OpenGL ES, orthopgraphics projection and viewport

Posted by DarkDeny on Game Development See other posts from Game Development or by DarkDeny
Published on 2013-12-10T10:41:41Z Indexed on 2014/06/08 15:46 UTC
Read the original article Hit count: 265

Filed under:

ios

|

opengl-es2

|

projection

I want to make some simple 2D game on iOS to familiarize myself with OpenGL ES. I started with Ray Wenderlich tutorial (How To Create A Simple 2D iPhone Game with OpenGL ES 2.0 and GLKit). That tutorial is quite good, but I miss some parts of a puzzle.

Ray creates orthographic projection using some magic numbers like 480 and 320. It is not clear to me why did he take these numbers, and as far as I can see - sprite is not mapped to the ipad simulator screen one-to-one pixel. I tried to play with parameters with which ortho matrix is created, but I cannot figure out what math is here.

How can I calculate numbers (bottom, top, left, right, close, far) which will be parameters to orthographic projection matrix creation and have sprite on the screen shown in its original size?

© Game Development or respective owner

Related posts about ios

Regarding Xcode SDK IOS 4.2 installation and missing iOS 4.1

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi All, i have download Xcode SDK 4.2(xcode_3.2.5_and_ios_sdk_4.2_final.dmg) from Apple developer site and installed successfully . when open my old xcode project it shows baseSDk missing ,when i try to change project setting ,i have found and set base SDk as 4.2 it works fine my problem is ,in… >>> More
fatal: pathspec for removing folder in git

as seen on Super User - Search for 'Super User'
I want to remove a folder from a Git repository but I get an error. I tried several commands, and here you can see my errors: selnaz:iOS Lnaz$ ls iOS-Tidinfo mockup readme.txt selnaz:iOS Lnaz$ git rm -r -- iOS-Tidinfo/ fatal: pathspec 'tidinfo/iOS/iOS-Tidinfo/' did not match any files selnaz:iOS… >>> More
Autorotate works for iOS 6 but gives weird behavior in iOS 5

as seen on Stack Overflow - Search for 'Stack Overflow'
I seem to be having the opposite problem from this post: Autorotate in iOS 6 has strange behaviour When I submitted my paid app to Apple, XCode made me update to iOS 6 on my test devices. I used the GUI in XCode to set my app to display only in portrait mode on the iPhone and only in landscape… >>> More
App is getting run in iOS 5.1.1 but crashed in iOS 6.1.3

as seen on Stack Overflow - Search for 'Stack Overflow'
I have implemented below code but app has been crashed in iPad with iOS version 6.1.3,while running perfectly in iPad with iOS version 5.1.1. when I am scrolling table view continuously it is crashed in ios version 6.1.3. what could be the issue. The implemented delegate and data source methods for… >>> More
No provisioned iOS devices are available with a compatible iOS version

as seen on Stack Overflow - Search for 'Stack Overflow'
I'm trying to test my app on an iPhone 3G, however I'm getting this error: No provisioned iOS devices are available with a compatible iOS version. Connect an iOS device with a recent enough version of iOS to run your application or choose an iOS simulator as the destination. Note that: The 3G… >>> More

Related posts about opengl-es2

Basic OpenGL ES2 (iPhone Simulator) question...

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi! I'm trying to modify the fragment shader which is part of the standard iPhone/XCode OpenGL ES template. I want to make it so that every other row of pixels is transparent. I have this code so far: varying lowp vec4 colorVarying; void main() { gl_FragColor = vec4(colorVarying.x, colorVarying… >>> More
Fragment shader seems to floor() imprecisely

as seen on Game Development - Search for 'Game Development'
I'm trying to interpolate coordinates in my fragment shader. Unfortunately if close to the upper edge the interpolated value of fVertexInteger seems to be rounded up instead of beeing floored. This happens above approximately fVertexInteger >= x.97. Example: floor(64.7) returns 64.0 -- correct floor(64… >>> More
Where are some good resources to learn Game Development with OpenGL ES 2.X

as seen on Game Development - Search for 'Game Development'
Background: From http://www.khronos.org/opengles/2_X/ OpenGL ES 2.0 combines a version of the OpenGL Shading Language for programming vertex and fragment shaders that has been adapted for embedded platforms, together with a streamlined API from OpenGL ES 1.1 that has removed any fixed functionality… >>> More
OpenGL 2 on Android: native window

as seen on Game Development - Search for 'Game Development'
According to OGLES specification, we have the following definition: EGLSurface eglCreateWindowSurface(EGLDisplay display, EGLConfig config, NativeWindowType native_window, EGLint const * attrib_list) More… >>> More
Android OpenGL ES 2 framebuffer not working properly

as seen on Game Development - Search for 'Game Development'
I'm trying to understand how framebuffers work. In order to achieve that, I want to draw a very basic triangle to a framebuffer texture and then draw the resulting texture to a quad on the default framebuffer. However, I only get a fraction of the triangle like below. LE: The triangle's coordinates… >>> More