dupe

pub fn dupe(self: *const Triangles, allocator: std.mem.Allocator) std.mem.Allocator.Error!Triangles {
    const vtx = try allocator.dupe(Vertex, self.vertexes);
    errdefer allocator.free(vtx);
    return .{
        .vertexes = vtx,
        .indices = try allocator.dupe(Vertex.Index, self.indices),
        .bounds = self.bounds,
    };
}