particleFieldSphericalHarmonicsAttributeAPI.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 USDVOL_GENERATED_PARTICLEFIELDSPHERICALHARMONICSATTRIBUTEAPI_H
#define USDVOL_GENERATED_PARTICLEFIELDSPHERICALHARMONICSATTRIBUTEAPI_H

/// \file usdVol/particleFieldSphericalHarmonicsAttributeAPI.h

#include "pxr/pxr.h"
#include "pxr/usd/usdVol/api.h"
#include "pxr/usd/usd/apiSchemaBase.h"
#include "pxr/usd/usd/prim.h"
#include "pxr/usd/usd/stage.h"
#include "pxr/usd/usdVol/tokens.h"

#include "pxr/usd/usdVol/particleFieldRadianceBaseAPI.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;

// -------------------------------------------------------------------------- //
// PARTICLEFIELDSPHERICALHARMONICSATTRIBUTEAPI                                //
// -------------------------------------------------------------------------- //

/// \class UsdVolParticleFieldSphericalHarmonicsAttributeAPI
///
/// A ParticleField related applied schema that provides spherical
/// harmonics attributes to define the radiance of the particles.
/// 
/// The spherical harmonics degree is constant across all the particles
/// in the ParticleField.
/// 
/// Attributes are provided in both `float` and `half` types for some
/// easy data footprint affordance, data consumers should prefer
/// `float` version if available.
/// 
/// The length of this attribute is expected to match the length of
/// the provided position data times the per-particle element size
/// derived from the SH degree (specifically element size =
/// (degree+1)*(degree+1)). If it is too long it will be truncated
/// to the number of particles define by the position data. If it is
/// too short it will be ignored.
/// 
/// If it is ignored or not populated, the particle should use a SH
/// coefficient corresponding to a DC signal of (0.5, 0.5, 0.5),
/// with degree 0.
/// 
///
class UsdVolParticleFieldSphericalHarmonicsAttributeAPI : public UsdAPISchemaBase
{
public:
    /// Compile time constant representing what kind of schema this class is.
    ///
    /// \sa UsdSchemaKind
    static const UsdSchemaKind schemaKind = UsdSchemaKind::SingleApplyAPI;

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

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

    /// Destructor.
    USDVOL_API
    virtual ~UsdVolParticleFieldSphericalHarmonicsAttributeAPI();

    /// 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.
    USDVOL_API
    static const TfTokenVector &
    GetSchemaAttributeNames(bool includeInherited=true);

    /// Return a UsdVolParticleFieldSphericalHarmonicsAttributeAPI 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
    /// UsdVolParticleFieldSphericalHarmonicsAttributeAPI(stage->GetPrimAtPath(path));
    /// \endcode
    ///
    USDVOL_API
    static UsdVolParticleFieldSphericalHarmonicsAttributeAPI
    Get(const UsdStagePtr &stage, const SdfPath &path);


    /// Returns true if this <b>single-apply</b> API schema can be applied to 
    /// the given \p prim. If this schema can not be a applied to the prim, 
    /// this returns false and, if provided, populates \p whyNot with the 
    /// reason it can not be applied.
    /// 
    /// Note that if CanApply returns false, that does not necessarily imply
    /// that calling Apply will fail. Callers are expected to call CanApply
    /// before calling Apply if they want to ensure that it is valid to 
    /// apply a schema.
    /// 
    /// \sa UsdPrim::GetAppliedSchemas()
    /// \sa UsdPrim::HasAPI()
    /// \sa UsdPrim::CanApplyAPI()
    /// \sa UsdPrim::ApplyAPI()
    /// \sa UsdPrim::RemoveAPI()
    ///
    USDVOL_API
    static bool 
    CanApply(const UsdPrim &prim, std::string *whyNot=nullptr);

    /// Applies this <b>single-apply</b> API schema to the given \p prim.
    /// This information is stored by adding "ParticleFieldSphericalHarmonicsAttributeAPI" to the 
    /// token-valued, listOp metadata \em apiSchemas on the prim.
    /// 
    /// \return A valid UsdVolParticleFieldSphericalHarmonicsAttributeAPI object is returned upon success. 
    /// An invalid (or empty) UsdVolParticleFieldSphericalHarmonicsAttributeAPI object is returned upon 
    /// failure. See \ref UsdPrim::ApplyAPI() for conditions 
    /// resulting in failure. 
    /// 
    /// \sa UsdPrim::GetAppliedSchemas()
    /// \sa UsdPrim::HasAPI()
    /// \sa UsdPrim::CanApplyAPI()
    /// \sa UsdPrim::ApplyAPI()
    /// \sa UsdPrim::RemoveAPI()
    ///
    USDVOL_API
    static UsdVolParticleFieldSphericalHarmonicsAttributeAPI 
    Apply(const UsdPrim &prim);

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

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

    static bool _IsTypedSchema();

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

public:
    // --------------------------------------------------------------------- //
    // RADIANCESPHERICALHARMONICSDEGREE 
    // --------------------------------------------------------------------- //
    /// The highest degree of the spherical harmonics. A degree of N
    /// implies a coefficient element size (per particle) of (N+1)*(N+1) values.
    /// The spherical harmonics degree is the same for all particles in the
    /// ParticleField.
    ///
    /// | ||
    /// | -- | -- |
    /// | Declaration | `uniform int radiance:sphericalHarmonicsDegree = 3` |
    /// | C++ Type | int |
    /// | \ref Usd_Datatypes "Usd Type" | SdfValueTypeNames->Int |
    /// | \ref SdfVariability "Variability" | SdfVariabilityUniform |
    USDVOL_API
    UsdAttribute GetRadianceSphericalHarmonicsDegreeAttr() const;

    /// See GetRadianceSphericalHarmonicsDegreeAttr(), 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.
    USDVOL_API
    UsdAttribute CreateRadianceSphericalHarmonicsDegreeAttr(VtValue const &defaultValue = VtValue(), bool writeSparsely=false) const;

public:
    // --------------------------------------------------------------------- //
    // RADIANCESPHERICALHARMONICSCOEFFICIENTS 
    // --------------------------------------------------------------------- //
    /// Flattened array of SH coefficients.
    /// The SH coefficients are grouped in the array by particle, meaning each
    /// particle has N contiguous coefficients, Y(m,l) sorted first by order (m)
    /// and then within the order by index (l). A renderer can compute an
    /// element size per particle based on the SH degree, and use that to stripe
    /// the array by particle.
    ///
    /// | ||
    /// | -- | -- |
    /// | Declaration | `float3[] radiance:sphericalHarmonicsCoefficients` |
    /// | C++ Type | VtArray<GfVec3f> |
    /// | \ref Usd_Datatypes "Usd Type" | SdfValueTypeNames->Float3Array |
    USDVOL_API
    UsdAttribute GetRadianceSphericalHarmonicsCoefficientsAttr() const;

    /// See GetRadianceSphericalHarmonicsCoefficientsAttr(), 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.
    USDVOL_API
    UsdAttribute CreateRadianceSphericalHarmonicsCoefficientsAttr(VtValue const &defaultValue = VtValue(), bool writeSparsely=false) const;

public:
    // --------------------------------------------------------------------- //
    // RADIANCESPHERICALHARMONICSCOEFFICIENTSH 
    // --------------------------------------------------------------------- //
    /// Flattened array of SH coefficients.
    /// The SH coefficients are grouped in the array by particle, meaning each
    /// particle has N contiguous coefficients, Y(m,l) sorted first by order (m)
    /// and then within the order by index (l). A renderer can compute an
    /// element size per particle based on the SH degree, and use that to stripe
    /// the array by particle.
    /// 
    /// If the float precision version is available it should be preferred.
    ///
    /// | ||
    /// | -- | -- |
    /// | Declaration | `half3[] radiance:sphericalHarmonicsCoefficientsh` |
    /// | C++ Type | VtArray<GfVec3h> |
    /// | \ref Usd_Datatypes "Usd Type" | SdfValueTypeNames->Half3Array |
    USDVOL_API
    UsdAttribute GetRadianceSphericalHarmonicsCoefficientshAttr() const;

    /// See GetRadianceSphericalHarmonicsCoefficientshAttr(), 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.
    USDVOL_API
    UsdAttribute CreateRadianceSphericalHarmonicsCoefficientshAttr(VtValue const &defaultValue = VtValue(), bool writeSparsely=false) const;

public:
    /// \name ParticleFieldRadianceBaseAPI
    /// 
    /// Convenience accessors for the built-in UsdVolParticleFieldRadianceBaseAPI
    /// 
    /// @{

    /// Constructs and returns a UsdVolParticleFieldRadianceBaseAPI object.
    /// Use this object to access UsdVolParticleFieldRadianceBaseAPI custom methods.
    USDVOL_API
    UsdVolParticleFieldRadianceBaseAPI ParticleFieldRadianceBaseAPI() 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)--
};

PXR_NAMESPACE_CLOSE_SCOPE

#endif