Revised Rotate Tool

DELFTship forum Feature requests Revised Rotate Tool


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    • #44259
      Terrance Egolf

      While the typical professional user of DELFTship probably doesn’t normally spend a lot of time rotating objects, or at least rotating a lot of objects, modelers creating detailed plans of ships from the Age of Sail often find themselves modeling long timbers that twist along the length of the ship. These can include railings, waterways, beam clamps, wales, etc.

      In my case, for the past six years, I have been modeling the hull and structure of the ship my grandfather sailed in during 1906 and 1907. It is the Galilee, which was chartered by the Carnegie Institution of Washington, DC, USA, to conduct the first-ever geomagnetic surveys of the Pacific Ocean. This vessel was a wooden brigantine built on the West Coast of the US in 1891. Very little is known about the ship’s construction other than an extensive library of random photographs owned by Carnegie Science, and some hull plans of unknown provenance that seem to agree somewhat with the photographs.

      As an example of the kind of work involved in reconstructing an older sailing ship, the following image shows the reconstructed deck beams, and the timbers called beam clamps, or shelves. On these latter timbers the deck beams were mounted during construction before being fastened in place.
      <p style=”text-align: center;”>Beams-and-Clamp</p>
      This DELFTship wireframe image shows a perspective view of how the deck beam clamp twists throughout the length of the ship.
      <p style=”text-align: center;”>Beam-Clamp-Control-Net</p>
      In order to construct this timber in DELFTship, I had to select the control points at each edge loop along its length to align the edge loop with the associated hull frame(s) at that location. This required rotating the selected points around a reference point in the edge loop to make the adjustment. Without getting into the details of how this worked, let us just say that I had to open the Rotate dialog hundreds of times to construct this particular component. Many of the adjustments to construct a smooth twist had to be repeated as many as six times, because the whole rotate operation must begin from scratch. Since there is no way to measure the actual required amount of rotation beforehand, each rotation operation had to be estimated, then additional adjustments had to be made.

      I think that the Rotate Tool could use some improvements. The following are some issues and suggested features that should be addressed when revising this tool:

      1. First and foremost, the rotation dialog should remain open and editable until the user is satisfied with the rotation operation. This would mean that the angle could be adjusted repeatedly without having to reenter all the start and end point information. When the adjustment is correct, a separate control should be used to close the dialog and save the change.
      2. Being engineers, the programmers probably learned in analytical geometry that positive angles are measured counterclockwise in a polar coordinate system, and negative angles are measured clockwise. However, for the rest of the world, modeled geometry rotations should work the opposite, which brings me to rotational axis orientation.
      3. Since attempting to rotate objects around an axis other than one parallel to the model’s x-, y-, or z-axis produces unpredictable results, I suggest that the dialog be redesigned to reinforce and facilitate this idea.
        1. The first row of fields should be the coordinates of the “near point” lying on the rotation axis. I have found through experience that this point is normally one of the control points of the object to be rotated.
        2. The second row of fields should be the coordinates of a “distant point” lying on the rotation axis—a farther point as the user looks along the rotation axis.
        3. Since the rotation axis is parallel to one of the model’s coordinate axes, the coordinates on this “distant point” differ only in one value from the coordinates of the “near point.” If the rotation axis is parallel to the longitudinal axis of the model, the x-value will be different; If the rotation axis is transverse, then the y-coordinate with be different; and if the rotation axis is vertical, then the z-coordinate will be different. The user is instructed in the program manual that the direction of view determines whether this value is larger or smaller than the corresponding near-point coordinate.
      4. When the user enters the appropriate values of the near-point coordinates, the dialog should automatically populate the corresponding fields of the distant-point’s coordinates with the same values. Then the user has to change only the single field representing the distant point on the axis of rotation.
      5. The user then enters a positive angle for a <u>clockwise</u> rotation or a negative angle for a <u>counterclockwise</u> rotation, <u>as viewed along the rotation axis from the near to far points</u>.
      6. Pressing a button in the dialog titled “Rotate,” for example, performs the rotation but leaves all the fields populated. If the angle needs to be increased or decreased, the user enters the revised <u>total</u> angle, then clicks on “Rotate” again until satisfied with the total adjustment. An additional refinement would be if angular adjustments could be entered in pre-defined increments by clicking an arrow button, just as points can be nudged in the Point dialog.
      7. Pressing a button titled “Finish,” for example, completes the adjustment, saves the change, and closes the dialog.
      8. Other adjustments that should be made to the dialog are as follows:
        1. No fields should have numerical values when the dialog opens. This precludes having to select all the digits in a field before entering the required digits.
        2. The cursor focus should be in the first field of the first line of fields when the dialog opens.
        3. The user should be permitted to enter as many numerical digits in the fields as desired, with no rounding or truncating.
      9. Here is a diagram of what the revised Rotate Tool dialog could look like:

      <p style=”text-align: center;”>Rotate-Tool


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