Whether every fadeable leaf material under root uses a blend mode that
cross-fades correctly (BLENDABLE_MODES — additive / luminous /
volumetric, where opacity is a linear knob on summed energy or on optical
depth). A group subtree (overview partition branch) must contain only
individually blendable leaves; mixing their compositing families is tolerated
for compatibility but has no common mid-fade conservation model. No fadeable
material at all ⇒ not blendable (nothing to fade —
e.g. a not-yet-loaded placeholder, or a max/normal/opaque layer which
keeps the hard swap).
Whether every fadeable leaf material under
rootuses a blend mode that cross-fades correctly (BLENDABLE_MODES — additive / luminous / volumetric, where opacity is a linear knob on summed energy or on optical depth). A group subtree (overview partition branch) must contain only individually blendable leaves; mixing their compositing families is tolerated for compatibility but has no common mid-fade conservation model. No fadeable material at all ⇒ not blendable (nothing to fade — e.g. a not-yet-loaded placeholder, or amax/normal/opaquelayer which keeps the hard swap).