#include "Macros.fxh"

DECLARE_TEXTURE(gPosition, 0);
DECLARE_TEXTURE(gAlbedo, 1);
DECLARE_TEXTURE(gNormal, 2);

BEGIN_CONSTANTS

float3 EyePosition                  _ps(c0)     _cb(c0);

float3 DirectionalLightDirection    _ps(c1)     _cb(c1);
float3 DirectionalLightColor        _ps(c2)     _cb(c2);

float Softness                      _ps(c3)     _cb(c3);

END_CONSTANTS

struct VertexInput
{
    float4 Position : POSITION;
    float2 TexCoord : TEXCOORD;
};

struct PixelInput
{
    float4 Position : SV_POSITION;
    float2 TexCoord : TEXCOORD0;
};

PixelInput main_vs(VertexInput input)
{
    PixelInput output;

    output.Position = input.Position;
    output.TexCoord = input.TexCoord;

    return output;
}

float4 main_ps(PixelInput input) : SV_TARGET0
{
    float3 worldPosition = SAMPLE_TEXTURE(gPosition, input.TexCoord).rgb;
    float3 normal = SAMPLE_TEXTURE(gNormal, input.TexCoord).xyz;
    float3 albedo = SAMPLE_TEXTURE(gAlbedo, input.TexCoord).rgb;

    float3 V = normalize(EyePosition - worldPosition);
    float3 L = normalize(DirectionalLightDirection);
    float3 N = normalize(normal);
    float3 H = normalize(V + L);

    float NdotL = dot(N, L);
    float NdotH = max(dot(N, H), 0.0);

    float lightIntensity;
    if (Softness > 0.0)
    {
        lightIntensity = smoothstep(0, Softness, NdotL);
    }
    else
    {
        lightIntensity = (NdotL > 0.0) ? 1.0 : 0.0;
    }

    float3 light = lightIntensity * DirectionalLightColor;

    float specularIntensity = pow(NdotH * lightIntensity, 32 * 32);
    float specularSmooth = smoothstep(0.005, 0.01, specularIntensity);

    float3 specular = specularSmooth * float3(1.0, 1.0, 1.0);

    float rimColor = float3(1.0, 1.0, 1.0);
    float rimThreshold = 0.1;
    float rimAmount = 0.76;
    float rimDot = 1 - dot(V, N);
    float rimIntensity = rimDot * pow(max(NdotL, 0.0), rimThreshold);
    rimIntensity = smoothstep(rimAmount - 0.01, rimAmount + 0.01, rimIntensity);
    float3 rim = rimIntensity * rimColor;

    float3 color = albedo * (light + specular + rim);

    return float4(color, 1.0);
}

Technique Deferred_Toon
{
    Pass
    {
        VertexShader = compile vs_3_0 main_vs();
        PixelShader = compile ps_3_0 main_ps();
    }
}