change .obj color by program!

readme.md

readme

0. 将脚本文件放到obj,png同目录下即可,python3 script.py，命令行中的输出为obj中平面的数量，与1.中的decimal设置有关

结果图(lenOfRGBs == 50)：

1. 可调参数，懒得写在命令行了，直接在py文件改

a. decimal(Line 32)，越小，平面数量越少 b. lenOfRGBs(Line 91)，越小，使用的png中的颜色越少，注释的话使用png中全部颜色

2. 问题

如何对应平面和png中的颜色，暂无办法 因此目前修改后的obj不好看

.obj example: obj&color.zip

script.py

from unicodedata import decimal
from PIL import Image

objFilePath = "obj&color/monu1.vox.obj"
pngFilePath = "obj&color/monu1.vox.png"
mtlFilePath = "obj&color/monu1.vox.mtl"

def loadPng():
    image = Image.open(pngFilePath)
    pixels = image.load()
    rgbs = []
    for x in range(image.size[0]):
        rgbs.append(pixels[x, 0])
    return rgbs

def writeMtl():
    rgbs = loadPng()
    with open(mtlFilePath, "w") as w:
        for i, rgb in enumerate(rgbs):
            w.write("newmtl mtl{}\n".format(i))
            w.write("Kd {} {} {}\n".format(rgb[0], rgb[1], rgb[2]))
            w.write("Ks 0.50 0.50 0.50\n")
            w.write("\n")
    return len(rgbs)

def calSurface(v1, v2, v3):
    a = (v2[1] - v1[1]) * (v3[2] - v1[2]) - (v2[2] - v1[2]) * (v3[1] - v1[1])
    b = (v2[2] - v1[2]) * (v3[0] - v1[0]) - (v2[0] - v1[0]) * (v3[2] - v1[2])
    c = (v2[0] - v1[0]) * (v3[1] - v1[1]) - (v2[1] - v1[1]) * (v3[0] - v1[0])
    d = -(a * v1[0] + b * v1[1] + c * v1[2])
    # remained decimal digits, the less decimal the less surfaces
    decimal = 2
    a, b, c, d = round(a, decimal), round(b, decimal), round(c, decimal), round(d, decimal)
    if a == -0.0: a = 0.0
    if b == -0.0: b = 0.0
    if c == -0.0: c = 0.0
    if d == -0.0: d = 0.0
    return "#".join([str(a), str(b), str(c), str(d)])

def readObj():
    fs, vs, fcnt, vcnt = {}, {}, 0, 1 # vcnt is the number of vertices, start with 1
    surfaces, revSurfaces = {}, {} # a*x + b*y + c*z = d => <i, str(a#b#c#d)>
    with open(objFilePath, "r") as r:
        for i, line in enumerate(r.readlines()):
            strs = line.split(" ")
            if strs[0] == "f":
                v1, v2, v3 = int(strs[1].split("/")[0]), int(strs[2].split("/")[0]), int(strs[3].split("/")[0])
                fs[i] = [fcnt, v1, v2, v3]
                fcnt += 1
            if strs[0] == "v":
                vs[vcnt] = (float(strs[1]), float(strs[2]), float(strs[3]))
                vcnt += 1
    newFs = {}
    for i, ps in fs.items():
        v1, v2, v3 = vs[ps[1]], vs[ps[2]], vs[ps[3]]
        surface = calSurface(v1, v2, v3)
        surfaces[i] = surface
        if surface not in revSurfaces: revSurfaces[surface] = [i]
        else: revSurfaces[surface].append(i)
        newFs[i] = [ps[0], surface]
    print(len(revSurfaces))
    return fs, newFs, surfaces, revSurfaces

def rewriteObj(lenOfRGBs):
    fs, newFs, surfaces, revSurfaces = readObj()
    # gap = len(fs) // lenOfRGBs
    gap_ = len(revSurfaces) // lenOfRGBs
    surface2mtlindex = {}
    for i, (fcnt, surface) in newFs.items():
        if surface not in surface2mtlindex:
            l = len(surface2mtlindex)
            if l // gap_ < lenOfRGBs:
                surface2mtlindex[surface] = l // gap_
            else:
                surface2mtlindex[surface] = lenOfRGBs - 1

    with open(objFilePath, "r") as r:
        with open("obj&color/monu1.vox.new.obj", "w") as w:
            for i, line in enumerate(r.readlines()):
                # if i in fs and fs[i][0] % gap == 0 and fs[i][0] // gap < lenOfRGBs:
                #     w.write("usemtl mtl{}\n".format(fs[i][0] // gap))
                if i in newFs:
                    # printfile(i, newFs[i], surface2mtlindex[newFs[i][1]])
                    with open("surface.txt", "a") as a:
                        a.write("{} {} {}\n".format(i, newFs[i], surface2mtlindex[newFs[i][1]]))
                    w.write("usemtl mtl{}\n".format(surface2mtlindex[newFs[i][1]]))
                w.write(line)

if __name__ == "__main__":
    lenOfRGBs = writeMtl() # total colors of .png
    lenOfRGBs = 50 # how many RGBs used in one mtl file, options, to make your obj less color...
    rewriteObj(lenOfRGBs)