LibraryLink: How to read from a Mathematica stream in C?

Mathematica has a flexible streams interface. Functions like Read can read from a "stream" that may be backed by a file, pipe, string, network resource, etc. We can even create our own custom streams.

I am looking to implement an importer for a certain file format in C. How can I make it work with arbitrary Mathematica streams?

More generally, how can I create a C++ iostreams-interoperable interface that reads from / writes to Mathematica streams?

LibraryLink has a WolframStreamsLibrary.h header, as well as some related functions in WolframLibrary.h. What is the purpose of these? Can I use them to read from arbitrary streams, or are they designed to implement new Mathematica stream types in C? My impression is that they're intended for the latter.

An alternative idea is to try to use Mathematica callbacks to fill the C++ input stream's buffer:

A big problem with this approach is that it is only practical if the C program is the exclusive user of the stream, or if it will read it all the way to the end. With this approach, the C code might read more data than it needs, and the stream might not be rewindable.

I am looking for advice on how to approach this problem, and feedback on the specific implementation ideas above.

Comments

plotting - Plot 4D data with color as 4th dimension

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plotting - Mathematica: 3D plot based on combined 2D graphs

I have several sigmoidal fits to 3 different datasets, with mean fit predictions plus the 95% confidence limits (not symmetrical around the mean) and the actual data. I would now like to show these different 2D plots projected in 3D as in but then using proper perspective. In the link here they give some solutions to combine the plots using isometric perspective, but I would like to use proper 3 point perspective. Any thoughts? Also any way to show the mean points per time point for each series plus or minus the standard error on the mean would be cool too, either using points+vertical bars, or using spheres plus tubes. Below are some test data and the fit function I am using. Note that I am working on a logit(proportion) scale and that the final vertical scale is Log10(percentage). (* some test data *) data = Table[Null, {i, 4}]; data[[1]] = {{1, -5.8}, {2, -5.4}, {3, -0.8}, {4, -0.2}, {5, 4.6}, {1, -6.4}, {2, -5.6}, {3, -0.7}, {4, 0.04}, {5, 1.0}, {1, -6.8}, {2, -4.7}, {3, -1....

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