OpenGL (Open Graphics Library) is a standard specification defining a cross-language, cross-platform API for writing applications that produce 2D and 3D computer graphics. The interface consists of over 250 different function calls which can be used to draw complex three-dimensional scenes from simple primitives. OpenGL was developed by Silicon Graphics Inc. (SGI) in 1992 and is widely used in CAD, virtual reality, scientific visualization, information visualization, and flight simulation. It is also used in video games, where it competes with Direct3D on Microsoft Windows platforms.
Microsoft DirectX is a collection of application programming interfaces (APIs) for handling tasks related to multimedia, especially game programming and video, on Microsoft platforms. Originally, the names of these APIs all began with Direct, such as Direct3D, DirectDraw, DirectMusic, DirectPlay, DirectSound, and so forth. The name DirectX was coined as shorthand term for all of these APIs (the X standing in for the particular API names) and soon became the name of the collection.
Direct3D (the 3D graphics API within DirectX) is widely used in the development of video games for Microsoft Windows, Microsoft Xbox, and Microsoft Xbox 360. Direct3D is also used by other software applications for visualization and graphics tasks such as CAD/CAM engineering. As Direct3D is the most widely publicized component of DirectX, it is common to see the names "DirectX" and "Direct3D" used interchangeably.
The DirectX software development kit (SDK) consists of runtime libraries in redistributable binary form, along with accompanying documentation and headers for use in coding. Originally, the runtimes were only installed by games or explicitly by the user. Windows 95 did not launch with DirectX, but DirectX was included with Windows 95 OEM Service Release 2.
The OpenSceneGraph is an open source high performance 3D graphics toolkit, used by application developers in fields such as visual simulation, games, virtual reality, scientific visualization and modelling. Written entirely in Standard C++ and OpenGL it runs on all Windows platforms, OSX, GNU/Linux, IRIX, Solaris, HP-Ux, AIX and FreeBSD operating systems. The OpenSceneGraph is now well established as the world leading scene graph technology, used widely in the vis-sim, space, scientific, oil-gas, games and virtual reality industries.
OpenGL (OGL) is a low level library that takes lists of simple polygons and renders them as quickly as possible. To do something more practical like “draw a house”, the programmer must break down the object into a series of simple OGL instructions and send them into the engine for rendering. One problem is that OGL performance is highly sensitive to the way these instructions are sent into the system, requiring the user to know which instructions to send and in which order, and forcing them to carefully cull the data to avoid sending in objects that aren't even visible in the resulting image. For simple programs a tremendous amount of programming has to be done just to get started.
CUDA (an acronym for Compute Unified Device Architecture) is a parallel computing architecture developed by NVIDIA. CUDA is the computing engine in NVIDIA graphics processing units or GPUs that is accessible to software developers through industry standard programming languages. Programmers use 'C for CUDA' (C with NVIDIA extensions), compiled through a PathScale Open64 C compiler, to code algorithms for execution on the GPU. CUDA architecture supports a range of computational interfaces including OpenCL and DirectCompute.Third party wrappers are also available for Python, Fortran, Java and Matlab.
The latest drivers all contain the necessary CUDA components. CUDA works with all NVIDIA GPUs from the G8X series onwards, including GeForce, Quadro and the Tesla line. NVIDIA states that programs developed for the GeForce 8 series will also work without modification on all future NVIDIA video cards, due to binary compatibility. CUDA gives developers access to the native instruction set and memory of the parallel computational elements in CUDA GPUs. Using CUDA, the latest NVIDIA GPUs effectively become open architectures like CPUs. Unlike CPUs however, GPUs have a parallel "many-core" architecture, each core capable of running thousands of threads simultaneously - if an application is suited to this kind of architecture, the GPU can offer large performance benefits.
In the computer gaming industry, in addition to graphics rendering, graphics cards are used in game physics calculations (physical effects like debris, smoke, fire, fluids); examples include PhysX and Bullet. CUDA has also been used to accelerate non-graphical applications in computational biology, cryptography and other fields by an order of magnitude or more.
OpenSG is a scene graph system to create realtime graphics programs, e.g. for virtual reality applications. It is developed following Open Source principles, LGPL licensed, and can be used freely. It runs on Microsoft Windows, Linux, Solaris and Mac OS X and is based on OpenGL.
Its main features are advanced multithreading and clustering support (with sort-first and sort-last rendering, amongst other techniques), although it is perfectly usable in a single-threaded single-system application as well.
It was started, just like many other systems, at the end of the scenegraph extinction in 1999 when Microsoft and SGI's Fahrenheit graphics API project died. Given that there was no other scene graph system on the market nor on the horizon with the features the authors wanted, they decided to start their own.
OpenSG should not be confused with OpenSceneGraph which is entirely different scene graph API, somewhat similar to OpenGL Performer. Development on both started about the same time, and both chose similar names.