I am trying to build my application with retina resolution (2048x1536) but using :
NSLog(#"resolution from xcode %f %f", [UIScreen mainScreen].bounds.size.width, [UIScreen mainScreen].bounds.size.height);
I always get 1024x768 resolution. any ideas how to setup retina resolution?
You're getting the value in points, not pixels.
From Apple's docs:
Points Versus Pixels
In iOS there is a distinction between the coordinates you specify in your drawing code and the pixels of the underlying device. When using native drawing technologies such as Quartz, UIKit, and Core Animation, you specify coordinate values using a logical coordinate space, which measures distances in points. This logical coordinate system is decoupled from the device coordinate space used by the system frameworks to manage the pixels on the screen. The system automatically maps points in the logical coordinate space to pixels in the device coordinate space, but this mapping is not always one-to-one. This behavior leads to an important fact that you should always remember:
One point does not necessarily correspond to one pixel on the screen.
The purpose of using points (and the logical coordinate system) is to provide a consistent size of output that is device independent. The actual size of a point is irrelevant. The goal of points is to provide a relatively consistent scale that you can use in your code to specify the size and position of views and rendered content. How points are actually mapped to pixels is a detail that is handled by the system frameworks. For example, on a device with a high-resolution screen, a line that is one point wide may actually result in a line that is two pixels wide on the screen. The result is that if you draw the same content on two similar devices, with only one of them having a high-resolution screen, the content appears to be about the same size on both devices.
Related
Pixels, abbreviated as "px", are also a unit of measurement commonly used in graphic and web design, equivalent to roughly 1⁄96 inch (0.26 mm). This measurement is used to make sure a given element will display as the same size no matter what screen resolution views it.
THIS IS WRITTEN IN WIKIPEDIA IS IS CORRECT SO LIKE LENGTH PIXEL HAVE UNIT AND DIMENSIONS
"Pixel" both refers to a standardized unit and the individual parts of a screen. A pixel(px) is a unit, which makes sure that objects on a page will be the same size no matter the screen. As for the screen pixel, the size of a pixel on your screen depends on the resolution of your screen and the image.
Assume that you have a square shaped and red coloured paper with a length of 5 centimetres.
I can detect it's (good enough) size (bounding box) in pixels on the image that camera takes.
I know the physical size.
On the other hand,
I do not know how to use the camera image's pixel size in the formula with the actual physical size of the paper. To do this, I would perhaps need a constant that will come from the specifications of the camera.
I believe mobile each iOS model has different calibration (and probably even the same models may be different than each other slightly?).
I think, if somehow I can get that information from the camera, I can map certain things and use the ratio to find the distance to a specific object.
Do you see any problems in the above ideas?
What would be the best way to get that constant from the camera? iOS Camera API? Announced specifications of the lens? Individually measuring and comparing size of the box on the image at the same camera distance on different iOS device models and saving those values per model type?
If all of these do not make any sense, what would you recommend me to look into? I appreciate the time taken by you to read this question and comment on it.
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.
I have a game that is extremely procedural and because of this one of the textures in the games can end up covering the space of (113 x 10) to (682 x 768) on iPad retina. Furthermore it isn't always even in the same aspect ratio. Furthermore the unscaled texture has to be at an aspect ratio of about 2:11 making things awkward.
I can not figure out how Xcode perceives pdf vector files.
For example the first time I made my svg into a pdf and followed all the instructions for making a single vector slot it ended up being all pixelated/anti-aliased on some devices. And I know that .pdf vectors can be rasterized to any resolution without loosing quality! So I am pretty sure Xcode compiles vectors into bitmaps for the SKTexture. And as far as I can tell the amount of pixels that it rasterizes from the vector is not even variable on a device.
For example after that one I scaled up the svg to double the pts of its dimensions and exported it. Now on some devices the texture looked perfect yet on others it looked like a rasterized mess! And it didn't seem to happen because of one device resolution being bigger then the other.
So then I decided to scale the vector one more time so at this point it had 4x more points then the vector started as. Things worked wonderfully, until I tested on the iPhone 6 and instead of being beautiful the texture got blacked out, I am fairly certain this is because the texture was to big for Spritekit. There is no happy medium I can find.
My goal is to get this vector file looking great on every device regardless of how it is scaled.
I have looked around to see what SpriteKit uses for its pt to pixel conversions and I haven't found any numbers that check out. How I can make my texture work for this project? How does Spritekit decide how many pixels to rasterize a vector as when I make an SKTexture.
Edit:
Here are some hypothetical questions.
H1. How many points wide and tall would a pdf vector need to be for it to be able to be up to these dimensions on any device. width = width of device, height = height of device / 2. So basically if I had a vector I knew was going to occupy that space what should its dimensions (in points) be?
H2. Is the amount of pixels rasterized for every point directly proportionate to the amount of pixels on the display or is their more then just pixels on a screen?
Android and iOS have a concept of a "density independent pixel" so your layouts look the same on devices with different densities and screen sizes.
Up until now I've written code to manually space elements using pixels (i.e. I want this button to be 10 pixels from the left side of the screen). This is great on a Curve, but when I load it up on a Bold the resolution is much higher, so 10 pixels is a much smaller physical space.
What are the best practices for multiple screen sizes on BlackBerry? Is there any easy way to define a density independent pixel? RIM seems to not offer much in terms of documentation or APIs to make this easy.
Points are density independent pixels (to a good degree of accuracy).
For BlackBerry, the most relevant class is net.rim.device.api.ui.Ui which defines a UNITS_pt constant (and a UNITS_px constant), a convertSize method to convert between points and pixels (since operations on Graphics take pixels instead of points).
A useful methodology for BlackBerry apps is to take everything in relation to your font sizes, which you define in points - there's a version of net.rim.device.api.ui.Font.derive that takes a units parameter and makes it easy to get fonts with a particular point size.
Of course, you can't take anything for granted - defining things in points will make things easier, but with BlackBerry you deal with lots of different pixel densities and aspect ratios so test thoroughly, at least on the simulators.