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Surface Trim with Limits
The Trim Surface with Limits command enables you to trim one or more surfaces of any kind using selected limiting entities, which may be curves or other surfaces: you will have to select the Limits (curves or surfaces), the Surfaces to be trimmed and, on such surfaces, the Regions to Keep.
If the limiting entities are curves, they need not necessarily lie on the surfaces to be trimmed, in which case their projection onto the surfaces along the view direction (of the view in which they were selected) will be used for trimming, unless you have selected the Disable Projection check box. In fact, when this box is cleared, automatic projection along the view direction is enabled. When it is checked, projection is disabled (which might be useful, for example, when the selected surfaces are more than one and the limits are curves lying on the said surfaces: in this case no projection is actually needed).
Please note that the Disable Projection check box is automatically checked when the selected limits are curves of the Curve on Surface type and the surfaces to be trimmed are their base surfaces.
| What happens if the view direction changes? Suppose you select the limits, the surface and the regions to keep. Then you rotate the model with the mouse, which implies a view direction change. In this case, when the Disable Projection check box is cleared, if you click the Update Projection button on top of the selection list (  ), the
Regions to Keep selector will be reset, so as to enable you to perform a new selection based on the new view direction. |
The limiting curves (i.e.: the ones actually used for trimming, which means their projections, in the case they don't lie on the surfaces) must never intersect and must form no loop inside one another (if they do, the Regions to Keep cannot be univocally determined). In such cases, the trimming operation must be carried out in two stages: first trim with one set of limits, then trim with a second set.
When the limits are curves, the following situations may occur:
In the default mode, in case 1 the curves are automatically extended, while in case 2 the chain is automatically adjusted (that is: gaps between free endpoints will be automatically closed if the distance is smaller than the value corresponding to the Parameter Domain (%) value under More Options - Advanced Options; the default value of such parameter is studied so as to match most situations in which you might reasonably want to automatically close the chain, but you can change it as you like in specific cases). This process is called "healing". Please note that the healing process of cases 1 and 2 does not take place when the limits are surfaces.
But, if the result automatically obtained by the program should not satisfy you, a proper set of options is available under More Options to enable you to perform operations manually so as to heal the trimming as you like. See "Using the Proximity Radius, Manual Repair and Advanced Options" for further details on the options and "Trimming with healing" for a general overview of the healing methods.
An additional option is also available under More Options: High quality approximation. It enables you to control the quality of the curve actually used for trimming, based on the curve/border selected as a limit.
You can specify what to do with the original surfaces. In the Base Entities drop-down list, select one of the following:
| Restoring selection When the command is applied to some entities, the settings used in the operation are stored by the program. Next time you start the command, the Restore Selection button (  ) is displayed on top of the selection list. If you click it, the parameter settings will automatically be restored to the values used last time you used the command and applied to the selected entities when you select  or  .See "Restore Selection modality for selections and settings" for details |