Expand to Components grows the current triangle selection to the whole connected parts of the mesh that contain the selected triangles. Selected edges act as borders: the selection grows only up to them. This makes the tool a quick way to select one face of a CAD-like part, or any area you have outlined with edges.
Expand a selection to whole parts
- In the Scene Tree, select one mesh.
- Select one or more triangles on each part you want, for example with Select Primitives.
- Click Select › Expand to Components.
The command works at once, without a panel. Each part that has at least one selected triangle becomes fully selected; parts without selected triangles stay as they are. When the mesh has no selected edges, a part is everything connected to the selected triangles, up to the gaps in the mesh. To select one part with a single click instead, use Select Component.
The button is unavailable when no triangles are selected (tooltip ObjectMesh doesn't have any selected triangles) or when all triangles are already selected. Undo (Ctrl+Z, or Cmd+Z on macOS) returns the previous selection.
Use selected edges as borders
Selected edges split the mesh into areas, and Expand to Components fills only the areas you started in. To select a whole face of a CAD-like part:
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Select the sharp edges of the part, for example with Select Creases by Angle (click Selected edges in its panel). You can also draw borders with Edge Selector or get them from Partitioner.
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Select a few triangles inside the face.
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Click Expand to Components. The selection fills the face and stops at the selected edges; the rounded side faces stay unselected.
The edges stay selected after the command. To grow the selection over them next time, remove them with Clear Selected Edges. The selected face can then be deleted or copied into a new object with Selection to Object.
