Method AddFieldReaderParam

Hydrogent/src/HnMaterialNetwork.cpp:1194–1237

}

void HnMaterialNetwork::AddFieldReaderParam(const pxr::HdMaterialNetwork2& Network,
                                            const pxr::HdMaterialNode2&    Node,
                                            const pxr::SdfPath&            NodePath,
                                            const pxr::TfToken&            ParamName,
                                            pxr::SdfPathSet&               VisitedNodes)
{
    if (!VisitedNodes.emplace(NodePath).second)
        return;

    // Volume Fields act more like a primvar then a texture.
    // There is a `Volume` prim with 'fields' that may point to a
    // OpenVDB file. We have to find the 'inputs:fieldname' on the
    // HWFieldReader in the material network to know what 'field' to use.
    // See also HdStVolume and HdStField for how volume textures are
    // inserted into Storm.

    HnMaterialParameter Param{HnMaterialParameter::ParamType::FieldRedirect, ParamName};

    // XXX Why HnMaterialPrivateTokens->fieldname:
    // Hard-coding the name of the attribute of HwFieldReader identifying
    // the field name for now.
    // The equivalent of the generic mechanism Sdr provides for primvars
    // is missing for fields: UsdPrimvarReader.inputs:varname is tagged with
    // SdrMetadata as primvarProperty="1" so that we can use
    // SdrNode->GetAdditionalPrimvarProperties to know what attribute to use.
    const pxr::TfToken& VarName = HnMaterialPrivateTokens->fieldname;

    auto const& param_it = Node.parameters.find(VarName);
    if (param_it != Node.parameters.end())
    {
        pxr::VtValue FieldName = param_it->second;
        if (FieldName.IsHolding<pxr::TfToken>())
        {
            // Stashing name of field in _samplerCoords.
            Param.SamplerCoords.push_back(FieldName.UncheckedGet<pxr::TfToken>());
        }
        else if (FieldName.IsHolding<std::string>())
        {
            Param.SamplerCoords.push_back(pxr::TfToken{FieldName.UncheckedGet<std::string>()});
        }
    }

    m_Parameters.emplace_back(std::move(Param));
}

void HnMaterialNetwork::AddTransform2dParam(const pxr::HdMaterialNetwork2& Network,
                                            const pxr::HdMaterialNode2&    Node,