Testing the maxim that happiness can’t be contrived, High School Musical 3: Senior Year sets off a joy bomb, and attempts to charm tween-leaning audiences through an explosion of primary colors, bright production design and sheer, indefatigable force of will. The first film in the Disney Channel’s huge hit TV movie series to receive a theatrical release is a relentlessly chipper toe-tapper, bluntly effective in its staged cathartic moments but powered by a puttering dramatic engine.

Against the spring backdrop of their senior year, a half dozen students at New Mexico’s Eastern High try to juggle competing interests for their time and attention, and figure out the paths for their respective futures. Fresh off winning their second state basketball championship, school hunk and big-man-on-campus Troy (Zac Efron) seems destined to follow in his father’s footsteps to the local university, by accepting a basketball scholarship alongside his best friend Chad (Corbin Bleu). Giving Troy pause, though, is the fact that his girlfriend Gabriella (Vanessa Hudgens) is headed out-of-state to Stanford.

As they prepare for one last school musical, eagerly anticipated by the self-involved Sharpay (Ashley Tisdale) and her more open-hearted twin brother Ryan (Lucas Grabeel), the group’s drama teacher adds a wrinkle to events by announcing that recruiters from Juilliard, the prestigious performing arts academy, will be on hand to observe the award one scholarship to a student at yet to be determined.

Returning series director Kenny Ortega creates an immaculately presented fashion showcase, and places a heavy emphasis on theatrical gesticulation that makes High School Musical 3 seem ever solicitous of its audience’s feelings, in ways perhaps contrived but no less forceful and effective. A couple musical numbers are shot in seemingly hurried fashion, with tight alternating close-ups, but for the most part there’s a nice fleshing-out consistent with the bump in production value from the previous made-for-television movies.

Somewhat unfortunately, the conflict here is of the paint-by-numbers variety, even for teen dramas. Sharpay’s conniving and antagonism is rather blithely dismissed, never carrying over to later scenes. Similarly, because it’s not evidenced by actual friction in their relationship, the emotional drift between Gabriella and Troy as they prepare for different post-high school paths never seems like more than a set-up for song. Troy, too, often seems an incidental bystander in his own unfolding future, the one exception to this being “My Own Dream,” which is the movie’s requisite Footloose-style, solo freak-out number, complete with shifting floor and ceiling dance bits to simulate angsty teen disorientation and confusion.

That said, there’s not much in the film’s look or execution to dissuade embrace by its core audience. Production design and overall packaging are slick, and the performances are sunny and engaging. (Walt Disney, G, 109 minutes)