In the early 20th century, Philadelphia native William Glackens—a realist painter often called the “American Renoir”—charmed the nation with his atmospheric scenes of boisterous seaside locales, inviting cafés, and lively city streets (such as Captain’s Pier and The Little Pier), as well as more intimate still-life renderings and portraiture (including The Soda Fountain and Armenian Girl). Now, in the first comprehensive Glackens showing in decades, a collection of more than 85 of the artist’s paintings and dr…