If I mix two shaders together, like the diffuse and glossy shaders, I understand that I can change the factor slider between 0 - 1.
and that having 0.5 factor will show a 50% mix of blue diffuse and green glossy.
What isn't clear to me is what is going on when something else is plugged into the fac input, if I plug in a checker texture for example, with white and black as its two color values.
This now clearly seperates the two shaders based on the checker texture, I understand its doing that but how does it get away with not just supplying 0 - 1?
If I am only allowed to supply 0 - 1 using the slider, what is the checker doing to the factor that I can't do with my slider? Can you explain what can be plugged in to the fac input and how it differs from the user control slider.