mv_easy_font

Simple font renderer library written in Opengl 3.3 using stb_truetype.h to load a packed bitmap into texture of a .ttf font.

Uses instanced rendering, so that only position, index and color of each glyph have to be updated instead of updating two triangles of vertex attributes per glyph.

Inspired by stb_easy_font.h.

Usage

Compile the example program with

gcc main.c -Iinclude -lglfw -lm

or similar linking options for your OS (like -ldl in linux). Run with:

./a.out path/to/font.ttf

or omit the file to use extra/Inconsolata-Regular.ttf.

To use mv_easy_font.h in any opengl project, #define MV_EASY_FONT_IMPLEMENTATION before including mv_easy_font.h in one .c/.cpp file, and include mv_easy_font.h wherever else needed. Simply call mv_ef_draw() with the appropriate parameters to draw text:

mv_ef_draw(str, col, offset, font_size, res);

somewhere in the render loop.

If

mv_ef_init(path_to_ttf, font_size, path_to_custom_vertex_shader, path_to_custom_fragment_shader);

is not called manually, it will try to look up a default font file using font size 48, and the built in shaders are used. All the three string arguments can be NULL to use default values.

Dependencies

mv_easy_font.h depends on stb_truetype.h and calls the OpenGL API, so make sure all the relevant OpenGL symbols and functions are loaded using something like GLEW, GLAD or whatever floats your boat.

You can optionally choose to use include stb_image_write.h (for generating font.png) and stb_rect_pack.h (for more efficient packing)

At the moment there are two shader files that need to be visible to the executable. These will probably be inlined in the near future.

console.ttf is hardcoded at the moment, so that will also have to be available in the current working directory when running.

The example code uses GLFW and GLAD, but those should not be required, as long as opengl symbols are loaded properly.

TODO

• ADd functionality to adjust the bitmap texture size based on the font size. currently it's using a hard-coded texture that we hope will fit (and is proably too big). Might not even care, since it doesn't really impact performance...

• Look into padding in the bitmap

Screenshot:

Font bitmap