In keeping with the recent effort to ease transitions from DX, how about a user defined depth range equation,
glDepthRangeEquation(GLclampf a, GLclampf b),
where the final Zw = a + b Zd and a + b = 1.
For DX, a = 0 and b = 1. For GL it’s business as usual with a=(n+f)/2 and b=(f-n)/2 (usually a=1/2 and b=1/2).
May need a GL_DEPTH_RANGE_EQUATION enable to change the sense of the parameters to the existing DepthRange or to otherwise indicate the desired behaviour in the presence of the two coexisting APIs.
Hurl your finest leafy greens…