COMMENT ⊗   VALID 00003 PAGES
C REC  PAGE   DESCRIPTION
C00001 00001
C00002 00002	PROCEDURE PICLIN(REAL X1,Y1,X2,Y2,BR
C00004 00003	PROCEDURE PIXLIN(REAL X1,Y1,X2,Y2,BR
C00007 ENDMK
C⊗;
PROCEDURE PICLIN(REAL X1,Y1,X2,Y2,BR;
                 REFERENCE INTEGER PIC;
                 REAL XLO(0),YLO(0),XHI(1),YHI(1));
   BEGIN
   REAL LEN,DX,DY,DTX,DTY,TX,TY,T; INTEGER IX,IY,IDX,IDY;
   X1←MEMORY[LOCATION(PIC)+LNBY]*(X1-XLO)/(XHI-XLO);
   X2←MEMORY[LOCATION(PIC)+LNBY]*(X2-XLO)/(XHI-XLO);
   Y1←MEMORY[LOCATION(PIC)+LNBY]*(Y1-YLO)/(YHI-YLO);
   Y2←MEMORY[LOCATION(PIC)+LNBY]*(Y2-YLO)/(YHI-YLO);
   DX←X2-X1; DY←Y2-Y1;
   IDX←IF DX>0 THEN 1 ELSE -1;
   IDY←IF DY>0 THEN 1 ELSE -1;
   LEN←SQRT(DX↑2+DY↑2);
   DTX←ABS(LEN/(X2-X1));  DTY←ABS(LEN/(Y2-Y1));
   IX←X1; IY←Y1;
   TX←(X1-IX)/DX; IF TX<0 THEN TX←(X1-IX-1)/DX;
   TX←TX*SQRT(1+DY↑2);
   TY←(Y1-IY)/DY; IF TY<0 THEN TY←(Y1-IY-1)/DY;
   TY←TY*SQRT(1+DX↑2);
   T←0;
   BR←BR*MEMORY[LOCATION(PIC)+BMAX]/SQRT(2);
   OUTSTR("BR "&CVF(BR)&"  TX "&CVF(TX)&"  TY "&CVF(TY)&"  DTX "&CVF(DTX)&"  DTY "&CVF(DTY)&'15&'12);
   WHILE T<LEN DO IF TX+DTX<TY+DTY THEN
      BEGIN
      TX←(TX+DTX) MIN LEN;
      ADDEL(PIC,IY,IX,(TX-T)*BR);
      T←TX;
      IX←IX+IDX;
      END
   ELSE
      BEGIN
      TY←(TY+DTY) MIN LEN;
      ADDEL(PIC,IY,IX,(TY-T)*BR);
      T←TY;
      IY←IY+IDY;
      END;
   END;

PROCEDURE PIXLIN(REAL X1,Y1,X2,Y2,BR;
                 REFERENCE INTEGER PIC;
                 REAL XLO(0),YLO(0),XHI(1),YHI(1));
   BEGIN
   SAFE REAL ARRAY WT[-1:1,-1:1];
   REAL LEN,DX,DY,DTX,DTY,TX,TY,T,CON; INTEGER IX,IY,IDX,IDY;
   X1←MEMORY[LOCATION(PIC)+LNBY]*(X1-XLO)/(XHI-XLO);
   X2←MEMORY[LOCATION(PIC)+LNBY]*(X2-XLO)/(XHI-XLO);
   Y1←MEMORY[LOCATION(PIC)+LNBY]*(Y1-YLO)/(YHI-YLO);
   Y2←MEMORY[LOCATION(PIC)+LNBY]*(Y2-YLO)/(YHI-YLO);
   DX←X2-X1; DY←Y2-Y1;
   IDX←IF DX>0 THEN 1 ELSE -1;
   IDY←IF DY>0 THEN 1 ELSE -1;
   LEN←SQRT(DX↑2+DY↑2);
   DTX←ABS(LEN/(X2-X1));  DTY←ABS(LEN/(Y2-Y1));
   IX←X1; IY←Y1;
   TX←(X1-IX)/DX; IF TX<0 THEN TX←(X1-IX-1)/DX;
   TX←TX*SQRT(1+DY↑2);
   TY←(Y1-IY)/DY; IF TY<0 THEN TY←(Y1-IY-1)/DY;
   TY←TY*SQRT(1+DX↑2);
   T←0;
   BR←BR*MEMORY[LOCATION(PIC)+BMAX]/SQRT(2);
   CON←X1*Y2-X2*Y1;
   OUTSTR("BR "&CVF(BR)&"  TX "&CVF(TX)&"  TY "&CVF(TY)&"  DTX "&CVF(DTX)&"  DTY "&CVF(DTY)&'15&'12);
   WHILE T<LEN DO IF TX+DTX<TY+DTY THEN
      BEGIN
      INTEGER II,JJ; REAL VAL;
      TX←(TX+DTX) MIN LEN;
      VAL←0;
      FOR II←-1,0,1 DO
      FOR JJ←-1,0,1 DO
         BEGIN
         WT[II,JJ]←(LEN-ABS((II+IY)*DX-(JJ+IX)*DY+CON)) MAX 0;
         VAL←VAL+WT[II,JJ];
         END;
      FOR II←-1,0,1 DO
      FOR JJ←-1,0,1 DO
         ADDEL(PIC,II+IY,JJ+IX,BR*(TX-T)*WT[II,JJ]/VAL);
      T←TX;
      IX←IX+IDX;
      END
   ELSE
      BEGIN
      INTEGER II,JJ; REAL VAL;
      TY←(TY+DTY) MIN LEN;
      VAL←0;
      FOR II←-1,0,1 DO
      FOR JJ←-1,0,1 DO
         BEGIN
         WT[II,JJ]←(LEN-ABS((II+IY)*DX-(JJ+IX)*DY+CON)) MAX 0;
         VAL←VAL+WT[II,JJ];
         END;
      FOR II←-1,0,1 DO
      FOR JJ←-1,0,1 DO
         ADDEL(PIC,II+IY,JJ+IX,BR*(TX-T)*WT[II,JJ]/VAL);
      T←TY;
      IY←IY+IDY;
      END;
   END;