SDL_FColor.3type - Man Page

SDL_FColor — The bits of this structure can be directly reinterpreted as a float-packed color which uses the SDL_PIXELFORMAT_RGBA128_FLOAT
format

Defined in SDL3/SDL_pixels.h

#include "SDL3/SDL.h"

typedef struct SDL_FColor
{
    float r;
    float g;
    float b;
    float a;
} SDL_FColor;

This struct is available since SDL 3.2.0.