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Vessel Types: Shaded Drawing |
By default, for shaded 3D Views, vessels are drawn using the wire frame data.
The wire frame drawing data comprises vertices and edges, but OrcaFlex needs a solid surface for the shaded graphics representation. OrcaFlex uses the following procedure to generate this surface from the wire frame vertices and edges.
First any edges with specified diameters (i.e. diameters not equal to '~') are drawn as cylinders. This allows you to use such edges to visualise parts of the structure that are not solid, e.g. crane boom latticework. These edges are now handled and are excluded from the remainder of the procedure.
The remaining edges are used to partition the vertices into sets of connected vertices. Two vertices are deemed to be connected if there exists a path of edges between the two vertices.
Finally, for each set of connected vertices, the smallest convex hull enclosing the set is drawn.
This algorithm does not always generate the shaded drawings that you might expect. Consider the following two wire frame vessels. When drawn in wire frame mode they look the same, but in shaded mode they differ.
| Figure: | Wire Frame and Shaded Drawing |
For the green vessel the superstructure and the hull share vertices and so all vertices are connected. This results in a single convex hull for all vertices being drawn. In the red vessel, the superstructure and hull do not share vertices and so there are two distinct sets of connected vertices. This results in two separate convex hulls and a better representation.
Alternatively the object can be represented by an imported 3D model by specifying the Shaded Drawing File. This must be a Direct X format file, usually with the .x file extension. If you use a relative path then the path will be taken as relative to the folder containing the OrcaFlex file.
The Browse button allows you to specify the Shaded Drawing File quickly and also provides quick access to the Orcina sample drawings via the Navigate to Orcina sample drawings button.
The Use Culling option is normally selected since it can provide a useful performance benefit. However, in order to work it requires that the triangles defined in the .x file have their outward facing directions defined correctly. In the unusual situation where the outward facing directions are not defined correctly then the .x file will not display correctly. If this happens then typically sections of the model will be missing when drawn by OrcaFlex. Disabling the Use Culling option resolves this problem.
Draw Size is provided to allow you to scale the drawing. All directions are scaled equally to arrange that the longest side in the drawing is drawn to the specified Draw Size. This longest side is calculated by first fitting the smallest possible cuboid around the vertices of the shaded drawing (these are defined in the .x file). This cuboid is aligned with the shaded drawing's local axes. Then the length of the longest side of this cuboid is found.
Specify a value of '~' to display the drawing using the absolute coordinates as specified in the .x file.
| Note: | If you use a value of '~' for Draw Size then OrcaFlex uses the coordinates in the .x file directly. If these coordinates use a different length units system from your OrcaFlex model then you should specify the units used in the .x file by including an auxiliary file called AdditionalInformation.txt. Examples of this can be found in the sample shaded drawings provided by Orcina. |
Shaded Drawing Origin is provided because the shaded drawing and the vessel type may have different origins. The Shaded Drawing Origin defines the origin of the shaded drawing with respect to the vessel type's local axis system. Similarly Shaded Drawing Orientation allows you to reorient the shaded drawing to match the vessel type's axis system.
If the vessel length and the vessel type length are different then the shaded drawing is scaled accordingly. This scaling is applied in addition to the scaling of the shaded drawing specified by the Draw Size.