'GL_BGR' : undeclared identifier

During the implementation of homework #02, I think it's better to be familiar to Picture Drawing and Texture Mapping first.


When I use the GL_BGR in "glDrawPixels()", it appear this compile error from VC++.


Solution is : 

try GL_BGR_EXT if it still dosnt work, you need to download updated GLext.h files from SGI or nVidia/ATi devloper relations. 

 by Silvermace in the GameDev Forum.

Why did we need to use GLext.h???  The OpenGL Website says:

Core API and Extension Header Files

Because extensions vary from platform to platform and driver to driver, OpenGL developers can't expect interfaces for all extensions to be defined in the standard gl.h, glx.h, and wgl.h header files. Additional header files - glext.h,glxext.h, and wglext.h - are provided here

Why  did we need to use BGR instead of RGB ??

Because the actual storage format of each pixel in Windows system is BGR, not RGB.

Just a debug record.