CubeSpinner.bas

10 REM 3D SPINNING CUBE FOR ZX SPECTRUM
20 BORDER 0: PAPER 0: INK 6: CLS
30 DEF FN R(A)=A*PI/180
40 REM CUBE VERTICES (X, Y, Z) - 8 CORNERS
50 DIM V(8,3): DIM P(8,2): DIM O(8,2)
60 FOR I=1 TO 8: READ V(I,1),V(I,2),V(I,3): NEXT I
70 DATA -20,-20,-20,  20,-20,-20,  20, 20,-20, -20, 20,-20
80 DATA -20,-20, 20,  20,-20, 20,  20, 20, 20, -20, 20, 20
90 REM CUBE EDGES
100 DIM E(12,2)
110 FOR I=1 TO 12: READ E(I,1),E(I,2): NEXT I
120 DATA 1,2, 2,3, 3,4, 4,1
130 DATA 5,6, 6,7, 7,8, 8,5
140 DATA 1,5, 2,6, 3,7, 4,8
150 REM ANGLES AND PERSPECTIVE
160 LET AX=0: LET AY=0: LET AZ=0: LET D=150
170 REM --- MAIN LOOP ---
180 LET CX=COS FN R(AX): LET SX=SIN FN R(AX)
190 LET CY=COS FN R(AY): LET SY=SIN FN R(AY)
200 LET CZ=COS FN R(AZ): LET SZ=SIN FN R(AZ)
210 REM ROTATE AND PROJECT
220 FOR I=1 TO 8
230 LET X=V(I,1): LET Y=V(I,2): LET Z=V(I,3)
240 REM ROTATE X AXIS
250 LET Y1=Y*CX-Z*SX: LET Z1=Y*SX+Z*CX
260 REM ROTATE Y AXIS
270 LET X2=X*CY+Z1*SY: LET Z2=-X*SY+Z1*CY
280 REM ROTATE Z AXIS
290 LET X3=X2*CZ-Y1*SZ: LET Y3=X2*SZ+Y1*CZ
300 REM PERSPECTIVE
310 LET P(I,1)=127+(X3*D)/(Z2+100)
320 LET P(I,2)=87+(Y3*D)/(Z2+100)
330 NEXT I
340 REM DRAW NEW FRAME
350 CLS
360 INK 6
370 FOR I=1 TO 12
380 PLOT P(E(I,1),1),P(E(I,1),2): DRAW P(E(I,2),1)-P(E(I,1),1),P(E(I,2),2)-P(E(I,1),2)
390 NEXT I
400 REM SPIN
410 LET AX=AX+5: LET AY=AY+7: LET AZ=AZ+3
420 IF AX>360 THEN LET AX=AX-360
430 IF AY>360 THEN LET AY=AY-360
440 IF AZ>360 THEN LET AZ=AZ-360
450 GO TO 180