What add on I need to set the view tab to 3D?
There is no add on to "set the view tab to 3D." The question, as phrased, has no meaning in Hitfilm.
If you are trying to create 3D layers and animation this is controlled by setting the compositing settings to an individual layer to 3D and adding a camera.
If you are asking about using 360-degree video the 360 Video Viewer will map the 360-degree video within the normal viewer window. The dedicated 360-degree viewer panel can be added with ANY of the 360-degree add on packs: (360 Toolkit, Neon Lights, or VFX)
If you are asking about stereoscopic video, Hitfilm does not support stereoscopic video.
Hopefull one of the above paragraphs covers what you're askin?
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