Mid-Point Ellipse Drawing Algorithm..!!

Mid-Point Elliplse ( XC, YC, RX, RY):

Description: Here XC and YC denote the x – coordinate and y – coordinate of the center of the
ellipse and RX and RY denote the x – radius and y – radius respectively.

1.  Set RXSq = RX * RX
2.  Set RYSq = RY * RY
3.  Set X = 0 and Y = RY
4.  Set PX = 0 and PY = 2 * RXSq * Y
5.  Call Draw Elliplse(XC, YC, X, Y)
6.  Set P = RYSq – (RXSq * RY) + (0.25 * RXSq)                                            [Region 1]
7.  Repeat While (PX < PY)
8.    Set X = X + 1
9.    PX = PX + 2 * RYSq
10.    If (P < 0) Then
11.      Set P = P + RYSq + PX
12.    Else
13.      Set Y = Y – 1
14.      Set PY = PY – 2 * RXSq
15.      Set P = P + RYSq + PX – PY
    [End of If]
16.    Call Draw Elliplse(XC, YC, X, Y)
  [End of Step 7 While]
17.  Set P = RYSq*(X + 0.5)^2 + RXSq*(Y – 1)^2  – RXSq*RYSq                          [Region 2]
18.  Repeat While (Y > 0)
19.    Set Y = Y – 1
20.    Set PY = PY – 2 * RXSq
21.    If (P > 0) Then
22.      Set P = P + RXSq – PY
23.    Else
24.      Set X = X + 1
25.      Set PX + 2 * RYSq
26.      Set P = P + RXSq – PY + PX
    [End of If]
27.    Call Draw Ellipse(XC, YC, X, Y)
  [End of Step 18 While]
28.  Exit