[u/mrichter/AliRoot.git] / GEANT321 / ggeom / gntube.F

*
* $Id$
*
* $Log$
* Revision 1.1.1.1  1995/10/24 10:20:54  cernlib
* Geant
*
*
#include "geant321/pilot.h"
*CMZ :  3.21/02 29/03/94  15.41.30  by  S.Giani
*-- Author :
      SUBROUTINE GNTUBE(X,P,IACT,IFL,SNEXT,SNXT,SAFE)
C.    ******************************************************************
C.    *                                                                *
C.    *      Compute distance to intersection with boundary surface of *
C     *      volume TUBE or TUBS, from point X(1),X(2),X(3)  INSIDE    *
C     *      the volume along track with direction cosines X(4),X(5),  *
C     *      X(6)                                                      *
C.    *      P     (input)  : volume parameters                        *
C.    *      IACT  (input)  : action flag                              *
C.    *         = 0  Compute SAFE only                                 *
C.    *         = 1  Compute SAFE, compute SNXT only if SAFE.LT.SNEXT  *
C.    *         = 2  Compute both SAFE and SNXT                        *
C.    *         = 3  Compute SNXT only                                 *
C.    *      IFL   (input)  : 1 for TUBE, 2 for PHI segmented TUBE     *
C.    *      SNEXT (input)  : see IACT = 1                             *
C.    *      SNXT  (output) : distance to volume boundary along track  *
C.    *      SAFE  (output) : not larger than scalar distance to       *
C.    *                       volume boundaray                         *
C.    *      Called by : GNEXT, GNPCON, GTNEXT                         *
C.    *                                                                *
C.    *      Authors   : Michel Maire and Rolf Nierhaus    21-JUN-1990 *
C.    *                                                                *
C.    ******************************************************************
C.    *                                                                *
C.    * 'TUBE'    is a tube. It has 3 parameters, the inside radius,   *
C.    *           the outside radius and the half length in z.         *
C.    * 'TUBS'    is a phi segment of a  tube.  It has 5 parameters,   *
C.    *           the same  3 as  'TUBE' plus  the phi  limits.  The   *
C.    *           segment  starts at  the first  limit and  includes   *
C.    *           increasing phi  value up  to the  second limit  or   *
C.    *           that plus 360 degrees.                               *
C.    *                                                                *
C.    ******************************************************************
#include "geant321/gconsp.inc"
      DIMENSION X(6),P(5)
*
*     this part has to be moved outside the routine
      IF (IFL.EQ.2) THEN
         P4=P(4)*DEGRAD
         P5=P(5)*DEGRAD
         IF (P5.LT.P4) P5=P5+TWOPI
         C1=COS(P4)
         S1=SIN(P4)
         C2=COS(P5)
         S2=SIN(P5)
         FIO=0.5*(P5+P4)
         CFIO=COS(FIO)
         SFIO=SIN(FIO)
      END IF
*
      SNXT=1.E10
      R=SQRT(X(1)**2+X(2)**2)
*
*     Compute SAFE radius
      IF (IACT.LT.3) THEN
         SAF1=R-P(1)
         SAF2=P(2)-R
         SAF3=P(3)-ABS(X(3))
         SAF4=1.E10
         IF (IFL.EQ.2) THEN
            IF ((X(2)*CFIO-X(1)*SFIO).LE.0.) THEN
               SAF4=ABS(X(1)*S1-X(2)*C1)
            ELSE
               SAF4=ABS(X(1)*S2-X(2)*C2)
            END IF
         ENDIF
         SAFE=MIN(SAF1,SAF2,SAF3,SAF4)
         IF (IACT.EQ.0) GO TO 999
         IF (IACT.EQ.1.AND.SNEXT.LE.SAFE) GO TO 999
      END IF
*
*     Intersection with z-plane
      IF (X(6).GT.1.E-20) THEN
         SZ= (P(3)-X(3))/X(6)
      ELSEIF (X(6).LT.-1.E-20) THEN
         SZ=-(P(3)+X(3))/X(6)
      ELSE
         SZ=1.E10
      END IF
*
*     Intersection with cylinders
*     Intersection point (x,y,z)
*     (x,y,z) is on track :    x=X(1)+t*X(4)
*                              y=X(2)+t*X(5)
*                              z=X(3)+t*X(6)
*     (x,y,z) is on cylinder : x**2 + y**2 = R**2
*
*     (X(4)**2+X(5)**2)*t**2
*     +2.*(X(1)*X(4)+X(2)*X(5))*t
*     +X(1)**2+X(2)**2-R**2=0
*
      T1=X(4)**2+X(5)**2
      T2=(X(1)*X(4)+X(2)*X(5))
      T3=X(1)**2+X(2)**2
      IF (T1.LE.0.) THEN
*        track parallel to the z-axis
         SNXT=SZ
         GO TO 999
      ENDIF
      B=T2/T1
*
*     Intersection with inner cylinder
      IF (P(1).GT.0.) THEN
         C=(T3-P(1)**2)/T1
         D=B**2-C
         IF (D.GE.0.) THEN
            SR=-B-SQRT(D)
            IF (SR.GE.0.) GO TO 101
         END IF
      END IF
*     Intersection with outer cylinder
         C=(T3-P(2)**2)/T1
         D=MAX(B**2-C,0.)
         SR=-B+SQRT(D)
*
*     Intersection with phi-planes
*     x=r*cos(phi)=X(1)+t*X(4)
*     y=r*sin(phi)=X(2)+t*X(5)
*     z           =X(3)+t*X(6)
*     t=(X(2)*cos(phi)-X(1)*sin(phi))/(X(4)*sin(phi)-X(5)*cos(phi))
  101 SFI1=1.E10
      SFI2=1.E10
      IF (IFL.EQ.2) THEN
*        track not parallel to the phi1 plane ?
         UN=X(4)*S1-X(5)*C1
         IF (UN.NE.0.) THEN
            S=(X(2)*C1-X(1)*S1)/UN
            IF (S.GE.0.) THEN
               XI=X(1)+S*X(4)
               YI=X(2)+S*X(5)
               IF ((YI*CFIO-XI*SFIO).LE.0.) SFI1=S
            END IF
         END IF
*        track not parallel to the phi2 plane ?
         UN=X(4)*S2-X(5)*C2
         IF (UN.NE.0.) THEN
            S=(X(2)*C2-X(1)*S2)/UN
            IF (S.GE.0.) THEN
               XI=X(1)+S*X(4)
               YI=X(2)+S*X(5)
               IF ((YI*CFIO-XI*SFIO).GE.0.) SFI2=S
            END IF
         END IF
      END IF
*
      SNXT=MIN(SZ,SR,SFI1,SFI2)
  999 END
Commit	Line	Data
fe4da5cc	1	*
	2	* $Id$
	3	*
	4	* $Log$
	5	* Revision 1.1.1.1 1995/10/24 10:20:54 cernlib
	6	* Geant
	7	*
	8	*
	9	#include "geant321/pilot.h"
	10	*CMZ : 3.21/02 29/03/94 15.41.30 by S.Giani
	11	*-- Author :
	12	SUBROUTINE GNTUBE(X,P,IACT,IFL,SNEXT,SNXT,SAFE)
	13	C. ******************************************************************
	14	C. * *
	15	C. * Compute distance to intersection with boundary surface of *
	16	C * volume TUBE or TUBS, from point X(1),X(2),X(3) INSIDE *
	17	C * the volume along track with direction cosines X(4),X(5), *
	18	C * X(6) *
	19	C. * P (input) : volume parameters *
	20	C. * IACT (input) : action flag *
	21	C. * = 0 Compute SAFE only *
	22	C. * = 1 Compute SAFE, compute SNXT only if SAFE.LT.SNEXT *
	23	C. * = 2 Compute both SAFE and SNXT *
	24	C. * = 3 Compute SNXT only *
	25	C. * IFL (input) : 1 for TUBE, 2 for PHI segmented TUBE *
	26	C. * SNEXT (input) : see IACT = 1 *
	27	C. * SNXT (output) : distance to volume boundary along track *
	28	C. * SAFE (output) : not larger than scalar distance to *
	29	C. * volume boundaray *
	30	C. * Called by : GNEXT, GNPCON, GTNEXT *
	31	C. * *
	32	C. * Authors : Michel Maire and Rolf Nierhaus 21-JUN-1990 *
	33	C. * *
	34	C. ******************************************************************
	35	C. * *
	36	C. * 'TUBE' is a tube. It has 3 parameters, the inside radius, *
	37	C. * the outside radius and the half length in z. *
	38	C. * 'TUBS' is a phi segment of a tube. It has 5 parameters, *
	39	C. * the same 3 as 'TUBE' plus the phi limits. The *
	40	C. * segment starts at the first limit and includes *
	41	C. * increasing phi value up to the second limit or *
	42	C. * that plus 360 degrees. *
	43	C. * *
	44	C. ******************************************************************
	45	#include "geant321/gconsp.inc"
	46	DIMENSION X(6),P(5)
	47	*
	48	* this part has to be moved outside the routine
	49	IF (IFL.EQ.2) THEN
	50	P4=P(4)*DEGRAD
	51	P5=P(5)*DEGRAD
	52	IF (P5.LT.P4) P5=P5+TWOPI
	53	C1=COS(P4)
	54	S1=SIN(P4)
	55	C2=COS(P5)
	56	S2=SIN(P5)
	57	FIO=0.5*(P5+P4)
	58	CFIO=COS(FIO)
	59	SFIO=SIN(FIO)
	60	END IF
	61	*
	62	SNXT=1.E10
	63	R=SQRT(X(1)2+X(2)2)
	64	*
65	* Compute SAFE radius
66	IF (IACT.LT.3) THEN
67	SAF1=R-P(1)
68	SAF2=P(2)-R
69	SAF3=P(3)-ABS(X(3))
70	SAF4=1.E10
71	IF (IFL.EQ.2) THEN
72	IF ((X(2)CFIO-X(1)SFIO).LE.0.) THEN
73	SAF4=ABS(X(1)S1-X(2)C1)
74	ELSE
75	SAF4=ABS(X(1)S2-X(2)C2)
76	END IF
77	ENDIF
78	SAFE=MIN(SAF1,SAF2,SAF3,SAF4)
79	IF (IACT.EQ.0) GO TO 999
80	IF (IACT.EQ.1.AND.SNEXT.LE.SAFE) GO TO 999
81	END IF
82	*
83	* Intersection with z-plane
84	IF (X(6).GT.1.E-20) THEN
85	SZ= (P(3)-X(3))/X(6)
86	ELSEIF (X(6).LT.-1.E-20) THEN
87	SZ=-(P(3)+X(3))/X(6)
88	ELSE
89	SZ=1.E10
90	END IF
91	*
92	* Intersection with cylinders
93	* Intersection point (x,y,z)
94	* (x,y,z) is on track : x=X(1)+t*X(4)
95	* y=X(2)+t*X(5)
96	* z=X(3)+t*X(6)
97	* (x,y,z) is on cylinder : x2 + y2 = R**2
98	*
99	* (X(4)2+X(5)2)t*2
100	* +2.(X(1)X(4)+X(2)X(5))t
101	* +X(1)2+X(2)2-R**2=0
102	*
103	T1=X(4)2+X(5)2
104	T2=(X(1)X(4)+X(2)X(5))
105	T3=X(1)2+X(2)2
106	IF (T1.LE.0.) THEN
107	* track parallel to the z-axis
108	SNXT=SZ
109	GO TO 999
110	ENDIF
111	B=T2/T1
112	*
113	* Intersection with inner cylinder
114	IF (P(1).GT.0.) THEN
115	C=(T3-P(1)**2)/T1
116	D=B**2-C
117	IF (D.GE.0.) THEN
118	SR=-B-SQRT(D)
119	IF (SR.GE.0.) GO TO 101
120	END IF
121	END IF
122	* Intersection with outer cylinder
123	C=(T3-P(2)**2)/T1
124	D=MAX(B**2-C,0.)
125	SR=-B+SQRT(D)
126	*
127	* Intersection with phi-planes
128	* x=rcos(phi)=X(1)+tX(4)
129	* y=rsin(phi)=X(2)+tX(5)
130	* z =X(3)+t*X(6)
131	* t=(X(2)cos(phi)-X(1)sin(phi))/(X(4)sin(phi)-X(5)cos(phi))
132	101 SFI1=1.E10
133	SFI2=1.E10
134	IF (IFL.EQ.2) THEN
135	* track not parallel to the phi1 plane ?
136	UN=X(4)S1-X(5)C1
137	IF (UN.NE.0.) THEN
138	S=(X(2)C1-X(1)S1)/UN
139	IF (S.GE.0.) THEN
140	XI=X(1)+S*X(4)
141	YI=X(2)+S*X(5)
142	IF ((YICFIO-XISFIO).LE.0.) SFI1=S
143	END IF
144	END IF
145	* track not parallel to the phi2 plane ?
146	UN=X(4)S2-X(5)C2
147	IF (UN.NE.0.) THEN
148	S=(X(2)C2-X(1)S2)/UN
149	IF (S.GE.0.) THEN
150	XI=X(1)+S*X(4)
151	YI=X(2)+S*X(5)
152	IF ((YICFIO-XISFIO).GE.0.) SFI2=S
153	END IF
154	END IF
155	END IF
156	*
157	SNXT=MIN(SZ,SR,SFI1,SFI2)
158	999 END