verve.gl — doubleSided materials

An upright MASK quad with "doubleSided":true in its glTF material, beside a translucent doubleSided BLEND card. The variant_double_sided shader flips the surface normal on back faces (gl_FrontFacing / front_facing), so both are correctly lit from both sides as the camera auto-rotates past them.

Drag to orbit · wheel to zoom. The back face is identically lit — normals are flipped, not ignored.