I am running a 3d realtime application (C++) on Virtual Machine (VMWare WinXP SP2). I have 3d acceleration always disabled in VMWare. I have tested it running with both the normal windows GDI OpenGL 1.1 and Mesa 3D (7.8.2). When running on Mesa I have full OpenGL functionality (VertexBufferObjects etc.) but it is much slower than the GDI implementation. I know Mesa is a software rastizer but I guess so is the GDI implementation. So why is Mesa slower? Or should Mesa be faster and its actually a problem in my application?
Mesa supports a fully programmable pipeline and hence the software rasterizer, which at some points uses Just-In-Time compilation and hence is not as aggressively optimized as the Win32 GDI one. This is a tradeoff between features and performance.
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In other word, is there any GPU that does not support OpenGL, and instead support other graphic rendering libraries like DirectX, OpenCl.
"GPU support of OpenGL" is not uniquely defined. It takes much more than hardware to make OpenGL work. Notably, OS driver infrastructure, and driver itself.
Therefore, it is possible to have a GPU that is capable of all OpenGL features, but have no OpenGL software implementation (either not exists, not installed etc.). Ex.: because of marketing reasons Microsoft does not support OpenGL on XBox. Same thing with Windows: often there is only basic OpenGL available with default Windows graphics drivers. It could be easily fixed by installing vendor driver, but most users don't bother.
And other way around, there are GPUs that are not capable of running some or all of the OpenGL features in hardware. Those features could be implemented in software. Ex.: First Android OS versions had software implementations of OpenGL ES in case phone didn't have dedicated GPU or if GPU was not fully capable of OpenGL ES.
Also, there are platforms that do not support OpenGL or DirectX and use their own APIs. Ex.: Sony use custom API for their Playstations.
At this day and age, no, you'll not find a GPU that won't support some version of OpenGL, with the possible exception of some super-specialised chips - but those won't support DirectX either.
We began learning OpenGL at school and, in particular, implemented a .obj mesh loader. When I run my code at school with quite heavy meshes (4M up to 17M faces), I have to wait a few seconds for the mesh to be loaded but once it is done, I can rotate and move the scene with a perfect fluidity.
I compiled the same code at home, and I have very low performances when moving in a scene where heavy meshes are displayed.
I'm using the 3.0 Mesa 10.1.3 version of OpenGL (this is the output of cout << glGetString(GL_version) << endl) and compiling with g++-4.9. I don't remember the version numbers of my school but I'll update my message as soon as possible if needed. Finally, I'm on Ubuntu 14.04 my graphic card is a Nvidia Geforce 605, my CPU is an Intel(R) Core(TM) i5-2320 CPU # 3.00GHz, and I have 8Go RAM.
If you have any idea to help me to understand (and fix it) why it is running so slowly on a quite good computer (certainly not a racehorse but good enough for that), please tell me. Thanks in advance !
TL;DR: You're using the wrong driver. Install the proprietary, closed source binary drivers from NVidia and you'll get very good performance. Also with a GeForce 605 you should get some OpenGL-4.x support.
I'm using the 3.0 Mesa 10.1.3 version of OpenGL
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my graphic card is a Nvidia Geforce 605
That's your problem right there. The open source "Noveau" drivers for NVidia GPUs that are part of Mesa are a very long way from offering any kind of reasonable HW acceleration support. This is because NVidia doesn't publish openly available documentation on their GPU's low level programming.
So at the moment the only option for getting HW accelerated OpenGL on your GPU is to install NVidia's proprietary drivers. They are available on NVidia's website; however since your GPU isn't "bleeding edge" right now I recommend you use those installable through the package manager; you'll have to add a "nonfree" package source repository though.
This is in stark contrast to the AMD GPUs which have full documentation coverage, openly accessible. Because of that the Mesa "radeon" drivers are quite mature; full OpenGL-3.3 core support, with performance good enough for most applications, in some applications even outperforming AMD's proprietary drivers. OpenGL-4 support is work in progress for Mesa at a whole and last time I checked the "radeon" drivers' development was actually moving at a faster pace than the Mesa OpenGL state tracker itself.
How I can use OpenGL without mesa? It's terrible - supports max. OpenGL 3.1.
I readed about loading openGL.so with dlopen but where is file to load, and how I can hang that?
Ah, I forgot, language is C++
Just linking to libGL.so is all that is necessary to use the hardware graphics driver.
If you have an NVIDIA or AMD graphics card and you have installed the nvidia or fglrx driver, you will get the maximum OpenGL version supported by your video card.
If you instead are using the open source nouveau, radeon, intel, or other graphics driver, Mesa will take over and you will have only the maximum version of OpenGL supported by Mesa (3.1) and the driver for your hardware. It will automatically use all hardware features it's capable of using.
You do not need to do any fancy dlopen tricks or anything else.
OpenGL is an open API to "standardize" the access to graphics pipeline. The graphics pipeline is supposed to be in a GPU! But this is not necessary! Mesa 3D is a an open-source implementation of the OpenGL specification that also contains a software implementation of a graphics pipeline (yes, software-based) that is supposed to deliver the same result of a regular GPU graphics pipeline (except for the speed, of course!).
You don't have to use MESA if you have GPU! In order to try OpenGL, I suggest you to read some basic tutorial of OpenGL:
http://duriansoftware.com/joe/An-intro-to-modern-OpenGL.-Table-of-Contents.html
http://www.opengl-tutorial.org/
dlopen() is used to load dynamic libraries. If you use helpers like GLFW or GLUT you don't need to care about those details.
What exactly does it mean to say that Mesa is an implementation of OpenGL? Don't the drivers of my Nvidia card implement all the OpenGL functions, etc.? So given that the drivers of my Nvidia card are taking Opengl calls and handing them off to the hardware, what exactly does Mesa do? Can someone clarify the distinction between Mesa and drivers?
Can someone clarify the distinction between Mesa and drivers?
Mesa provides the client side OpenGL interface for the open source GPU drivers based on the DRI2/DRM architecture. Or in other words: It's also a part of a driver.
If you've got the proprietary drivers from NVidia or AMD installed you don't need Mesa. If you want to use the open source drivers (nouveau, radeon, radeonhd, intel) you need Mesa.
I believe LinuxQuestions.org forum member geeman2.0 provided a good explanation for this matter:
OpenGL and Mesa aren't really two separate choices, but rather Mesa is a specific type of OpenGL.
OpenGL is simply an interface that defines a standard set of functions needed for drawing 3d graphics. It doesn't involve the actual code that makes these functions happen, it only specifies what the functions are called and what they are supposed to do.
An openGL implementation provides the actual code that runs the methods specified by the OpenGL standard. Without an implementation installed, you cannot run any opengl programs.
Mesa is just one of many OpenGL implementations, and is the most standard one included in linux distributions. It does all the work in software, which is why it is slow.
When you install Nvidia or ATI drivers for a fancy graphics card, these drivers provide a new OpenGL implementation that runs on the graphics card. This implementation would take the place of the Mesa implementation, but it is still an openGL implementation. That is, all of Mesa/ATI/NVidia drivers implement the same set of functions, they just do it in different ways, and they are all openGL.
Source
What exactly does it mean to say that Mesa is an implementation of
OpenGL?
First of all, OpenGL is an API Specification created between Khronos and the videocard manufacturer (Nvidia, ATI, Intel, etc), it's like an agreement on what functions the hardware is capable of.
Mesa is a software library for 3D computer graphics that provides a generic Khronos-compliant OpenGL implementation for rendering three-dimensional graphics on multiple platforms. So, for example, if you are running Linux you will probably have to install Mesa in order to generate any kind of graphics. For Microsoft Windows there is already an implementation installed.
Don't the drivers of my Nvidia card implement all the OpenGL
functions, etc.?
Yes, your Nvidia card driver implements OpenGL functions.
So given that the drivers of my Nvidia card are taking Opengl calls
and handing them off to the hardware, what exactly does Mesa do?
Your program communicates to Mesa, Mesa to your video card's driver, the driver to the actual GPU, the GPU sends the signal to the monitor for you to finally watch the drawing.
I have a PC with a good CPU but slow GPU (integrated graphics card). I have noticed that some commercial games work much better using their software renderers instead of OpenGL or DirectX. I am making a Java app that will use JOGL/LWJGL to access OpenGL. To enable a software rendering option, should I look at a pure-Java software renderer, or native software-only OpenGL implementations?
You can install Mesa 3D. This OSS project supplies an OpenGL driver for Windows which is based on a software renderer.