Thanks for the kind words !
However, I really must say that I would not know most of what I now have learned, had it not been for the generous help provided by Luis Sa', Luis Feliz-Tirado, Richard Ludowise (aka "rhumbaflappy"), Arno Gerritsen, Holger Sandmann, Jon Masterson (aka "Scruffyduck"), Jim Vile, Scott Smart, Jim Keir, Christian Stock, and many others who have taken the time to post information and tutorials for FS development.
The FS SDK and infrastructure of the FS rendering engine is so complex, that it is best studied and worked with in a spirit of open-mindedness, as there is always something new to be learned.
As we consider the possible underlying mechanism at work in the FS SDK infrastructure and rendering engine which may be involved with the VTP line scenario display / non-display explored in this thread, when we ask 'why' VTP lines must be at least 20 pixels wide in FS9 (and perhaps prior FS2Kx versions as well ?), perhaps we can better understand why certain terrain quad mesh LOD grid sizes for quads and 'Area Point' mini-quads, and their integrally-associated 'known and calculable' terrain grid vertices, may determine whether a terrain object will- or will not- be displayed at all- in FS at run time (...and if it is
displayed, whether it will be with lesser LOD and/or MIPMAP resolutions for a mapped texture "Material").
: For example, I have ongoing questions about why Leo's FS9 terrain mesh (from another project in the same world region) will not
display, which I am hoping to better comprehend from the standpoint of ex
: minimum Geographic extents of coverage (...as a function of "terrain quad mesh LOD grid sizes for quads and 'Area Point' mini-quads, and their integrally-associated 'known and calculable' terrain grid vertices, that may determine whether a terrain object will- or will not- be displayed at all- in FS at run time).
I would be very grateful for an opportunity some time soon, to explore that (separate) topic with Luis Sa', Luis Feliz-Tirado, Richard Ludowise (aka "rhumbaflappy"), Arno Gerritsen, Holger Sandmann and others who have worked with both FS2Kx and FSX terrain mesh creation in the past, in order to achieve a better understanding of what criteria may apply to certain terrain mesh creation scenarios that initially defy comprehension when terrain mesh 'successfully' made with SDK Resample-compatible source files will not
display in FS9 at run time.
AFAIK, no version of the SDK documentation that I am familiar with appears to have discussed this, and the Help file for SBuilder only briefly alludes to a LOD-8 sized gridding minimum source data coverage extent criteria which must be satisfied to achieve successful display in FS9 at run time.
I have yet to fully decipher the (2) 'minimally explained' utilities by Dick for calculating minimum terrain quad LOD Geographic extents for SDK Resample source files.
But that is best regarded as a topic for yet another thread in the future, and an example that there is always something new to learn about FS Development for all