ModifyCurveAdvanced Continuity

The Advanced Curve Continuity command enables you to modify continuity between curves and chains of curves. The result of the command is a new chain of curves matching the chosen continuity conditions (while the original curves will still be there).

• First, select a chain of curves to modify (the Curves to Be Modified item in the selection list will turn to green — you can end selection by right-clicking and selecting Continue in the context menu or by clicking Reference Curves).
• Then, select a chain of curves to be used as a reference (the Reference Curves item in the selection list will turn to green; end selection by right-clicking and selecting Continue in the context menu).

Please take into account that both chains can obviously be reduced to just one curve; from now on, the term contour will be used instead of curve/chain of curves.

Once the two contours have been selected:

• You will be able to set the continuity conditions between the two contours, which can be positional, tangency, curvature, torsion, smooth curvature or curvature continuity between the curvature plots. As to the meaning of continuity types, see Continuity Types.
• The application automatically detects the two nearest endpoints and shows the solution you would get with positional continuity. In fact, a preview mechanism is available, enabling you to interactively assess the result you are obtaining.

You can also change the position of the endpoint on the reference contour (Reference U) and of the one on the contour to be modified ( Fixed U ). The position of its second endpoint ( Modified U ) can be modified as well. The number of curves the command will actually create is the same as the one of the curves belonging to the contour to be modified in the range between the fixed and the modified endpoint.

Starting from tangency and up to higher continuity values, a Weight value is also available. The weight will enable you to adjust the tangency factor (supplying negative values will cause the tangent to get the opposite direction).

The Associative Mode check box enables you to create curves which retain a link to the surfaces/curves they derive from.

	When the check box is selected, the resulting curves will be associative. The new curve will retain a link to the entities it derives from. A specific node displaying both the original entities and the resulting associative curve will be added to the Model Structure.
	When the check box is cleared, the resulting curves will not be associative.

Some particularly advanced options are available under More Options.

• Using the Shape factor, which can vary in the range from 0.0 to 1.0, you can control the way the result is computed. When the value is 0.0 the result will be computed only based on a shape similarity criterion with the initial part of the chain. When the value is set to 1.0, the result will be computed only based on the distance from the initial part of the chain. When the value is set to an intermediate value between 0.0 and 1.0, both the said criteria will be taken into account proportionally to the value itself.
• Also the Flexibility of the resulting curve can be chosen, in a set of four values, from Minimum to Big. The higher the chosen value, the more flexible and complex the resulting curve will be.

Finally, you can use the Curvature command to obtain a curvature plot taking into account the modified contour and the part of the reference contour resulting in the most "natural" connecting contour.

The Restore Selection button ( ) — enabling you to use the last selections and settings again without having to repeat them all — is available on top of the selection list in the situations described in "Restore Selection modality for selections and settings".

Try to ...

• Modify continuity between two chains of curves

Related topics

• Curve Continuity Commands: a comparison
• Restore Selection modality for selections and settings