100 '***********　初期設定　************************************
110 CLS 3 : SCREEN 3 :OPTION BASE 1
120 SC=0 : W=1 '　描画用
130 X0=200 : Y0=350
140 PAI=3.141592653#
150 R=30 : ALP=.25#
160 PHAI=30/180*PAI
170 DIM XC(12),YC(12),XP(12),YP(12),XCL(12),YCL(12),XCR(12),YCR(12)
180 DIM XSL(12),YSL(12),XSR(12),YSR(12),PHASE(12)
190 DIST=30 : D=8 : H=10 : ZOOM=3
200 '***********　発生条件　************************************
210 N=4:'発生気筒数
220 PHASE(1)=0:PHASE(2)=1*2*PAI/2:PHASE(3)=1*2*PAI/2:PHASE(4)=0 '各気筒数における位相角
230 PHASE(5)=2*PAI/3:PHASE(6)=0:PHASE(7)=0:PHASE(8)=0
240 PHASE(9)=0:PHASE(10)=0:PHASE(11)=0:PHASE(12)=0
250 '**********  計算　＆　描画　ルーチン　*********************
255 XXX=5*COS(PHAI):YYY=5*SIN(PHAI)
260 FOR T=0 TO 2*PAI STEP .05
266  SC=W MOD 2 : DP=1+((W+1) MOD 2)*16
267  SCREEN ,,SC,DP
270  FOR I= 1 TO N STEP 1
280   XC(I)=R*COS(T+PHASE(I))/COS(PHAI)+DIST*I*COS(PHAI)
290   YC(I)=R*SIN(T+PHASE(I))-R*COS(T+PHASE(I))*TAN(PHAI)+DIST*I*SIN(PHAI)
300   XP(I)=DIST*I*COS(PHAI)
310   YP(I)=R*SIN(T+PHASE(I))+R/ALP*SQR(1-ALP^2*(COS(T+PHASE(I)))^2)+DIST*I*SIN(PHAI)
320   XSL(I)=DIST*I*COS(PHAI)-XXX : YSL(I)=DIST*I*SIN(PHAI)-YYY
330   XSR(I)=DIST*I*COS(PHAI)+XXX : YSR(I)=DIST*I*SIN(PHAI)+YYY
340   XCL(I)=XC(I)-XXX : YCL(I)=YC(I)-YYY
350   XCR(I)=XC(I)+XXX : YCR(I)=YC(I)+YYY
360  NEXT I
370  FOR I=1 TO N STEP 1
380   LINE(X0,Y0)-(X0+XSL(1),Y0-YSL(1)),7
390   LINE(X0+XSL(I),Y0-YSL(I))-(X0+XCL(I),Y0-YCL(I)),7
400   LINE(X0+XCL(I),Y0-YCL(I))-(X0+XCR(I),Y0-YCR(I)),7
410   LINE(X0+XCR(I),Y0-YCR(I))-(X0+XSR(I),Y0-YSR(I)),7
420   LINE(X0+XC(I),Y0-YC(I))-(X0+XP(I),Y0-YP(I)),7
425 '*************　ピストン描画　*************************************
430   CIRCLE (X0+XP(I),Y0-YP(I)),4
440   LINE (X0+XP(I)-D,Y0-YP(I)-H)-(X0+XP(I)-D,Y0-YP(I)+H)
450   LINE (X0+XP(I)+D,Y0-YP(I)-H)-(X0+XP(I)+D,Y0-YP(I)+H)
460   CIRCLE (X0+XP(I),Y0-YP(I)-H),D,,,,3/D
470  NEXT I
480  FOR P= 1 TO N-1 STEP 1
490   LINE (X0+XSR(P),Y0-YSR(P))-(X0+XSL(P+1),Y0-YSL(P+1))
500   LINE (X0+XSR(N),Y0-YSR(N))-(X0+(XSR(N)+DIST *COS(PHAI)),Y0-(YSR(N)+DIST *SIN(PHAI)))
510  NEXT P
950 SC2=(W+1) MOD 2:DP2=1+((W) MOD 2)*16
960 SCREEN ,, SC2,DP2
970 W=W+1
980 CLS 3
990 NEXT T
1000 GOTO 260