Free search with control points

The contour is defined by a set of freely placed control points that lie on the surface or wireframe. The search engine connects these control points with a curve element.

Although the method builds upon connecting two control points, it also supports to connect these points along edges and curves. It enables to build the required contour with maximum flexibility. This can be either an open or a closed contour.

There are at least two control points needed to start the contour search engine. They can be placed on a surface, based upon the WYSIWYG principle, or by selecting an edge or curve. The general workflow to build the contour however remains the same.

To start from an initial point on a surface, the pie menu has to be opened on the wanted surface to place the first control point.

The control point is displayed as a (green) sphere.

From there, additional control points can be inserted, both on the surface as on an edge or curve. The initial starting point colors red, all intermediate points are grey and the end point colors green. The connections between the control points that build the whole contour are computed immediately and are being displayed.



Initial control point		Second control point		And more …

With the Execution button in the contour search panel the found solution becomes permanent. The default shortcut for this button is using the key on the keyboard.

The workflow can be terminated without solution by pressing the key on the keyboard.

The search engine tries to connect two control points with each other to build the contour, or part of the contour. Because different solutions would be possible, the search engine uses a strategy to find a result. The software supports four strategies.


	Surface outer boundary Searches for the shortest solution over the outer boundaries of the reference surfaces. See the white contour in the picture.
	Surface inner edges Searches for the shortest solution over the inner edges of the reference surfaces.
	Shortest distance Searches for the shortest distance solution between the control points across the reference surfaces.
	Straight Builds the straight, linear connection between the control points, regardless from any reference surface.

The strategies as shown above are listed in the order of priority. Initially the outer boundary search, looking for the shortest track along that boundary, is the default strategy when creating a new contour. However, when it cannot be applied or does not lead to any possible solution, the second strategy in line is applied. And when that strategy also does not lead to any result, the last strategy is applied, where control points are linear connected, the shortest possible distance between them.

Once a solution has been found, for each contour element the strategy can be set individually.

Boundary and inner edges, or curves, can only be found when at least two control points in sequence lie exactly on the boundary or inner edge.

Contour search on edges and curves

The contour search can also be started directly on a surface edge or curve. In that case the pie menu has to be opened to define the search strategy.


	Search tangentially along edges Searches along the edges or curves for as long as the tangential conditions are met.
	Search for edge Picks the selected edge or curve.
	Search for outer boundary Searches for reference surface outer boundary with respect to the tangential conditions of that boundary.

While finding the contour multiple control points are generated along the solution.

When edges or curves are used to search along and the control point is located at the vertex of that edge or curve, it will display green cone markers. Each of them shows a possible direction in which the contour search could continue. Selecting such marker will extend the solution.



Start		Direction markers		After picking

Search parameters

The search engine uses the following parameters to find and build the resulting contour:


	Tangent continuous angle	The automatic contour search stops when the tangent angle between the already found contour and a next curve element is larger than the specified value.
	Max. distance	The automatic contour search stops when the gap between the already found contour and the next curve element is larger than the specified value.
	Sag for regular shape check	Tolerance or allowed deviation to convert a searched closed contour into a (best fit) regular shape contour, such as a circle or rectangle.
	Manifold solution	When multiple possible solutions exist to merge adjacent surfaces, activating the option results in the solution where the angle between the adjacent surfaces is the smallest.
	Disassemble bodies	Bodies can be disassembled in single surfaces, to generate other domains.

Modify the contour

There are many different ways to modify the found contour solution.

Each control points can be moved freely. Picking such a point enables to move it anywhere over the reference surface.



Pick control point		Move

When moving it near to an edge or boundary and pressing the

-key, a green marker appears to drop it exactly onto that element. Releasing the control point then will drop it spot on the boundary.



Pick control point		Pressing Shift-key		Release

New control points can be added to the existing contour. Picking a new point on the surface will extend the contour from the last point.



Pick position		Contour extended

And while hovering over a connection element, pressing the left mouse button will split the connection at that position and generates an additional control point.



Connection		Hover over and press		Additional control point

Additional functionality is available in the different pie menus.

On a control point the pie menu includes:

And on a connection element the pie menu includes:

Search over gaps

The contour search is an intelligent engine that can cross gaps and holes in the reference surface.

Where possible the gap or hole is closed by making use of the (interpolated) information of the reference surface. Otherwise the gap or hole is closed by a straigth connection.



Interpolated gap crossing		Straight gap crossing

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