0032422: Mesh - Weird rendering
0029641: Mesher produce 'bad' result for extruded spline with given deviation coefficient
Added method BRepMesh_NURBSRangeSplitter::getUndefinedInterval() intended to compute checkpoint parameters for those NURBS surfaces which have no intervals at all. In this case number of poles is used to produce artificial regular grid which can be refined further. Add at least one midpoint for surfaces with one interval and only two poles.
Added BRepMesh_ExtrusionRangeSplitter and BRepMesh_UndefinedRangeSplitter derivatives from BRepMesh_NURBSRangeSplitter intended to handle special cases of extrusion surfaces and general surfaces with undefined parameters.
1. Check whether the mesh satisfies the required angular deflection has been amended. Namely normals (to the surface) in the ends of any not "frontier" link are made collinear (with the given angular tolerance).
2. New parameters AngleInterior and DeflectionInterior have been added in IMeshTools_Parameters structure.
3. In case of thin long faces with internal edges, add points of internal edges to control parameters using grabParamsOfInternalEdges() in order to avoid aberrations on its ends. Disable addition of parameters from boundary edges in case of BSpline surface. Deviation can be controlled through the deflection parameter.
4. Grab parameters from edges in case if there is just a single interval on BSpline surface along U and V direction.
Removed tight connections between data structures, auxiliary tools and algorithms in order to create extensible solution, easy for maintenance and improvements;
Code is separated on several functional units responsible for specific operation for the sake of simplification of debugging and readability;
Introduced new data structures enabling possibility to manipulate discrete model of particular entity (edge, wire, face) in order to perform computations locally instead of processing an entire model.
The workflow of updated component can be divided on six parts:
* Creation of model data structure: source TopoDS_Shape passed to algorithm is analyzed and exploded on faces and edges. For each topological entity corresponding reflection is created in data model. Note that underlying algorithms use data model as input and access it via common interface which allows user to create custom data model with necessary dependencies between particular entities;
* Discretize edges 3D & 2D curves: 3D curve as well as associated set of 2D curves of each model edge is discretized in order to create coherent skeleton used as a base in faces meshing process. In case if some edge of source shape already contains polygonal data which suites specified parameters, it is extracted from shape and stored to the model as is. Each edge is processed separately, adjacency is not taken into account;
* Heal discrete model: source TopoDS_Shape can contain problems, such as open-wire or self-intersections, introduced during design, exchange or modification of model. In addition, some problems like self-intersections can be introduced by roughly discretized edges. This stage is responsible for analysis of discrete model in order to detect and repair faced problems or refuse model’s part for further processing in case if problem cannot be solved;
* Preprocess discrete model: defines actions specific for implemented approach to be performed before meshing of faces. By default, iterates over model faces and checks consistency of existing triangulations. Cleans topological faces and its adjacent edges from polygonal data in case of inconsistency or marks face of discrete model as not required for computation;
* Discretize faces: represents core part performing mesh generation for particular face based on 2D discrete data related to processing face. Caches polygonal data associated with face’s edges in data model for further processing and stores generated mesh to TopoDS_Face;
* Postprocess discrete model: defines actions specific for implemented approach to be performed after meshing of faces. By default, stores polygonal data obtained on previous stage to TopoDS_Edge objects of source model.
Component is now spread over IMeshData, IMeshTools, BRepMeshData and BRepMesh units.
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1. Extend "tricheck" DRAW-command in order to find degenerated triangles.
2. Class BRepMesh_FastDiscret::Parameters has been declared as deprecated.
3. NURBS range splitter: do not split intervals without necessity. Intervals are split only in case if it is impossible to compute normals directly on intervals.
4. Default value of IMeshTools_Parameters::MinSize has been changed. New value is equal to 0.1*Deflection.
5. Correction of test scripts:
1) perf mesh bug27119: requested deflection is increased from 1e-6 to 1e-5 to keep reasonable performance (but still reproducing original issue)
2) bugs mesh bug26692_1, 2: make snapshot of triangulation instead of wireframe (irrelevant)
Correction in upgrade guide.
1) Reduce the number of calls to malloc by grouping requests to larger blocks. To achieve this goal, the following ways are used:
- Containers of types sequence, list and map are initialized with an instance of NCollection_IncAllocator, at this taking care of the time of life of allocated objects, so that not to occupy huge amount of memory.
- Allocation of several arrays having the same and short life time is changed so that to allocate a buffer array of necessary size and to place arrays in this buffer.
2) In BRepMesh_FastDiscretFace, optimize the function filterParameters so that to avoid excess memory allocations.
3) In NCollection_CellFilter, change declaration of the method Reset to accept array by reference rather than by value.
4) Add Allocator() method in map, sequence and vector collection classes by analogy with list collection.
5) Correct the size of block for IncAllocator for x64 platform. In order free-ed block to be returned to the system its size should be at least 1024K on x64 and 512K on x86. This allows to retain free virtual space almost to the state before algorithm run.
6) Decrease amount of memory zeroed by calloc. For that, reduce theIncrement parameter of the embedded vectors of the classes NCollection_UBTreeFiller and BRepMesh_VertexInspector to default value 256.
7) Avoid computing bounding box when not necessary (if no relative deflection is used)
8) Cycles by wires of face using TopExp_Explorer are converted to use TopoDS_Iterator instead.
9) BRepMesh_FastDiscret::Add optimized to avoid storing sequences of faces and edges
10) The tests "mesh standard_* W7" are corrected to accept the new behavior. Earlier the following error took place:
Not connected mesh inside face 9
{12 13}
Now this error was replaced with another one:
free nodes (in pairs: face / node):
{9 12}
Actually it is not a regression, rather improvement, if we look at the snapshot.
11) Change other test cases to their actual state.
Check deviation of normals at vertices of triangles for complex surface types different from Bezier and BSpline.
Modified test cased according to changes in BRepMesh.
Do not remove more intermediate parameters than N - 3 in order to have at least one parameter related to surface internals.
Check angle for angular deflection before removement of intermediate parameters.
Unify computation of internal vertices for complex surfaces.
Discretization points of edges are taken into account during computation of step of mesh grid.
Remove parameters only if they fit the constrains along the whole surface.
Do not add random internal parameters in case if their number is just 2.
Force freezing parameters both for U and V in case of significant control point.
Modified test cases
Warnings elimination in vc14.
- Added function checkprops, set default tolerance parameter to 1.0e-4
- Using "area" instead of "square".
- Options "-equal\notequal" isn't used together with "-s" in blend and offset test cases.
- Correct regressions/differences/improvements and CPU problem (set props tolerance to 0.1)
- Corrected test cases to use checkprops proc.
- Correct image difference
- Updated TODOs in test cases.
- Updated test cases to get correct images of result shape
