import Common;

interface IBRDF
{
    float3 evaluate(float3x3 tbn, float3 viewDir_WS, float3 lightDir_WS, float3 lightColor);
};

struct BlinnPhong : IBRDF
{
    float3 baseColor;
    float metallic;
    float3 normal;
    float specular;
    float roughness;
    float sheen;

    __init()
    {
        metallic = 0;
        normal = float3(0, 0, 1);
        specular = 0.5;
        roughness = 0.5;
        sheen = 1;
    }

    float3 evaluate(float3x3 tbn, float3 viewDir_WS, float3 lightDir_WS, float3 lightColor)
    {
        float3 normal_WS = mul(normal, tbn);
        float diffuse = max(dot(normal_WS, lightDir_WS), 0);
        float3 h = lightDir_WS + viewDir_WS;
        float specular = dot(normal_WS, h);
		
        return (viewDir_WS + float3(1, 1, 1)) / 2;//baseColor * (diffuse + specular) * lightColor;
    }
};

struct DisneyBRDF : IBRDF
{
    float3 baseColor;
    float metallic = 0;
    float3 normal = float3(0, 1, 0);
    float subsurface = 0;
    float specular = 0.5;
    float roughness = 0.5;
    float specularTint = 0;
    float anisotropic = 0;
    float sheen = 0;
    float sheenTint = 0.5f;
    float clearCoat = 0;
    float clearCoatGloss = 1;

    float3 evaluate(float3x3 tbn, float3 viewDir_TS, float3 lightDir_TS, float3 lightColor)
    {
        return baseColor;
    }
};