean Core Animation when you say Quartz. Quartz handles static 2-D drawing within views or layers. On the iPhone, all Quartz drawing for display is done to a Core Animation layer, either directly or through a layer-backed view. Each time this drawing is performed, the layer is sent to the GPU to be cached. This re-caching is an expensive operation, so attempting to animate something by redrawing it each frame using Quartz results in terrible performance.
However, if you can split your graphics into sprites whose content doesn't change frequently, you can achieve very good performance using Core Animation. Each one of those sprites would be hosted in a Core Animation CALayer or UIKit UIView, and then animated about the screen. Because the layers are cached on the GPU, basically as textures, they can be moved around very smoothly. I've been able to move 50 translucent layers simultaneously at 60 FPS (100 at 30 FPS) on the original iPhone (not 3G S).
You can even do some rudimentary 3-D layout and animation using Core Animation, as I show in this sample application. However, you are limited to working with flat, rectangular structures (the layers).
If you need to do true 3-D work, or want to squeeze the last bit of performance out of the device, you'll want to look at OpenGL ES. However, OpenGL ES is nowhere near as easy to work with as Core Animation, so my recommendation has been to try Core Animation first and switch to OpenGL ES only if you can't do what you want. I've used both in my applications, and I greatly prefer working with Core Animation.