hongchen/Floorplan/test_overlap2.py

# 测试 Liang-Barsky 算法计算重叠长度

bbox = [-3.41, -2.0, -3.17, -0.7]  # [x0, y0, x1, y1]

# seg[28]: (-3.33,-0.18)->(-3.33,-1.40)
va = (-3.33, -0.18)
vb = (-3.33, -1.40)
dx, dy = vb[0] - va[0], vb[1] - va[1]
seg_len = (dx*dx + dy*dy) ** 0.5

bx0, by0 = bbox[0], bbox[1]  # -3.41, -2.0
bx1, by1 = bbox[2], bbox[3]  # -3.17, -0.7

print(f'seg[28]: {va}->{vb}, len={seg_len:.3f}')
print(f'bbox: [{bx0}, {by0}, {bx1}, {by1}]')

t_start = 0.0
t_end = 1.0

# 与 bbox 左右边界的交点 (dx=0, 跳过)
print(f'dx={dx}, 跳过左右边界')

# 与 bbox 上下边界的交点
if abs(dy) > 1e-8:
    t_bottom = (by0 - va[1]) / dy
    t_top = (by1 - va[1]) / dy
    print(f't_bottom={t_bottom:.4f}, t_top={t_top:.4f}')
    if dy > 0:
        t_start = max(t_start, min(t_bottom, t_top))
        t_end = min(t_end, max(t_bottom, t_top))
    else:
        t_start = max(t_start, min(t_top, t_bottom))
        t_end = min(t_end, max(t_top, t_bottom))
    print(f'After y-clip: t_start={t_start:.4f}, t_end={t_end:.4f}')

if t_end > t_start:
    overlap = (t_end - t_start) * seg_len
    print(f'overlap = ({t_end:.4f} - {t_start:.4f}) * {seg_len:.3f} = {overlap:.3f}')
else:
    overlap = 0
    print(f'overlap = 0 (t_end <= t_start)')

print()

# seg[29]: (-3.33,-1.08)->(-3.33,-2.02)
va = (-3.33, -1.08)
vb = (-3.33, -2.02)
dx, dy = vb[0] - va[0], vb[1] - va[1]
seg_len = (dx*dx + dy*dy) ** 0.5

print(f'seg[29]: {va}->{vb}, len={seg_len:.3f}')

t_start = 0.0
t_end = 1.0

if abs(dy) > 1e-8:
    t_bottom = (by0 - va[1]) / dy
    t_top = (by1 - va[1]) / dy
    print(f't_bottom={t_bottom:.4f}, t_top={t_top:.4f}')
    if dy > 0:
        t_start = max(t_start, min(t_bottom, t_top))
        t_end = min(t_end, max(t_bottom, t_top))
    else:
        t_start = max(t_start, min(t_top, t_bottom))
        t_end = min(t_end, max(t_top, t_bottom))
    print(f'After y-clip: t_start={t_start:.4f}, t_end={t_end:.4f}')

if t_end > t_start:
    overlap = (t_end - t_start) * seg_len
    print(f'overlap = ({t_end:.4f} - {t_start:.4f}) * {seg_len:.3f} = {overlap:.3f}')
else:
    overlap = 0
    print(f'overlap = 0 (t_end <= t_start)')