Push/pull is the signature gesture of direct modeling: select a face, drag it, and the solid updates instantly. Popularized by SketchUp on the desktop and refined by Shapr3D on the iPad, it compresses "sketch → extrude → boolean" into a single motion.
The rules of push/pull
- Pull away from the body along the face normal → material is added (an implicit union).
- Push into the body → material is removed (an implicit subtract). Push all the way through and you get a hole.
- Type for precision: a good implementation lets you tap the distance and enter an exact value mid-drag.
- Validity feedback: the tool warns (before you commit) when the drag would create impossible geometry.
These "automatic boolean" semantics are what make the gesture feel like shaping clay while still producing exact, watertight solids underneath.
Push/pull on sketch profiles
The same gesture starts new geometry: draw a closed profile on any face or plane, then pull the filled region up into a solid. Nested profiles become holes automatically, and pulling a profile drawn on an existing body joins or cuts it according to drag direction. Combined with a numeric extrude dialog (distance, symmetric extents, explicit New Body/Union/Subtract/Intersect overrides), you get both speed and control.
Why it fits touch devices perfectly
On a desktop, push/pull is convenient. On a tablet, it's transformative: your finger or Apple Pencil is directly on the face you're moving, with pinch-to-zoom and orbit on the same hand. There is no command line, no dialog-first workflow — the geometry is the interface.
Try it free
OpenShape3D implements Shapr3D-style push/pull on iPad and iPhone — tap a body to select the face under your finger, drag to extrude, push to cut, with automatic booleans computed exactly by the OpenCASCADE kernel. It's free and open source, so it's also a readable reference implementation of how these rules work.