Snap-To may be controlled interactively by dragging individual component parameters using “Alt/Opt + Drag”. This is a quick way of manipulating component placement and design to reach your target minimum distance. However, you may notice that the reliability of Snap-To using this method is dependent on certain settings.
First, even though you are using Snap-To outside of the feature window, the settings chosen in Snap-To still apply. For example, if you are trying to snap a component to the surface of another with all other geometries hidden but the Snap-To Set is “All”, then the component will snap to the nearest geometry in the entire model. The target minimum distance is also enforced.
Secondly, the update speed of the GUI will affect how easily Snap-To can find a solution. Recall that the parameter sliders in OpenVSP have variable ranges where much larger or smaller steps are taken with each “update” as the component changes depending on the range. With very large steps, Snap-To may skip over a solution to the next available. This can be corrected by re-dragging the slider in the proper direction until you find the placement you needed. Alternatively, you can decrease the slider range using the left and right collapse range buttons (>|<) and Snap-To will have an easier time of catching the solution.
Snap-To is an interactive collision detection function that enables components to be placed at a fixed, normal distance from another set of components or to check a model for clearance or collision. In this tutorial, the Snap-To function is introduced and demonstrated to provide a general sense of operation.
Subsurface Ellipses are another closed boundary type that may be placed on the surface of an OpenVSP component. Similar to other closed subsurfaces, the boundary is defined by a UW center location, UW lengths, and a theta rotation. Ellipses, like other subsurface types, may be used to define isolated regions of the surface for export, analysis, or visualization.
Ellipses are unique in that they are also defined by the Num Points used to define the segments forming the ellipse. This means that they are technically N-sided polygons. You can use this to your advantage to create triangles, rectangles, pentagons, etc. on the surface of your component. If you wish to either bisect a corner of a polygon or make one side ‘normal’ in UW space, the quickest way to accomplish this is to use OpenVSP’s Smart Input feature and enter “180/N” in the Theta field where N is the Num Points used to define the shape.
Subsurface Rectangles are a closed boundary placed along UW coordinates on the surface of an OpenVSP component. Similar to other closed boundary subsurfaces, the shape is defined by a UW center location. UW lengths, and a theta rotation. These closed subsurface boundaries are useful for identifying regions for vents, hatches, doors, etc. in visualization or analyses.
Subsurface lines may be defined at either U or W locations on the surface of a component and will be placed for all W or U, respectively, for that location. Lines are a handy way of isolating or splitting regions of a component surface into sections by defining the relevant region either ahead (less than) or behind (greater than) the line location in the U or W directions. For Stacks or Fuselage components that wrap W around the component body, Lines may be used to define a face or region that is intended to be an inlet or outlet. This video tutorial demonstrates the Line subsurface type control and some applications.
