| 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 GNTRAP (X, PAR, IACT, IFLAG, SNEXT, SNXT, SAFE) |
| 13 | C. |
| 14 | C. ****************************************************************** |
| 15 | C. * * |
| 16 | C. * COMPUTE DISTANCE UP TO INTERSECTION WITH 'TRD1' OR 'TRD2' * |
| 17 | C. * VOLUME, FROM INSIDE POINT X(1-3) ALONG DIRECTION X(4-6) * |
| 18 | C. * * |
| 19 | C. * PAR (input) : volume parameters * |
| 20 | C. * IACT (input) : action flag * |
| 21 | C. * = 0 Compute SAFE only * |
| 22 | C. * = 1 Compute SAFE, and SNXT only if SNEXT .GT.new SAFE * |
| 23 | C. * = 2 Compute both SAFE and SNXT * |
| 24 | C. * = 3 Compute SNXT only * |
| 25 | C. * IFLAG (input) : 1 for TRD1, 2 for TRD2 * |
| 26 | C. * SNEXT (input) : see IACT = 1 * |
| 27 | C. * SNXT (output) : distance to volume boundary * |
| 28 | C. * SAFE (output) : shortest distance to any boundary * |
| 29 | C. * * |
| 30 | C. * ==>Called by : GNEXT, GTNEXT * |
| 31 | C. * Author A.McPherson, P.Weidhaas ********* * |
| 32 | C. * * |
| 33 | C. ****************************************************************** |
| 34 | C. |
| 35 | #include "geant321/gconsp.inc" |
| 36 | DIMENSION X(6),PAR(5) |
| 37 | C. |
| 38 | C. ------------------------------------------------------------------ |
| 39 | C. |
| 40 | SNXT = BIG |
| 41 | IF (IFLAG .EQ. 1) THEN |
| 42 | FACTX = (PAR(2) - PAR(1)) / (2.0 * PAR(4)) |
| 43 | ELSEIF (IFLAG .EQ. 2) THEN |
| 44 | FACTX = (PAR(2) - PAR(1)) / (2.0 * PAR(5)) |
| 45 | FACTY = (PAR(4) - PAR(3)) / (2.0 * PAR(5)) |
| 46 | ENDIF |
| 47 | |
| 48 | IF (IACT .LT. 3) THEN |
| 49 | |
| 50 | C ------------------------------------------------- |
| 51 | C | Compute safety-distance 'SAFE' (P.Weidhaas) | |
| 52 | C ------------------------------------------------- |
| 53 | |
| 54 | IF (IFLAG .EQ. 1) THEN |
| 55 | C******************************************************* |
| 56 | C |
| 57 | C...... Shape "TRD1": only x varies with z. |
| 58 | C |
| 59 | C******************************************************* |
| 60 | |
| 61 | SAF2 = PAR(3) - ABS(X(2)) |
| 62 | SAF3 = PAR(4) - ABS(X(3)) |
| 63 | C |
| 64 | C...... Distance alng x-direction to slanted wall. |
| 65 | C |
| 66 | DISTX = PAR(1) + FACTX * (PAR(4) + X(3)) - ABS(X(1)) |
| 67 | SAF1 = DISTX / SQRT (1.0 + FACTX*FACTX) |
| 68 | ELSE |
| 69 | C******************************************************* |
| 70 | C |
| 71 | C...... Shape "TRD2": both x and y vary with z. |
| 72 | C |
| 73 | C******************************************************* |
| 74 | SAF3 = PAR(5) - ABS(X(3)) |
| 75 | C |
| 76 | C...... Distance along x-direction to slanted wall. |
| 77 | C |
| 78 | DISTX = PAR(1) + FACTX * (PAR(5) + X(3)) - ABS(X(1)) |
| 79 | SAF1 = DISTX / SQRT (1.0 + FACTX*FACTX) |
| 80 | C |
| 81 | C...... Distance along y-direction to slanted wall. |
| 82 | C |
| 83 | DISTY = PAR(3) + FACTY * (PAR(5) + X(3)) - ABS(X(2)) |
| 84 | SAF2 = DISTY / SQRT (1.0 + FACTY*FACTY) |
| 85 | ENDIF |
| 86 | |
| 87 | SAFE = MIN (SAF1, SAF2, SAF3) |
| 88 | |
| 89 | IF (IACT .EQ. 0) GO TO 999 |
| 90 | IF (IACT .EQ. 1) THEN |
| 91 | IF (SNEXT .LT. SAFE) GO TO 999 |
| 92 | ENDIF |
| 93 | ENDIF |
| 94 | |
| 95 | |
| 96 | C ------------------------------------------------ |
| 97 | C | Compute vector-distance 'SNXT' (McPherson) | |
| 98 | C ------------------------------------------------ |
| 99 | |
| 100 | |
| 101 | IF(IFLAG.NE.1) GO TO 20 |
| 102 | C |
| 103 | C Only x-thickness varies with z. |
| 104 | C |
| 105 | C |
| 106 | C First check z. |
| 107 | C |
| 108 | ZEND=PAR(4) |
| 109 | IF(X(6).LT.0.0) ZEND=-ZEND |
| 110 | IF(X(6).EQ.0.)GO TO 5 |
| 111 | SNXT=(ZEND-X(3))/X(6) |
| 112 | C |
| 113 | C Now do Y. |
| 114 | C |
| 115 | 5 YEND=PAR(3) |
| 116 | IF(X(5).LT.0.0) YEND=-YEND |
| 117 | IF(X(5).EQ.0.)GO TO 7 |
| 118 | SN=(YEND-X(2))/X(5) |
| 119 | IF(SN.LT.SNXT) SNXT=SN |
| 120 | C |
| 121 | C Now do X. |
| 122 | C |
| 123 | 7 DXM=0.5*(PAR(1)+PAR(2)) |
| 124 | ANUM=DXM+FACTX*X(3)-X(1) |
| 125 | DENO=X(4)-FACTX*X(6) |
| 126 | C |
| 127 | IF(DENO.EQ.0.0) GO TO 10 |
| 128 | QUOT = ANUM/DENO |
| 129 | IF(QUOT.LE.0.0.OR.QUOT.GT.SNXT) GO TO 10 |
| 130 | SNXT=QUOT |
| 131 | GO TO 999 |
| 132 | C |
| 133 | 10 CONTINUE |
| 134 | C |
| 135 | ANUM=-FACTX*X(3)-X(1)-DXM |
| 136 | DENO=FACTX*X(6)+X(4) |
| 137 | C |
| 138 | IF(DENO.EQ.0.0) GO TO 999 |
| 139 | QUOT = ANUM/DENO |
| 140 | IF(QUOT.GT.0.0.AND.QUOT.LT.SNXT) SNXT=QUOT |
| 141 | C |
| 142 | GO TO 999 |
| 143 | 20 CONTINUE |
| 144 | C |
| 145 | C x- and y-thicknesses vary with z. |
| 146 | C |
| 147 | C |
| 148 | C First check z |
| 149 | C |
| 150 | ZEND=PAR(5) |
| 151 | IF(X(6).LT.0.0) ZEND=-ZEND |
| 152 | IF(X(6).EQ.0.)GO TO 25 |
| 153 | SNXT=(ZEND-X(3))/X(6) |
| 154 | C |
| 155 | C Now do x. |
| 156 | C |
| 157 | 25 DXM=0.5*(PAR(1)+PAR(2)) |
| 158 | ANUM=DXM+FACTX*X(3)-X(1) |
| 159 | DENO=X(4)-FACTX*X(6) |
| 160 | C |
| 161 | IF(DENO.EQ.0.0) GO TO 40 |
| 162 | QUOT = ANUM/DENO |
| 163 | IF(QUOT.LE.0.0.OR.QUOT.GT.SNXT) GO TO 40 |
| 164 | SNXT=QUOT |
| 165 | GO TO 60 |
| 166 | C |
| 167 | 40 CONTINUE |
| 168 | C |
| 169 | ANUM=-FACTX*X(3)-X(1)-DXM |
| 170 | DENO=FACTX*X(6)+X(4) |
| 171 | C |
| 172 | IF(DENO.EQ.0.0) GO TO 60 |
| 173 | QUOT = ANUM/DENO |
| 174 | IF(QUOT.GT.0.0.AND.QUOT.LT.SNXT) SNXT=QUOT |
| 175 | C |
| 176 | 60 CONTINUE |
| 177 | C |
| 178 | C Now do y. |
| 179 | C |
| 180 | DYM=0.5*(PAR(3)+PAR(4)) |
| 181 | ANUM=DYM+FACTY*X(3)-X(2) |
| 182 | DENO=X(5)-FACTY*X(6) |
| 183 | C |
| 184 | IF(DENO.EQ.0.0) GO TO 80 |
| 185 | QUOT = ANUM/DENO |
| 186 | IF(QUOT.LE.0.0.OR.QUOT.GT.SNXT) GO TO 80 |
| 187 | SNXT=QUOT |
| 188 | GO TO 999 |
| 189 | C |
| 190 | 80 CONTINUE |
| 191 | C |
| 192 | ANUM=-FACTY*X(3)-X(2)-DYM |
| 193 | DENO=FACTY*X(6)+X(5) |
| 194 | C |
| 195 | IF(DENO.EQ.0.0) GO TO 999 |
| 196 | QUOT = ANUM/DENO |
| 197 | IF(QUOT.GT.0.0.AND.QUOT.LT.SNXT) SNXT=QUOT |
| 198 | C |
| 199 | 999 CONTINUE |
| 200 | END |
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