World-space length of the toward-sun march. ~1–3 reads as fine contact AO.
Occluder thickness for the depth-crossing test, world units (~0.2–0.5).
March sample count. 0 disables contact shadows; ~8–16 is typical.
Darkening applied when occluded, [0, 1] (1 = full contact shadow).
Screen-space contact-shadow tuning for the sun (see DeferredLightingPass.setContactShadows).