Is there a open source OpenGL implementation for MS Windows? [closed]

Question

As the title asks,

Is there an open source OpenGL implementation for MS Windows?

Not such an example code that using opengl, but the one that gives opengl32.dll after building.

Answer 1

First and foremost you must understand that OpenGL is not a library, but an API specification. Libraries may implement this API. But normally OpenGL is implemented by the GPU device driver.

The opengl32.dll ships as part of Windows. All Windows Versions since WindowsNT-4 and Windows95-B ship with the opengl32.dll as part of the base installation. It acts as a conduit for programs that make use of OpenGL to talk to the GPU drivers that actually implement it. The OpenGL magic does not happen in the opengl32.dll but in the GPU drivers! There's a mechanism called the OpenGL ICD which the GPU drivers use to hook their OpenGL stuff into the DLL.

Is there an open source OpenGL implementation for MS Windows?

Well yes, Mesa3D also can be built for Windows, but the resulting DLL will not be able to talk to the GPU drivers, but merely implement all OpenGL functionality through a software renderer. In Linux Mesa3D also implements the device drivers for a number of GPUs, but those drivers require kernel interfaces specific to Linux and are not portable (however other open source operating systems like FreeBSD adopted the Linux kernel APIs Mesa3D uses, so it works there as well).