lwjgl3-generated | LWJGL 3 - Generated Sources | Generator Utils library

The LWJGL3 library contains bindings to STB TrueType and other libraries made by Sean Barrett.

In order to modify the packing API provided by this library to render SDF glyphs into the backing texture instead of normal bitmaps, I am reproducing the texture-rendering code from the library in java.

I managed to get it to almost work but I am hitting a stumbling stone where I am getting mangled garbage data for the very top-left corner of the texture. I am somewhat confident that the error must be located somewhere in the code for my version of the stbtt__h_prefilter(...), as this is where the assertion fails.

Edit: I forgot to take into consideration the current buffer position when doing read/write operations on the buffer. Now I still have some garbage data in the bitmap, but it's more evenly distributed.

In fact looking at the updated second picture it seems that somehow the very left-most part of every glyph is shifted half the glyph height down. I cannot find out where or why it happens, especially considering that the bitmap processing works on each glyph individually after it is rendered into the font, so to my understanding the next line of glyphs should just overwrite this..?

Bitmap generated by the original library:

Bitmap generated by my version (see the offset half-lines cutting into some letters):

Addendum: Bitmap generated by my version without the prefilter_... methods:

Below you find my versions of the methods from the library. The originals can be found here.

The references to STB... functions refer to the generated bindings form lwjgl3.