[u/mrichter/AliRoot.git] / GEANT321 / cgpack / cghpla.F.ori

*
* $Id$
*
* $Log$
* Revision 1.1.1.1  1995/10/24 10:19:44  cernlib
* Geant
*
*
#include "geant321/pilot.h"
*CMZ :  3.21/02 29/03/94  15.41.31  by  S.Giani
*-- Author :
      SUBROUTINE CGHPLA(IFACE,XYZ,ABCD)
************************************************************************
*                                                                      *
*     Name: CGHPLA                                                     *
*     Author: E. Chernyaev                       Date:    08.08.88     *
*                                                Revised:              *
*                                                                      *
*     Function: Compute face plane equation coefficients:              *
*                    Ax + By + Cz + D = 0                              *
*                                                                      *
*     References: none                                                 *
*                                                                      *
*     Input: IFACE(*) - face                                           *
*            XYZ(3,*) - node coordinates                               *
*                                                                      *
*     Output: ABCD(4) - plane equation coefficients                    *
*                                                                      *
*     Errors: none                                                     *
*                                                                      *
************************************************************************
      REAL            XYZ(3,*),ABCD(4),GRAV(3)
*SG
      INTEGER         IFACE(*)
*SG
*-
      NEDGE = IFACE(1)
      A      = 0.
      B      = 0.
      C      = 0.
      GRAV(1)= 0.
      GRAV(2)= 0.
      GRAV(3)= 0.
      JF     = 2
      DO 100 NE=1,NEDGE
        N1     = IFACE(JF)
        N2     = IFACE(JF+1)
        JF     = JF + 2
        A      = A + XYZ(2,N1)*XYZ(3,N2) - XYZ(2,N2)*XYZ(3,N1)
        B      = B + XYZ(3,N1)*XYZ(1,N2) - XYZ(3,N2)*XYZ(1,N1)
        C      = C + XYZ(1,N1)*XYZ(2,N2) - XYZ(1,N2)*XYZ(2,N1)
        GRAV(1)= GRAV(1) + XYZ(1,N1) + XYZ(1,N2)
        GRAV(2)= GRAV(2) + XYZ(2,N1) + XYZ(2,N2)
        GRAV(3)= GRAV(3) + XYZ(3,N1) + XYZ(3,N2)
  100   CONTINUE
      HNGRAV = 0.5/NEDGE
      GRAV(1)= GRAV(1) * HNGRAV
      GRAV(2)= GRAV(2) * HNGRAV
      GRAV(3)= GRAV(3) * HNGRAV
      IF (ABS(A) .LT. 0.000001) A=0.
      IF (ABS(B) .LT. 0.000001) B=0.
      IF (ABS(C) .LT. 0.000001) C=0.
      AREAI  = 1./SQRT(A*A + B*B + C*C)
      ABCD(1)= A * AREAI
      ABCD(2)= B * AREAI
      ABCD(3)= C * AREAI
      ABCD(4)=-(A*GRAV(1) + B*GRAV(2) + C*GRAV(3)) * AREAI
      END
Commit	Line	Data
fe4da5cc	1	*
	2	* $Id$
	3	*
	4	* $Log$
	5	* Revision 1.1.1.1 1995/10/24 10:19:44 cernlib
	6	* Geant
	7	*
	8	*
	9	#include "geant321/pilot.h"
	10	*CMZ : 3.21/02 29/03/94 15.41.31 by S.Giani
	11	*-- Author :
	12	SUBROUTINE CGHPLA(IFACE,XYZ,ABCD)
	13	************************************************************************
	14	* *
	15	* Name: CGHPLA *
	16	* Author: E. Chernyaev Date: 08.08.88 *
	17	* Revised: *
	18	* *
	19	* Function: Compute face plane equation coefficients: *
	20	* Ax + By + Cz + D = 0 *
	21	* *
	22	* References: none *
	23	* *
	24	* Input: IFACE() - face
	25	* XYZ(3,) - node coordinates
	26	* *
	27	* Output: ABCD(4) - plane equation coefficients *
	28	* *
	29	* Errors: none *
	30	* *
	31	************************************************************************
	32	REAL XYZ(3,*),ABCD(4),GRAV(3)
	33	*SG
	34	INTEGER IFACE(*)
	35	*SG
	36	*-
	37	NEDGE = IFACE(1)
	38	A = 0.
	39	B = 0.
	40	C = 0.
	41	GRAV(1)= 0.
	42	GRAV(2)= 0.
	43	GRAV(3)= 0.
	44	JF = 2
	45	DO 100 NE=1,NEDGE
	46	N1 = IFACE(JF)
	47	N2 = IFACE(JF+1)
	48	JF = JF + 2
	49	A = A + XYZ(2,N1)XYZ(3,N2) - XYZ(2,N2)XYZ(3,N1)
	50	B = B + XYZ(3,N1)XYZ(1,N2) - XYZ(3,N2)XYZ(1,N1)
	51	C = C + XYZ(1,N1)XYZ(2,N2) - XYZ(1,N2)XYZ(2,N1)
	52	GRAV(1)= GRAV(1) + XYZ(1,N1) + XYZ(1,N2)
	53	GRAV(2)= GRAV(2) + XYZ(2,N1) + XYZ(2,N2)
	54	GRAV(3)= GRAV(3) + XYZ(3,N1) + XYZ(3,N2)
	55	100 CONTINUE
	56	HNGRAV = 0.5/NEDGE
	57	GRAV(1)= GRAV(1) * HNGRAV
	58	GRAV(2)= GRAV(2) * HNGRAV
	59	GRAV(3)= GRAV(3) * HNGRAV
	60	IF (ABS(A) .LT. 0.000001) A=0.
	61	IF (ABS(B) .LT. 0.000001) B=0.
	62	IF (ABS(C) .LT. 0.000001) C=0.
	63	AREAI = 1./SQRT(AA + BB + C*C)
	64	ABCD(1)= A * AREAI
65	ABCD(2)= B * AREAI
66	ABCD(3)= C * AREAI
67	ABCD(4)=-(AGRAV(1) + BGRAV(2) + CGRAV(3)) AREAI
68	END