how to create line with bresenham algorythm ??

[hady1606]

hy masters ,, i want your help , cause i want to create line with bresenham algorythm , not with "line method" ... please help me ..
what i mean , is create a line from "dot"

submit your answer in reply message or you can send me message , in [e-mail]

thanks for your attention ..

[matthew]

I've never heard of Bresenham's Line Algorithm before (I had to look it up on Wikipedia) however if you're interested in drawing lines with dots then you should take a look at this example written by Tom; it's a 3D Function Graphics Calculator.

[DJLinux]

Here are one solution for the 2D mode.

By the way in the case of homework you should try it first self
and we can help if somethings goes wrong.

How ever Wikipedia can be your friend ;-)

DJ

' #######################
' # 2D mode(True/False) #
' #######################
sub Mode2D(onoff)
  if (onoff<>FALSE) then
    ' save current 3D mode and enable 2D mode
    glDisable(GL_DEPTH_TEST)
    glDisable(GL_LIGHTING)
    
    glMatrixMode(GL_PROJECTION)
    glPushMatrix() 
    glLoadIdentity()
    glOrtho(0,WindowWidth(),WindowHeight(),0,-1,1)
    
    glMatrixMode(GL_MODELVIEW)
    glPushMatrix()
    glLoadIdentity()
  else
    ' disable 2D and restore 3D mode
    glPopMatrix()
    glMatrixMode(GL_PROJECTION)
    
    glPopMatrix()     
    glMatrixMode(GL_MODELVIEW)
    
    glEnable(GL_LIGHTING)
    glEnable(GL_DEPTH_TEST)
  end if
end sub

' ###################################
' # Draw a line from x1,y1 to x2,y2 #
' ###################################
sub BresenhamLine(x1,y1,x2,y2)
  dim dx = x2-x1
  dim dy = y2-y1
  ' only one pixel
  if dx=0 land dy=0 then 
    glBegin(GL_POINTS)
    glVertex2f(x1,y1)
    glEnd()
    return
  end if

  dim adx = ABS(dx), ady = ABS(dy)
  dim sdx = SGN(dx), sdy = SGN(dy)
  dim pdx,pdy,ddx,ddy,es,el
  
  IF adx > ady THEN
    ' loop in x direction
    pdx = sdx: pdy = 0
    ddx = sdx: ddy = sdy
    es  = ady: el  = adx
  ELSE
    ' loop in y direction
    pdx = 0  : pdy = sdy
    ddx = sdx: ddy = sdy
    es  = adx: el  = ady
  END IF
 
  dim i,error = el/2 
  glBegin(GL_POINTS)
  glVertex2f(x1,y1)
  FOR i=1 TO el
    ' new error therm   
    error = error - es
    IF error < 0 THEN
      error = error + el
      x1 = x1 + ddx: y1 = y1 + ddy
    ELSE
      x1 = x1 + pdx: y1 = y1 + pdy
    END IF
    glVertex2f(x1,y1)
  NEXT
  glEnd()
end sub
' ################################
' # create a random float number #
' ################################
function RND#()
  return rnd()*(1.0/RND_MAX)
end function

dim w = WindowWidth()
dim h = WindowHeight()
dim frames
Mode2d(true)

while inkey$()=""
  frames=frames+1
  if frames % 50=0 then
    SwapBuffers()
    glClear(GL_COLOR_BUFFER_BIT) 
    sleep(10)
  end if
  glColor3ub(rnd#()*255,rnd#()*255,rnd#()*255)
  BresenhamLine(rnd#()*w,rnd#()*h,rnd#()*w,rnd#()*h)

wend
Mode2d(false)