Forward refractive transmission overlay (KHR_materials_transmission +
KHR_materials_volume). Slots in after deferred lighting (and any forward
overlay): it snapshots frame.hdr, draws the glass meshes refracting that
snapshot, and writes the composite back to frame.hdr, depth-testing against
the opaque scene depth (frame.gbuffer.depth in deferred, frame.depth in
forward).
Forward refractive transmission overlay (
KHR_materials_transmission+KHR_materials_volume). Slots in after deferred lighting (and any forward overlay): it snapshotsframe.hdr, draws the glass meshes refracting that snapshot, and writes the composite back toframe.hdr, depth-testing against the opaque scene depth (frame.gbuffer.depthin deferred,frame.depthin forward).