Explain Bresenhams Line Drawing Algorithm?
Bresenhams line drawing algorithm
In Bresenham’s approach the pixel position along a line path are determined by sampling unit X intervals.
Starting from the left end point(X0, Y0)of a given line we step to each successive columns and plot the pixel whose scan line Y-value is closest to the line path.Assuming the Kth step in process, determined that the pixel at (Xk, Yk)decide which pixel to plot in column Xk+1.
The choices are (Xk+1, Yk) and (Xk+1, Yk+1)
Algorithm
Step 1: Input the line endpoints and store the left endpoint in (X0, Y0) Step 2: Load (X0, Y0) in to the frame buffer.
Step 3: Calculate constants x, y, 2 y, -2 x, and obtain the decision parameters as
P0 = 2 y – x
Step 4 : At each Xk along the line, starting at k = 0, perform the following test If Pk < 0, the next point to plot is (Xk+1, Yk) and
Pk+1 = Pk+2 y
Otherwise, the next point to plot is (Xk+1, Yk+1) and
Pk+1 = Pk+2 y - 2 x
Step 5: Repeat step 4 x times
