NewRibbons

The `NewRibbons' representation is similar to `Tube' in that it follows the a spline curve for both the protein and nucleic acids. However, it uses additional information (the O of the protein backbone or some of the phosphate oxygens for nucleic acids) to find a normal for drawing an oriented ribbon. (There may be some problems with the ribbon definition for nucleic acids as it is possible for the nucleic acid detection routine to label a residue as a nucleic acid even though it does not have phosphate oxygens.)

The NewRibbons representation uses the alpha Carbons as control points for a spline which defines the ribbon backbone. The ribbon is drawn by extruding a two-dimensional cross section along the length of the spline orienting it by referencing the positions of the Oxygens on the protein backbone. As with the `Tube' representation, the six ribbon segments nearest the given atom are drawn with the color assigned to that atom and the atom can be selected by clicking near the center of those six elements.

The Aspect Ratio parameter controls the width of the ribbon relative to the thickness value, as a multiplicative factor. An aspect ratio of 1.0 yields a Tube-like representation. The Resolution parameter controls the degree to which the ribbon surface is tesselated with triangles. Higher settings yield nicer looking images at the expense of interactive rendering performance. Points can be interpolated with either a Catmull Rom or B-Spline by changing the value of Spline Style. Note that the B-Spline does not always pass through the C${}_\alpha$ positions, as it is a smoother spline.