obj2scratch.py

f = open('dog.obj','r')

verts = []
uvs = []
normals = []
faces = []

for line in f:
    if line[:2] == 'v ':
        verts.append(tuple(map(lambda s:float(s),line.split()[1:])))
    elif line[:3] == 'vt ':
        uvs.append(tuple(map(lambda s:float(s),line.split()[1:])))
    elif line[:3] == 'vn ':
        normals.append(tuple(map(lambda s:float(s),line.split()[1:])))
    elif line[:2] == 'f ':
        faces.append(list(map(lambda s:tuple(map(lambda t:int(t),s.split('/'))),line.split()[1:])))

f.close()
print(f"""{len(verts)} vertices
{len(normals)} normals
{len(uvs)} tex coords
{len(faces)} faces""")

with open('vertices.txt','w') as verts_file:
    with open('texcoords.txt', 'w') as uvs_file:
        with open('normals.txt', 'w') as normals_file:
            for face in faces:
                for (i, j, k) in face:
                    vert = verts[i - 1]
                    uv = uvs[j - 1]
                    normal = normals[k - 1]
                    for coord in vert:
                        verts_file.write(f"{coord}\n")
                    for coord in normal:
                        normals_file.write(f"{coord}\n")
                    for coord in uv:
                        uvs_file.write(f"{coord}\n")

print("Written to vertices.txt/normals.txt/texcoords.txt")

simple_rle.py

import sys

value_size = 3

def rle_compress(data):
    result = bytearray()
    run_val = int.from_bytes(data[0:value_size])
    run_length = 0
    index = 0
    while index < len(data):
        val = int.from_bytes(data[index:index + value_size])
        if val == run_val and run_length < 0xff:
            run_length += 1
        else:
            result.append(run_length)
            result += run_val.to_bytes(value_size)
            run_val = val
            run_length = 1
        index += value_size
    result.append(run_length)
    result += run_val.to_bytes(value_size)
    return bytes(result)

for path in sys.argv[1:]:
    with open(path, 'rb') as f:
        data = f.read()
        result = rle_compress(data)
        index = 0
        while index < len(result):
            print(hex(int.from_bytes(result[index:index + 4])))
            index += 4