////////////////////////////////////////////////////////////
//~ Shader math types

#define Pi              ((f32)3.14159265358979323846)
#define Tau             ((f32)6.28318530717958647693)
#define GoldenRatio     ((f32)1.61803398874989484820)

typedef float2 Vec2;
typedef float3 Vec3;
typedef float4 Vec4;
typedef int2 Vec2I32;
typedef int3 Vec3I32;
typedef int4 Vec4I32;
typedef uint2 Vec2U32;
typedef uint3 Vec3U32;
typedef uint4 Vec4U32;
typedef float2x3 Xform;
typedef float4 Rect;
typedef float4 ClipRect;
typedef float4 Aabb;
typedef float4 Quad;
typedef float4x4 Mat4x4;

////////////////////////////////////////////////////////////
//~ Handle dereference wrappers

/* TODO: Non-uniform resource access is assumed as the default behavior. We
 * may want to add explicit "uniform" variants for optimization on AMD devices
 * in the future. */

template<typename T> StructuredBuffer<T>   StructuredBufferFromHandle(StructuredBufferHandle h)     { return ResourceDescriptorHeap[NonUniformResourceIndex(h.v)]; }
template<typename T> RWStructuredBuffer<T> RWStructuredBufferFromHandle(RWStructuredBufferHandle h) { return ResourceDescriptorHeap[NonUniformResourceIndex(h.v)]; }

ByteAddressBuffer   ByteAddressBufferFromHandle(ByteAddressBufferHandle h)     { return ResourceDescriptorHeap[NonUniformResourceIndex(h.v)]; }
RWByteAddressBuffer RWByteAddressBufferFromHandle(RWByteAddressBufferHandle h) { return ResourceDescriptorHeap[NonUniformResourceIndex(h.v)]; }

template<typename T> Texture1D<T>   Texture1DFromHandle(Texture1DHandle h)     { return ResourceDescriptorHeap[NonUniformResourceIndex(h.v)]; }
template<typename T> Texture3D<T>   Texture3DFromHandle(Texture3DHandle h)     { return ResourceDescriptorHeap[NonUniformResourceIndex(h.v)]; }
template<typename T> RWTexture1D<T> RWTexture1DFromHandle(RWTexture1DHandle h) { return ResourceDescriptorHeap[NonUniformResourceIndex(h.v)]; }
template<typename T> Texture2D<T>   Texture2DFromHandle(Texture2DHandle h)     { return ResourceDescriptorHeap[NonUniformResourceIndex(h.v)]; }
template<typename T> RWTexture2D<T> RWTexture2DFromHandle(RWTexture2DHandle h) { return ResourceDescriptorHeap[NonUniformResourceIndex(h.v)]; }
template<typename T> RWTexture3D<T> RWTexture3DFromHandle(RWTexture3DHandle h) { return ResourceDescriptorHeap[NonUniformResourceIndex(h.v)]; }

SamplerState SamplerStateFromHandle(SamplerStateHandle h) { return SamplerDescriptorHeap[NonUniformResourceIndex(h.v)]; }

////////////////////////////////////////////////////////////
//~ Countof

template<typename T, u32 N> u32         countof(T arr[N])                   { return N; }
template<typename T>        u32         countof(StructuredBuffer<T> buff)   { u32 result; buff.GetDimensions(result); return result; }
template<typename T>        u32         countof(RWStructuredBuffer<T> buff) { u32 result; buff.GetDimensions(result); return result; }
                            u32         countof(ByteAddressBuffer buff)     { u32 result; buff.GetDimensions(result); return result; }
                            u32         countof(RWByteAddressBuffer buff)   { u32 result; buff.GetDimensions(result); return result; }
                            u32         countof(Texture1D tex)              { u32 result; tex.GetDimensions(result); return result; }
template<typename T>        u32         countof(RWTexture1D<T> tex)         { u32 result; tex.GetDimensions(result); return result; }
                            Vec2U32     countof(Texture2D tex)              { Vec2U32 result; tex.GetDimensions(result.x, result.y); return result; }
template<typename T>        Vec2U32     countof(RWTexture2D<T> tex)         { Vec2U32 result; tex.GetDimensions(result.x, result.y); return result; }
                            Vec3U32     countof(Texture3D tex)              { Vec3U32 result; tex.GetDimensions(result.x, result.y, result.z); return result; }
template<typename T>        Vec3U32     countof(RWTexture3D<T> tex)         { Vec3U32 result; tex.GetDimensions(result.x, result.y, result.z); return result; }

////////////////////////////////////////////////////////////
//~ Color helpers

Vec4 Vec4FromU32(u32 v)
{
    Vec4 result;
    result.x = ((v >> 0) & 0xFF) / 255.0;
    result.y = ((v >> 8) & 0xFF) / 255.0;
    result.z = ((v >> 16) & 0xFF) / 255.0;
    result.w = ((v >> 24) & 0xFF) / 255.0;
    return result;
}

u32 U32FromVec4(Vec4 v)
{
    u32 result;
    result |= (((u32)(v.x * 255.0)) & 0xFF) << 0;
    result |= (((u32)(v.y * 255.0)) & 0xFF) << 8;
    result |= (((u32)(v.z * 255.0)) & 0xFF) << 16;
    result |= (((u32)(v.w * 255.0)) & 0xFF) << 24;
    return result;
}

////////////////////////////////////////////////////////////
//~ Vertex ID helpers

Vec2 RectUvFromVertexId(u32 id)
{
    static const Vec2 uvs[4] = {
        Vec2(0, 0),
        Vec2(1, 0),
        Vec2(1, 1),
        Vec2(0, 1)
    };
    return uvs[id];
}

////////////////////////////////////////////////////////////
//~ Ndc helpers

Vec2 NdcFromPos(Vec2 pos, Vec2 size)
{
    Vec2 result;
    result = pos / size;
    result *= Vec2(2, -2);
    result += Vec2(-1, 1);
    return result;
}

Vec2 NdcFromUv(Vec2 uv)
{
    Vec2 result;
    result = uv;
    result *= Vec2(2, -2);
    result += Vec2(-1, 1);
    return result;
}