func GetIntegrationPoints(nip, nipf int, cellType string) (ipsElem, ipsFace []*shp.Ipoint) {
// get integration points of element
var err error
ipsElem, err = shp.GetIps(cellType, nip)
if LogErr(err, io.Sf("cannot get integration points for element with shape type=%q and nip=%d", cellType, nip)) {
return nil, nil
}
// get integration points of face
faceType := shp.GetFaceType(cellType)
ipsFace, err = shp.GetIps(faceType, nipf)
if LogErr(err, io.Sf("cannot get integration points for face with face-shape type=%q and nip=%d", faceType, nip)) {
return nil, nil
}
return
}
// NodesOnPlane finds vertices located on {x,y,z} plane and returns an iterator
// that can be used to extract results on the plane. An {u,v}-coordinates system is built
// on the plane.
// Input:
// ftag -- cells' face tag; e.g. -31
// Output:
// dat -- plane data holding vertices on plane and other information; see above
// Note:
// 1) this function works with 3D cells only
// 2) faces on cells must be either "qua4" or "qua8" types
// 3) middle nodes in "qua8" are disregarded in order to buidl an {u,v} grid
// 4) the resulting mesh on plane must be equally spaced; i.e. Δx and Δy are constant;
// but not necessarily equal to each other
func NodesOnPlane(ftag int) *PlaneData {
// check
ndim := Dom.Msh.Ndim
if ndim != 3 {
chk.Panic("this function works in 3D only")
}
// loop over cells on face with given face tag
var dat PlaneData
dat.Plane = -1
dat.Ids = make(map[int]bool)
dat.Dx = make([]float64, ndim)
Δx := make([]float64, ndim)
first := true
cells := Dom.Msh.FaceTag2cells[ftag]
for _, cell := range cells {
ctype := cell.C.Type
for fidx, cftag := range cell.C.FTags {
if cftag == ftag {
// check face type
ftype := shp.GetFaceType(ctype)
if !(ftype == "qua4" || ftype == "qua8") {
chk.Panic("can only handle qua4 or qua8 faces for now. ftype=%q", ftype)
}
// vertices on face
flvids := shp.GetFaceLocalVerts(ctype, fidx)
nv := len(flvids)
if nv == 8 {
nv = 4 // avoid middle nodes
}
for i := 0; i < nv; i++ {
vid := cell.C.Verts[flvids[i]]
dat.Ids[vid] = true
}
// compute and check increments in global coordinates
for i := 1; i < nv; i++ {
a := cell.C.Verts[flvids[i]]
b := cell.C.Verts[flvids[i-1]]
xa := Dom.Msh.Verts[a].C
xb := Dom.Msh.Verts[b].C
for j := 0; j < ndim; j++ {
Δx[j] = max(Δx[j], math.Abs(xa[j]-xb[j]))
}
}
if first {
for j := 0; j < ndim; j++ {
dat.Dx[j] = Δx[j]
}
first = false
} else {
for j := 0; j < ndim; j++ {
if math.Abs(dat.Dx[j]-Δx[j]) > 1e-10 {
chk.Panic("all faces must have the same Δx,Δy,Δz")
}
}
}
// find which plane vertices are located on => which plane this face is parallel to
perpto := -1 // "perpendicular to" indicator
switch {
case Δx[0] < DIST_TOL: // plane perpendicular to x-axis
perpto = 0
case Δx[1] < DIST_TOL: // plane perpendicular to y-axis
perpto = 1
case Δx[2] < DIST_TOL: // plane perpendicular to z-axis
perpto = 2
default:
chk.Panic("planes must be perpendicular to one of the x-y-z axes")
}
if dat.Plane < 0 {
dat.Plane = perpto
} else {
if perpto != dat.Plane {
chk.Panic("all planes must be perperdicular to the same axis")
}
}
}
}
}
// uv: indices and increments
dat.Iu = make([]int, 2)
dat.Du = make([]float64, 2)
switch dat.Plane {
case 0: // plane perpendicular to x-axis
dat.Iu = []int{1, 2}
case 1: // plane perpendicular to y-axis
dat.Iu = []int{0, 2}
case 2: // plane perpendicular to z-axis
dat.Iu = []int{0, 1}
}
for j := 0; j < 2; j++ {
dat.Du[j] = dat.Dx[dat.Iu[j]]
}
// uv: limits
dat.Umin = make([]float64, 2)
dat.Umax = make([]float64, 2)
first = true
for vid, _ := range dat.Ids {
x := Dom.Msh.Verts[vid].C
if first {
for j := 0; j < 2; j++ {
dat.Umin[j] = x[dat.Iu[j]]
dat.Umax[j] = x[dat.Iu[j]]
}
first = false
} else {
for j := 0; j < 2; j++ {
dat.Umin[j] = min(dat.Umin[j], x[dat.Iu[j]])
dat.Umax[j] = max(dat.Umax[j], x[dat.Iu[j]])
}
}
}
// uv: size of grid
dat.Nu = make([]int, 2)
for j := 0; j < 2; j++ {
dat.Nu[j] = int((dat.Umax[j]-dat.Umin[j])/dat.Du[j]) + 1
}
// uv: bins
dd := DIST_TOL * 2
nb := 20
dat.Ubins.Init([]float64{dat.Umin[0] - dd, dat.Umin[1] - dd}, []float64{dat.Umax[0] + dd, dat.Umax[1] + dd}, nb)
u := []float64{0, 0}
for vid, _ := range dat.Ids {
x := Dom.Msh.Verts[vid].C
for j := 0; j < 2; j++ {
u[j] = x[dat.Iu[j]]
}
err := dat.Ubins.Append(u, vid)
if err != nil {
chk.Panic("cannot append {u,v} coordinate to bins. u=%v", u)
}
}
// allocate F
dat.F = la.MatAlloc(dat.Nu[0], dat.Nu[1])
return &dat
}