static const float HALF_PI = 1.57079633f;
static const float PI = 3.14159265f;
static const float TAU = 6.28318530f;

struct VertexData
{
    float4 normal;
    float2 uv0;
    float2 uv1;
    float4 color0;
};

struct TransformData
{
    float4x4 transform;
    float4x4 normalTransform;
};

struct MaterialData
{
    float4 albedoFactor;
    float4 emissionFactor;
    Sampler2D.Handle albedoTex;
    Sampler2D.Handle normalTex;
    Sampler2D.Handle metalRoughTex;
    Sampler2D.Handle occlusionTex;
    Sampler2D.Handle emissionTex;
    float metalFactor;
    float roughFactor;
};

struct PointLight
{
    float3 Position;    // 12
    float Range;        // 16
    uint Color;         // 20
    float Intensity;    // 24
    uint pad0;
    uint pad1;
};

struct DirectionalLight
{
    float3 Direction;
    float Validity_;
    uint Color;
    float Intensity;
    uint pad0;
    uint pad1;
};

struct CameraData
{
    float4x4 view;    // 64
    float4x4 proj;    // 128
    float4x4 invView; // 192
    float4x4 invProj; // 256
    float4 position;  // 272
};

struct Indexer
{
    uint16_t count;
    uint16_t offset;
};

struct Lighting
{
    SamplerCube.Handle environment;       // 8
    SamplerCube.Handle diffuseIrradiance; // 16
    SamplerCube.Handle prefilter;         // 24
    Sampler2D<float2>.Handle brdfLUT;     // 32
    ByteAddressBuffer.Handle lights;      // 40
    Indexer pointLightIndexer;            // 44
    Indexer dirLightIndexer;              // 48
};

struct Block
{
    static const uint USE_DIFFUSE_BIT = 1;
    static const uint USE_SPECULAR_BIT = 2;
    static const uint SHOW_DIFFUSE_BIT = 4;
    static const uint SHOW_PREFILTER_BIT = 8;

    StructuredBuffer<float4>.Handle vertexBuffer;         // 8
    StructuredBuffer<VertexData>.Handle vertexData;       // 16
    StructuredBuffer<MaterialData>.Handle materialBuffer; // 24
    StructuredBuffer<TransformData>.Handle nodeBuffer;    // 32
    StructuredBuffer<CameraData>.Handle camera;           // 40
    StructuredBuffer<Lighting>.Handle lights;             // 48

    uint debugFlags; // 52

    int materialIdx; // 56
    uint nodeIdx;    // 60

    property ignoreDiffuse : bool
    {
        get {
            return (debugFlags & USE_DIFFUSE_BIT) == 0;
        }
    }

    property ignoreSpecular : bool
    {
        get {
            return (debugFlags & USE_SPECULAR_BIT) == 0;
        }
    }

    property showDiffuse : bool
    {
        get {
            return (debugFlags & SHOW_DIFFUSE_BIT) != 0;
        }
    }

    property showPrefilter : bool
    {
        get {
            return (debugFlags & SHOW_PREFILTER_BIT) != 0;
        }
    }
};

float3 Uncharted2Tonemap(float3 color)
{
    float A = 0.15f;
    float B = 0.50f;
    float C = 0.10f;
    float D = 0.20f;
    float E = 0.02f;
    float F = 0.30f;
    float W = 11.2f;
    return ((color * (A * color + C * B) + D * E) / (color * (A * color + B) + D * F)) - E / F;
}