Opengl Simple Fading Shader Effect

How to make a simple fading shader effect?

Why there isn’t any tutorial talking about changing a texture on the internet??? Wtf, I can’t find anything. “Opengl Shader How to make fade effect”, “Opengl Shader How to make fade effect on texture”, “Opengl Shader How to change texture”, “Opengl Shader How to change color of texture”, “Opengl How to change texture”, “Opengl How to change color of texture”, “Opengl how to change texture rgba”, “Opengl Shader fade texture”. NOTHING AT ALL…