|
| 1 | +""" |
| 2 | +Midpoint Line Drawing Algorithm |
| 3 | +------------------------------- |
| 4 | +
|
| 5 | +Handles all lines with arbitrary slopes using the midpoint method. |
| 6 | +
|
| 7 | +Referece: |
| 8 | +https://www.geeksforgeeks.org/dsa/mid-point-line-generation-algorithm/ |
| 9 | +
|
| 10 | +>>> midpoint_line((0, 0), (5, 3)) |
| 11 | +[(0, 0), (1, 1), (2, 1), (3, 2), (4, 2), (5, 3)] |
| 12 | +>>> midpoint_line((5, 5), (2, 3)) |
| 13 | +[(5, 5), (4, 4), (3, 4), (2, 3)] |
| 14 | +""" |
| 15 | + |
| 16 | +import matplotlib.pyplot as plt |
| 17 | + |
| 18 | + |
| 19 | +def midpoint_line(p1: tuple[int, int], p2: tuple[int, int]) -> list[tuple[int, int]]: |
| 20 | + x1, y1 = p1 |
| 21 | + x2, y2 = p2 |
| 22 | + |
| 23 | + points = [] |
| 24 | + |
| 25 | + dx = x2 - x1 |
| 26 | + dy = y2 - y1 |
| 27 | + |
| 28 | + # Determine the direction of the step |
| 29 | + sx = 1 if dx >= 0 else -1 |
| 30 | + sy = 1 if dy >= 0 else -1 |
| 31 | + |
| 32 | + dx = abs(dx) |
| 33 | + dy = abs(dy) |
| 34 | + |
| 35 | + if dx > dy: |
| 36 | + # Shallow slope: iterate over x |
| 37 | + d = dy - dx / 2 |
| 38 | + x, y = x1, y1 |
| 39 | + while x != x2 + sx: |
| 40 | + points.append((x, y)) |
| 41 | + if d >= 0: |
| 42 | + y += sy |
| 43 | + d -= dx |
| 44 | + x += sx |
| 45 | + d += dy |
| 46 | + else: |
| 47 | + # Steep slope: iterate over y |
| 48 | + d = dx - dy / 2 |
| 49 | + x, y = x1, y1 |
| 50 | + while y != y2 + sy: |
| 51 | + points.append((x, y)) |
| 52 | + if d >= 0: |
| 53 | + x += sx |
| 54 | + d -= dy |
| 55 | + y += sy |
| 56 | + d += dx |
| 57 | + |
| 58 | + return points |
| 59 | + |
| 60 | + |
| 61 | +if __name__ == "__main__": |
| 62 | + import doctest |
| 63 | + |
| 64 | + doctest.testmod() |
| 65 | + |
| 66 | + x1 = int(input("Enter x1: ")) |
| 67 | + y1 = int(input("Enter y1: ")) |
| 68 | + x2 = int(input("Enter x2: ")) |
| 69 | + y2 = int(input("Enter y2: ")) |
| 70 | + |
| 71 | + points = midpoint_line((x1, y1), (x2, y2)) |
| 72 | + print("Generated points:", points) |
| 73 | + |
| 74 | + xs, ys = zip(*points) |
| 75 | + plt.plot(xs, ys, marker="o") |
| 76 | + plt.title("Midpoint Line Drawing Algorithm") |
| 77 | + plt.grid() |
| 78 | + plt.show() |
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