The branch CR24157_12 deals with the parallelization of building the solids in case of lot internal faces.
Test case for issue CR24157

class IntTools_FaceFace
method
  void IntTools_FaceFace::Perform(const TopoDS_Face& aF1,
                                  const TopoDS_Face& aF2)
Change the approximation flags according to the order of faces.

Test case for issue CR25019

Implement SAT intersection tests and frustum culling algorithm using BVH trees.

New Draw command vfrustumculling to manage frustum culling.
Add test cases bugs/vis/bug24307_1 and bugs/vis/bug24307_2.
Remove CALL_DEF_BOUNDBOX and CALL_DEF_BOUNDS.

Test case for issue CR25027

0024902: Visualization, StdPrs_ShadedShape - advanced processing of Compounds containing mixture of closed Solids and open Shells

StdPrs_ShadedShape, add flag theToExploreSolids to method ::Add().
Previously the tool collected triagnulations from all Faces into single graphic group.
The automated algorithm for back-face culling activation has to disable culling
when within closed Solids single Compound contains also open Shells.
Now tool is able to optionally (enabled by default) split these two categories of primitives
into dedicated groups with independent back-face culling settings.

In addition, this closed flag is now stored in Graphic3d_Group::myIsClosed which allows
capping algorithm OpenGl_CappingAlgo to automatically filter improper groups.

the check for degenerated edges added
Test case for issue CR25020

Test case for issue CR24964

Check is the shape to be meshed has correct poly data, i.e. PolygonOnTriangulation of particular edge connected to the same Triangulation data structure as stored inside a parent face.
Adding test cases for issue CR23631 bugs/mesh/bug23631
Parallel checking of faces/edges
Make BRepMesh_IncrementalMesh class imported from BRepMesh package.
Resolve GCC warnings on Linux platform
Fix compilation errors on MacOs: remove mutable modificator on reference fields.

SameParameter check is fixed to verify the correct pairs of parameters

Fix the crash in IntAna_QuadQuadGeo by checking the number of intersections

0024998: The incorrect _USE_MATH_DEFINES definition in Standard_math.hxx prevents the clean build for client applications

Add #ifndef clause to avoid redefinition compile error

0024987: Visualization - Add missing implementation of Select3D_SensitiveTriangulation::DetectedTriangle()

A missed method is implemented.

0024989: Visualization - workaround vc12 32-bit compiler optimizer bug resulted in crash in AIS_Axis

Test case for issue CR24989

NCollection classes amended to be compatible with TCollection equivalents:

- List and Maps: copy constructor is used for placement of new items in collection instead of assignment operator, thus default constructor is not necessary any more for the item class
- Constructors with additional argument of element type added in array classes operated by Handle, defined by NCollection_DefineHArray*.hxx, allowing to initialize array immediately by specified value
- Non-const methods First() and Last() are added in List class, and method Value() in TListIterator class
- Method Append() accepting Handle(HSequence) provided in NCollection_DefineHSequence.hxx
- Default implementation of global function IsEqual() is provided as template (using operator ==)

Code using lists and maps of sequences is refactored to operate sequence by Handle (since Sequence does not to have public copy constructor).

In addition, error checking code is simplified to use macros _Raise_if instead of custom #ifdefs with the same meaning.
Comments within declaration of instances of generic classes in CDL removed.

Fixed bug in copy constructor of NCollection_BaseVector leading to corrupt data if original vector is empty; simplistic test command for vectors is added.

class IntTools_Tools
method
  Standard_Boolean IntTools_Tools::AdjustPeriodic
      (const Standard_Real thePar,
       const Standard_Real theParMin,
       const Standard_Real theParMax,
       const Standard_Real thePeriod,
       Standard_Real &theNewPar,
       Standard_Real &theOffset,
       const Standard_Real theEps)
The new function has been implemented for fast adjustment of pcurves to the range of surface.
Test case correction for issue CR24981

Modification:
class IntTools_EdgeEdge
For correct computation of resolution for curves of type Hyperbola and Parabola two new static functions have been implemented:
static
  Standard_Real ResolutionCoeff(const BRepAdaptor_Curve& theBAC,
                                const IntTools_Range& theRange);
static
  Standard_Real Resolution(const Handle(Geom_Curve)& theCurve,
                           const GeomAbs_CurveType theCurveType,
                           const Standard_Real theResCoeff,
                           const Standard_Real theR3D);

bugs moddata_2 bug26_2 - improvement.
Test case for issue CR24939
Test case correction for issue CR24939

class: BOPTools_AlgoTools2D
method:
void BOPTools_AlgoTools2D::MakePCurveOnFace
  (const TopoDS_Face& aF,
   const Handle(Geom_Curve)& aC3D,
   const Standard_Real aFirst,
   const Standard_Real aLast,
   Handle(Geom2d_Curve)& aC2D,
   Standard_Real& TolReached2d)
has been modified to provide the conformity with the location of the surface

Test case for issue CR24973

class: BOPAlgo_Algo
method:
void BOPAlgo_Algo::SetProgressIndicator
  (const Handle(Message_ProgressIndicator)& theObj)
Purpose: Set the Progress Indicator object <theObj>.

method:
void BOPAlgo_Algo::UserBreak() const
Purpose: Breaks the execution if the break signal is indicated.

All necessary files were included.
Unused files from package PColStd were removed.

0024945: Extrema_ExtPElC::Perform does not consider angular tolerance when calculates angle between two vectors

Consider angular tolerance during calculation of angle between two vectors for protection against deviations that are significantly less than tolerance.
Simplified code to reduce number of comparison
Added QA command OCC24945 and test case bugs/moddata_3/bug24945

Code where DownCast was applied to Handle of the type being not a base class of the target one is revised and (hopefully) corrected.
Code corrected following review remarks
GeomConvert::CurveToBSplineCurve() is called even for b-spline curves to ensure that result is non-periodic
Check for conic is corrected

Files in QANCollection tests reorganized to avoid placing code in header files

NCollection_BaseCollection class, relevant header files, and macro DEFINE_BASECOLLECTION removed.
Hence methods Assign() from other compatible (via inheritance of BaseCollection) collections are not available any more, as well as base Iterator class.

All methods of Iterator classes are made non-virtual, allowing their inline expansion for better performance.

OCCT-specific operators new and delete added to collection classes and removed from iterator classes.

Backslash at the end of the line within comment escaped by dot to avoid GCC warning

Compilation errors in qt samples were fixed.

Add checks for cone-like surfaces during seam fixing
Delete check for missing degenerated edge for cones in FixMissingSeam() function, because this check is exist in FixPeriodicDegenerated(). Check for uniqueness of wire is unnecessary after this.
Update of test-cases

1. DRAW-command for testing was created (see QABugs_19.cxx)
2. Alignments were changed in other files.

Main Changes are into IntCurve_IntConicConic_1.cxx file (variable isOutOfRange was added).
If found intersection point is out of range, minimal distance between corresponding ends of interval is taken. If this distance is less than tolerance, this point replaces found intersection point. Otherwise, found intersection point is ignored.
Modified QA command OCC24889 and added test case bugs/modalg_5/bug24889

0024960: Value of result tolerance after "fixshape" is bigger than value of set "Maximal tolerance".

Description of using "Maximal tolerance" and "Minimal tolerance" values in class ShapeFix_Shape was updated.

Compilation warning eliminated.

Reason of exception was liquidated.

Fixes in Extrema Curve/Curve algorithm and in corresponding testcase.
Added test case bugs/modalg_5/bug24946

STL-compatible iterators returned methods begin() and end() are provided in collection classes from NCollection package.
NCollection_Array1::Iterator is redesigned to use pointer instead of index.
Iterators of Sequence, Array, and Vector are extended by new methods to iterate backwards.

Use of SortTools_QuickSortOfReal is replaced by std::sort() in a few places (where possible).

Delete check for top-level shape during writing invisibility property.
Added QA command OCC23951.
Fix crash in QA command OCC23951: initialize document, initialize shape.
Added test case bugs/xde/bug23951
Modified QABugs/QABugs_19.cxx to avoid warnings