Using Dynamic Snapping to build networks of X-Topology Curves

Dynamic snapping is one of the most important features of X-Topology curves allowing networks to be quickly and easily defined. The benefit of dynamic snapping is that the curves accurately maintain their connection to other curves which is fundamental to the generation of the surface and also means that as a curve is manipulated, any curves which are attached to it update.

This example starts with two curves. The first part will demonstrate how the lower curve can be attached to the upper curves.

To attach the lower curve to the upper curve anywhere along it, drag a control point near the upper curve away from the upper curve's connection nodes, indicated by a small filled circle. The point will snap to the curve, indicated by a yellow cross and a dynamic snapping link will be constructed, indicated by the set of chain links beneath the mouse cursor.

The lower curve is now attached to the upper the curve. The lower curve's control point can now be dragged along the upper curve and if dragged away from the upper curve the snap relationship can be removed, indicated by a set of broken chain links beneath the mouse cursor.

If the upper curve is modified, the lower curve will update its position as the upper curve is manipulated.

If the lower curves control points are dragged close to the upper curves nodes it will snap to the point, indicated by the yellow rectangle and a dynamic relationship will be constructed, indicated by the chain links beneath the cursor. Note that if the lower curve is already snapped to the upper curve, it will have to be first dragged away from the upper curve to change the relationship from a curve snap to a point snap and vice-versa.

Now if the points on the upper curve are moved, the lower curves snapped point's follow.

Now we will build up a simple rectangular network of curves using snapping. First curve starts at the origin...

...and goes 20 up.

Another similar curve.

Now connect the two curves together, begin drawing a curve at the origin and allow it to snap.

Now drag it across to the start of the other curve and allow it to snap, finish the curve.

Start another curve at the top, allow it to snap...

...and drag it across and snap it to the curve on the right.

Removing the grid illustrates the rectangle.

If we move one one of the non-snapped definition points, the shape deforms as the points are manipulated.

The shape is returned to its previous shape.

Now we will refine the shape. Change the view to see the rectangle in 3D and start a new curve. Attach it one of the sides of the rectangle.

Now drag it up to create a new point overhead. Note that the drawing plane is indicated beneath the mouse cursor. This drawing plane is located through the first point of the curve.

Finally, snap the point to the opposite side of the rectangle.

Now to complete the mesh we will drag a curve in the other direction. Rotate the view and attach a curve to the left edge.

Drag it up and attach it to the previously drawn curve.

Complete the curve by dragging it to the right curve.

Now select the previous curve and manipulate the middle point.

When this point is manipulated, the attached curves follow its changes. At this point we have a valid topology and we could generate a surface from this network of curves.