I found this tool while trying to make a custom symbol font that'd work with the ProggyClean pixel font with Dear ImGui. The tool itself works well but when I tried exporting it and loading it in my ImGui program, it was very blurry and no amount of tweaking things in the tool itself and the exported font in FontForge fixed it. To be honest, I have very little idea on how to use FontForge. I also have little idea on what the units for em size ascent descent pixel size mean and not enough patience at the time to learn it. I was trying to make a 6x12 monospaced font. (well i think proggy clean is 6x12) How would i fix this?

I should note that I found another solution to my underlying problem, by registering custom glyph rects using imgui's font api and then blitting the raw pixels for the glyphs into the font atlas. but I would also like to know how to do this using a ttf font. Maybe it'll be useful in the feature.

For ascent/descent quick reference, check out to the tooltip that displays when you hold your mouse over “Highlight glyphs under the mouse”. Then check how it goes for the example font.

For 6x12 you could likely use default ascent/descent with pixel size of 64. Then the optimal size will usually be either 12 or 16, depending on how software counts font sizes.

And some libraries just like to aggressively apply anti-aliasing when rasterizing glyphs for rendering so you may not always get what you want with a TTF/OTF font.