I'm a little bit confused by the examples for surface-test game and inside-test game. Why is that we don't have access to the equation "x-1.5" for the surface test game, but we do have access to "x^2 + y^2 + z^2 - 1" (http://cs248.stanford.edu/winter19/lecture/geometry/slide_024) in for the inside-test game ?
I'm a little bit confused by the examples for surface-test game and inside-test game. Why is that we don't have access to the equation "x-1.5" for the surface test game, but we do have access to "x^2 + y^2 + z^2 - 1" (http://cs248.stanford.edu/winter19/lecture/geometry/slide_024) in for the inside-test game ?