Industry 4.0 passes through the concept of smart factories, bringing into the industrial context a new vision of production lines and workflows, which can now be designed considering ergonomics and thus the interaction among operators, machines, and tools, in accordance with human-centered design principles. Virtual simulations help in reproducing such interactions and in foreseeing solutions to improve the working conditions before installing tools and equipment. In addition, motion capture techniques have proven capable to guarantee the reproduction of human motion with sufficient accuracy. The present work aims at the development of an integrated tool for ergonomics risk assessment index calculation, using motion capture in 3D environments. With this purpose, starting from motion capture acquisitions, an engine for postural angle calculation, in accordance with international standards, and a Unity-based application have been specifically designed and validated. The work is part of the IM.PR.ES.S.E.D. (IMmersive PRocESs ergonomicS by wEarable Devices) project.