OpenGL learning Process (1) Introduction to OpenGL

In this section, let's take a brief look at OpenGL.

(1) OpenGL Overview:

OpenGL (Open graphics Library) is a professional graphics program interface that defines a cross-programming language, cross-platform programming interface specification. It is used for three-dimensional image (two-dimensional also), is a powerful, easy to call the bottom three-dimensional graphics processing library, is also the industry standard in this field.

computer three-dimensional graphics refers to the data described by the three-dimensional space through the calculation to convert to two-dimensional image and display or print out of the technology.

(2) Graphics library functions for OpenGL

OpenGL is not a programming language, and is the software interface of the graphics hardware, an API (Application programming Interface). OpenGL's graphics library functions are encapsulated in the dynamic-link library OpenGL32.DLL, where OpenGL-based applications are developed and the library functions of OpenGL must be understood first.

OpenGL function commands are very regular, each library function has the prefix GL, Glu, aux, respectively, that the function belongs to the OpenGL Core Library, the utility library or the auxiliary library:

1) OpenGL Core Library functions: 100+, with GL as the prefix, used to build a variety of geometric models, coordinate transformation, produce lighting effects, texture mapping, produce atomization effect, such as all the two and three-dimensional graphics operations .

2) OpenGL Utility library functions: 43, with Glu as the prefix; The utility library is a higher level function library than the core library;

3) OpenGL Auxiliary Library functions: 31, with aux as the prefix; The following is an example of the glut library.

Since OpenGL is a graphical standard that is independent of any windowing system or operating system, there are no functions for window management and Message Event response in OpenGL, and no function for mouse and keyboard read events. So in the programming auxiliary Library provides some basic window management functions, event handlers and simple event functions. This type of function is prefixed with "aux". It is worth mentioning that the current AUX programming Auxiliary library has been largely replaced by the Glut library .

4) Windows Special Library function (WGL): 6, with WGL as prefix;

5) Win32API function (WGL): 5, no prefix.

6) Glut represents the OpenGL Application Toolkit (OpenGL Utility Toolkit) and is a window-system-agnostic toolkit. It serves as a more powerful alternative to the AUX library and is used to hide the complexities of different Windows system APIs. The prefix of the Glut subroutine uses "glut".

(3) The difference between OpenGL and DirectX:

The ability to handle multimedia-related operations (such as graphics cards, sound cards, handle inputs, network transmissions of multimedia streams, and so on) is not a common practice for both OpenGL and DirectX. They are a standard that requires hardware to satisfy, provide a function name, and hardware to implement the function content. It allows us to invoke the various services provided by the hardware very simply and quickly.

1) Introduction to DirectX:

DirectX is an application interface API that allows Windows-based gaming or multimedia programs to achieve higher execution efficiency, enhance 3d graphics and sound effects, and provide designers with a common hardware-driven standard that allows game developers to write different drivers for each brand of hardware. It also reduces the complexity of user installation and hardware setup.

2) The difference between OpenGL and DirectX:

1.OpenGL is just a library of graphics functions, DirectX contains graphics, sound, input, network and other modules.

2. The graphics library performance of DirectX is not as good as OpenGL for graphics alone. OpenGL is stable and can be used across platforms, but OpenGL requires graphics support.

3.DirectX is available only for Windows series platforms, including the Windows Mobile/ce series and xbox/xbox360.

3) Recommendation:

Do Windows platform games, of course, is DX, want to cross-platform, want to do scientific computing program, want to do CAD, want to do distribution calculation, want to do industrial applications, preferably with OpenGL.

(4) Reference documents:

1) Why should you use OpenGL instead of directx:http://www.cnblogs.com/baesky/archive/2011/04/08/2009128.html

2) The difference between OpenGL and DirectX: Http://blog.163.com/[email protected]/blog/static/2955727520083661133565/

3) OpenGL and directx:http://blog.sina.com.cn/s/blog_4cc16fc50100bx6m.html

OpenGL learning Process (1) Introduction to OpenGL