There is a new version 2.0.2 of Jupyter VPython, the 3D graphics module (*pip
install vpython* or *pip install vpython --upgrade*; see vpython.org for
more details):
* It supports extrusion and 3D text objects.
* There are important improvements to the way compound objects work.
* The axis and up attributes of an object are now always perpendicular to
each other.
*EXTRUSION AND 3D TEXT*
The extrusion object lets you specify a 2D shape and a path along which to
extrude that shape. Here is an example and the documentation:
http://www.glowscript.org/#/user/GlowScriptDemos/folder/Examples/program/Extrusions
http://www.glowscript.org/docs/VPythonDocs/extrusion.html
The text object creates an extrusion of a specified text, making 3D text
available in a scene. Here is an example and the documentation:
http://www.glowscript.org/#/user/GlowScriptDemos/folder/Examples/program/BillboardingText
http://www.glowscript.org/docs/VPythonDocs/text.html
*CHANGES TO COMPOUND OBJECTS*
Working with compound objects in GlowScript 2.1 uncovered some significant
design issues which later versions of GlowScript addressed. Here are the
changes to the compound object, which are part of the Jupyter VPython 2.0.2
release:
1) The compound object is now very similar to the box object. In GlowScript
2.1 (and up till now in Jupyter VPython), the bounding box (size) was
vector(1,1,1), the actual bounding box was not known, and size could only
be changed multiplicatively. In later versions of GlowScript the bounding
box (size) is the actual size of the object, which can be changed by
setting size to the desired value.
2) Now, when you create a compound object, the value of "pos" is set to the
computed center of the object. If you specify "pos" when creating the
object, the object is moved so that its center is located at the new
location.
3) As with other objects such as box or cylinder, changing the axis of an
extrusion or compound object not only rotates the object but its length
(size.x) is set equal to the magnitude of the axis vector. Similarly,
changing the size sets the magnitude of the axis vector to be equal to the
length (size.x).
Here is the documentation on the updated compound object:
http://www.glowscript.org/docs/VPythonDocs/compound.html
*AXIS AND UP KEPT PERPENDICULAR TO EACH OTHER*
Jupyter VPython 2.0.2 incorporates changes implemented in GlowScript 2.4
that fixed a long-standing error in changing "axis" without updating "up"
to remain perpendicular to axis (and vice versa). The result was that
rotating an object by continually changing its axis could cause abrupt
changes in the appearance of the object. This was noticeable only if an
object had a texture or a compound object lacked symmetry, which is
presumably why the problem doesn't seem to have been noted for many years.
Here is an example of a program running in GlowScript 2.3 that illustrates
the problem. Note that "up" doesn't change, and there's a problem when
"axis" and "up" point in the same direction:
http://www.glowscript.org/#/user/Bruce_Sherwood/folder/Pub/program/RotatingAxis2.3
Here is the same program running GlowScript 2.4 (or Jupyter VPython 2.0),
which works properly. Note that "axis" and "up" are always perpendicular to
each other:
http://www.glowscript.org/#/user/Bruce_Sherwood/folder/Pub/program/RotatingAxis2.4
For further details, see
http://www.glowscript.org/docs/VPythonDocs/box.html
*GLOWSCRIPT VPYTHON CLOSER TO TRUE VPYTHON*
The RapydScript Python-to-JavaScript transpiler used with GlowScript
VPython now comes closer to handling standard Python syntax, which will
facilitate moving programs between GlowScript and Juptyer environments. The
new transpiler is RapydScript-NG, developed by Kovid Goyal. For example,
among its features is that it provides most of the standard Python string
methods: capitalize, strip, lstrip, rstrip, islower, isupper, isspace,
lower, upper, swapcase, center, count, endswith, startswith, find, rfind,
index, rindex, format, join, ljust, rjust, partition, rpartition, replace,
split, rsplit, splitlines, and zfill.
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