flattenedDataSourceProvider.h

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//
// Copyright 2023 Pixar
//
// Licensed under the Apache License, Version 2.0 (the "Apache License")
// with the following modification; you may not use this file except in
// compliance with the Apache License and the following modification to it:
// Section 6. Trademarks. is deleted and replaced with:
//
// 6. Trademarks. This License does not grant permission to use the trade
//    names, trademarks, service marks, or product names of the Licensor
//    and its affiliates, except as required to comply with Section 4(c) of
//    the License and to reproduce the content of the NOTICE file.
//
// You may obtain a copy of the Apache License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the Apache License with the above modification is
// distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied. See the Apache License for the specific
// language governing permissions and limitations under the Apache License.
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#ifndef PXR_IMAGING_HD_FLATTENED_DATA_SOURCE_PROVIDER_H
#define PXR_IMAGING_HD_FLATTENED_DATA_SOURCE_PROVIDER_H

#include "pxr/imaging/hd/api.h"

#include "pxr/imaging/hd/dataSource.h"
#include "pxr/imaging/hd/retainedDataSource.h"
#include "pxr/usd/sdf/path.h"

PXR_NAMESPACE_OPEN_SCOPE

class HdSceneIndexBase;
using HdFlattenedDataSourceProviderSharedPtr =
    std::shared_ptr<class HdFlattenedDataSourceProvider>;

/// \class HdFlattenedDataSourceProvider.
///
/// Given to HdFlatteningSceneIndex to determine how to compute the
/// flattened data source which is in the prim container data
/// source.
///
class HdFlattenedDataSourceProvider
{
public:
    class Context
    {
    public:
        Context(
            const HdSceneIndexBase &flatteningSceneIndex,
            const SdfPath &primPath,
            const TfToken &name,
            const HdContainerDataSourceHandle &inputPrimDataSource)
          : _flatteningSceneIndex(flatteningSceneIndex)
          , _primPath(primPath)
          , _name(name)
          , _inputPrimDataSource(inputPrimDataSource)
        {
        }

        // Returns data source of input scene index which is in
        // the prim container data source.
        HD_API
        HdContainerDataSourceHandle GetInputDataSource() const;
        // Returns flattened data source which is in the flattened
        // container data source of the parent prim.
        HD_API
        HdContainerDataSourceHandle GetFlattenedDataSourceFromParentPrim() const;

    private:
        const HdSceneIndexBase &_flatteningSceneIndex;
        const SdfPath &_primPath;
        const TfToken &_name;
        const HdContainerDataSourceHandle &_inputPrimDataSource;
    };

    /// Returns flattened data source.
    virtual HdContainerDataSourceHandle GetFlattenedDataSource(
        const Context &ctx) const = 0;

    /// If data source locators are dirtied in the input scene index, the
    /// locators relevant for the input data source serving this provider
    /// are extracted and made relative to the input data source.
    ///
    /// They are later used to invalidate the flattened data source of the
    /// dirtied prim and its descendants and send prim dirtied messages to
    /// the descendants.
    ///
    /// Example: If a prim dirtied for locator xform:matrix was received, the
    /// flattening scene index will call the flattened data source provider
    /// for xform. The locators given to ComputeDirtyLocatorsForDescendants
    /// will be { matrix }. If ComputeDirtyLocatorsForDescendants sets it to
    /// the universal set, the flatening scene index will emit a prim dirtied
    /// locator xform for the descendants.
    ///
    /// The implementation of ComputeDirtyLocatorsForDescendants gives a chance
    /// to drop locators or expand the locator set in between.
    ///
    /// Note that ComputeDirtyLocatorsForDescendants will never be called with
    /// the empty or universal set as these cases are already handled by the
    /// callee.
    ///
    virtual void ComputeDirtyLocatorsForDescendants(
        HdDataSourceLocatorSet * locators) const = 0;
};

namespace HdMakeDataSourceContainingFlattenedDataSourceProvider
{

template<typename T>
HdTypedSampledDataSource<HdFlattenedDataSourceProviderSharedPtr>::Handle
Make()
{
    using DataSource =
        HdRetainedTypedSampledDataSource<HdFlattenedDataSourceProviderSharedPtr>;
    return DataSource::New(std::make_shared<T>());
}

}

PXR_NAMESPACE_CLOSE_SCOPE

#endif