boundable.h

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//
// Copyright 2016 Pixar
//
// Licensed under the terms set forth in the LICENSE.txt file available at
// https://openusd.org/license.
//
#ifndef USDGEOM_GENERATED_BOUNDABLE_H
#define USDGEOM_GENERATED_BOUNDABLE_H

/// \file usdGeom/boundable.h

#include "pxr/pxr.h"
#include "pxr/usd/usdGeom/api.h"
#include "pxr/usd/usdGeom/xformable.h"
#include "pxr/usd/usd/prim.h"
#include "pxr/usd/usd/stage.h"
#include "pxr/usd/usdGeom/tokens.h"

#include "pxr/base/vt/value.h"

#include "pxr/base/gf/vec3d.h"
#include "pxr/base/gf/vec3f.h"
#include "pxr/base/gf/matrix4d.h"

#include "pxr/base/tf/token.h"
#include "pxr/base/tf/type.h"

PXR_NAMESPACE_OPEN_SCOPE

class SdfAssetPath;

// -------------------------------------------------------------------------- //
// BOUNDABLE                                                                  //
// -------------------------------------------------------------------------- //

/// \class UsdGeomBoundable
///
/// Boundable introduces the ability for a prim to persistently
/// cache a rectilinear, local-space, extent.
/// 
/// \section UsdGeom_Boundable_Extent Why Extent and not Bounds ?
/// Boundable introduces the notion of "extent", which is a cached computation
/// of a prim's local-space 3D range for its resolved attributes <b>at the
/// layer and time in which extent is authored</b>.  We have found that with
/// composed scene description, attempting to cache pre-computed bounds at
/// interior prims in a scene graph is very fragile, given the ease with which
/// one can author a single attribute in a stronger layer that can invalidate
/// many authored caches - or with which a re-published, referenced asset can
/// do the same.
/// 
/// Therefore, we limit to precomputing (generally) leaf-prim extent, which
/// avoids the need to read in large point arrays to compute bounds, and
/// provides UsdGeomBBoxCache the means to efficiently compute and
/// (session-only) cache intermediate bounds.  You are free to compute and
/// author intermediate bounds into your scenes, of course, which may work
/// well if you have sufficient locks on your pipeline to guarantee that once
/// authored, the geometry and transforms upon which they are based will
/// remain unchanged, or if accuracy of the bounds is not an ironclad
/// requisite. 
/// 
/// When intermediate bounds are authored on Boundable parents, the child prims
/// will be pruned from BBox computation; the authored extent is expected to
/// incorporate all child bounds.
///
class UsdGeomBoundable : public UsdGeomXformable
{
public:
    /// Compile time constant representing what kind of schema this class is.
    ///
    /// \sa UsdSchemaKind
    static const UsdSchemaKind schemaKind = UsdSchemaKind::AbstractTyped;

    /// Construct a UsdGeomBoundable on UsdPrim \p prim .
    /// Equivalent to UsdGeomBoundable::Get(prim.GetStage(), prim.GetPath())
    /// for a \em valid \p prim, but will not immediately throw an error for
    /// an invalid \p prim
    explicit UsdGeomBoundable(const UsdPrim& prim=UsdPrim())
        : UsdGeomXformable(prim)
    {
    }

    /// Construct a UsdGeomBoundable on the prim held by \p schemaObj .
    /// Should be preferred over UsdGeomBoundable(schemaObj.GetPrim()),
    /// as it preserves SchemaBase state.
    explicit UsdGeomBoundable(const UsdSchemaBase& schemaObj)
        : UsdGeomXformable(schemaObj)
    {
    }

    /// Destructor.
    USDGEOM_API
    virtual ~UsdGeomBoundable();

    /// Return a vector of names of all pre-declared attributes for this schema
    /// class and all its ancestor classes.  Does not include attributes that
    /// may be authored by custom/extended methods of the schemas involved.
    USDGEOM_API
    static const TfTokenVector &
    GetSchemaAttributeNames(bool includeInherited=true);

    /// Return a UsdGeomBoundable holding the prim adhering to this
    /// schema at \p path on \p stage.  If no prim exists at \p path on
    /// \p stage, or if the prim at that path does not adhere to this schema,
    /// return an invalid schema object.  This is shorthand for the following:
    ///
    /// \code
    /// UsdGeomBoundable(stage->GetPrimAtPath(path));
    /// \endcode
    ///
    USDGEOM_API
    static UsdGeomBoundable
    Get(const UsdStagePtr &stage, const SdfPath &path);


protected:
    /// Returns the kind of schema this class belongs to.
    ///
    /// \sa UsdSchemaKind
    USDGEOM_API
    UsdSchemaKind _GetSchemaKind() const override;

private:
    // needs to invoke _GetStaticTfType.
    friend class UsdSchemaRegistry;
    USDGEOM_API
    static const TfType &_GetStaticTfType();

    static bool _IsTypedSchema();

    // override SchemaBase virtuals.
    USDGEOM_API
    const TfType &_GetTfType() const override;

public:
    // --------------------------------------------------------------------- //
    // EXTENT 
    // --------------------------------------------------------------------- //
    /// Extent is a three dimensional range measuring the geometric
    /// extent of the authored gprim in its own local space (i.e. its own
    /// transform not applied), \em without accounting for any shader-induced
    /// displacement. If __any__ extent value has been authored for a given 
    /// Boundable, then it should be authored at every timeSample at which 
    /// geometry-affecting properties are authored, to ensure correct 
    /// evaluation via ComputeExtent(). If __no__ extent value has been 
    /// authored, then ComputeExtent() will call the Boundable's registered 
    /// ComputeExtentFunction(), which may be expensive, which is why we 
    /// strongly encourage proper authoring of extent.
    /// \sa ComputeExtent()
    /// \sa \ref UsdGeom_Boundable_Extent.
    /// 
    /// An authored extent on a prim which has children is expected to include
    /// the extent of all children, as they will be pruned from BBox computation
    /// during traversal.
    ///
    /// | ||
    /// | -- | -- |
    /// | Declaration | `float3[] extent` |
    /// | C++ Type | VtArray<GfVec3f> |
    /// | \ref Usd_Datatypes "Usd Type" | SdfValueTypeNames->Float3Array |
    USDGEOM_API
    UsdAttribute GetExtentAttr() const;

    /// See GetExtentAttr(), and also 
    /// \ref Usd_Create_Or_Get_Property for when to use Get vs Create.
    /// If specified, author \p defaultValue as the attribute's default,
    /// sparsely (when it makes sense to do so) if \p writeSparsely is \c true -
    /// the default for \p writeSparsely is \c false.
    USDGEOM_API
    UsdAttribute CreateExtentAttr(VtValue const &defaultValue = VtValue(), bool writeSparsely=false) const;

public:
    // ===================================================================== //
    // Feel free to add custom code below this line, it will be preserved by 
    // the code generator. 
    //
    // Just remember to: 
    //  - Close the class declaration with }; 
    //  - Close the namespace with PXR_NAMESPACE_CLOSE_SCOPE
    //  - Close the include guard with #endif
    // ===================================================================== //
    // --(BEGIN CUSTOM CODE)--
    
    /// If an extent is authored on this boundable, it queries the \p extent 
    /// from the extent attribute, otherwise if ComputeExtentFunction is 
    /// registered for the boundable's type, it computes the \p extent at 
    /// \p time. Returns true when extent is successfully populated, false 
    /// otherwise.
    ///
    /// \sa ComputeExtentFromPlugins
    /// \sa UsdGeomRegisterComputeExtentFunction
    USDGEOM_API
    bool ComputeExtent(const UsdTimeCode &time, VtVec3fArray *extent) const;
    
    /// Compute the extent for the Boundable prim \p boundable at time
    /// \p time.  If successful, populates \p extent with the result and
    /// returns \c true, otherwise returns \c false.
    ///
    /// The extent computation is based on the concrete type of the prim
    /// represented by \p boundable.  Plugins that provide a Boundable
    /// prim type may implement and register an extent computation for that
    /// type using #UsdGeomRegisterComputeExtentFunction.
    /// ComputeExtentFromPlugins will use this function to compute extents
    /// for all prims of that type.  If no function has been registered for
    /// a prim type, but a function has been registered for one of its 
    /// base types, that function will be used instead.
    ///
    /// \note This function may load plugins in order to access the extent
    /// computation for a prim type.
    USDGEOM_API
    static bool ComputeExtentFromPlugins(const UsdGeomBoundable &boundable,
                                         const UsdTimeCode &time,
                                         VtVec3fArray *extent);

    /// \overload
    /// Computes the extent as if the matrix \p transform was first applied.
    USDGEOM_API
    static bool ComputeExtentFromPlugins(const UsdGeomBoundable &boundable,
                                         const UsdTimeCode &time,
                                         const GfMatrix4d &transform,
                                         VtVec3fArray *extent);

};

PXR_NAMESPACE_CLOSE_SCOPE

#endif