CONST numr = 1000 : REM num of random position in pool CONST nums = 20 : REM number of stars in starfield CONST speed = 8 : REM speed of stars (smaller = faster) CONST clock = 50 : REM Number of TI per second CONST bg = BLACK : REM background color CONST fg = WHITE : REM forteground color DIM xrnd AS POSITION (numr+1) DIM yrnd AS POSITION (numr+1) DIM xtab AS POSITION (nums+1) DIM ytab AS POSITION (nums+1) BITMAP ENABLE (320,200,2) REM BITMAP ENABLE(320,200,4) REM BITMAP ENABLE(160,200,16) CLS bg COLOR BORDER bg REM init pool of random position (faster than calling RND over and over again) FOR i=0 TO numr xrnd(i) = RND(SCREEN WIDTH) yrnd(i) = RND(SCREEN HEIGHT) NEXT irnd = 0 REM initial stars FOR i=0 TO nums ' REPEAT : c = RND(SCREEN COLORS) : UNTIL c<>bg xtab(i) = RND(SCREEN WIDTH) ytab(i) = RND(SCREEN HEIGHT) PLOT xtab(i),ytab(i),fg NEXT VAR x0 AS SIGNED WORD = (SCREEN WIDTH / 2) VAR y0 AS SIGNED WORD = (SCREEN HEIGHT / 2) VAR x AS SIGNED WORD = 0 VAR y AS SIGNED WORD = 0 VAR z AS SIGNED WORD = 0 VAR t AS SIGNED WORD = 0 VAR dx AS SIGNED WORD = 0 VAR dy AS SIGNED WORD = 0 TI=0: frames = 0 DO INC frames PLOT x0,y0,WHITE IF TI>=clock THEN LOCATE 0,0 : PRINT frames;" "; frames = 0 TI = 0 ENDIF FOR i=0 TO nums z = xtab(i) x = z + (z - x0)/speed t = ytab(i) y = t + (t - y0)/speed IF (((x OR y)<0) OR (y>=SCREEN HEIGHT)) OR (x>=SCREEN WIDTH) THEN REPEAT x = xrnd(irnd) y = yrnd(irnd) ADD irnd,1,0 TO numr REM avoid fixed stars, these are the ones where REM ((x-x0)/speed)==0 or ((y-y0)/speed)==0 REM which result in the folowing bitwise AND expression UNTIL ((x-x0)/speed) AND ((y-y0)/speed) ENDIF xtab(i) = x ytab(i) = y PLOT z,t,bg PLOT x,y,fg 'PLOT x,y,bg NEXT WAIT VBL joy = JOY(0) : dx = 0 : dy = 0 IF joy HAS BIT LEFT THEN : DEC dx : ENDIF IF joy HAS BIT RIGHT THEN : INC dx : ENDIF IF joy HAS BIT UP THEN : DEC dy : ENDIF IF joy HAS BIT DOWN THEN : INC dy : ENDIF IF (dx OR dy)<>0 THEN IF joy HAS BIT FIRE THEN : MUL dx,4 : MUL dy,4 : ENDIF PLOT x0,y0,bg ADD x0,dx,0 TO SCREEN WIDTH ADD y0,dy,0 TO SCREEN HEIGHT ENDIF LOOP