'===========================================================================
' Subject: MASKS                             Date: 08-15-00 (15:47)       
' Author:  Jacob Wieles                      Code: QB, QBasic, PDS, PB    
' Origin:  j.wieles@hccnet.nl              Packet: GRAPHICS.ABC
'===========================================================================
'programma      : MASKS.BAS   (15-08-2000)
'               : Playing with sine and cosine and find masks
'
'auteur         : Jacob Wieles
'basics ?       : PowerBASIC and Q(uick)BASIC

defint b-z
defdbl a,p
ColOn=1
ColOff=0
screen 12
'Find out on which basic the program runs
  out &H3C7,15
  cr=inp(&H3C9)
  cg=inp(&H3C9)
  cb=inp(&H3C9)
'    if cr=42 then the program runs on PowerBasic
'    if cr=63 then the program runs on Q(uick)Basic
  timedivisor=100'=====================>> For PowerBASIC
  if cr=63 then timedivisor=8'=========>> For Q(uick)BASIC
'The value for the timedivisor are found for a Pentium 100 PC
'For an other PC maybe you must change this value
'To prevent flickering monitor and SetUpDrawSpeed
  t!=timer
  wp&=0
  do while timer< t!+1
    wp&=wp&+1
  loop
DrawLoop&=wp&/timedivisor
TS$=" Key for stop. "
XM=point(0)
YM=point(1)
pi=4*atn(1)
window (-XM,-YM)-(XM-1,YM-1)
Radius=(YM-4)/2
TotalMask=12
RunFlag=1
restore ShapeMaskNumb
for Mask=1 to TotalMask
  read ShapeNumber
  SidePolygon=720/ShapeNumber
  locate 1,60
  print Mask;"from";TotalMask
  DrawColor=ColOn
  gosub DrawMask
  t!=timer
  while timer< t!+2:wend
  DrawColor=ColOff
  gosub DrawMask
next Mask
QuitProg:
cls
screen 0
print" Hit a key for the source."
end

DrawMask:
  locate 1,1
  print TS$
  for DrawStep=0 to 720
    Angle=DrawStep*2*pi/720
    Angle2=ShapeNumber*Angle
    R1=Radius*sin(Angle2+Angle)
    X1=Radius*cos(Angle2-Angle)
    Y1=R1*sin(Angle)
    X=X1+Radius*cos(Angle)
    Y=Y1+Radius*sin(Angle2-Angle)
    col=14-DrawStep mod SidePolygon
    if DrawColor=ColOff then col=0
    if DrawStep=0 then
      pset (X,Y)
    else
      line -(X,Y),col
      for w&=0 to DrawLoop&:next w&
    end if
    inv$=inkey$
    if inv$<>"" then gosub KeyNext
    if RunFlag=0 then goto QuitProg
  next DrawStep
return

KeyNext:
RunFlag=1
locate 1,1
print" Key for go on."
locate 2,1
print" Esc for end. "
do
keyhit$=inkey$
loop until keyhit$<>""
if keyhit$=CHR$(27) then RunFlag=0
locate 1,1
print TS$
locate 2,1
print string$(14," ")
return

ShapeMaskNumb:
data 120,121,122,142,146,178,179,180,181,182,238,242