When Sam Houser first showed interest in using the Euphoria software in the game, he was told that it would be impossible or only limited to cutscenes, but some members of the team were able to make it work. Engineers from NaturalMotion worked on-site at Rockstar North for several months at a time to incorporate Euphoria software into the game. Rockstar also worked with Image Metrics for the game's facial animations. The facial rigs had around 100 joints, with a total of 300 minutes of facial animation. The scale of the project caused some issues for the animators, forcing them to have rigs completed before animation began. They also faced difficulty in the direction of the actor's head—either straight on when looking at the teleprompter, or down when looking at a script. Image Metrics head of production David Barton noted that "having realistic eyes is 90 percent of the battle", as it allows the player to believe the character. A head camera was used when recording to capture facial movements. SpeedTree was used for in-game environment rendering.