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Aside from mouse-based actions there are also commands for zooming, and resetting the viewport in the “View” menu:
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Reset View
Restores RealFlow's default point of view.
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Fast View
Display all scene nodes (except Hybrido particles) as bounding boxes when zooming, panning, or rotating the viewport.
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Zoom All
Fits all scene elements into the viewport.
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Zoom Selected
Fits the currently selected node(s) into the viewport.
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Center selected
Centres the selected node(s) in the viewport.
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Follow Selected
Keeps the currently selected node in the viewport's centre.
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