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xformCache.h
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2 // Copyright 2016 Pixar
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24 #ifndef USDGEOM_XFORMCACHE_H
25 #define USDGEOM_XFORMCACHE_H
26 
27 #include "pxr/pxr.h"
28 #include "pxr/usd/usdGeom/api.h"
30 #include "pxr/usd/usd/prim.h"
31 
33 
34 #include "pxr/base/gf/matrix4d.h"
35 #include "pxr/base/tf/hashmap.h"
36 #include "pxr/base/tf/token.h"
37 
38 #include <hboost/functional/hash.hpp>
39 
41 
42 
43 /// \class UsdGeomXformCache
44 ///
45 /// A caching mechanism for transform matrices. For best performance, this
46 /// object should be reused for multiple CTM queries.
47 ///
48 /// Instances of this type can be copied, though using Swap() may result in
49 /// better performance.
50 ///
51 /// It is valid to cache prims from multiple stages in a single XformCache.
52 ///
53 /// WARNING: this class does not automatically invalidate cached values based
54 /// on changes to the stage from which values were cached. Additionally, a
55 /// separate instance of this class should be used per-thread, calling the Get*
56 /// methods from multiple threads is not safe, as they mutate internal state.
57 ///
59 {
60 public:
61  /// Construct a new XformCache for the specified \p time.
63  explicit UsdGeomXformCache(const UsdTimeCode time);
64 
65  /// Construct a new XformCache for UsdTimeCode::Default().
68 
69  /// Compute the transformation matrix for the given \p prim, including the
70  /// transform authored on the Prim itself, if present.
71  ///
72  /// \note This method may mutate internal cache state and is not thread
73  /// safe.
76 
77  /// Compute the transformation matrix for the given \p prim, but do NOT
78  /// include the transform authored on the prim itself.
79  ///
80  /// \note This method may mutate internal cache state and is not thread
81  /// safe.
84 
85  /// Returns the local transformation of the prim. Uses the cached
86  /// XformQuery to compute the result quickly. The \p resetsXformStack
87  /// pointer must be valid. It will be set to true if \p prim resets
88  /// the transform stack.
89  /// The result of this call is cached.
92  bool *resetsXformStack);
93 
94  /// Returns the result of concatenating all transforms beneath \p ancestor
95  /// that affect \p prim. This includes the local transform of \p prim
96  /// itself, but not the local transform of \p ancestor. If \p ancestor is
97  /// not an ancestor of \p prim, the resulting transform is the
98  /// local-to-world transformation of \p prim.
99  /// The \p resetXformTsack pointer must be valid. If any intermediate prims
100  /// reset the transform stack, \p resetXformStack will be set to true.
101  /// Intermediate transforms are cached, but the result of this call itself
102  /// is not cached.
105  const UsdPrim &ancestor,
106  bool *resetXformStack);
107 
108  /// Whether the attribute named \p attrName, belonging to the
109  /// given \p prim affects the local transform value at the prim.
110  ///
111  /// \note This method may mutate internal cache state and is not thread
112  /// safe.
115  const TfToken &attrName);
116 
117  /// Whether the local transformation value at the prim may vary over time.
118  ///
119  /// \note This method may mutate internal cache state and is not thread
120  /// safe.
122  bool TransformMightBeTimeVarying(const UsdPrim &prim);
123 
124  /// Whether the xform stack is reset at the given prim.
125  ///
126  /// \note This method may mutate internal cache state and is not thread
127  /// safe.
129  bool GetResetXformStack(const UsdPrim &prim);
130 
131  /// Clears all pre-cached values.
133  void Clear();
134 
135  /// Use the new \p time when computing values and may clear any existing
136  /// values cached for the previous time. Setting \p time to the current time
137  /// is a no-op.
139  void SetTime(UsdTimeCode time);
140 
141  /// Get the current time from which this cache is reading values.
142  UsdTimeCode GetTime() { return _time; }
143 
144  /// Swap the contents of this XformCache with \p other.
146  void Swap(UsdGeomXformCache& other);
147 
148 private:
149 
150  // Traverses backwards the hierarchy starting from prim
151  // all the way to the root and computes the ctm
152  GfMatrix4d const* _GetCtm(const UsdPrim& prim);
153 
154  // Map of cached values.
155  struct _Entry {
156  _Entry() = default;
157  _Entry(const UsdGeomXformable::XformQuery & query_,
158  const GfMatrix4d& ctm_,
159  bool ctmIsValid_)
160  : query(query_)
161  , ctm(ctm_)
162  , ctmIsValid(ctmIsValid_)
163  { }
164 
166  GfMatrix4d ctm;
167  bool ctmIsValid;
168  };
169 
170  // Helper function to get or create a new entry for a prim in the ctm cache.
171  _Entry * _GetCacheEntryForPrim(const UsdPrim &prim);
172 
174  _PrimHashMap _ctmCache;
175 
176  // The time at which this stack is querying and caching attribute values.
177  UsdTimeCode _time;
178 };
179 
180 #define USDGEOM_XFORM_CACHE_API_VERSION 1
181 
182 
184 
185 #endif // USDGEOM_XFORMCACHE_H
USDGEOM_API GfMatrix4d GetLocalTransformation(const UsdPrim &prim, bool *resetsXformStack)
GT_API const UT_StringHolder time
UsdTimeCode GetTime()
Get the current time from which this cache is reading values.
Definition: xformCache.h:142
USDGEOM_API void SetTime(UsdTimeCode time)
GLenum query
Definition: glew.h:5704
USDGEOM_API bool GetResetXformStack(const UsdPrim &prim)
Definition: token.h:89
USDGEOM_API void Clear()
Clears all pre-cached values.
USDGEOM_API bool TransformMightBeTimeVarying(const UsdPrim &prim)
USDGEOM_API GfMatrix4d GetLocalToWorldTransform(const UsdPrim &prim)
Definition: prim.h:131
USDGEOM_API UsdGeomXformCache()
Construct a new XformCache for UsdTimeCode::Default().
USDGEOM_API GfMatrix4d GetParentToWorldTransform(const UsdPrim &prim)
PXR_NAMESPACE_CLOSE_SCOPE PXR_NAMESPACE_OPEN_SCOPE
Definition: path.h:1245
USDGEOM_API GfMatrix4d ComputeRelativeTransform(const UsdPrim &prim, const UsdPrim &ancestor, bool *resetXformStack)
#define PXR_NAMESPACE_CLOSE_SCOPE
Definition: pxr.h:83
USDGEOM_API bool IsAttributeIncludedInLocalTransform(const UsdPrim &prim, const TfToken &attrName)
#define USDGEOM_API
Definition: api.h:40
USDGEOM_API void Swap(UsdGeomXformCache &other)
Swap the contents of this XformCache with other.