I find SDF example for SDL2 here https://github.com/oxygine/oxygine-framework/tree/master/examples in Demo example.
After some debugging I found vertex and fraxment SDF font shaders and try use in my sample project.
My sample project here https://github.com/akk0rd87/SDL_SDFFONT
First I try to render whole SDF Font texture atlas. But insead of atlas I get black rectangle.
openglesdriver.h - the class for openGLES functions loading.
sdf.h - it is my example code.
Could you help me and say where I wrong?