any good automotive glass shop can cut flat glass for a windshield.
it needs to be designated AS1, which is the classification of windshield glass.
flat side and rear glass is classified as AS2.
this glass can be clear or tints of several colors are available.
if the piece of windshield, when cut, doesn't contain the AS1 designation, the shop has a stencil that acid etches that into the glass. usually in the lower, right hand corner that will be visible from the outside after installation.