instancedBySchema.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.
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//
//     http://www.apache.org/licenses/LICENSE-2.0
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/* ************************************************************************** */
/* ** This file is generated by a script.  Do not edit directly.  Edit     ** */
/* ** defs.py or the (*)Schema.template.h files to make changes.           ** */
/* ************************************************************************** */

#ifndef PXR_IMAGING_HD_INSTANCED_BY_SCHEMA_H
#define PXR_IMAGING_HD_INSTANCED_BY_SCHEMA_H

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

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

PXR_NAMESPACE_OPEN_SCOPE

//-----------------------------------------------------------------------------

#define HDINSTANCEDBY_SCHEMA_TOKENS \
    (instancedBy) \
    (paths) \
    (prototypeRoots) \

TF_DECLARE_PUBLIC_TOKENS(HdInstancedBySchemaTokens, HD_API,
    HDINSTANCEDBY_SCHEMA_TOKENS);

//-----------------------------------------------------------------------------

// A schema marking a prim as instanced by another prim.
//
// Many renderers need to know not what prototypes an instancer has, but
// rather what instancers a prototype has; this is encoded in
// "instancedBy".  A prim is "instancedBy" /Instancer if /Instancer has
// a prototype path that's a parent of the prim.  A complicating exception is
// if /A instances /A/B, which instances /A/B/C, we don't consider /A to be
// instancing /A/B/C directly; this is to support nested explicit instancing
// of things like leaves/trees/forests.
//
// This value is computed based on the instancer topology of instancer prims in
// the scene.
//
// Note: if multiple instancers reference a prototype, it's possible for
// instancedBy to contain multiple entries.  Some renderers may be able to
// read this directly, but some may need to duplicate prims with an op so that
// each prim has a single instancer, depending on how the renderer exposes
// instancing.


class HdInstancedBySchema : public HdSchema
{
public:
    HdInstancedBySchema(HdContainerDataSourceHandle container)
    : HdSchema(container) {}

    //ACCESSORS

    HD_API
    HdPathArrayDataSourceHandle GetPaths();
    HD_API
    HdPathArrayDataSourceHandle GetPrototypeRoots();

    // RETRIEVING AND CONSTRUCTING

    /// Builds a container data source which includes the provided child data
    /// sources. Parameters with nullptr values are excluded. This is a
    /// low-level interface. For cases in which it's desired to define
    /// the container with a sparse set of child fields, the Builder class
    /// is often more convenient and readable.
    HD_API
    static HdContainerDataSourceHandle
    BuildRetained(
        const HdPathArrayDataSourceHandle &paths,
        const HdPathArrayDataSourceHandle &prototypeRoots
    );

    /// \class HdInstancedBySchema::Builder
    /// 
    /// Utility class for setting sparse sets of child data source fields to be
    /// filled as arguments into BuildRetained. Because all setter methods
    /// return a reference to the instance, this can be used in the "builder
    /// pattern" form.
    class Builder
    {
    public:
        HD_API
        Builder &SetPaths(
            const HdPathArrayDataSourceHandle &paths);
        HD_API
        Builder &SetPrototypeRoots(
            const HdPathArrayDataSourceHandle &prototypeRoots);

        /// Returns a container data source containing the members set thus far.
        HD_API
        HdContainerDataSourceHandle Build();

    private:
        HdPathArrayDataSourceHandle _paths;
        HdPathArrayDataSourceHandle _prototypeRoots;
    };

    /// Retrieves a container data source with the schema's default name token
    /// "instancedBy" from the parent container and constructs a
    /// HdInstancedBySchema instance.
    /// Because the requested container data source may not exist, the result
    /// should be checked with IsDefined() or a bool comparison before use.
    HD_API
    static HdInstancedBySchema GetFromParent(
        const HdContainerDataSourceHandle &fromParentContainer);

    /// Returns a token where the container representing this schema is found in
    /// a container by default.
    HD_API
    static const TfToken &GetSchemaToken();

    /// Returns an HdDataSourceLocator (relative to the prim-level data source)
    /// where the container representing this schema is found by default.
    HD_API
    static const HdDataSourceLocator &GetDefaultLocator();

};

PXR_NAMESPACE_CLOSE_SCOPE

#endif