offscreenCasterCascades

How many cascades (closest first) recruit OFF-SCREEN shadow casters. A caster outside the view frustum is kept alive - rasterizing into the depth maps but skipping the color pass - when its bounds intersect one of the first N cascades' light-space boxes, so its shadow still reaches visible ground. 0 disables keepalive: off-screen objects cast nothing (cheapest, matches most engines). Higher values extend correct shadows to coarser cascades at the cost of a larger resident caster set - in dense 3D-Tiles scenes each step roughly grows the kept-alive tile ring by the next cascade's footprint. Clamped to cascadeCount.