I'm getting started developing with OpenGL ES on ARM/Linux, and I would like to draw something full-screen but don't know where to start.
I'm not developping on iPhone, nor Android. This is a Linux/OpenGL ES question.
I know it's possible to draw on the framebuffer with OpenGL ES without any library but I don't find any resources about that topic, could you help me?
I don't have any code to show how to do it but basicly you use de framebuffer device as the target of OpenGL|ES operations.
Are you developing with an embedded platform as a target? If so, you could use software implementations on your host system and then the actual driver on the embedded device.
There is a small project for supporting OpenGLES 1.1 on linux called dlges. You could also try mesa.
I imagine that the driver itself might have a header for OpenGL that you could look at and see if it supports OpenGLES calls. Alternatively, you could set up function pointers to make your OpenGL Code look more like OpenGL ES.
Good luck!
Don't forget that desktop Linux comes with OpenGL, not OpenGLES! They're similar but not quite compatible. If you want to do work on OpenGLES on a desktop Linux platform, ARM or otherwise, you'll need an OpenGLES emulator library. Sorry, can't recommend any, I'm looking for one myself.
OpenGLES just handles the process of drawing stuff into the window. You also need a windowing library, which handles the process of creating a window to draw stuff into, and an event library, which deals with input events coming back from the window.
SDL will provide both of the last two, as will a bunch of other libraries. Khronos themselves have standardised on EGL as the windowing library and OpenKODE as the event library... but I don't actually know where to get open source implementations of these for Linux. (I work for a company that does EGL and OpenKODE for embedded platforms, so I've never needed to find an open source version!)
ARM offers few GPUs that support OpenGL 2.0. You can find some examples and and emulator that runs on linux on the Mali Developer site.
Of course that's mostly to target ARM GPUs, but I am pretty sure it could be used to examine OpenGL ES programming possibilities.
Here is a tutorial showing how to use SDL in combination with OpenGL ES. It's for the OpenPandora platform, but since that runs Linux, it should be applicable on the desktop if you can get the proper library versions.
Use of SDL is more or less standard with this kind of programming, in Linux. You can of course go the longer route and open the window yourself, attach a GL rendering context and so on, but usually it's easier to learn the relevant parts of SDL. That also gives you easy-to-use API:s for input reading, which is almost always necessary.
You can use PowerVR SDK for Linux http://community.imgtec.com/developers/powervr/graphics-sdk/
There are a lot of samples.
Related
Upon considering the driver side implementation for DirectX API on windows systems for modern video cards I was wondering why this implementation is not available on non-windows system, most notably linux.
Since there is an obvious absence of this functionality I can only assume there is a good reason which I am blind to, but in my primitive understanding I simply see the DirectX calls as no more than function entry points on the hardware device. And for the record I am not referring to a compatibility layer (most notably WINE, a project I am amazed by every single day) but a library making direct hardware calls.
Is it possible to create an open source version of directx? Would it be possible but obscenely difficult?
AFAIK, the DirectX contains 3 parts
Vendor driver (provide low level API defined by DX)
DirectX library (use low level API defined by DX to access hardware, provide DirectX API)
Software (use DirectX API, ex. game)
There are no driver providing the low level API defined by DX on linux, so even it is possible to provide the DirectX library, but it won't work without proper vendor driver, and I can't see if there is any vendor is going to create one for their hardware platform.
Why not just use OpenGL? It supports all the functionality that DirectX does. Do you have a specific reason to use DirectX? As for a reason, Microsoft made DirectX and I guess they didn't see any need to allow it to run on Linux.
You can run DirectX games in Linux using Wine. You can program XNA on Linux using MonoGame. But all of these use OpenGL to provide hardware-accelerated rendering. AFAIK, OpenGL has been (and probably will be) the only option on Linux for the foreseeable future.
Is it possible to write your own DirectX implementation? Sure - but it involves writing drivers, proprietary knowledge and probably too much cost for anyone to REALLY benefit from it.
EDIT: These days, DXVK is a very real and performant way to run DirectX applications on Linux.
DirectX is a suit of API's:
Direct3D (drawing 3D graphics)
DirectX Graphics Infrastructure (enumerating adapters and monitors and managing swap chains)
Direct2D (drawing 2D graphics)
DirectWrite (fonts)
DirectCompute (GPU Computing)
DirectSound3D (playback of 3D sounds)
DirectX Media (DirectAnimation for 2D/3D web animation, DirectShow for multimedia playback and streaming media, DirectX Transform for web interactivity, and Direct3D Retained Mode for higher level 3D graphics)
DirectX Diagnostics (tool for diagnosing and generating reports on components related to DirectX, such as audio, video, and input drivers)
DirectX Media Objects (support for streaming objects such as encoders, decoders, and effects)
DirectSetup (installation of DirectX components, and the detection of the current DirectX version)
DirectX components deprecated, but still supported
DirectDraw
DirectInput
DirectPlay
DirectSound
DirectMusic
As you can see many parts of the DirectX suit of API's would need to be rewritten with functionality for Drivers written for Linux. Also some parts of the DirectX suit are likely going to make calls to the Windows OS and that code would have to rewritten for a Linux machine without infringement of the copy-written parts of either DirectX or the Windows OS.
Yes you could write a open source API suit which does the same kind of thing as DirectX for Linux, however without a great knowledge of sound and graphic drivers/support by their manufactures for Linux, it would be a very hard task to do.
However if you question was more of a "Can I get/write something to be able to run games and programs made with DirectX to run on Linux?" in it's meaning, in short no due to more likely copyright infringement.
Your question is wrong in 2019. DXVK is an implementation of D3D11 and D3D10 implementation for Linux using Vulkan and Wine
Also mesa has native Direct3D 9 implementation but in my knowledge, no one uses it except wine
The work to create a port for DirectX would create the same problems as you encounter in WINE. It will never be the same as on Windows. Derived from that principle you would have to look into OpenGL and related multi-platform libraries.
At this very moment WINE would be your closest medium if you want to accomplish something with DirectX code you already have. Then again, I'm not sure in what manner Visual Studio or plain typing would get you closer yo a fluent environment. The WINE libraries aren't that far from native, but there always exists emulation, what is acceptable to a certain point in my honest opinion.
If I look at how superbly Final Fantasy XIV ran on full settings on my iMac (2011) I think it's not that bad to rely on WINE's implementation. The game exactly rendered as on Bootcamp (Windows) on my iMac.
If you really want to make work on this front you could try to ask WINE Devs at their forums or mailing lists how you could maybe use the implementation of their DirectX compatibility only and use that in your project. Where you maybe can call libraries instead of requesting DirectX through Windows-emulated system calls.
Edit: I fully agree with user956030's answer too.
DirectX is a propriety products designed for Microsoft targets, so for this to happen would be very unusual
There are two other pieces of software that come to mind, SDL and OpenGL
OpenGL provides the hardware alternative to DirectX, and SDL works with OpenGL to provide the software support you would expect from DirectX
Since 2020, Microsoft has been working to port DirectX 12 to WSL2, which is being done in this repository. In a mailist, Steve Pronovost commented that they might work to port this driver to Linux to have it running natively.
However, in order to do this, they would need to implement the driver on top of the kernel's DRM stack, which itself needs to be modified if they want to keep the driver similar to the Windows one and have related APIs.
There is some effort being done in the Mesa library as well, to support D3D12 within itself, the main purpose being to optimize server-sided GPU calculations that are heavily used in machine learning algorithms.
Even though this is great, it's unlikely that we will ever see any advantage running Windows games on Linux with that driver. The open source community would only have the upper ground if more games start supporting Vulkan, which is faster and better than DirectX, there had been experiments where using DXVK on Windows would be faster than DirectX 9 or even 11, such as the one mentioned here, but DXVK tends to be less reliable and more prone to errors and crashes.
There exist a class of applications that use opengl to provide hardware acceleration, but are not GUI based. However it seems that in the default case, to use opengl, there must be running an X-server with GLX (on the same virtual terminal) for those applications to function.
My specific case is attempting to use gstreamer's gl plugins on a headless machine, but I'm asking a more general question.
Is there some way around this (esp without modifying the original code)?
I've been trying to research using the framebuffer kernel module, but not getting very far.
Mesa supports software rasterization on offscreen surfaces.
You can use EGL and render to a PbufferSurface instead of a WindowSurface.
See my answer here: https://stackoverflow.com/a/74226995/1884837
Have you tried Xvfb?
Can Anybody explain me what is EGL and what it does?
How can i use EGL with OpenGL-ES On Linux?
Is EGL a Layer Between Hardware And Operating System?
EGL is a window system-independent equivalent to the GLX and WGL APIs, which respectively enable OpenGL support in X and Microsoft Windows. It is an interface between Khronos rendering APIs such as OpenGL ES or OpenVG and the underlying native platform window system. It handles graphics context management, surface/buffer binding, and rendering synchronization and enables high-performance, accelerated, mixed-mode 2D and 3D rendering using other Khronos APIs.
There is an implementation for Mesa called EGL and covered in the Mesa EGL Wiki.
Realistically you can't use XEGL / EGL,
If you're running on Linux and don't need X then look at Wayland which is a replacement server built on top of MESA.
I think you're best reading up definitive references such as this. I don't see value in paraphrasing that.
There seem to be some Linux implementations referenced in that article. You can't expect folks to give you detailed tutorials here. Instead attempt to use these references and ask specific questions when you get stuck.
Maybe you could view EGL as a kind of dedicated Graphics "OS", personally I see it yet another API, which abstracts graphics.
I'm moving from windows programming (By windows programming I mean using Windows API) to Linux Programming.
For programming Windows, the option we have is Win32API (MFC is just a C++ wrapper for the same).
I want to know if there is something like Linux API (equivalent to WINAPI) that is exposed directly to the programmer? Where can I find the reference?
With my little knowledge of POSIX library I see that it wraps around part of Linux API. But what about creating GUI applications? POSIX doesn't offer that. I know there are tons of 3rd party Widget toolkits like gtk, Qt etc. But I don't want to use the libraries that encapsulates Linux API. I want to learn using the "Core Linux API".
If there are somethings that I should know, please inform. Any programmer who is familiar with both Windows & Linux programming, please map the terminologies of Linux world so that I can quickly move on.
Any resources (books,tutorials,references) are highly appreciated.
I think you're looking for something that doesn't exactly exist. Unlike the Win32 API, there is no "Linux API" for doing GUI applications. The closest you can get is the X protocol itself, which is a pretty low level way of doing GUI (it's much more detailed and archaic than Win32 GDI, for example). This is why there exist wrappers such as GTK and Qt that hide the details of the X protocol.
The X protocol is available to C programs using XLib.
What you must understand is that Linux is very bare as to what is contained within it. The "Core" Linux API is POSIX and glibc. Linux is NOT graphical by default, so there is no core graphics library. Really, Windows could be stripped down to not have graphics also and thus not have parts of the win32 API like GDI. This you must understand. Linux is very lightweight compared to Windows.
For Linux there are two main graphical toolkits, GTK and Qt. I myself prefer GTK, but I'd research both. Also note that GTK and Qt exist for Windows to, because they are just wrappers. If you go take a look at the X protocol code for say xterm, you'll see why no one tries to actually creating graphical applications on top of it.
Oh, also SDL is pretty nice, it is pretty bare, but it is nice if your just needing a framebuffer for a window. It is portable between Linux and Windows and very easy to learn. But it will only stretch so far..
Linux and win aren't quite as different as it looks.
On both systems there exists a kernel that is not graphical.
It's just that Microsoft doesn't document this kernel and publishes an API that references various different components.
On Unix, it's more transparent. There really is a (non-GUI) kernel API and it is published. Then, there are services that run on top of this, optionally, and their interfaces are published without an attempt to merge them into an imaginary layer that doesn't really exist.
So, the lowest GUI level is a the X Window System and it has a lowest level library called Xlib. There are various libraries that run on top of this one, as you have noted.
I would highly recommended looking at the QT/C++ UI framework, it's arguably the most comprehensive UI toolkit for any platform.
We're using it at work developing cross platform apps that run on windows, osx and linux.
It also runs on Nokia's smart phone Operating System Maemo which has recently been merged with Intel's Moblin Linux OS, now called MeeGo.
This is going to sound insane since you're asking about "serious" stuff like C++ and C (and the "core linux API"), but you might want to consider building in something else. For instance:
Java Swing (many people love it! Others hate it and call it obsolete)
Mono GTK# (C# or VisualBasic or whatever you want, lots of people say it's pretty cool, but they're not not that many people)
Adobe AIR (ActionScript, you might hate it)
Titanium (totally new and unproven, but getting a lot of buzz in the iPhone world, at least)
And many other possibilities, some of which let you work on multiple platforms at once.
Sorry if this answer is not at all what you're looking for. The "real" answers on Linux are "pick a toolkit," which is also no answer at all :)
Have a look at Cairo. This something roughly similar to GDI+ and is under the hood of some of of the few usable GUI programs for Linux i.e. Firefox or Eclipse (SWT). It wraps most the natsy and ancient Linux stuff for you into a nice API that runs on most Linux installations without locking you into a entire subsystems like GTK or QT.
There is also the docs for the two different desktop platforms: Gnome and KDE that might help you down that road.
In windows, what does Flash use under the hood?
It's a relatively simple question which I can never find the answer to. Is it GDI (for windows VM implementations) or something else?
You don't need to go into any of the new GPU acceleration features of Flash. I just really want to know the inner workings because it's NEVER discussed.
On 64-bit Linux, the Flash plugin does not link against SDL (according to ldd). It does, however, link against GTK, GDK, and Cairo. It appears, therefore, that it is using either Cairo or raw Xlib calls to do its drawing on Linux.
I don't know on Windows. Flash tends to have minimal dependencies, but Direct-X may be standard enough that they use it. With some kind of a process examiner to tell you what libraries a process has loaded, you could examine a simple web browser embedding Flash and see what system facilities are actually in use.
DirectX mostly. It's hard to achieve good graphics performance with GDI.
I agree with george, GDI is very bad for speed. DirectX for Windows and SDL or similar for Linux (note this is an assumption!). In that sense it probably uses a layer that communicates with the native graphics subsystem on whatever platform it's running on.