Bind-group index the palette occupies for one variant — always the slot after the family's existing groups, so unlit untextured is group 1, textured unlit and untextured lit are group 2, and textured lit is group 3 (WebGPU's last slot).
Bind-group index the palette occupies for one variant — always the slot after the family's existing groups, so unlit untextured is group 1, textured unlit and untextured lit are group 2, and textured lit is group 3 (WebGPU's last slot).