Trailing-Edge
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PDP-10 Archives
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decuslib10-08
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43,50476/pltcut.for
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SUBROUTINE PLTCUT(IPLCUT,IX,IY,JX,JY,MINX,MINY,
1MAXX,MAXY)
C RENBR(/CLIP PORTION OF LINE OUTSIDE WINDOW)
C
C DONALD BARTH, CHEMISTRY DEPT., HARVARD UNIVERSITY
C
C ROUTINE BASED ON GENPLT-II PLOTTER COUPLING
C ROUTINES PUBLISHED IN VOLUME 3 OF COMPUTER
C PROGRAMS FOR CHEMISTRY
C
C IPLCUT = RETURNED AS 0 IF LINE DOES NOT PASS THRU
C WINDOW.
C = RETURNED AS 1 IF LINE PASSES THRU WINDOW
C
C IX = HORIZONTAL COORDINATE OF START OF LINE
C IY = VERTICAL COORDINATE OF START OF LINE
C JX = HORIZONTAL COORDINATE OF END OF LINE
C JY = VERTICAL COORDINATE OF END OF LINE
C MINX = HORIZONTAL COORDINATE OF LOWER LEFT
C CORNER OF WINDOW
C MINY = VERTICAL COORDINATE OF LOWER LEFT CORNER
C OF WINDOW
C MAXX = HORIZONTAL COORDINATE OF UPPER RIGHT
C CORNER OF WINDOW
C MAXY = VERTICAL COORDINATE OF UPPER RIGHT CORNER
C OF WINDOW
C
C ROUTINE RETURNS JX, JY, IX AND IY CHANGED IF
C WINDOWING IS NECESSARY
C
C TEST IF LINE NEEDS TO BE WINDOWED
IF(IX-MINX)8,1,1
1 IF(IX-MAXX)2,2,8
2 IF(JX-MINX)8,3,3
3 IF(JX-MAXX)4,4,8
4 IF(IY-MINY)8,5,5
5 IF(IY-MAXY)6,6,8
6 IF(JY-MINY)8,7,7
7 IF(JY-MAXY)38,38,8
8 IIX=IX
IIY=IY
IJX=JX
IJY=JY
MOVEX=JX-IX
MOVEY=JY-IY
C
C INTERSECTION WITH LEFT AND RIGHT BORDERS
IF(IIX-MINX)9,10,10
9 IIX=MINX
IF(IJX-MINX)36,14,14
10 IF(IIX-MAXX)12,12,11
11 IIX=MAXX
IF(IJX-MAXX)12,12,36
12 IF(IJX-MINX)13,14,14
13 IJX=MINX
GO TO 16
14 IF(IJX-MAXX)16,16,15
15 IJX=MAXX
16 IF(MOVEX)17,18,17
17 IIY=IY+((MOVEY*(IIX-IX))/MOVEX)
IJY=JY-((MOVEY*(JX-IJX))/MOVEX)
C
C INTERSECTION WITH LOWER AND UPPER BORDERS
18 IF(IIY-MINY)19,20,20
19 IIY=MINY
IF(IJY-MINY)36,24,24
20 IF(IIY-MAXY)22,22,21
21 IIY=MAXY
IF(IJY-MAXY)22,22,36
22 IF(IJY-MINY)23,24,24
23 IJY=MINY
GO TO 26
24 IF(IJY-MAXY)26,26,25
25 IJY=MAXY
26 IF(MOVEY)27,28,27
27 IIX=IX+((MOVEX*(IIY-IY))/MOVEY)
IJX=JX-((MOVEX*(JY-IJY))/MOVEY)
28 IF(IIX-MINX)29,30,30
29 IIX=MINX
30 IF(IIX-MAXX)32,32,31
31 IIX=MAXX
32 IF(IJX-MINX)33,34,34
33 IJX=MINX
34 IF(IJX-MAXX)37,37,35
35 IJX=MAXX
GO TO 37
C
C IPLCUT=0 IF LINE NOT WITHIN WINDOW
36 IPLCUT=0
GO TO 39
C
C IPLCUT=1 IF LINE IS WITHIN WINDOW
37 JX=IJX
JY=IJY
IX=IIX
IY=IIY
38 IPLCUT=1
C
C RETURN TO CALLING PROGRAM
39 RETURN
C372613660265
END