## Some perceivable inconsistencies, about whether the embedded worksheets can be viewed.

One of the facts which I did mention in an earlier posting, concern worksheets which I sometimes embedded into my postings as ‘<iframe>s’. In reality, there could be two reasons, why such worksheets fail to display in any one person’s browser:

1. I could have embedded them, specifying (insecure) URLs that begin with ‘http://’, even though the reader may be visiting my blog, using a (secure) URL that begins with ‘httpS://’. Or,
2. The posting might suggest that the reader “may need to” enable JavaScript from the domain ‘mathjax.org’, but, in certain cases this is not needed, while in other cases, it is.

‘Problem 1′ above is harder for the reader to fix at their end. It can be solved by fetching my posting using the insecure ‘http://’ URL, or, as I’ve done in a very recent posting, I could decide to embed the ‘<iframe>’ using a URL, which does not specify my domain-name, and just assumes that it’s to be the same, as the domain-name of my site.

‘Problem 2′ above represents a contradiction which may confuse some readers. Sometimes, when I generated an HTML version of a worksheet, I did this by simply clicking on a button, in the GUI of my software. In such cases, the HTML will require that the JavaScript be enabled. But, in certain other cases, all I really did was, to output the worksheet as a LaTeX document, and then to run a custom script on it, to generate other types of documents, one of which would have been an HTML document.

If I ran my custom script on some generic LaTeX document, that generates ‘HTML with equations’, it will do so in the form of ‘a hybrid document’. The resulting document is hybrid, because it can then be viewed in one of two ways:

1. Using the built-in support for ‘MathML’, that some readers’ browsers have. This is less likely, because I only know of one browser that actually support it: ‘Firefox’. If the reader is using ‘MS Edge’ or the ‘Chrome’ browser to view my posting, I know that they do not support MathML as a built-in feature. But,
2. Such a hybrid HTML document can also be viewed, by enabling the JavaScript that gets referred to as ‘MathJax’, and which essentially allows other browsers, including ‘MS Edge’ and ‘Chrome’, to view the equations.

I try to accommodate as many possible configurations of the readers’ browsers as I can, but the unfortunate reality is, that merely pressing the GUI button within my application, may generate HTML which is highlighted more nicely, but which is not a hybrid HTML document.

Dirk

## A butterfly is being oppressed by 6 evil spheroids!

As this previous posting of mine chronicles, I have acquired an Open-Source Tool, which enables me to create 3D / CGI content, and to distribute that in the form of a WebGL Scene.

The following URL will therefore test the ability of the reader’s browser more, to render WebGL properly:

http://dirkmittler.homeip.net/WebGL/Marbles6.html

And this is a complete rundown of my source files:

http://dirkmittler.homeip.net/WebGL

(Updated 01/07/2020, 17h00 … )

(As of 01/04/2020, 22h35 : )

On one of my alternate computers, I also have Firefox ESR running under Linux, and that browser was reluctant to Initialize WebGL. There is a workaround, but I’d only try it if I’m sure that graphics hardware / GPU is strong on a given computer, and properly installed, meaning, stable…

## Firefox Quantum now available under Debian Linux

There has been an ongoing subject, concerning Debian distributions of Linux, and Firefox upgrades. The Debian users, at least if they were restricting themselves to standard repositories, were being held back to a version of Firefox, which was referred to as Firefox-ESR, which stands for ‘Extended Support Release’. This release was receiving regular security patches, but no major upgrade in the version number, which meant that it was always at some sub-version of Firefox 52…

Well only yesterday, my two Debian / Stretch computers, which I name ‘Plato’ and ‘Klexel’, finally received a much-anticipated upgrade to Firefox Quantum, which is also known as Firefox-ESR, v60…

I am happy with Firefox Quantum, but perhaps only, because certain earlier, unstable versions of it, never made it into the Debian repositories? There is one observation about this updated browser-version which I need to make. As was announced, Mozilla dropped support for the old, ‘Netscape Plugin API’, which I had still been using to custom-compile plug-ins. Instead of using this API, up-to-date developers are being asked to use the ‘firefox-esr-dev’ package. but alas, the last time I checked, this package was not up to version 60… This package was still at version 52…

## Maintaining My Ability to View VRML 2.0 on the Web

What some modern readers may not realize, is that even before the Shockwave Flash plug-in allowed it, and before WebGL inherited the responsibility of displaying 3D content in a Web-browser, there existed A more-straightforward way to display 3D scenes within our Web-browser, which was referred to as “VRML”.

Most browsers today lack the ability to display this format of content, but I usually make sure to custom-compile a version of the plug-in which does this, which is named “FreeWRL”.

When doing so, I need to set up the configuration of the source-tree with the following line:


./configure --enable-plugin --with-plugindir=/usr/lib/mozilla/plugins --with-target=motif --with-imageconvert=/usr/bin/convert --with-unzip=/usr/bin/unzip --enable-libeai --enable-docs --with-wget=/usr/bin/wget




And, even if I give this command, often, the Firefox plug-in will not be built, because an additional dependency which I may not have installed, would be

‘npapi-sdk-dev’

This build-dependency gives our computers the header files necessary, to compile old-fashion plug-ins, which ‘Netscape’ and ‘Firefox’ allowed as add-ons, to view additional content-types embedded within the browser. And, Mozilla recently gave notice, that they would be dropping support for this plug-in API shortly. However, ‘firefox-esr’, available under Linux, still supports this plug-in API.

What I find additionally, is that even if I get the most-recent versions of ‘FreeWRL’ to compile, the resulting program does not work correctly, and that I need to compile an older version instead.

Well on the box which I name ‘Plato’, I just recently compiled and tested v2.3.3 of ‘FreeWRL’ and found that it still works. What I was also reminded of, was that support for VRML 1.0 was dropped a long time ago, and that only VRML97 / VRML 2.0 is still supported for on-line viewing. Thus, VRML 2.0 was already defined, in 1997.

Content can still be found on the Web, even though the examples are sparse. Other examples, not linked to here, such as the NASA examples, were simply hosted on a non-NASA computer, and then abandoned, which means that most NASA VRML-links are broken links. Further, some graphics students will display their VRML-worlds, as proof that they’ve achieved some level of competency in graphics in general, but will fail to publish a URL.