Lucian Piane's official cause of death has been revealed nearly three weeks after the "RuPaul's Drag Race" music producer was struck and killed by a car in California ... he died from blunt force trauma.

According to the Los Angeles County Medical Examiner, his manner of death was ruled an accident.

While his cause of death has been determined, the medical examiner's office tells TMZ the full autopsy report remains pending and is not yet ready for release.

As we first reported ... Piane was struck by a vehicle in Glendale early on October 12. Emergency responders attempted to save him, but he was pronounced dead at the scene.

His death came just hours after he was released from police custody following an alleged confrontation with a hotel manager at an Embassy Suites in Glendale.

Sources previously told TMZ Piane was arrested after allegedly throwing a water bottle at the manager. He was booked and later released ... hours before the fatal crash.

Piane had also been cited the previous day for allegedly being under the influence of a controlled substance.

The music producer and songwriter was best known for his work on "RuPaul's Drag Race," where he contributed music to multiple seasons of the hit reality competition series.