ES 2.0 Fundamentals - Learn OpenGL ES: For Mobile Game and Graphics Development - page 85

fy the viewport settings for any of the application discussed, and you can try to
shift the viewport at various positions on the display screen. If you set the view-
port smaller than the display screen, you will still see the clear color (specified us-
ing glClearColor ) in the area outside viewport. This is so because the call to the
glClear method is unaffected by the call to the glViewport method. Therefore,
regardless of viewport area, the rest of the display screen also gets colored.
Note Similar to color buffer, there is another kind of framebuffer
associated with the EGL window, which is discussed in the final sec-
tion of this chapter.
GLSL
Finally, we can start the discussion on GLSL , but please note that, for all examples
we work with in this topic, we restrict their rendering to two dimensions (as shown
in Figure 3-6 ) , because we haven't yet discussed OpenGL ES coordinate systems.
Figure 3-6 . Normalized 2D space
GLSL (OpenGL Shading Language) is a graphics programming language that en-
ables us to create shader programs to perform rendering effects in a flexible manner.
These programs are a part of the programmable rendering pipeline that does not