The ellipse has a major and minor axis. If a1 and b1are major and minor axis respectively. The centre of ellipse is (i, j). The value of x will be incremented from i to a1and value of y will be calculated using the following formula
Drawback of Polynomial Method:
- It requires squaring of values. So floating point calculation is required.
- Routines developed for such calculations are very complex and slow.
1. Set the initial variables: a = length of major axis; b = length of minor axis; (h, k) = coordinates of ellipse center; x = 0; i = step; xend = a.
2. Test to determine whether the entire ellipse has been scan-converted. If x>xend, stop.
3. Compute the value of the y coordinate:
4. Plot the four points, found by symmetry, at the current (x, y) coordinates:
Plot (x + h, y + k) Plot (-x + h, -y + k) Plot (-y – h, x + k) Plot (y + h, -x + k)
5. Increment x; x = x + i.
6. Go to step 2.
Program to draw an Ellipse using Polynomial Method: