I want all the geometries in a group to be transparent, not the material,how do it
Could you put a bit more explanation about the thing you want to achieve?
In general, geometries contain information about vertices and how to form triangles of them (in case of an indexed geometries). It’s not clear what result you want to get. Would be great to add explanatory pictures.
Transparency can only be controlled over materials.
group.visible = false;?