nearest_seg.F

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!||====================================================================
!||    nearest_seg   ../common_source/interf/nearest_seg.F
!||--- called by ------------------------------------------------------
!||    i3msr3        ../engine/source/interfaces/inter3d/i3msr3.F
!||    invoi3        ../starter/source/interfaces/inter3d1/invoi3.F
!||====================================================================
      SUBROUTINE nearest_seg(X, IS, M1, M2, M3, LSEG, LSEG_NEW, BMIN, BMAX)
C
C  COMPUTE BARYCENTRIC COORDINATES OF PROJECTION OF NODE IS ON TRIANGLE M1 M2 M3
C  WOLFGANG HEIDRICH, 2005
C-----------------------------------------------
C   I m p l i c i t   T y p e s
C-----------------------------------------------
#include      "implicit_f.inc"
C-----------------------------------------------
C   D u m m y   A r g u m e n t s
C-----------------------------------------------
        INTEGER, INTENT(IN)  :: IS, M1, M2, M3, LSEG
        INTEGER, INTENT(OUT) :: LSEG_NEW
        my_real, INTENT(IN)  :: x(3,*)
        my_real, INTENT(OUT) :: bmin
        my_real, INTENT(INOUT) :: bmax
C-----------------------------------------------
C   C o m m o n   B l o c k s
C-----------------------------------------------
C-----------------------------------------------
C   L o c a l   V a r i a b l e s
C-----------------------------------------------
        my_real n(3), u(3), v(3), w(3), uw(3), wv(3)
        my_real b0, b1, b2, fac
C---------------------------------------------------
        u(1)=x(1,m2)-x(1,m1)
        u(2)=x(2,m2)-x(2,m1)
        u(3)=x(3,m2)-x(3,m1)
C
        v(1)=x(1,m3)-x(1,m1)
        v(2)=x(2,m3)-x(2,m1)
        v(3)=x(3,m3)-x(3,m1)
C
        n(1)=u(2)*v(3)-u(3)*v(2)
        n(2)=u(3)*v(1)-u(1)*v(3)
        n(3)=u(1)*v(2)-u(2)*v(1)
C
        w(1)=x(1,is)-x(1,m1)
        w(2)=x(2,is)-x(2,m1)
        w(3)=x(3,is)-x(3,m1)
C
        uw(1)=u(2)*w(3)-u(3)*w(2)
        uw(2)=u(3)*w(1)-u(1)*w(3)
        uw(3)=u(1)*w(2)-u(2)*w(1)
C
        wv(1)=w(2)*v(3)-w(3)*v(2)
        wv(2)=w(3)*v(1)-w(1)*v(3)
        wv(3)=w(1)*v(2)-w(2)*v(1)
C
        fac=one/(n(1)*n(1)+n(2)*n(2)+n(3)*n(3))
        b2 =(uw(1)*n(1)+uw(2)*n(2)+uw(3)*n(3))*fac
        b1 =(wv(1)*n(1)+wv(2)*n(2)+wv(3)*n(3))*fac
        b0 = one - b1 - b2
        bmin=min(b0,b1,b2)
C BMIN > 0 Projection est a l'interieur du triangle
C BMIN = 0 Projection est sur un cote du triangle
C BMIN < 0 Projection est a l'exterieur du triangle
        IF(bmin > bmax) THEN
          lseg_new=lseg
          bmax=bmin
        ENDIF
        RETURN
      END