Matthew Smith was in the midst of a thriving painting career when he made a sharp detour to musical composition. He’s now a multidisciplinary artist, threading film, visual art and experimental theater and movement. Admittance, running Thursday through Saturday at the Ritz Theater, is an ambitious and deeply personal work created in collaboration with local choreographers Cathy Wright and Deborah Jinza Thayer. 3-Minute Egg peeked into a dress rehearsal at Thayer’s studio and spoke with Smith about his artistic evolution.