OpenGL ES 2.0 Multiple Programs or Multiple Shaders or what? How does it work?

Question

The Problem (TL;DR)

My problem, fundamentally, is that I do not know how OpenGL ES 2.0 expects me to write and use multiple shaders; or if it is even advisable/expected that a person will do so.

The fundamental question here is: if I have an apple, a glowing rock and a fuzzy mesh, all in the same 3D world, all best drawn with different shader programs but using the same mvpMatrix then how would I go about using all of them in the same OpenGL render such that they all use their most appropriate shaders that I have written?

What Have I done

So I have written a basic OpenGL ES 2.0 program for my Android Game that works perfectly in that it can draw the outline of the objects to the screen. But it does nothing else; pretty much because the shaders look like this:

Vertex Shader

uniform mat4 uMVPMatrix;
attribute vec4 aPosition;

void main() {
    gl_Position = uMVPMatrix * aPosition;
}

Fragment Shader

void main() {
    gl_FragColor = vec4(1.0, 1.0, 1.0, 1.0);
}

Now they are pretty basic. The reason that I have not gone further is because I cannot figure out if I am supposed to write one shader to apply to all of my different objects or if I am supposed to use multiple shaders. And if I am supposed to use multiple shaders to draw multiple different objects then how do I go about doing that in an efficient way?

I get the feeling that this must be basic knowledge to anybody that does OpenGL ES 2.0 day in and day out so I am hoping that somebody can answer my question or point me in the right direction.

I have:

• Looked at multiple tutorials; none of which use anything but the most basic shaders.
• Read the entire OpenGL ES 2.0 GLSL Spec (none of which mentioned how it was intended to be used; it was just about what everything did rather than how it fits together).
• Tried to modify my shaders a bit.

So I'm hoping that I am close to understanding the OpenGL workflow but I don't seem to be there yet.

Edit: I found this well afterwards:

If your application is written for OpenGL ES 2.0, do not create a single shader with lots of switches and conditionals that performs every task your application needs to render the scene. Instead, compile multiple shader programs that each perform a specific, focused task.

That is from the iOS OpenGL ES 2.0 guidelines.

Solution

You can use multiple shaders, but to switch between them can be quite costly so the recommended practise is to draw every object of a shader, then switch to the next shader and draw all the objects using that one and so on.
To switch between shaders, you call glUseProgram().