C++ UsdRelationship::GetForwardedTargets方法代码示例

UsdVolVolume::FieldMap
UsdVolVolume::GetFieldPaths() const
{
    std::map<TfToken, SdfPath> fieldMap;
    const UsdPrim &prim = GetPrim();

    if (prim) {
        std::vector<UsdProperty> fieldProps =
            prim.GetPropertiesInNamespace(_tokens->fieldPrefix);
        for (const UsdProperty &fieldProp : fieldProps) {
            UsdRelationship fieldRel = fieldProp.As<UsdRelationship>();
            SdfPathVector targets;

            // All relationships starting with "field:" should point to
            // UsdVolFieldBase primitives.
            if (fieldRel && fieldRel.GetForwardedTargets(&targets)) {
                if (targets.size() == 1 && 
                    targets.front().IsPrimPath()) {
                    fieldMap.emplace(fieldRel.GetBaseName(), targets.front());
                }
            }
        }
    }

    return fieldMap;
}

static SdfPathVector
_GetForwardedTargets(const UsdRelationship &self,
                     bool forwardToObjectsInMasters)
{
    SdfPathVector result;
    self.GetForwardedTargets(&result, forwardToObjectsInMasters);
    return result;
}

bool
UsdRiStatementsAPI::GetModelScopedCoordinateSystems(SdfPathVector *targets) const
{
    if (GetPrim().IsModel()) {
        UsdRelationship rel =
            GetPrim().GetRelationship(_tokens->modelScopedCoordsys);
        return rel && rel.GetForwardedTargets(targets);
    }

    return true;
}

SdfPath
UsdVolVolume::GetFieldPath(const TfToken &name) const
{
    UsdRelationship fieldRel =  GetPrim().GetRelationship(_MakeNamespaced(name));
    SdfPathVector targets;
    
    if (fieldRel && fieldRel.GetForwardedTargets(&targets)) {
        if (targets.size() == 1 && 
            targets.front().IsPrimPath()) {
            return targets.front();
        }
    }

    return SdfPath::EmptyPath();
}

PXR_NAMESPACE_OPEN_SCOPE


// TODO: We should centralize this logic in a UsdImaging ShaderAdapter.

/*static*/
UsdPrim
UsdImaging_MaterialStrategy::GetTargetedShader(UsdPrim const& materialPrim,
                                        UsdRelationship const& materialRel)
{
    SdfPathVector targets;
    if (!materialRel.GetForwardedTargets(&targets))
        return UsdPrim();

    if (targets.size() != 1) {
        // XXX: This should really be a validation error once USD gets that
        // feature.
        TF_WARN("We expect only one target on relationship %s of prim <%s>, "
                "but got %zu.",
                materialRel.GetName().GetText(),
                materialPrim.GetPath().GetText(),
                targets.size());
        return UsdPrim();
    }

    if (!targets[0].IsPrimPath()) {
        // XXX: This should really be a validation error once USD gets that
        // feature.
        TF_WARN("We expect the target of the relationship %s of prim <%s> "
                "to be a prim, instead it is <%s>.",
                materialRel.GetName().GetText(),
                materialPrim.GetPath().GetText(),
                targets[0].GetText());
        return UsdPrim();
    }

    return materialPrim.GetStage()->GetPrimAtPath(targets[0]);
}

//.........这里部分代码省略.........
        else
        {
            _PathToPrimMap::const_iterator pcIt = primCache.find(protoPath);
            const UsdPrim &protoPrim = pcIt->second;
            if (!protoPrim) {
                continue;
            }

            // Determine where (what path) to start building the prototype prim
            // such that its material bindings will be preserved. This could be
            // the prototype path itself or an ancestor path.
            //
            SdfPathVector commonPrefixes;

            UsdRelationship materialBindingsRel =
                    UsdShadeMaterial::GetBindingRel(protoPrim);

            auto assetAPI = UsdModelAPI(protoPrim);
            std::string assetName;
            bool isReferencedModelPrim =
                    assetAPI.IsModel() and assetAPI.GetAssetName(&assetName);

            if (!materialBindingsRel or isReferencedModelPrim)
            {
                // The prim has no material bindings or is a referenced model
                // prim (meaning that materials are defined below it); start
                // building at the prototype path.
                //
                commonPrefixes.push_back(protoPath);
            }
            else
            {
                SdfPathVector materialPaths;
                materialBindingsRel.GetForwardedTargets(&materialPaths);
                for (auto materialPath : materialPaths)
                {
                    const SdfPath &commonPrefix =
                            protoPath.GetCommonPrefix(materialPath);
                    if (commonPrefix.GetString() == "/")
                    {
                        // XXX Unhandled case.
                        // The prototype prim and its material are not under the
                        // same parent; start building at the prototype path
                        // (although it is likely that bindings will be broken).
                        //
                        commonPrefixes.push_back(protoPath);
                    }
                    else
                    {
                        // Start building at the common ancestor between the
                        // prototype prim and its material.
                        //
                        commonPrefixes.push_back(commonPrefix);
                    }
                }
            }

            // XXX Unhandled case.
            // We'll use the first common ancestor even if there is more than
            // one (which shouldn't appen if the prototype prim and its bindings
            // are under the same parent).
            //
            SdfPath::RemoveDescendentPaths(&commonPrefixes);
            const std::string buildPath = commonPrefixes[0].GetString();

            // See if the path is a child of the point instancer. If so, we'll

static FnKat::Attribute
_GetMaterialAssignAttr(
        const UsdPrim& prim,
        const PxrUsdKatanaUsdInPrivateData& data)
{
    if (not prim or prim.GetPath() == SdfPath::AbsoluteRootPath()) {
        // Special-case to pre-empt coding errors.
        return FnKat::Attribute();
    }

    UsdRelationship usdRel = UsdShadeLook::GetBindingRel(prim);
    if (usdRel) {
        // USD shading binding
        SdfPathVector targetPaths;
        usdRel.GetForwardedTargets(&targetPaths);
        if (targetPaths.size() > 0) {
            if (not targetPaths[0].IsPrimPath()) {
                FnLogWarn("Target path " << prim.GetPath().GetString() <<
                          " is not a prim");
                return FnKat::Attribute();
            }

            // This is a copy as it could be modified below.
            SdfPath targetPath = targetPaths[0];
            UsdPrim targetPrim = data.GetUsdInArgs()->GetStage()->GetPrimAtPath(targetPath);
            // If the target is inside a master, then it needs to be re-targeted 
            // to the instance.
            // 
            // XXX remove this special awareness once GetMasterWithContext is
            //     is available as the provided prim will automatically
            //     retarget (or provide enough context to retarget without
            //     tracking manually).
            if (targetPrim and targetPrim.IsInMaster()) {
                if (not data.GetInstancePath().IsEmpty() and 
                        not data.GetMasterPath().IsEmpty()) {

                    // Check if the source and the target of the relationship 
                    // belong to the same master.
                    // If they do, we have the context necessary to do the 
                    // re-mapping.
                    if (data.GetMasterPath().GetCommonPrefix(targetPath).
                            GetPathElementCount() > 0) {
                        targetPath = data.GetInstancePath().AppendPath(
                            targetPath.ReplacePrefix(targetPath.GetPrefixes()[0],
                                SdfPath::ReflexiveRelativePath()));
                    } else {
                        // Warn saying the target of relationship isn't within 
                        // the same master as the source.
                        FnLogWarn("Target path " << prim.GetPath().GetString() 
                            << " isn't within the master " << data.GetMasterPath());
                        return FnKat::Attribute();
                    }
                } else {
                    // XXX
                    // When loading beneath a master via an isolatePath
                    // opArg, we can encounter targets which are within masters
                    // but not within the context of a material.
                    // While that would be an error according to the below
                    // warning, it produces the expected results.
                    // This case can occur when expanding pointinstancers as
                    // the sources are made via execution of PxrUsdIn again
                    // at the sub-trees.
                    
                    
                    // Warn saying target of relationship is in a master, 
                    // but the associated instance path is unknown!
                    // FnLogWarn("Target path " << prim.GetPath().GetString() 
                    //         << " is within a master, but the associated "
                    //         "instancePath is unknown.");
                    // return FnKat::Attribute();
                }
            }

            // Convert the target path to the equivalent katana location.
            // XXX: Looks may have an atypical USD->Katana 
            // path mapping
            std::string location =
                PxrUsdKatanaUtils::ConvertUsdLookPathToKatLocation(targetPath, data);
                
            // XXX Looks containing only display terminals are causing issues
            //     with katana material manipulation workflows.
            //     For now: exclude any material assign which doesn't include
            //     /Looks/ in the path
            if (location.find(UsdKatanaTokens->katanaLooksScopePathSubstring)
                    == std::string::npos)
            {
                return FnKat::Attribute();
            }
                
                
            // location = TfStringReplace(location, "/Looks/", "/Materials/");
            // XXX handle multiple assignments
            return FnKat::StringAttribute(location);
        }
    }

    return FnKat::Attribute();
}