Breaking Surfaces

This task shows you how to break surfaces. Surfaces can be broken by any combination of curves, planes and surfaces. See also Breaking Curves.
Available functionalities from the Dashboard are:
Open the FreeStyle_Part_40.CATPart document.

  1. Click the Break Surface or Curve icon:
    The Break dialog box and the Tools Palette  appear.

  2. Click the Break Surfaces option:

    The Break dialog box content has been modified according to the selected type.

    The Break dialog box displays the following information:

    • Break Type:

      • Break Curves: breaks the curves.

      •  Break Surfaces: breaks the surfaces.

    • Selection

      • Elements: defines the set of curves or surfaces to be cut.

        Elements List: displays the list of elements to be cut.

      • Limitation: defines the set of limiting elements: points, curves, planes or surfaces.

        Limitation List: displays the list of limiting elements.

      • Break Both: breaks elements to be cut and limiting elements by each other.
      • Fragments: fragments an input curve(s) or surface(s) without selecting the Limitation inputs set. If you select a curve(s) or surface(s) in the Elements input set and checks the Fragment option, the Limitation input selector would be inactive. Also, all the other options will be inactive. Now when you press the Apply button the curve(s) or surface(s) will be broken by its segment boundaries. Report shows the status for the cutting elements. In this option as there is no cutting element, report will always display “No computation done”.

    • Trim Type:

      • Face Trim: surfaces are topologically relimited and the control points of the initial surfaces are kept.

      • Surface Trim: surfaces are geometrically relimited and the control points of the resulting surfaces are kept.
        Only 4 edge-patches are created with Surfaces by curves option.

    • Order

      • U: defines the U order.
        Available only with Break Surfaces and Surface Trim options.
        The U and V order maximum values are set with the Order setting option of the FreeStyle settings.

      • V: defines the V order.
        Available only with Break Surfaces and Surface Trim options.
        The U and V order maximum values are set with the Order setting option of the FreeStyle settings.

    • Projection: By default the points that do not lie on the trimmed elements will not be projected onto the trimming elements.

      • Along Compass: projects along the compass direction.

      • Along Normal: projects along the normal direction.

      • Along Viewing Direction: projects along the viewing direction.

    • Extrapolation:

      • Tangential Extrapolation: extrapolates along the tangent direction.
        Available only with Break Surfaces option.

      • Curvature Extrapolation: extrapolates along the curvature direction.
        Available only with Break Surfaces option.

    • Report: displays a status about cutting elements:

      • Cutting elements that can be used for the Break (marked by a green tip). When you click on the text, the corresponding curve is highlighted in green in the 3D geometry.

      • Cutting elements that cannot be used for the Break (marked by the condition to be applied so that they can be used: projection, etc). When you click on the text, the corresponding curve is highlighted in red in the 3D geometry.

        • When there is no selection of cutting elements, an error message is issued and the Break Report panel informs you that no element is selected.

        • When a red cross is displayed, it means that the problem cannot be managed by the application.

    • Max deviation: displays the maximal deviation between original surface and the resultant surface in the dialog box and on the geometry.
      Available only with Break Curves and Trim Surface options.

  3. Select the surface.

  4. Select the Cutting field in the Break dialog box and select the six curves as shown.

  5. Click Apply in the Break dialog box.
    The surface has been trimmed. By default, only one trimmed element is kept (no transparency has been applied) other not (a transparency has been applied).

  6. Click the curve segment to be kept: it appears with no transparency in the 3D geometry.

  7. Right-click any relimited element to display the following contextual menu.
    • Keep all: all parts of the all curves are kept.
    • Keep all but this: all parts of all curves are kept except the selected one.
    • Remove all but this: all parts of all curves are removed except the selected one.
    To keep, or do not keep, some elements press the Ctrl key and click them.

  8. Click the Along Compass option:

  9. Click Apply in the Break dialog box.
    Elements that do not lie on the trimmed elements will be projected (pseudo-intersections) onto the trimming elements according to the compass direction.

  10. Click the Along Normal option:

  11. Click Apply in the Break dialog box.
    Elements that do not lie on the trimmed elements will be projected (pseudo-intersections) onto the trimming elements according to the normal direction. The surface has been trimmed.

  12. Click the Shorten Mesh option:

  13. Click Apply in the Break dialog box.
    • The maximal deviation is displayed in the Break dialog box and on the geometry (yellow label).
    • The maximum degree variation allowed for each patch of the new surface as compared to patches of the initial surface can be modified.
    • Click the U Order and the V Order text to edit and modify the values (besides is an example with U and V values set to 8).

  14. Click the Tangential Extrapolation option:

  15. Click Apply in the Break dialog box.
    As a consequence, one edge is added.

  16. Click OK in the Break dialog box.