Missing methods and constants in OpenGL ES 2.0 headers

I'm starting to learn to OpenGL for using it with iOS. I'm wondering why methods like glMatrixMode or constants like GL_PROJECTION are there in <OpenGLES/ES1/gl.h>, but not in <OpenGLES/ES2/gl.h>. Why? Are you enforced to write your own shaders开发者_运维问答 when using OpenGL ES 2.0 instead of 1.1?

The Fixed function pipeline, including the built in matrices were completely taken out of OpenGL ES 2.0 so constants like GL_PROJECTION, and functions such as glPushMatrix, glRotate, glMatrixMode etc have been removed.

This change requires you to write shaders and pass/calculate your own model and projection matrices to it. While ES 2 provides you with much more flexibility it also makes it very difficult to work with older code and get started as a beginner.

If you don't have a full understanding of how the projection and model matrices, you may want to stick with ES 1.

A Presentation with a further explanation can be found here