I’m currently learning raycasting and I was able to render several objects in terminal using functions like this (vec3 is just a struct with xyz variables) :

float hit_sphere(vec3 center, float radius, vec3 ray) {
    float a = pow(magnitude(ray), 2.0);
    float h = dot(ray, center);
    float c = pow(magnitude(center), 2.0) - radius*radius;

    float discriminant = h*h - a*c;
    if (discriminant < 0.0f) return -1.0f;
    else {
        return (h - sqrt(discriminant)) / a;
    }
}

I tried to find such a function for a torus, but all I found were some books with fancy equations that I don’t really understand.
So it would be great if you could explain to me how to make such a function for a torus.