Curve Creation
These parametric curves can be created:
- Through an intersection
or projection
of 3D geometry in the
sketch. After isolating the resulting geometry, you
can use constraints to change the position of the curve. The system is unable
to directly modify the shape because the curve, which has no internal freedoms
that the system can control, only has three degrees of freedom.
- Using
Spline
. The curve is defined from other geometries. The parametric
curve is said dependent. It is constructed so it passes through a series of
control points.
Constraints and dimensions can be added between a dependent parametric
curve and other geometries in the sketch.
Solving problems will occur:
- If the position of the defining geometry depends upon the position
of the parametric curve, either directly or indirectly.
- When the other geometry of the constraint or dimension is an other
parametric curve or dependent parametric curve.
Recommendations
Always use
Constraint without dialog box
to specify where the constraint must be created on the curve.
When using this command, selection points are not taken into account.
On fully under-constrained sketches, the system can have difficulties
in choosing between changing the shape and/or moving its defining geometry
especially when it supposes to make large changes. Moving the geometry helps
the system find a consistent solution in that case.