Date: 2026-03-01T05:24:38+00:00

Actual source code: plexextrude.c

      1: #include <petsc/private/dmpleximpl.h>
      2: #include <petscdmplextransform.h>

      4: /*@
      5:   DMPlexExtrude - Extrude a volumetric mesh from the input surface mesh

      7:   Input Parameters:
      8: + dm          - The surface mesh
      9: . layers      - The number of extruded layers
     10: . thickness   - The total thickness of the extruded layers, or `PETSC_DETERMINE`
     11: . tensor      - Flag to create tensor product cells
     12: . symmetric   - Flag to extrude symmetrically about the surface
     13: . periodic    - Flag to extrude periodically
     14: . normal      - Surface normal vector, or `NULL`
     15: . thicknesses - Thickness of each layer, or `NULL`
     16: - activeLabel - `DMLabel` to extrude from, or `NULL` to extrude entire mesh

     18:   Output Parameter:
     19: . edm - The volumetric mesh

     21:   Options Database Keys:
     22: + -dm_plex_transform_extrude_thickness <t>           - The total thickness of extruded layers
     23: . -dm_plex_transform_extrude_use_tensor <bool>       - Use tensor cells when extruding
     24: . -dm_plex_transform_extrude_symmetric <bool>        - Extrude layers symmetrically about the surface
     25: . -dm_plex_transform_extrude_periodic <bool>         - Extrude layers periodically
     26: . -dm_plex_transform_extrude_normal <n0,...,nd>      - Specify the extrusion direction
     27: - -dm_plex_transform_extrude_thicknesses <t0,...,tl> - Specify thickness of each layer

     29:   Level: intermediate

     31:   Notes:
     32:   Extrusion is implemented as a `DMPlexTransform`, so that new mesh points are produced from old mesh points. In the example below,
     33:   we begin with an edge (v0, v3). It is extruded for two layers. The original vertex v0 produces two edges, e1 and e2, and three vertices,
     34:   v0, v2, and v2. Similarly, vertex v3 produces e3, e4, v3, v4, and v5. The original edge produces itself, e5 and e6, as well as face1 and
     35:   face2. The new mesh points are given the same labels as the original points which produced them. Thus, if v0 had a label value 1, then so
     36:   would v1, v2, e1 and e2.

     38: .vb
     39:   v2----- e6    -----v5
     40:   |                  |
     41:   e2     face2       e4
     42:   |                  |
     43:   v1----- e5    -----v4
     44:   |                  |
     45:   e1     face1       e3
     46:   |                  |
     47:   v0--- original ----v3
     48: .ve

     50: .seealso: [](ch_unstructured), `DM`, `DMPLEX`, `DMExtrude()`, `DMPlexTransform`, `DMPlexTransformExtrudeSetThickness()`, `DMPlexTransformExtrudeSetTensor()`
     51: @*/
     52: PetscErrorCode DMPlexExtrude(DM dm, PetscInt layers, PetscReal thickness, PetscBool tensor, PetscBool symmetric, PetscBool periodic, const PetscReal normal[], const PetscReal thicknesses[], DMLabel activeLabel, DM *edm)
     53: {
     54:   DMPlexTransform tr;
     55:   DM              cdm;
     56:   PetscObject     disc;
     57:   PetscClassId    id;
     58:   const char     *prefix;
     59:   PetscOptions    options;
     60:   PetscBool       cutMarker = PETSC_FALSE;

     62:   PetscFunctionBegin;
     63:   PetscCall(DMPlexTransformCreate(PetscObjectComm((PetscObject)dm), &tr));
     64:   PetscCall(PetscObjectSetName((PetscObject)tr, "Extrusion Transform"));
     65:   PetscCall(DMPlexTransformSetDM(tr, dm));
     66:   PetscCall(DMPlexTransformSetType(tr, DMPLEXEXTRUDETYPE));
     67:   PetscCall(PetscObjectGetOptionsPrefix((PetscObject)dm, &prefix));
     68:   PetscCall(PetscObjectSetOptionsPrefix((PetscObject)tr, prefix));
     69:   PetscCall(PetscObjectGetOptions((PetscObject)dm, &options));
     70:   PetscCall(PetscObjectSetOptions((PetscObject)tr, options));
     71:   if (activeLabel) PetscCall(DMPlexTransformSetActive(tr, activeLabel));
     72:   PetscCall(DMPlexTransformExtrudeSetLayers(tr, layers));
     73:   if (thickness > 0.) PetscCall(DMPlexTransformExtrudeSetThickness(tr, thickness));
     74:   PetscCall(DMPlexTransformExtrudeSetTensor(tr, tensor));
     75:   PetscCall(DMPlexTransformExtrudeSetSymmetric(tr, symmetric));
     76:   PetscCall(DMPlexTransformExtrudeSetPeriodic(tr, periodic));
     77:   if (normal) PetscCall(DMPlexTransformExtrudeSetNormal(tr, normal));
     78:   if (thicknesses) PetscCall(DMPlexTransformExtrudeSetThicknesses(tr, layers, thicknesses));
     79:   PetscCall(DMPlexTransformSetFromOptions(tr));
     80:   PetscCall(PetscObjectSetOptions((PetscObject)tr, NULL));
     81:   PetscCall(DMPlexTransformSetUp(tr));
     82:   PetscCall(PetscObjectViewFromOptions((PetscObject)tr, NULL, "-dm_plex_transform_view"));
     83:   PetscCall(DMPlexTransformApply(tr, dm, edm));
     84:   PetscCall(DMCopyDisc(dm, *edm));
     85:   // Handle periodic viewing
     86:   PetscCall(PetscOptionsGetBool(options, ((PetscObject)dm)->prefix, "-dm_plex_periodic_cut", &cutMarker, NULL));
     87:   PetscCall(DMPlexTransformExtrudeGetPeriodic(tr, &periodic));
     88:   if (periodic && cutMarker) {
     89:     DMLabel  cutLabel;
     90:     PetscInt dim, pStart, pEnd;

     92:     PetscCall(DMGetDimension(dm, &dim));
     93:     PetscCall(DMCreateLabel(*edm, "periodic_cut"));
     94:     PetscCall(DMGetLabel(*edm, "periodic_cut", &cutLabel));
     95:     PetscCall(DMPlexGetChart(dm, &pStart, &pEnd));
     96:     for (PetscInt p = pStart; p < pEnd; ++p) {
     97:       DMPolytopeType  ct;
     98:       DMPolytopeType *rct;
     99:       PetscInt       *rsize, *rcone, *rornt;
    100:       PetscInt        Nct;

    102:       PetscCall(DMPlexGetCellType(dm, p, &ct));
    103:       PetscCall(DMPlexTransformCellTransform(tr, ct, p, NULL, &Nct, &rct, &rsize, &rcone, &rornt));
    104:       for (PetscInt n = 0; n < Nct; ++n) {
    105:         PetscInt pNew, pdim = DMPolytopeTypeGetDim(rct[n]);

    107:         if (ct == rct[n] || pdim > dim) {
    108:           PetscCall(DMPlexTransformGetTargetPoint(tr, ct, rct[n], p, 0, &pNew));
    109:           PetscCall(DMLabelSetValue(cutLabel, pNew, !pdim ? 1 : 2));
    110:         }
    111:       }
    112:     }
    113:   }
    114:   // It is too hard to raise the dimension of a discretization, so just remake it
    115:   PetscCall(DMGetCoordinateDM(dm, &cdm));
    116:   PetscCall(DMGetField(cdm, 0, NULL, &disc));
    117:   PetscCall(PetscObjectGetClassId(disc, &id));
    118:   if (id == PETSCFE_CLASSID) {
    119:     PetscSpace sp;
    120:     PetscInt   deg;

    122:     PetscCall(PetscFEGetBasisSpace((PetscFE)disc, &sp));
    123:     PetscCall(PetscSpaceGetDegree(sp, &deg, NULL));
    124:     PetscCall(DMPlexCreateCoordinateSpace(*edm, deg, PETSC_FALSE, PETSC_TRUE));
    125:   }
    126:   PetscCall(DMPlexTransformCreateDiscLabels(tr, *edm));
    127:   PetscCall(DMPlexTransformDestroy(&tr));
    128:   PetscCall(DMPlexCopy_Internal(dm, PETSC_FALSE, PETSC_FALSE, *edm));
    129:   PetscFunctionReturn(PETSC_SUCCESS);
    130: }

    132: PetscErrorCode DMExtrude_Plex(DM dm, PetscInt layers, DM *edm)
    133: {
    134:   PetscFunctionBegin;
    135:   PetscCall(DMPlexExtrude(dm, layers, PETSC_DETERMINE, PETSC_TRUE, PETSC_FALSE, PETSC_FALSE, NULL, NULL, NULL, edm));
    136:   PetscCall(DMSetMatType(*edm, dm->mattype));
    137:   PetscCall(DMViewFromOptions(*edm, NULL, "-check_extrude"));
    138:   PetscFunctionReturn(PETSC_SUCCESS);
    139: }