Explain Bresenham s circle drawing algorithm, OR Explain midpoint circle algorithm for scan converting a circle.
Midpoint Circle Algorithm 1. Input radius r and circle center (x c , y c) , and obtain the first point on the circumference of a circle centered on the origin as (x0, y0,) = (0, r) 2. Calculate the initial value of the decision parameter as p0 = 5/4-r 3. At each x k position, starting at k = 0, perform the following test: If p k <0 , the next point along the circle centered on (0,0) is (x k+1,y k) and p k+1 = p k + 2x k+1 + 1 Otherwise, the next point the circle is ( x k + 1, y k -1) and p k+1 = p k+ 2x k+1 + 1 -2 y k where 2x k+1 = 2xk +2 and 2yk+1 = 2y k -2. 4. Determine symmetry points in the other seven octants. 5. Move each calculated pixel position (x, y) onto the circular path centered on (x c,y c) and plot the coordinate values: x = x +x c, y = y + y c 6. Repeat steps 3 through 5 until x > y