## 2019年6月19日水曜日

### Python - Triangles - Wavefront OBJFiles - OBJ File with Vertex Data - Vertex Record

The Ray Tracer Challenge: A Test-Driven Guide to Your First 3D Renderer (Jamis Buck(著)、Pragmatic Bookshelf)、Chapter 15(Triangles)のWavefront OBJFiles、Test #9: OBJ File with Vertex Dataを取り組んでみる。

コード

obj_file_test.py

```#!/usr/bin/env python3
from unittest import TestCase, main
from obj_file import Parser
import io
from tuples import Point

class ParserTest(TestCase):
def setUp(self):
pass

def tearDown(self):
pass

def test_ingoring_unrecognized_lines(self):
gibberish = io.StringIO('''There was a young lady named Bright
who traveled much faster than light.
She set out one day
in a relative way,
and came back the previous night.
''')
parser = Parser(gibberish)
self.assertEqual(parser.ignored_lines, 5)

def test_vertex_records(self):
f = io.StringIO('''v -1 1 0
v -1.0000 0.5000 0.0000
v 1 0 0
v 1 1 0
''')
parser = Parser(f)
self.assertEqual(parser.vertices[1], Point(-1, 1, 0))
self.assertEqual(parser.vertices[2], Point(-1, 0.5, 0))
self.assertEqual(parser.vertices[3], Point(1, 0, 0))
self.assertEqual(parser.vertices[4], Point(1, 1, 0))

if __name__ == '__main__':
main()
```

obj_file.py

```from tuples import Point

class Parser:
def __init__(self, fh):
self.ignored_lines = 0
self.vertices = [None]
for line in fh:
cols = line.split()
if len(cols) < 4 or cols[0] not in ['v', 'f']:
self.ignored_lines += 1
continue
if cols[0] == 'v':
try:
point = Point(*[float(col) for col in cols[1:]])
except ValueError as err:
self.ignored_lines += 1
else:
self.vertices.append(point)
```

```C:\Users\...>py obj_file_test.py
..
----------------------------------------------------------------------
Ran 2 tests in 0.000s

OK

C:\Users\...>
```