系列文章

一、逆向工程
Sketchup 逆向工程（一）破解.skp文件数据结构
Sketchup 逆向工程（二）分析三维模型数据结构
Sketchup 逆向工程（三）软件逆向工程从何处入手
Sketchup 逆向工程（四）破解的乐趣 钩子 外挂 代码注入

二、OpenGL渲染模型
Python+OpenGL绘制3D模型（一）Python 和 PyQt环境搭建
Python+OpenGL绘制3D模型（二）程序框架PyQt5
Python+OpenGL绘制3D模型（三）程序框架PyQt6
Python+OpenGL绘制3D模型（四）绘制线段
Python+OpenGL绘制3D模型（五）绘制三角型
Python+OpenGL绘制3D模型（六）材质文件载入和贴图映射
Python+OpenGL绘制3D模型（七）制作3dsmax导出插件
Python+OpenGL绘制3D模型（八）绘制插件导出的插件
Python+OpenGL绘制3D模型（九）完善插件功能: 矩阵,材质,法线
Python+OpenGL 杂谈（一）

三、成果
疫情期间关在家里实在没事干，破解了Sketchup，成功做出可以读取并显示.skp文件的程序SuViewer

前言

Sketchup作为目前设计院最为流行的设计软件(非工程制图软件），深受设计师的喜爱，软件小巧，而功能强大，有不少为之开发的插件应运而生，不过呢，关于底层数据结构和工作原理相关的文章少之又少，本文意在填补一下这方面的空缺，通过逆向软件分析，展示软件内部奥秘。本文用到的工具：IDA Pro，Immunity Debugger，Visual Studio （逆向工程三件套）数据结构属于知识产权的核心机密：

---

一、模型的变换矩阵

TODO

二、导出材质、贴图

TODO

三、导出法线

TODO

四、 源代码

1、maxplus_export_sel_model.py

import MaxPlus
import pickle
import base64
from CModel import CModel, CMaterial, CMesh, CTriangle, CVector3################################
#                   FILE DESCRIPTION
#  文件描述：CModelExport
#  对应文章：Python+OpenGL绘制3D模型（九） 完善插件功能: 矩阵,材质,法线
#  作者：李航 Lihang
#  使用方法：
#   1、选择要导出的模型
#   2、在命令行窗口中输入
#          python.ExecuteFile "C:/_proj/SuViewer/articles/step3/maxplus_export_sel_model.py"
#   3、把命令行拖入工具栏可以生成快捷方式，方便下次使用
#   4、测试可使用的版本：3dsmax2016
#   ELSE..
################################# 注意: 保证c:/temp目录存在，否则无法导出
EXPORT_PATH_FILE = "c:/temp/CModel.pickle"############
# CModelExport
############  
class CModelExport:def __init__(self):self.list_mats = []############# export#   插件主入口############  def export(self):model = CModel()for n, obj, triObj in self.EnumSeletciontGeometry():print ("find %s, class:%s"%(n, obj.GetClassName()) )mesh = triObj.GetMesh()out_mesh = self.ProcMesh(n, mesh)model.list_mesh.append(out_mesh)self.printMats()model.list_mats = [mo for mi, mo in self.list_mats]hf = open("c:/temp/CModel.pickle",  "wb")pickle.dump(model,  hf,  2)hf.close()############# EnumSeletciontGeometry#   1、遍历选择的物体#   2、生成列表sel_list并返回############  def EnumSeletciontGeometry(self):sel_list = []for n in MaxPlus.SelectionManager.Nodes:        # objectobj = n.EvalWorldState().Getobj()if obj.CanConvertToType(MaxPlus.ClassIds.TriMeshGeometry):triObj = obj.ConvertToType(MaxPlus.ClassIds.TriMeshGeometry)item = (n, obj, MaxPlus.TriObject._CastFrom(triObj))sel_list.append(item)#print ("find %s, class:%s"%(n, obj.GetClassName()) )else:print("can't conv triMesh, Type is:%s" % obj.GetClassName())return sel_list############# ProcMesh#   1、处理max中的模型#   2、转成需要的CModel数据############def ProcMesh(self, node, mesh):print("---ProcMesh()---")#=====================# Collect Infomation#=====================tm = node.GetWorldTM()# colornew_mesh = CMesh()color1 = node.GetWireColor()new_mesh.color = (color1.GetR(), color1.GetG(), color1.GetB())# materialm = node.GetMaterial()new_mesh.mat = self.ProcMeshMaterial(m, mesh) if m else None#=====================# Vertices#=====================num_verts = mesh.GetNumVertices()print ("numVertics:%d"%num_verts)for i in range(num_verts):loc_pos = mesh.GetVertex(i)point = tm.PointTransform(loc_pos)nv = CVector3(point.X, point.Y, point.Z)new_mesh.list_vertices.append(nv)#=====================# Normals#=====================normalBuilder = NormalBuilder()normalBuilder.BuildNormals(mesh)num_normals = len(normalBuilder.list_normals)print("numNormals:%d"%num_normals)for i in range(num_normals):ln = normalBuilder.list_normals[i]nm = tm.VectorTransform(ln).Normalize()new_mesh.list_normals.append(CVector3(nm.X,  nm.Y, nm.Z))#=====================# UV#=====================num_tverts = mesh.GetNumTVerts()print ("numTVerts:%d"%num_tverts)for i in range(num_tverts):uv = mesh.GetTVert(i)nv = CVector3(uv.X, uv.Y, uv.Z)new_mesh.list_uvs.append(nv)#=====================# Triangles#=====================num_faces = mesh.GetNumFaces()print ("numFaces:%d"%num_faces)for i in range(num_faces):tri = mesh.GetFace(i)smGroup = tri.GetSmGroup()vi1 = tri.GetVert(0)vi2= tri.GetVert(1)vi3 = tri.GetVert(2)ni1 = normalBuilder.GetNormal(vi1, smGroup )ni2 = normalBuilder.GetNormal(vi2, smGroup )ni3 = normalBuilder.GetNormal(vi3, smGroup )tface = mesh.GetTVFace(i)ui1 = tface.GetA()ui2 = tface.GetB()ui3 = tface.GetC()ev1 = True if tri.GetEdgeVis(0) else Falseev2 = True if tri.GetEdgeVis(1) else Falseev3 = True if tri.GetEdgeVis(2) else Falsent = CTriangle()nt.a = (vi1, ni1, ui1)nt.b = (vi2, ni2, ui2)nt.c = (vi3, ni3, ui3)norm = mesh.FaceNormal(i)nt.matId = tri.GetMatID()nt.faceNormal = CVector3(norm.X, norm.Y, norm.Z)nt.smGroup = tri.GetSmGroup()nt.edgevis = (ev1, ev2, ev3)new_mesh.list_tris.append(nt)#print(" Tri: %d %d %d"%(tri.GetVert(0), tri.GetVert(1), tri.GetVert(2) ))return new_mesh############# Material############def ProcMeshMaterial(self, m, mesh):print("---CollectMeshMaterials()---")if m.IsMultiMtl():num_submat = m.GetNumSubMtls()refcount = [0] * num_submatnum_faces = mesh.GetNumFaces()for i in range(num_faces):f = mesh.GetFace(i)mid = f.GetMatID()refcount[mid] += 1print("refcount:"+str(refcount))list_submats = []for i in range(num_submat):if refcount[i]:mMat = m.GetSubMtl(i)if mMat:cm = self.addMaterial(mMat)list_submats.append(cm)else:list_submats.append(None)else:list_submats.append(None)return list_submatselse:return self.addMaterial(m)def addMaterial(self, mi):#==============#  Find Exist#==============for min, mout in self.list_mats:if min == mi:return mout#==============#  Create Out Material#==============mo = CMaterial()# Diffusecolor1 = mi.GetDiffuse()mo.diffuse = (color1.GetR(), color1.GetG(), color1.GetB())# Textureisubmap = MaxPlus.ISubMap._CastFrom(mi)#assert(isubmap, "can't cast to ISubMap")tex = isubmap.GetSubTexmap(1)if tex:bitmap = MaxPlus.BitmapTex._CastFrom(tex)texmap = bitmap.GetMapName()mo.tex_filepath = texmapmo.tex_bindata = self.loadFileData(texmap)# Add to listitem = (mi, mo)self.list_mats.append(item)return modef loadFileData(self, filename):file1 = open(filename,  mode='rb')imgdata = bytes(file1.read())file1.close()return base64.b64encode(imgdata)def printMats(self):print("---printMats()---")print("Number of Materials: %d"% len(self.list_mats))print("----------------")for matId, m in enumerate(self.list_mats):mi, mo = mprint("ID: %d"% matId)print("source:" + str(mi))print("diffuse: " + str(mo.diffuse))print("texture: " + mo.tex_filepath)############
# NormalBuilder
############
class NormalBuilder:def __init__(self):self.list_verts = []self.list_normals = []class Vertex:def __init__(self, p):self.v = pself.an = Nonedef normals(self):if self.an is None:return ()elif type(self.an) is list:return self.anelse:return (self.an, )def addNormal(self, n, sg):for vn in self.normals():if vn.sg & sg:vn.n = vn.n + nreturn#not findvn = NormalBuilder.VNormal(n, sg)if self.an is None:self.an = vnelif type(self.an) is list:self.an.append(vn)else:self.an = [self.an, vn]class VNormal:def __init__(self, n, sg):self.n = nself.sg = sgself.idx = -1def add(self, n):self.n =  self.n + ndef BuildNormals(self, mesh):print("-----BuildNormals------")#=====================# Vertices#=====================num_verts = mesh.GetNumVertices()for i in range(num_verts):point = mesh.GetVertex(i)v = NormalBuilder.Vertex(point)self.list_verts.append(v)num_faces = mesh.GetNumFaces()for i in range(num_faces):f = mesh.GetFace(i)faceNormal = mesh.FaceNormal(i)smGroup = f.GetSmGroup()v1 = f.GetVert(0)self.list_verts[v1].addNormal(faceNormal, smGroup)v2 = f.GetVert(1)self.list_verts[v2].addNormal(faceNormal, smGroup)v3 = f.GetVert(2)self.list_verts[v3].addNormal(faceNormal, smGroup)idx = 0for v in self.list_verts:for vn in v.normals():vn.n = vn.n.Normalize()self.list_normals.append(vn.n)vn.idx = idxidx += 1def GetNormal(self, vi, sg):v = self.list_verts[vi]for vn in v.normals():if vn.sg & sg:return vn.idxassert(False)############
# Main
#   1、创建插件导出对象CModelExport
#   2、执行export
############
modelExport = CModelExport()
modelExport.export()

2、CModel.py

import mathclass CModel:def __init__(self):self.list_mats = []self.list_mesh = []class CMaterial:def __init__(self):self.diffuse = (0, 0, 0)self.tex_filepath = ""self.tex_bindata = Noneclass CMesh:def __init__(self):self.name = ""self.color = (0, 0, 0)self.list_vertices = []self.list_normals = []self.list_uvs = []self.list_tris = []class CTriangle:def __init__(self):self.a=(0, 0, 0)self.b=(0, 0, 0)self.c=(0, 0, 0)self.faceNormal = CVector3.zero()self.matId = 0self.smGroup = 0self.edgevis=(True, True, True)class CVector3:def __init__(self, x, y, z):self.x=xself.y=yself.z=z@classmethoddef zero2(cls):return CVector3(0.0, 0.0, 0.0)@staticmethoddef zero():return CVector3(0.0, 0.0, 0.0)def normalize(self):s = 1.0 / math.sqrt(self.x*self.x + self.y*self.y + self.z*self.z)self.x *= sself.y *= sself.z *= sdef __add__(self,  R):return CVector3(self.x + R.x, self.y + R.y, self.z + R.z)

系列文章预告

目标是一个完善的Viewer，能够显示Sketchup的.skp文件中的3D模型

Corona渲染器照片级渲染效果