[Visualpython-users] VPython 5.3

[Bruce S. <Bru...@nc...>]

VPython 5.3 is now available for all platforms. It offers the following 
enhancements.

*New 3D text object*

Thanks to great work by Kadir Haldenbilen, there is a new "text" object 
that from any True Type (.ttf) font produces extruded 3D text. This 
supercedes the very limited old visual.text machinery (which however is 
being left in place for upward compatibility). Kadir had to identify and 
exploit various font-related modules to find a font, identify its 
contours, and split the solid portions of characters into triangles to 
be used in a faces object. These additional font-related modules are 
bundled into the Windows and Mac versions. As usual, until and unless 
someone makes a distribution package, Linux users will have to install 
them manually: they are FontTools, ttfquery, and Polygon.

See the detailed documentation on the new text object in the help that 
is installed with VPython.

You may find some minor glitches. For example, the "&" is filled in on 
the sans-serif font Verdana, other fonts show o's and other such letters 
filled in, and some fonts give execution errors due to being ill-formed. 
You are invited to report problems with fonts or specific characters of 
fonts.

Polygon is being distributed in the Windows and Mac installers subject 
to the following conditions: "This distribution contains code from the 
GPC Library, and/or code resulting from the use of the GPC Library. This 
usage has been authorized by The University of Manchester, on the 
understanding that the GPC-related features are used only in the context 
of this distribution. It is not permitted to extract the GPC code from 
the distribution as the basis for commercial exploitation, unless a GPC 
Commercial Use Licence is obtained from The University of Manchester, 
contact: http://www.cs.man.ac.uk/~toby/gpc/".

*Enhancements to faces object*

You can now create a faces object f, specifying only the positions of 
the vertices, then use f.make_normals() to create normals that are 
perpendicular to all the faces. You can also use f.make_twosided() to 
convert a one-sided faces object into a two-sided one. You can now say 
f.append(pos=(x,y,z)), whereas formerly you also had to give a normal 
when appending a vertex.

You can use the previously announced f.smooth() to average similar 
normals in adjacent triangles to make the object look smoother, and with 
VPython 5.3 you can specify the smoothing criterion: f.smooth(0.7) means 
that normals whose directions differ by an angle whose cosine is greater 
than 0.7 (about 45 degrees) will be averaged. The simple form f.smooth() 
corresponds to f.smooth(0.95), in which case normals within 18 degrees 
of each other will be averaged.

*Highlighting a curve when making a graph*

When using gcurve to graph a function, there is a problem that you may 
not notice any plotting if the function repeats back on itself. You can 
now highlight the current plotting position in the gcurve by specifying 
a "dot" option: gcurve(dot=True). By default the dot has the same color 
as the gcurve, is round, and has a width of 8 pixels. You can change 
these defaults: gcurve(dot=True, dot_color=color.blue, shape='square', 
size=15).

*Minor bug fixes*

Some bugs were fixed. The helix object didn't have a "visible" 
attribute. If you had more than one points object, some with round 
points and some with square points, you saw only round points. Some 
technical bugs in the faces object were corrected.