# Introduction

PolyCAD 10 developments are primarily concerned with an updated user interface and the introduction of intersection, fitting and lofting as core workflow behind the development of X-Topology Surfaces. One of the primary aims of the new user interface is to promote consistency and create the impression of different task orientated areas.

Most of the "new" tools are not exactly new but have been in PolyCAD for sometime. However, the old interface did not allow these features to be always promoted in the right way. Many were only available through context sensitivity. This is good for hiding many commands until they become available but also means that the feature is never found until the right selection combination is applied by the user. The new user interface now promotes:

- X-Topology Surfaces
- X-Topology Surface Groups
- X-Topology Surface Combinations
- Ruled Surfaces
- Extruded Surfaces
- IntelliHull Surfaces
- IntelliSurface Surfaces
- Project Curve onto Plane
- Project two Curves together
- Intersection of Two Planes
- Arc and Leader Dimensions

and introduces new research topics:

- X-Topology Initial Sizing
- X-Topology Hull Shape Generation
- Internal Subdivision Surfaces, i.e. Decks, Transverse and Longitudinal Bulkheads

# Toolbar

The new toolbar is inspired by the Microsoft Fluent interface but it explicity does not follow the same rules. In particular, it is slightly larger to accomodate a better organisation of buttons. Originally I was against following this new fashion because I quite like the fact that I maximised the size of the design area. However, I found that many new tools were hidden away, menus were getting larger but could only support small buttons. After some though and the realisation that I could use Inkscape to create button images which could be produced in different resolutions and considered developing the toolbar in a way that would support different tasks. Both Microsoft Office and AutoCAD have aquired the new interface and it became a problem to learn where certain buttons have go to. To address this, Saving, Copying, Pasting, Transforming and Viewing are available on every page. Then the specialisation functions associated with the title of the toolbar page are added. Therefore, all the functions associated with a particular modelling task should all be on one page and the need to swap between pages should be minimised.

Of course, there will be some people who will not like this or will find it hard to get used to it. PolyCAD 9 will remain available for some time and the software had always been backwards and forward compatible as much as possible.

# Minibar - ...Its a small toolbar that appears!

The Minibar came about before the toolbar despite the fact that its also part of the Microsoft Fluent concept. I introduced it because there was often a lot of mouse travel up to the toolbar to change between rotation and selection. Now that is no longer necessary. That said, I am still not used to this new feature and keep going up to the toolbar with the mouse. There are two parts to the Minibar. The first sets of buttons are user defined, which can be done from **Home -> Entity Details -> Minibar Properties**. When an Entity is edited, it has the opportunity to add further buttons, such as the constraint options provided by X-Topology Curves, above left. When PolyCAD is first installed the Minibar will have the Selection, Rotate, Pan and Zoom buttons. You should feel free to customise the options you want on this toolbar.

You can make several different sets of button selections and assign them to appear during selection, editing operations or both. These toolbar sets are assigned in PolyCAD Settings.

# Loft Curves, Intersection and Fitting: Using Output geometry to generate input Definition

Continuing research into the X-Topology Surface Fitting, Lofting and Hull Generation tools highlighted that assemblies of lofted curves could be a core concept of X-Topology and surface modelling throughout. The X-Topology Lofting, X-Topology Surface Fitting and X-Topology Form Generation all use the same code to generate lofting curves.

As loft curves are generated using an intersection process, there is no reason why X-Topology definition curves themselves cannot be generated from lofting curves creating a process where new definition is created from the output of other definition curves. Intersecting an assembly of lofted curves will produce a significant number of datapoints, far to many for a sensible definition curve. Therefore, Least-Squares fitting is introduced to generate a definition curves with a specified number of points. Furthermore, smoothing is introduced to improve the quality of the shape picked up from other geometry. Curves generated using a least squares fit are setup to interpolate any tangent curves but not X-Topology curves without tangent information. Options allow these curves to attached to the newly fitted curve. Consequently, the new curve will become a child of tangent curves and a parent to any ordinary curves.

The intersection process is extended to pick up any points which may be generated on other entities. Least Squares generation can also be applied to Polylines and BSpline curves allowing the generation of non-planar curves such as chines.

# X-Topology Curves

To support these additional options, the creation of X-Topology Curves has been split and extended. The basic X-Topology now allows only sketching and can constrain the curve to a plane. Three new tools are introduced for intersection and fitting. The Intersect Spline Fit allows an X-Topology curve to be spline fitted to a set of intersection point generated using a plane. This tool allows the use of both principle and inclined planes. Intersection points are not generated from lofted curves in this particular case as this will generate far to many definiition points. The Intersection Least Squares will fit to points generated by the intersection of lofted curves and plane, providing smoothing functions to improve the quality of the curve generated from the data points. The number of fitted points and smoothing on each individual segment of the fitted curve can be controlled independantly.

X-Topology Curve Fairing is introduced allowing the application of least squares curve fitting and smoothing models to existing curves.

# X-Topology Surfaces, Groups, Combinations and Surface Fit

There new surfaces are introduced. X-Topology Surface Groups collects the output of several X-Topology surfaces so that it can be used as a single representation, for hydrostatics and other operations. X-Topology Surface Groups collect the output of several X-Topology surfaces together, unioning them together to produce a new boundary representation. This representation may be used for X-Topology Hull Surface transformations and exporting to ACIS.

X-Topology Surface Fit combine the output of an X-Topology Surface and an X-Topology Loft improving the quality of the surface. It takes a good deal of skill to generate a good quality lofting that will improve a the surface but if you understand what you are doing it possible to generate a high quality surface very quickly. These developments are documents in more detail toward the end of this article.

The number of different surfaces available on X-Topology Surfaces has been reduced to those that are supported by other CAD systems. The default option is now Bi-Cubic Bezier Blended, i.e. BSplines Surfaces.

Creation tools are introduced for all of these tools to assist the generation process.

# Isophotes and Curvature

The setup of Isophotes and Curvature have been added as tool windows to allow you to modify the display while entities are selected and being edited.

# New Dimensions

New Arc and Leader dimension tools have been added joining the Linear Dimension. The leader dimension is very useful for annotating a model