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SwanFindPoint.f90
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SwanFindPoint.f90
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subroutine SwanFindPoint ( x, y, kvert )
!
! --|-----------------------------------------------------------|--
! | Delft University of Technology |
! | Faculty of Civil Engineering and Geosciences |
! | Environmental Fluid Mechanics Section |
! | P.O. Box 5048, 2600 GA Delft, The Netherlands |
! | |
! | Programmer: Marcel Zijlema |
! --|-----------------------------------------------------------|--
!
!
! SWAN (Simulating WAves Nearshore); a third generation wave model
! Copyright (C) 1993-2015 Delft University of Technology
!
! This program is free software; you can redistribute it and/or
! modify it under the terms of the GNU General Public License as
! published by the Free Software Foundation; either version 2 of
! the License, or (at your option) any later version.
!
! This program is distributed in the hope that it will be useful,
! but WITHOUT ANY WARRANTY; without even the implied warranty of
! MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
! GNU General Public License for more details.
!
! A copy of the GNU General Public License is available at
! http://www.gnu.org/copyleft/gpl.html#SEC3
! or by writing to the Free Software Foundation, Inc.,
! 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
!
!
! Authors
!
! 40.80: Marcel Zijlema
!
! Updates
!
! 40.80, June 2007: New subroutine
!
! Purpose
!
! Finds the closest vertex index of the given point
!
! Modules used
!
use ocpcomm4
use swcomm3
use SwanGriddata
use SwanGridobjects
!
implicit none
!
! Argument variables
!
integer, intent(out) :: kvert ! closest vertex index of given point
! Note: kvert = -1 indicate point is not found
real, intent(in) :: x ! x-coordinate of given point
real, intent(in) :: y ! y-coordinate of given point
!
! Local variables
!
integer, save :: ient = 0 ! number of entries in this subroutine
integer :: iface ! loop counter over faces
integer :: ivert ! loop counter over vertices
integer :: v1 ! first vertex of present face
integer :: v2 ! second vertex of present face
!
real :: dismin ! minimal distance found
real :: dist ! computed distance
real :: dxb ! x-component of length of boundary face
real :: dyb ! y-component of length of boundary face
real :: r ! relative distance of point to begin of boundary face
real :: reldis ! relative distance of point to boundary face
real :: x1 ! x-coordinate of begin of boundary face
real :: x2 ! x-coordinate of end of boundary face
real :: xc ! x-coordinate of closest vertex
real :: y1 ! y-coordinate of begin of boundary face
real :: y2 ! y-coordinate of end of boundary face
real :: yc ! y-coordinate of closest vertex
!
logical :: SwanPointinMesh ! indicate whether a point is inside mesh
!
type(facetype), dimension(:), pointer :: face ! datastructure for faces with their attributes
!
! Structure
!
! Description of the pseudo code
!
! Source text
!
if (ltrace) call strace (ient,'SwanFindPoint')
!
! point to face object
!
face => gridobject%face_grid
!
! check whether point is outside the grid
!
if ( x < XCGMIN .or. x > XCGMAX .or. y < YCGMIN .or. y > YCGMAX ) then
!
kvert = -1
return
!
endif
!
if ( SwanPointinMesh( x, y ) ) then
!
! if point is inside the mesh then compute closest index
!
dismin = 1.e20
!
do ivert = 1, nverts
!
xc = xcugrd(ivert)
yc = ycugrd(ivert)
!
dist = sqrt( (x-xc)**2 + (y-yc)**2 )
if ( dist < dismin ) then
kvert = ivert
dismin = dist
endif
!
enddo
!
else
!
! scan the boundary to look for the given point
!
! loop over faces (both internal and boundary faces)
!
faceloop: do iface = 1, nfaces
!
if ( face(iface)%atti(FMARKER) == 1 ) then ! boundary face
!
v1 = face(iface)%atti(FACEV1)
v2 = face(iface)%atti(FACEV2)
!
x1 = xcugrd(v1)
y1 = ycugrd(v1)
x2 = xcugrd(v2)
y2 = ycugrd(v2)
!
dxb = x2 - x1
dyb = y2 - y1
!
reldis = abs( dyb*(x-x1) - dxb*(y-y1) ) / ( dxb*dxb + dyb*dyb )
!
if ( reldis < 0.01 ) then
!
r = ( dxb*(x-x1) + dyb*(y-y1) ) / ( dxb*dxb + dyb*dyb )
!
if ( r < -0.01 .or. r > 1.01 ) then ! 41.13
kvert = -1
else
!
if ( r < 0.5 ) then
kvert = v1
else
kvert = v2
endif
exit faceloop
!
endif
!
else
kvert = -1
endif
!
endif
!
enddo faceloop
!
endif
!
end subroutine SwanFindPoint