//
//   Copyright 2015 Pixar
//
//   Licensed under the terms set forth in the LICENSE.txt file available at
//   https://opensubdiv.org/license.
//

//----------------------------------------------------------
// Patches.VertexGregoryBasis
//----------------------------------------------------------

void vs_main_patches( in InputVertex input,
                      out HullVertex output )
{
    output.position = input.position;
    OSD_PATCH_CULL_COMPUTE_CLIPFLAGS(input.position);
}

//----------------------------------------------------------
// Patches.HullGregoryBasis
//----------------------------------------------------------

[domain("quad")]
[partitioning(OSD_PARTITIONING)]
[outputtopology("triangle_cw")]
[outputcontrolpoints(20)]
[patchconstantfunc("HSConstFunc")]
OsdPerPatchVertexGregoryBasis hs_main_patches(
    in InputPatch<HullVertex, 20> patch,
    uint primitiveID : SV_PrimitiveID,
    in uint ID : SV_OutputControlPointID )
{
    OsdPerPatchVertexGregoryBasis output;

    float3 cv = patch[ID].position.xyz;

    int3 patchParam = OsdGetPatchParam(OsdGetPatchIndex(primitiveID));
    OsdComputePerPatchVertexGregoryBasis(patchParam, ID, cv, output);

    return output;
}

HS_CONSTANT_FUNC_OUT
HSConstFunc(
    InputPatch<HullVertex, 20> patch,
    uint primitiveID : SV_PrimitiveID)
{
    HS_CONSTANT_FUNC_OUT output;

    int3 patchParam = OsdGetPatchParam(OsdGetPatchIndex(primitiveID));

    float4 tessLevelOuter = float4(0,0,0,0);
    float2 tessLevelInner = float2(0,0);
    float4 tessOuterLo = float4(0,0,0,0);
    float4 tessOuterHi = float4(0,0,0,0);

    OSD_PATCH_CULL(20);

#if defined OSD_ENABLE_SCREENSPACE_TESSELLATION
    // Gather bezier control points to compute limit surface tess levels
    OsdPerPatchVertexBezier bezcv[16];
    bezcv[ 0].P = patch[ 0].position.xyz;
    bezcv[ 1].P = patch[ 1].position.xyz;
    bezcv[ 2].P = patch[ 7].position.xyz;
    bezcv[ 3].P = patch[ 5].position.xyz;
    bezcv[ 4].P = patch[ 2].position.xyz;
    bezcv[ 5].P = patch[ 3].position.xyz;
    bezcv[ 6].P = patch[ 8].position.xyz;
    bezcv[ 7].P = patch[ 6].position.xyz;
    bezcv[ 8].P = patch[16].position.xyz;
    bezcv[ 9].P = patch[18].position.xyz;
    bezcv[10].P = patch[13].position.xyz;
    bezcv[11].P = patch[12].position.xyz;
    bezcv[12].P = patch[15].position.xyz;
    bezcv[13].P = patch[17].position.xyz;
    bezcv[14].P = patch[11].position.xyz;
    bezcv[15].P = patch[10].position.xyz;

    OsdEvalPatchBezierTessLevels(
                bezcv, patchParam,
                tessLevelOuter, tessLevelInner,
                tessOuterLo, tessOuterHi);
#else
    OsdGetTessLevelsUniform(
                patchParam,
                tessLevelOuter, tessLevelInner,
                tessOuterLo, tessOuterHi);
#endif

    output.tessLevelOuter[0] = tessLevelOuter[0];
    output.tessLevelOuter[1] = tessLevelOuter[1];
    output.tessLevelOuter[2] = tessLevelOuter[2];
    output.tessLevelOuter[3] = tessLevelOuter[3];

    output.tessLevelInner[0] = tessLevelInner[0];
    output.tessLevelInner[1] = tessLevelInner[1];

    output.tessOuterLo = tessOuterLo;
    output.tessOuterHi = tessOuterHi;

    return output;
}

//----------------------------------------------------------
// Patches.DomainGregoryBasis
//----------------------------------------------------------

[domain("quad")]
void ds_main_patches(
    in HS_CONSTANT_FUNC_OUT input,
    in OutputPatch<OsdPerPatchVertexGregoryBasis, 20> patch,
    in float2 domainCoord : SV_DomainLocation,
    out OutputVertex output )
{
    float3 P = float3(0,0,0), dPu = float3(0,0,0), dPv = float3(0,0,0);
    float3 N = float3(0,0,0), dNu = float3(0,0,0), dNv = float3(0,0,0);

    float3 cv[20];
    for (int i = 0; i < 20; ++i) {
        cv[i] = patch[i].P;
    }

    float2 UV = OsdGetTessParameterization(domainCoord,
                                           input.tessOuterLo,
                                           input.tessOuterHi);

    int3 patchParam = patch[0].patchParam;
    OsdEvalPatchGregory(patchParam, UV, cv, P, dPu, dPv, N, dNu, dNv);

    // all code below here is client code
    output.position = mul(OsdModelViewMatrix(), float4(P, 1.0f));
    output.normal = mul(OsdModelViewMatrix(), float4(N, 0.0f)).xyz;
    output.tangent = mul(OsdModelViewMatrix(), float4(dPu, 0.0f)).xyz;
    output.bitangent = mul(OsdModelViewMatrix(), float4(dPv, 0.0f)).xyz;
#ifdef OSD_COMPUTE_NORMAL_DERIVATIVES
    output.Nu = dNu;
    output.Nv = dNv;
#endif
#if defined OSD_PATCH_ENABLE_SINGLE_CREASE
    output.vSegments = float2(0,0);
#endif

    output.patchCoord = OsdInterpolatePatchCoord(UV, patchParam);

    OSD_DISPLACEMENT_CALLBACK;

    output.positionOut = mul(OsdProjectionMatrix(), output.position);
    output.edgeDistance = 0;
}
