R"###(  
#version 330 core

out vec4 FragColor;
in vec2 texCoords;

vec3 center = vec3(0.0f,0.0f,20.0f);
float radius = 5.0f;

float planeHeight = -7.0f;

struct Ray {
    vec3 dir;
    vec3 pos;
    float min;
    float len;
    vec3 color;
};
        
Ray applyMin(Ray ray) {
    vec3 off = ray.dir * ray.min;
    ray.pos = ray.pos + off;
    ray.len = ray.len +  ray.min;
    return ray;
}


Ray planeMin(Ray ray){
    ray.min = ray.pos.y - planeHeight;
    ray.color = vec3(1.0,1.0,1.0);
    return applyMin(ray);
}

Ray sphereMin(Ray ray){
    ray.min = length(ray.pos - center) - radius;
    ray.color = vec3(1.0,0.0,0.0);
    return applyMin(ray);
}

Ray minFn(Ray ray){
    Ray sp = sphereMin(ray);
    Ray pl = planeMin(ray);

    if (sp.min < pl.min){
        return sp;
    } else {
        return pl;
    }
}

void main()
{
    vec3 dir = vec3(texCoords.x, texCoords.y,2.0f);
    dir = (dir - 0.5f) * 2;
    vec3 pos = dir;
    Ray ray = Ray(pos,normalize(dir),.0,.0,vec3(.0));


    ray = minFn(ray);

    while( (ray.min < 100.0f) && (ray.min > 0.1f) ) {
        //ray.dir = normalize(ray.dir);
        ray = minFn(ray);
        //vec3 off = ray.dir * min;
        //ray.pos = ray.pos + off;
        
    }
    
    
    if(ray.min <= 0.2f){
        FragColor = vec4(ray.color, 1.0f);
    } else {
        FragColor = vec4(.0,0.0f,0.0f,1.0f);
    }

} 
)###";