There Will Be Blood, a nerve-racking American epic written and directed by P.T. Anderson, is so remarkably self-assured, so fully realized — hell, it’s such a flat-out masterpiece — that it’s surprising to think that this Anderson, this ferocious, uncompromising genius, is the same pastiche artist who made Boogie Nights and Magnolia. I preferred his grittier debut, Hard Eight (well, it was gritty as any movie that stars Gwyneth Paltrow as a cocktail waitress can be) partly because it was more vague in its numerous antecedents. What it didn’t have was any indication of Anderson’s ambition, which started to bubble up through the ersatz Scorsese set pieces in Boogie Nights and the character-driven melodrama of Magnolia, which culminated in a galvanizing meteorological event that stretched too far to infuse the film with a literally Biblical gravity. Punch Drunk Love, casting Adam Sandler in a semi-serious role, seemed at the time like an Altmanesque trifle (the soundtrack presence of “He Needs Me” making the reference explicit) but in retrospect it’s the work of a director who hooked up smartly with an expert cinematographer (Robert Elswit), developed chops in both story and character, and started wrapping eager fingers around his own newly developing voice.