comparison: geometry.py
geometry.py
- changeset 28
- 5933250813a3
- parent 24
- f8080ffceaa9
- child 30
- 0d9ca37901ed
equal
deleted
inserted
replaced
| 27:3089611c99d1 | 28:5933250813a3 |
|---|---|
| 408 | 408 |
| 409 def triangle_plane_normal(polygon): | 409 def triangle_plane_normal(polygon): |
| 410 assert(len(polygon.vertices) == 3) | 410 assert(len(polygon.vertices) == 3) |
| 411 a, b, c = polygon.vertices[:3] | 411 a, b, c = polygon.vertices[:3] |
| 412 return cross_product(b - a, b - c) | 412 return cross_product(b - a, b - c) |
| 413 | |
| 414 def line_intersection_xy(line_1, line_2): | |
| 415 ''' | |
| 416 Computes 2D line intersection. Can return a point outside the given | |
| 417 segments. Z is ignored. | |
| 418 ''' | |
| 419 a, b = line_1.vertices | |
| 420 c, d = line_2.vertices | |
| 421 denominator = (a.x - b.x) * (c.y - d.y) - (a.y - b.y) * (c.x - d.x) | |
| 422 x = (c.x - d.x) * (a.x * b.y - a.y * b.x) | |
| 423 x -= (a.x - b.x) * (c.x * d.y - c.y * d.x) | |
| 424 y = (c.y - d.y) * (a.x * b.y - a.y * b.x) | |
| 425 y -= (a.y - b.y) * (c.x * d.y - c.y * d.x) | |
| 426 try: | |
| 427 x /= denominator | |
| 428 y /= denominator | |
| 429 except ZeroDivisionError: | |
| 430 return None | |
| 431 else: | |
| 432 return Vertex(x, y, 0) | |
| 433 | |
| 434 def line_segment_intersection_xy(line_1, line_2): | |
| 435 ''' | |
| 436 Computes 2D line intersection. Only returns a result if it falls | |
| 437 inside the line segments. Z is ignored. | |
| 438 ''' | |
| 439 from math import inf | |
| 440 intersection = line_intersection_xy(line_1, line_2) | |
| 441 if intersection: | |
| 442 a, b = line_1.vertices | |
| 443 c, d = line_2.vertices | |
| 444 try: | |
| 445 t = (intersection.x - a.x) / (b.x - a.x) | |
| 446 except ZeroDivisionError: | |
| 447 t = inf | |
| 448 try: | |
| 449 u = (intersection.y - a.y) / (b.y - a.y) | |
| 450 except ZeroDivisionError: | |
| 451 u = inf | |
| 452 if 0 < t < 1 or 0 < u < 1: | |
| 453 return intersection | |
| 454 else: | |
| 455 return None | |
| 456 else: | |
| 457 return None |
