Jordin Sparks (left) and Whitney Houston, as Sparkle and Emma, in Sparkle
02/13/2012 at 12:00 PM EST
Last fall during production, Whitney Houston embodied the title of her final movie
, the producer of the new movie tells PEOPLE.
The pop superstar was also wholly professional. "Whitney was always on time while we were making this, and she stayed on set after she was done," says Debra Martin Chase, who was also a friend of Houston's for 20 years. "She loved hanging out on the set with the crew."
Chase also described Houston as "fully present" with "such spirit about her, so much love. She was healthy, gorgeous and always so positive."
The movie, which also stars Jordin Sparks
, wrapped at Thanksgiving, prompting Houston to gather "everyone up on that last day, the cast and crew, and had us all hold hands in a circle and [say] a prayer."
Added Chase: "She looked me in the eye and told me that she was going to do this ... she was going to come through for us. And she did."
is scheduled to open Aug. 17. "We screened it for the first time Tuesday, and she is amazing," the producer says. "She didn't have a chance to see it, but she knew she had really delivered. I hope that this is how she will be remembered – in a positive light."