BENDING
Bend is a set of deformation tools which enable you to precisely re-shape a part of your model. Although this is usually about bending a part of model which resembles a rod or cylinder, using Bend on other shapes can have “interesting effects”.
There are two subsets of the Bend tools: with or without setting clamped points.
The descriptions below show what the tools do, rather than a step by step guide on how you could use them – IMO there’s quite a learning curve to climb to become a skilled Bender.
Judging by the discussion in the Forum, even experienced Wings 3D practitioners (still) have trouble getting their heads around how this tool is best used!
There is a Tutorial on Bend in puzzledpauls collection which you can follow for a detailed walk-through of the options.
Vertex | Bend
Depending on which mouse button is used, you can choose between different bending behaviors:
- Plastic Bend – LMB
- Pivot Bend – MMB
- TopRad Bend – RMB
Plastic Bend
In this mode, you put an imaginary rod through your selection and bend the rod. The selection follows the curvature of the rod.
The bend amount is specified in degrees. At 0 degrees, the rod is straight. At 180 degrees, the center and both ends are located on the line you specify. If you extended the curvature of the rod further, you would get a circle or a flat spiral.
Note that the length of the rod stays the same, only the curvature changes.
To visualize what Plastic Bend does, find a ballpoint pen and take out the ink reservoir and the spring. Put the spring in the middle of the reservoir tube and wrap the reservoir round the side of a cup. The spring follows suit. In this real-life example, the ink reservoir represents the rod that you use with Plastic Bend, and the spring represents your vertex selection.
Specify three things for Plastic Bend:
- Rod Center – This is the point that marks the middle of the rod.
- Rod Top – This is the point where the positive extreme end of the rod is located. The other end is located opposite it at the same distance from the center. The rod top does not mean that bending ends there. The curvature remains constant even past this point. The rod top and bottom are simply the points that will find themselves on a straight line passing through them and the rod center at a 180-degree bend.
- Bend Normal – This is the direction of a line that passes through the center. At a 180-degree bend, the rod center, the rod top and the rod bottom are all located along this line.
Pivot Bend
In this mode, you also have a rod, but you use it differently. First you specify where the rod is located and how it is curved, and then you stretch the vertex selection proportionally along it.
The bend amount is specified in degrees. At 0 degrees, the vertex selection is flattened about the rod center. At other values, it is stretched along the rod curve. If you extended the curvature of the rod, you would get a circle, a helix (spring shape) or a 3D spiral.
To continue our ink reservoir and spring analogy, you first wrap the reservoir with the spring on it round the side of a cup and hold it there, and then start stretching the spring. The stretching spring follows the curvature of the ink reservoir.
Specify four things for Pivot Bend:
- Rod Center – This is the point that marks the middle of the rod.
- Rod Top – This is the point where the positive extreme end of the rod is located. The other end is located opposite it at the same distance from the center. The rod top does not mean that bending ends there. The curvature remains constant even past this point.
- Pivot Axis – This axis defines how the final bent rod will be oriented. As we have pointed out, the resulting curvature can be a circle, a helix or a 3D spiral. If it’s a circle, then the pivot axis is perpendicular to the circle’s plane. If it’s a helix or 3D spiral, then the pivot axis is a line that this helix or spiral coils around.
- Pivot Location – This is the point through which the pivot axis runs.
TopRad Bend
In this mode, you first define the curvature of the rod and then stretch the flattened selection along the rod, as in Pivot Bend. However, you define the curvature in the same way as for Plastic Bend – you specify a line that runs through the center, and both ends of the curved rod.
The bend amount is specified in degrees. At 0 degrees, the vertex selection is flattened about the rod center. At other values, it is stretched along the rod curve. If you extended the curvature of the rod, you would get a circle or a 2D spiral.
Specify three things for TopRad Bend:
- Rod Center – This is the point that marks the middle of the rod.
- Rod Top – This is the point where the positive extreme end of the rod is located. The other end is located opposite it at the same distance from the center. The rod top does not mean that bending ends there. The curvature remains constant even past this point.
- Bend Normal – This is the direction of a line that passes through the center. The rod is bent in such a way that the rod center, the rod top and the rod bottom are all located along this line.
Vertex | Bend Clamped
Bend Clamped has the same functionality as Bend and the same three modes:
- Bend Clamped Plastic – LMB
- Bend Clamped Pivot – MMB
- Bend Clamped TopRad – RMB
See above for details.
The difference is that Bend Clamped lets you set limits for rod curvature. In addition to the Bend options, Bend Clamped requires that you specify two more:
- Top Clamp Point – This is a point up the rod (or up the rod extension) at which the rod stops curving and continues as a straight line.
- Bottom Clamp Point – This is a point down the rod (or down the rod extension) at which the rod stops curving and continues as a straight line.
{Source Notes: The above is based on the description of Bend in the Wikibook version.}