OpenCL and path tracing material system - gpu

Question

I started developing my own path tracing program with Opencl using GPU (for the speed). I had easily created path tracer with basic mateial with standard properties (as metallic, specular, refractionChance, emission etc.).
But what I am interested in now is option to create more complex materials something as in Blender's shader graph where you can use for example Fresnel function.
I imagine this as function for every material (and stop me if this is horrible approach) and the function returns basic information about point where ray landed (base color ,metallic...). It is some sort of sampler for object's material.
This would be easily done with C++ on CPU. But OpenCL doesnt support virtual functions and creating big switch for every material's function is really bad for GPU performance by my knowledge.
Does anyone have some expirience with material systems or just some small tip to get started? I would be thanks for any answer.
This is my C++ CPU approach:
struct MaterialProp{
float3 baseColor;
float metallic;
float specular;
// ETC.
};
struct Material {
virtual MaterialProp sampleMaterial(Ray ray, ... ){
MaterialProp prop;
prop.baseColor = float3(0.0f, 0.0f, 0.0f);
prop.metallic = 0.0f;
prop.specular = 0.0f;
...
prop;
}
};
// Brand new material
struct NewMaterial : public Material{
Texture tex;
virtual MaterialProp sampleMaterial(Ray ray, ... ){
MaterialProp prop;
prop.baseColor = sampleTex(tex);
prop.metallic = fresnel;
prop.specular = 0.0f;
...
prop;
}
};
Color trace(Ray ray){
Object* hitObj = intersectScene(ray);
if(hitObj){
MaterialProp prop = hitObj.Material.sampleMaterial(ray);
//Do other stuff with properties;
//return color;
}else{
return Color(0.0f, 0.0f, 0.0f);
}
};