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#include <xformable.h>
Inheritance diagram for UsdGeomXformable:Classes | |
| class | XformQuery |
Static Public Member Functions | |
| static USDGEOM_API const TfTokenVector & | GetSchemaAttributeNames (bool includeInherited=true) |
| static USDGEOM_API UsdGeomXformable | Get (const UsdStagePtr &stage, const SdfPath &path) |
| static USDGEOM_API bool | GetTimeSamples (std::vector< UsdGeomXformOp > const &orderedXformOps, std::vector< double > *times) |
| static USDGEOM_API bool | GetTimeSamplesInInterval (std::vector< UsdGeomXformOp > const &orderedXformOps, const GfInterval &interval, std::vector< double > *times) |
| static USDGEOM_API bool | GetLocalTransformation (GfMatrix4d *transform, std::vector< UsdGeomXformOp > const &ops, const UsdTimeCode time) |
| static USDGEOM_API bool | IsTransformationAffectedByAttrNamed (const TfToken &attrName) |
| Static Public Member Functions inherited from UsdGeomImageable | |
| static USDGEOM_API const TfTokenVector & | GetSchemaAttributeNames (bool includeInherited=true) |
| static USDGEOM_API UsdGeomImageable | Get (const UsdStagePtr &stage, const SdfPath &path) |
| static USDGEOM_API const TfTokenVector & | GetOrderedPurposeTokens () |
| Static Public Member Functions inherited from UsdTyped | |
| static USD_API const TfTokenVector & | GetSchemaAttributeNames (bool includeInherited=true) |
| static USD_API UsdTyped | Get (const UsdStagePtr &stage, const SdfPath &path) |
| Static Public Member Functions inherited from UsdSchemaBase | |
| static const TfTokenVector & | GetSchemaAttributeNames (bool includeInherited=true) |
Static Public Attributes | |
| static const UsdSchemaKind | schemaKind = UsdSchemaKind::AbstractTyped |
| Static Public Attributes inherited from UsdGeomImageable | |
| static const UsdSchemaKind | schemaKind = UsdSchemaKind::AbstractTyped |
| Static Public Attributes inherited from UsdTyped | |
| static const UsdSchemaKind | schemaKind = UsdSchemaKind::AbstractBase |
| Static Public Attributes inherited from UsdSchemaBase | |
| static const UsdSchemaKind | schemaKind = UsdSchemaKind::AbstractBase |
Protected Member Functions | |
| USDGEOM_API UsdSchemaKind | _GetSchemaKind () const override |
| Protected Member Functions inherited from UsdTyped | |
| USD_API bool | _IsCompatible () const override |
| Protected Member Functions inherited from UsdSchemaBase | |
| virtual UsdSchemaKind | _GetSchemaType () const |
| const TfType & | _GetType () const |
| USD_API UsdAttribute | _CreateAttr (TfToken const &attrName, SdfValueTypeName const &typeName, bool custom, SdfVariability variability, VtValue const &defaultValue, bool writeSparsely) const |
Friends | |
| class | UsdSchemaRegistry |
Base class for all transformable prims, which allows arbitrary sequences of component affine transformations to be encoded.
Supported Component Transformation Operations
UsdGeomXformable currently supports arbitrary sequences of the following operations, each of which can be encoded in an attribute of the proper shape in any supported precision:
Creating a Component Transformation
To add components to a UsdGeomXformable prim, simply call AddXformOp() with the desired op type, as enumerated in UsdGeomXformOp::Type, and the desired precision, which is one of UsdGeomXformOp::Precision. Optionally, you can also provide an "op suffix" for the operator that disambiguates it from other components of the same type on the same prim. Application-specific transform schemas can use the suffixes to fill a role similar to that played by AbcGeom::XformOp's "Hint" enums for their own round-tripping logic.
We also provide specific "Add" API for each type, for clarity and conciseness, e.g. AddTranslateOp(), AddRotateXYZOp() etc.
AddXformOp() will return a UsdGeomXformOp object, which is a schema on a newly created UsdAttribute that provides convenience API for authoring and computing the component transformations. The UsdGeomXformOp can then be used to author any number of timesamples and default for the op.
Each successive call to AddXformOp() adds an operator that will be applied "more locally" than the preceding operator, just as if we were pushing transforms onto a transformation stack - which is precisely what should happen when the operators are consumed by a reader.
Data Encoding and Op Ordering
Because there is no "fixed schema" of operations, all of the attributes that encode transform operations are dynamic, and are scoped in the namespace "xformOp". The second component of an attribute's name provides the type of operation, as listed above. An "xformOp" attribute can have additional namespace components derived from the opSuffix argument to the AddXformOp() suite of methods, which provides a preferred way of naming the ops such that we can have multiple "translate" ops with unique attribute names. For example, in the attribute named "xformOp:translate:maya:pivot", "translate" is the type of operation and "maya:pivot" is the suffix.
The following ordered list of attribute declarations in usda define a basic Scale-Rotate-Translate with XYZ Euler angles, wherein the translation is double-precision, and the remainder of the ops are single, in which we will:
The attributes appear in the dictionary order in which USD, by default, sorts them. To ensure the ops are recovered and evaluated in the correct order, the schema introduces the xformOpOrder attribute, which contains the names of the op attributes, in the precise sequence in which they should be pushed onto a transform stack. Note that the order is opposite to what you might expect, given the matrix algebra described in UsdGeom_LinAlgBasics. This also dictates order of op creation, since each call to AddXformOp() adds a new op to the end of the xformOpOrder array, as a new "most-local" operation. See Example 2 below for C++ code that could have produced this USD.
If it were important for the prim's rotations to be independently overridable, we could equivalently (at some performance cost) encode the transformation also like so:
Again, note that although we are encoding an XYZ rotation, the three rotations appear in the xformOpOrder in the opposite order, with Z, followed, by Y, followed by X.
Were we to add a Maya-style scalePivot to the above example, it might look like the following:
Paired "Inverted" Ops
We have been claiming that the ordered list of ops serves as a set of instructions to a transform stack, but you may have noticed in the last example that there is a missing operation - the pivot for the scale op needs to be applied in its inverse-form as a final (most local) op! In the AbcGeom::Xform schema, we would have encoded an actual "final" translation op whose value was authored by the exporter as the negation of the pivot's value. However, doing so would be brittle in USD, given that each op can be independently overridden, and the constraint that one attribute must be maintained as the negation of the other in order for successful re-importation of the schema cannot be expressed in USD.
Our solution leverages the xformOpOrder member of the schema, which, in addition to ordering the ops, may also contain one of two special tokens that address the paired op and "stack resetting" behavior.
The "paired op" behavior is encoded as an "!invert!" prefix in xformOpOrder, as the result of an AddXformOp(isInverseOp=True) call. The xformOpOrder for the last example would look like:
When asked for its value via UsdGeomXformOp::GetOpTransform(), an "inverted" Op (i.e. the "inverted" half of a set of paired Ops) will fetch the value of its paired attribute and return its negation. This works for all op types - an error will be issued if a "transform" type op is singular and cannot be inverted. When getting the authored value of an inverted op via UsdGeomXformOp::Get(), the raw, uninverted value of the associated attribute is returned.
For the sake of robustness, setting a value on an inverted op is disallowed. Attempting to set a value on an inverted op will result in a coding error and no value being set.
Resetting the Transform Stack
The other special op/token that can appear in xformOpOrder is "!resetXformStack!", which, appearing as the first element of xformOpOrder, indicates this prim should not inherit the transformation of its namespace parent. See SetResetXformStack()
Expected Behavior for "Missing" Ops
If an importer expects Scale-Rotate-Translate operations, but a prim has only translate and rotate ops authored, the importer should assume an identity scale. This allows us to optimize the data a bit, if only a few components of a very rich schema (like Maya's) are authored in the app.
#1. Creating a simple transform matrix encoding
#2. Creating the simple SRT from the example above
#3. Creating a parameterized SRT with pivot using UsdGeomXformCommonAPI
#4. Creating a rotate-only pivot transform with animated rotation and translation
Definition at line 252 of file xformable.h.
Construct a UsdGeomXformable on UsdPrim prim . Equivalent to UsdGeomXformable::Get(prim.GetStage(), prim.GetPath()) for a valid prim, but will not immediately throw an error for an invalid prim
Definition at line 264 of file xformable.h.
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Construct a UsdGeomXformable on the prim held by schemaObj . Should be preferred over UsdGeomXformable(schemaObj.GetPrim()), as it preserves SchemaBase state.
Definition at line 272 of file xformable.h.
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Destructor.
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Returns the kind of schema this class belongs to.
Reimplemented from UsdGeomImageable.
Reimplemented in UsdMediaSpatialAudio, UsdLuxLightFilter, UsdProcGenerativeProcedural, UsdVolVolume, UsdLuxPluginLight, UsdLuxPluginLightFilter, UsdSkelRoot, UsdSkelSkeleton, UsdVolField3DAsset, UsdVolOpenVDBAsset, UsdLuxRectLight, UsdLuxCylinderLight, UsdLuxGeometryLight, UsdLuxPortalLight, UsdLuxDiskLight, UsdLuxDistantLight, UsdLuxSphereLight, UsdVolFieldAsset, UsdLuxBoundableLightBase, UsdLuxNonboundableLightBase, and UsdVolFieldBase.
| USDGEOM_API UsdGeomXformOp UsdGeomXformable::AddOrientOp | ( | UsdGeomXformOp::Precision const | precision = UsdGeomXformOp::PrecisionFloat, |
| TfToken const & | opSuffix = TfToken(), |
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| bool | isInverseOp = false |
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| ) | const |
Add a orient op (arbitrary axis/angle rotation) to the local stack represented by this xformable.
| USDGEOM_API UsdGeomXformOp UsdGeomXformable::AddRotateXOp | ( | UsdGeomXformOp::Precision const | precision = UsdGeomXformOp::PrecisionFloat, |
| TfToken const & | opSuffix = TfToken(), |
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| bool | isInverseOp = false |
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| ) | const |
Add a rotation about the X-axis to the local stack represented by this xformable.
Set the angle value of the resulting UsdGeomXformOp in degrees
| USDGEOM_API UsdGeomXformOp UsdGeomXformable::AddRotateXYZOp | ( | UsdGeomXformOp::Precision const | precision = UsdGeomXformOp::PrecisionFloat, |
| TfToken const & | opSuffix = TfToken(), |
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| bool | isInverseOp = false |
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| ) | const |
Add a rotation op with XYZ rotation order to the local stack represented by this xformable.
Set the angle value of the resulting UsdGeomXformOp in degrees
| USDGEOM_API UsdGeomXformOp UsdGeomXformable::AddRotateXZYOp | ( | UsdGeomXformOp::Precision const | precision = UsdGeomXformOp::PrecisionFloat, |
| TfToken const & | opSuffix = TfToken(), |
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| bool | isInverseOp = false |
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| ) | const |
Add a rotation op with XZY rotation order to the local stack represented by this xformable.
Set the angle values of the resulting UsdGeomXformOp in degrees
| USDGEOM_API UsdGeomXformOp UsdGeomXformable::AddRotateYOp | ( | UsdGeomXformOp::Precision const | precision = UsdGeomXformOp::PrecisionFloat, |
| TfToken const & | opSuffix = TfToken(), |
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| bool | isInverseOp = false |
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| ) | const |
Add a rotation about the YX-axis to the local stack represented by this xformable.
Set the angle value of the resulting UsdGeomXformOp in degrees
| USDGEOM_API UsdGeomXformOp UsdGeomXformable::AddRotateYXZOp | ( | UsdGeomXformOp::Precision const | precision = UsdGeomXformOp::PrecisionFloat, |
| TfToken const & | opSuffix = TfToken(), |
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| bool | isInverseOp = false |
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| ) | const |
Add a rotation op with YXZ rotation order to the local stack represented by this xformable.
Set the angle values of the resulting UsdGeomXformOp in degrees
| USDGEOM_API UsdGeomXformOp UsdGeomXformable::AddRotateYZXOp | ( | UsdGeomXformOp::Precision const | precision = UsdGeomXformOp::PrecisionFloat, |
| TfToken const & | opSuffix = TfToken(), |
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| bool | isInverseOp = false |
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| ) | const |
Add a rotation op with YZX rotation order to the local stack represented by this xformable.
Set the angle values of the resulting UsdGeomXformOp in degrees
| USDGEOM_API UsdGeomXformOp UsdGeomXformable::AddRotateZOp | ( | UsdGeomXformOp::Precision const | precision = UsdGeomXformOp::PrecisionFloat, |
| TfToken const & | opSuffix = TfToken(), |
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| bool | isInverseOp = false |
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| ) | const |
Add a rotation about the Z-axis to the local stack represented by this xformable.
| USDGEOM_API UsdGeomXformOp UsdGeomXformable::AddRotateZXYOp | ( | UsdGeomXformOp::Precision const | precision = UsdGeomXformOp::PrecisionFloat, |
| TfToken const & | opSuffix = TfToken(), |
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| bool | isInverseOp = false |
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| ) | const |
Add a rotation op with ZXY rotation order to the local stack represented by this xformable.
Set the angle values of the resulting UsdGeomXformOp in degrees
| USDGEOM_API UsdGeomXformOp UsdGeomXformable::AddRotateZYXOp | ( | UsdGeomXformOp::Precision const | precision = UsdGeomXformOp::PrecisionFloat, |
| TfToken const & | opSuffix = TfToken(), |
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| bool | isInverseOp = false |
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| ) | const |
Add a rotation op with ZYX rotation order to the local stack represented by this xformable.
Set the angle values of the resulting UsdGeomXformOp in degrees
| USDGEOM_API UsdGeomXformOp UsdGeomXformable::AddScaleOp | ( | UsdGeomXformOp::Precision const | precision = UsdGeomXformOp::PrecisionFloat, |
| TfToken const & | opSuffix = TfToken(), |
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| bool | isInverseOp = false |
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| ) | const |
Add a scale operation to the local stack represented by this xformable.
| USDGEOM_API UsdGeomXformOp UsdGeomXformable::AddTransformOp | ( | UsdGeomXformOp::Precision const | precision = UsdGeomXformOp::PrecisionDouble, |
| TfToken const & | opSuffix = TfToken(), |
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| bool | isInverseOp = false |
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Add a tranform op (4x4 matrix transformation) to the local stack represented by this xformable.
Note: This method takes a precision argument only to be consistent with the other types of xformOps. The only valid precision here is double since matrix values cannot be encoded in floating-pt precision in Sdf.
| USDGEOM_API UsdGeomXformOp UsdGeomXformable::AddTranslateOp | ( | UsdGeomXformOp::Precision const | precision = UsdGeomXformOp::PrecisionDouble, |
| TfToken const & | opSuffix = TfToken(), |
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| bool | isInverseOp = false |
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| ) | const |
Add a translate operation to the local stack represented by this xformable.
| USDGEOM_API UsdGeomXformOp UsdGeomXformable::AddXformOp | ( | UsdGeomXformOp::Type const | opType, |
| UsdGeomXformOp::Precision const | precision = UsdGeomXformOp::PrecisionDouble, |
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| TfToken const & | opSuffix = TfToken(), |
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| bool | isInverseOp = false |
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| ) | const |
Add an affine transformation to the local stack represented by this Xformable. This will fail if there is already a transform operation of the same name in the ordered ops on this prim (i.e. as returned by GetOrderedXformOps()), or if an op of the same name exists at all on the prim with a different precision than that specified.
The newly created operation will become the most-locally applied transformation on the prim, and will appear last in the list returned by GetOrderedXformOps(). It is OK to begin authoring values to the returned UsdGeomXformOp immediately, interspersed with subsequent calls to AddXformOp() - just note the order of application, which can be changed at any time (and in stronger layers) via SetXformOpOrder().
| opType | is the type of transform operation, one of UsdGeomXformOp::Type. |
| precision | allows you to specify the precision with which you desire to encode the data. This should be one of the values in the enum UsdGeomXformOp::Precision . |
| opSuffix | allows you to specify the purpose/meaning of the op in the stack. When opSuffix is specified, the associated attribute's name is set to "xformOp:<opType>:<opSuffix>". |
| isInverseOp | is used to indicate an inverse transformation operation. |
| USDGEOM_API bool UsdGeomXformable::ClearXformOpOrder | ( | ) | const |
Clears the local transform stack.
| USDGEOM_API UsdAttribute UsdGeomXformable::CreateXformOpOrderAttr | ( | VtValue const & | defaultValue = VtValue(), |
| bool | writeSparsely = false |
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See GetXformOpOrderAttr(), and also Usd_Create_Or_Get_Property for when to use Get vs Create. If specified, author defaultValue as the attribute's default, sparsely (when it makes sense to do so) if writeSparsely is true - the default for writeSparsely is false.
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Return a UsdGeomXformable holding the prim adhering to this schema at path on stage. If no prim exists at path on 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:
| USDGEOM_API bool UsdGeomXformable::GetLocalTransformation | ( | GfMatrix4d * | transform, |
| bool * | resetsXformStack, | ||
| const UsdTimeCode | time = UsdTimeCode::Default() |
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Computes the fully-combined, local-to-parent transformation for this prim.
If a client does not need to manipulate the individual ops themselves, and requires only the combined transform on this prim, this method will take care of all the data marshalling and linear algebra needed to combine the ops into a 4x4 affine transformation matrix, in double-precision, regardless of the precision of the op inputs.
| transform | is the output parameter that will hold the local transform. |
| resetsXformStack | is the output parameter that informs client whether they need to reset the transform stack before pushing transform. |
| time | is the UsdTimeCode at which to sample the ops. |
transform or resetsXformStack is NULL. | USDGEOM_API bool UsdGeomXformable::GetLocalTransformation | ( | GfMatrix4d * | transform, |
| bool * | resetsXformStack, | ||
| const std::vector< UsdGeomXformOp > & | ops, | ||
| const UsdTimeCode | time = UsdTimeCode::Default() |
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This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. Computes the fully-combined, local-to-parent transformation for this prim as efficiently as possible, using a pre-fetched (cached) list of ordered xform ops supplied by the client.
| transform | is the output parameter that will hold the local transform. |
| resetsXformStack | is the output parameter that informs client whether they need to reset the transform stack before pushing transform. |
| ops | is the ordered set of xform ops for this prim, and will be queried without any validity checking. Passing this in can save significant value-resolution costs, if the client is able to retain this data from a call to GetOrderedXformOps(). |
| time | is the UsdTimeCode at which to sample the ops. |
transform or resetsXformStack is NULL.
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This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. This is a static version of the preceding function that takes a cached list of ordered xform ops.
| transform | is the output parameter that will hold the local transform. |
| ops | is the ordered set of xform ops that must be combined together to compute the local transformation. |
| time | is the UsdTimeCode at which to sample the ops. |
| USDGEOM_API std::vector<UsdGeomXformOp> UsdGeomXformable::GetOrderedXformOps | ( | bool * | resetsXformStack | ) | const |
Return the ordered list of transform operations to be applied to this prim, in least-to-most-local order. This is determined by the intersection of authored op-attributes and the explicit ordering of those attributes encoded in the xformOpOrder attribute on this prim. Any entries in xformOpOrder that do not correspond to valid attributes on the xformable prim are skipped and a warning is issued.
A UsdGeomTransformable that has not had any ops added via AddXformOp() will return an empty vector.
The function also sets resetsXformStack to true if "!resetXformStack!" appears anywhere in xformOpOrder (i.e., if the prim resets its parent's inherited transformation).
| USDGEOM_API bool UsdGeomXformable::GetResetXformStack | ( | ) | const |
Does this prim reset its parent's inherited transformation?
Returns true if "!resetXformStack!" appears anywhere in xformOpOrder. When this returns true, all ops upto the last "!resetXformStack!" in xformOpOrder are ignored when computing the local transformation.
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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 bool UsdGeomXformable::GetTimeSamples | ( | std::vector< double > * | times | ) | const |
Sets times to the union of all the timesamples at which xformOps that are included in the xformOpOrder attribute are authored.
This clears the times vector before accumulating sample times from all the xformOps.
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Returns the union of all the timesamples at which the attributes belonging to the given orderedXformOps are authored.
This clears the times vector before accumulating sample times from orderedXformOps.
| USDGEOM_API bool UsdGeomXformable::GetTimeSamplesInInterval | ( | const GfInterval & | interval, |
| std::vector< double > * | times | ||
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Sets times to the union of all the timesamples in the interval, interval, at which xformOps that are included in the xformOpOrder attribute are authored.
This clears the times vector before accumulating sample times from all the xformOps.
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Returns the union of all the timesamples in the interval at which the attributes belonging to the given orderedXformOps are authored.
This clears the times vector before accumulating sample times from orderedXformOps.
| USDGEOM_API UsdAttribute UsdGeomXformable::GetXformOpOrderAttr | ( | ) | const |
Encodes the sequence of transformation operations in the order in which they should be pushed onto a transform stack while visiting a UsdStage's prims in a graph traversal that will effect the desired positioning for this prim and its descendant prims.
You should rarely, if ever, need to manipulate this attribute directly. It is managed by the AddXformOp(), SetResetXformStack(), and SetXformOpOrder(), and consulted by GetOrderedXformOps() and GetLocalTransformation().
| Declaration | uniform token[] xformOpOrder |
| C++ Type | VtArray<TfToken> |
| Usd Type | SdfValueTypeNames->TokenArray |
| Variability | SdfVariabilityUniform |
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Returns true if the attribute named attrName could affect the local transformation of an xformable prim.
| USDGEOM_API UsdGeomXformOp UsdGeomXformable::MakeMatrixXform | ( | ) | const |
Clears the existing local transform stack and creates a new xform op of type 'transform'.
This API is provided for convenience since this is the most common xform authoring operation.
| USDGEOM_API bool UsdGeomXformable::SetResetXformStack | ( | bool | resetXform | ) | const |
Specify whether this prim's transform should reset the transformation stack inherited from its parent prim.
By default, parent transforms are inherited. SetResetXformStack() can be called at any time during authoring, but will always add a '!resetXformStack!' op as the first op in the ordered list, if one does not exist already. If one already exists, and resetXform is false, it will remove all ops upto and including the last "!resetXformStack!" op.
| USDGEOM_API bool UsdGeomXformable::SetXformOpOrder | ( | std::vector< UsdGeomXformOp > const & | orderedXformOps, |
| bool | resetXformStack = false |
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Reorder the already-existing transform ops on this prim.
All elements in orderedXformOps must be valid and represent attributes on this prim. Note that it is not required that all the existing operations be present in orderedXformOps, so this method can be used to completely change the transformation structure applied to the prim.
If resetXformStack is set to true, then "!resetXformOp! will be set as the first op in xformOpOrder, to indicate that the prim does not inherit its parent's transformation.
orderedXformOps vector. From there you can call AddXformOp() just as if you were authoring to the prim from scratch.orderedXformOps are not extant on this prim, or if an error occurred while authoring the ordering metadata. Under either condition, no scene description is authored.| USDGEOM_API bool UsdGeomXformable::TransformMightBeTimeVarying | ( | ) | const |
Determine whether there is any possibility that this prim's local transformation may vary over time.
The determination is based on a snapshot of the authored state of the op attributes on the prim, and may become invalid in the face of further authoring.
| USDGEOM_API bool UsdGeomXformable::TransformMightBeTimeVarying | ( | const std::vector< UsdGeomXformOp > & | ops | ) | const |
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. Determine whether there is any possibility that this prim's local transformation may vary over time, using a pre-fetched (cached) list of ordered xform ops supplied by the client.
The determination is based on a snapshot of the authored state of the op attributes on the prim, and may become invalid in the face of further authoring.
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Definition at line 311 of file xformable.h.
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Compile time constant representing what kind of schema this class is.
Definition at line 258 of file xformable.h.
1.8.6