some basic GLSL fragment shader show casing physical correct lighting

physical.c

in vec3 normal;  
in vec3 eye;//from vertex to eye/origin

const light = vec3(0.12708472893924555, -2.5399460893115735, 2.8320502943377743) // from vertex to lightsource
const vec3 LIGHT_COLOR = vec3(1, 0.7, 0.4);

//created textures have to have realistic values
//Fresh asphalt  0.04
//Worn asphalt   0.12
//Bare soil      0.17
//Green grass    0.25
//Desert sand    0.40
//New concrete   0.55
//Fresh snow     0.80–0.90
const vec3 directDiffuse = vec3(0.5);//normal diffuse color, from a texture i.e.

//the following values should be used:
//No value under 0.02
// gemstones 0.05-0.17
// liquids 0.02-0.04
//Skin      0.028
// when no idea set value of 0.04 (around plastic)
// for metals:
//Silver      0.971519    0.959915    0.915324
//Aluminium   0.913183    0.921494    0.924524
//Gold        1           0.765557    0.336057
//Copper      0.955008    0.637427    0.538163
const vec3 specColor = vec3(0.0225);

//how shiny things should be
const float gloss = 0.9;

const float SpecularPower = exp2(10 * gloss + 1);
const float normFactor = ((SpecularPower + 2) / 8 );

//about textures: directDiffuse, specColor or gloss can of course be read from textures or mixed with uniforms before they are used.
//remember when you want to use a diffuse texture that to have gamma correct colors to linearize the color after the texture read
// e.g. vec4 diff = toLinear(texture(sampler, uv))

vec4 toLinear(vec4 x){ return pow(x, vec4(2.2)) }
vec4 toGamma(vec4 x){ return pow(x, vec4(1/2.2)) } 

float saturate(float a)
{
    return min(1,max(0,a));
}

#define OneOnLN2_x6 8.656170 // == 1/ln(2) * 6   (6 is SpecularPower of 5 + 1)
vec3 FresnelSchlick(vec3 E,vec3 H)
{
    return specColor + (1.0f - specColor) * exp2(-OneOnLN2_x6 * saturate(dot(E, H)));
}

float BlinnPhong(vec3 N, vec3 H)
{
    return pow(saturate(dot(N, H)), SpecularPower);
}

vec3 light(vec3 N, vec3 V, vec3 L, vec3 lightColor)
{
    vec3 H = normalize(L+V);
    float NdotL = dot(N, L);

    vec3 directSpecular = FresnelSchlick(L, H) * BlinnPhong(N, H) * normFactor;
    return (directDiffuse + directSpecular) * lightColor * max(0,NdotL);
}

void main()
{   
    vec3 N = normalize(normal);
    vec3 V = normalize(eye);
    vec3 L = normalize(light);


    vec3 color = light(N, V, L, LIGHT_COLOR);
    //color += ...  now add other lightsource or ambient light(directDiffuse * ambientLigthColor)
    FragColor = toGamma(vec4(color, 1));
}