But Mr. Irwin doesn’t make sculptures or, for that matter, very many of what would be considered art objects of any kind. Instead, he has spent most of a restless career, based in Los Angeles and then San Diego, creating subtle, at times vanishingly evanescent, environments with plain materials — fabric scrim, glass, lights, plants and trees — “to make you a little more aware than you were the day before,” as he puts it, “of how beautiful the world is.”