'===========================================================================
' Subject: EYE PLOT                          Date: 12-14-98 (14:35)       
' Author:  Dave Navarro, Jr.                 Code: QB, QBasic, PDS        
' Origin:  dave@powerbasic.com             Packet: GRAPHICS.ABC
'===========================================================================
'Eye Plot
'From "Microcomputer Graphics Techniques and Applications" by Donald Heard
'ported to PB by Dave Navarro (dave@powerbasic.com)

SCREEN 7

FOR I = -3.2 TO 3.05 STEP .05
  GOSUB DOPLOT
NEXT
  I = -3.2
  GOSUB DOPLOT

C = 10
DO
  SLEEP .05
  FOR I = -3.2 TO 3.05 STEP .05
    J = SIN(I) * 25
    K = COS(I) * 23
    L = SIN(I+.8) * 25
    M = COS(I+.8) * 23
    LINE (159-J, 99-K) - (159+L, 99+M), C
    IF LEN(INKEY$) THEN
      EXIT DO
    END IF
  NEXT
  C = C + 1
  IF C = 15 THEN C = 1
LOOP

END

DOPLOT:
  X = SIN(I) * 105
  Y = COS(I) * 90
  A = SIN(I+.6) * 105
  B = COS(I+.6) * 90
  J = SIN(I) * 25
  K = COS(I) * 23
  L = SIN(I+.8) * 25
  M = COS(I+.8) * 23
  LINE (159-X, 99-Y) - (159+A, 99+B)
  LINE (159-J, 99-K) - (159+L, 99+M), 9
  IF D THEN
    LINE (159-X, 99-Y) - (159 - D, 99 - E)
    LINE (159+A, 99+B) - (159 + F, 99 + G)
  END IF
  D = X
  E = Y
  F = A
  G = B
  RETURN