Shape Manipulation and Cleanup


Edit toolbar items for polygonal, rectangular and 3d shape creation.

Shape Component Manipulation

The following operations directly work on the components of shapes: Polygons (faces), vertices and edges. They can be used to clean up imported shapes, separate or combine shapes.

Separate Faces

Select a shape, and click Separate Faces. This creates an individual shape for every face. All new shapes are put in the layer of the original shape.

Combine Shapes

Select multiple shapes, and click Combine Shapes. This creates one shape containing all components of the selected shapes.

Cleanup Shapes

This tool cleans the geometry of selected shapes. It is very useful to prepare imported meshes for 3D editing. The 3D editing works best after cleanup is performed, as this ensures correct connectivity information in the mesh. If you ever encounter problems with 3D editing, try a cleanup operation with the default values.


The Cleanup Shape window with it's cleanup settings

The individual operations are performed in the direction indicated by the dialog, and work as follows:



Example of the Cleanup Tool in action, removing collinear vertices

Further Manipulation Operations

Reverse normals. This operation reverses the normals (i.e., the orientation) of all selected faces. This step is often necessary after importing shapes with reversed orientation.

Set First Edge. This operation sets the first edge of a face to the currently selected edge. This step is often needed to orient a face's "zero" edge towards a street (e.g. for placing the buildings front correctly). If a face is selected, the highlighted gradient line indicates the first edge (with gradient from vertex 0 to vertex 1).

Set Street Edges. This operation marks selected edges as street edges. More specifically, it sets the street width object attribute array to 1 for selected edge indices. When mapped to a CGA rule, the streetWidth() attribute can be used to identify edges or faces that are facing a street. (see also comp() in CGA reference)

Compute First/Street Edges. This operation automatically calculates the first and street width attributes of the selected shapes. It works as follows: First it finds the nearest street (within 100m) for every edge of a shape. The corresponding street width attribute is set to the width of the nearest street. The edge closest to a street is set as the first edge (edge 0).

Convert models to shapes In order to manually edit CGA generated models, they have to be converted to shapes first, using this command. Note that after this conversion, changes in attributes and CGA rules do not affect the shapes anymore.

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