# Topology Operations

Topology describes the way objects are connected together independent of their shape definition (geometry). In Caedium there are a range of topology operations, using our **Flexile Technology**, that allow you to modify your models in ways that would be prevented by standard geometry operations in a CAD system. Also topology operations allow you to combine faceted and analytic geometry into single hybrid models.

Topology operations are available when the Caedium Builder or Professional add-ons are activated.

The topology-related tools can all be found in the **Geometry** Tool Palette.

### Topology Tools

#### Connect

**Connect** tools are available for faces, edges, and vertices. Connections are based on topology matching of two or more entities and a relative tolerance. When the connect constraint is satisfied, two or more entities are replaced by a single entity and the associated upper topology (e.g., for a face the upper topology is a volume) and lower topology (e.g., for a face the lower topology is edges and vertices) are updated.

#### Join

**Join** tools are available for edge and faces. Joins are based on an entity (e.g., face) sharing one or more common lower entities (e.g., for a face the lower entities would be edges). Joins can only be accomplished on connected entities.

#### Double Sided

The** Faces->2 Sided** tool converts faces that are embedded within a volume into zero-thickness walls or double-sided faces.

### Tools with Topology Extensions

Some geometry tools have a** Topology Only** property that disables geometry constraints during an operation.

#### Stitch

Having first connected all edges, a set of faces can be stitched into one or more volumes based on topology alone using the **Volumes->Stitch** tool. The topology-based stitch operation will not change shapes whereas the standard geometry-based operation may. Also the topology-based stitch operation can deal with faceted and hybrid models whereas the geometry based operation can only deal with analytic geometry.

#### Subtract

Setting the** Topology Only** property to **on** for the **Boolean->Subtract** tool allows a number of operations that are not permitted with analytic geometry. You can:

- Create hybrid models of faceted and analytic geometry.
- Create non-manifold models, e.g., you can subtract a face from a volume to embed a standalone face within the volume and also make the face part of the volume. Such a face can then be converted into a double-sided face using the
**Faces->2 Sided**tool.

The topology subtract operation only applies to entities that fully intersect, i.e., the extent of the subtracted entity must be fully within the bounds of the receiving entity.

#### Decompose

Setting the** Topology Only** property to **on** for the **Boolean->Decompose **tool performs the topology subtract operation described above and also connects the shared entities (e.g., faces in a volume decompose) to form a non-manifold multi-volume model.

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