The code in imgui.cpp embeds a copy of 'ProggyClean.ttf' that you can use without any external files.
Those are only provided as a convenience, you can load your own .TTF files.
---------------------------------
LOADING INSTRUCTIONS
---------------------------------
Load default font with:
ImGuiIO& io = ImGui::GetIO();
io.Fonts->AddFontDefault();
Load .TTF file with:
ImGuiIO& io = ImGui::GetIO();
io.Fonts->AddFontFromFileTTF("font.ttf", size_pixels);
Detailed options:
ImFontConfig config;
config.OversampleH = 3;
config.OversampleV = 3;
config.GlyphExtraSpacing.x = 1.0f;
io.Fonts->AddFontFromFileTTF("font.ttf", size_pixels, &config);
Combine two fonts into one:
// Load main font
io.Fonts->AddFontDefault();
// Add character ranges and merge into main font
// The ranges array is not copied by the AddFont* functions and is used lazily
// so ensure it is available for duration of font usage
static const ImWchar icons_ranges[] = { 0xf000, 0xf3ff, 0 }; // will not be copied by AddFont* so keep in scope.
ImFontConfig config;
config.MergeMode = true;
io.Fonts->AddFontFromFileTTF("DroidSans.ttf", 18.0f, &config, io.Fonts->GetGlyphRangesJapanese());
io.Fonts->AddFontFromFileTTF("fontawesome-webfont.ttf", 18.0f, &config, icons_ranges);
Add a fourth parameter to bake specific font ranges only:
// Basic Latin, Extended Latin
io.Fonts->AddFontFromFileTTF("font.ttf", size_pixels, NULL, io.Fonts->GetGlyphRangesDefault());
// Include full set of about 21000 CJK Unified Ideographs
io.Fonts->AddFontFromFileTTF("font.ttf", size_pixels, NULL, io.Fonts->GetGlyphRangesJapanese());
// Default + Hiragana, Katakana, Half-Width, Selection of 1946 Ideographs
io.Fonts->AddFontFromFileTTF("font.ttf", size_pixels, NULL, io.Fonts->GetGlyphRangesChinese());
Offset font vertically by altering the io.Font->DisplayOffset value:
ImFont* font = io.Fonts->AddFontFromFileTTF("font.ttf", size_pixels);
font->DisplayOffset.y += 1; // Render 1 pixel down
---------------------------------
EMBED A FONT IN SOURCE CODE
---------------------------------
Compile and use 'binary_to_compressed_c.cpp' to create a compressed C style array. Then load the font with:
ImFont* font = io.Fonts->AddFontFromMemoryCompressedTTF(compressed_data, compressed_data_size, size_pixels, ...);
Or
ImFont* font = io.Fonts->AddFontFromMemoryCompressedBase85TTF(compressed_data_base85, size_pixels, ...);
---------------------------------
INCLUDED FONT FILES
---------------------------------
Cousine-Regular.ttf
Digitized data copyright (c) 2010 Google Corporation.
Licensed under the SIL Open Font License, Version 1.1
DroidSans.ttf
Copyright (c) Steve Matteson
Apache License, version 2.0
http://www.google.com/fonts/specimen/Droid+Sans
ProggyClean.ttf
Copyright (c) 2004, 2005 Tristan Grimmer
MIT License
recommended loading setting in ImGui: Size = 13.0, DisplayOffset.Y = +1
ProggyTiny.ttf
Copyright (c) 2004, 2005 Tristan Grimmer
MIT License
recommended loading setting in ImGui: Size = 10.0, DisplayOffset.Y = +1
Karla-Regular
Copyright (c) 2012, Jonathan Pinhorn
SIL OPEN FONT LICENSE Version 1.1
---------------------------------
LINKS
---------------------------------
Icon fonts
https://fortawesome.github.io/Font-Awesome/
https://github.com/SamBrishes/kenney-icon-font
Typefaces for source code beautification
https://github.com/chrissimpkins/codeface
Programmation fonts
http://s9w.github.io/font_compare/
Proggy Programming Fonts
http://upperbounds.net
Inconsolata
http://www.levien.com/type/myfonts/inconsolata.html
Adobe Source Code Pro: Monospaced font family for user interface and coding environments
https://github.com/adobe-fonts/source-code-pro
Monospace/Fixed Width Programmer's Fonts
http://www.lowing.org/fonts/
(Japanese) M+ fonts by Coji Morishita are free and include most useful Kanjis you would need.
http://mplus-fonts.sourceforge.jp/mplus-outline-fonts/index-en.html
Or use Arial Unicode or other Unicode fonts provided with Windows for full characters coverage (not sure of their licensing).