三维模型文件中的OBJ格式在OpenGL中的输入与处理

ComputerKnowledgeandTechnology：710(20114)OBJOpenGL，（（），100083）：Maya，MayaOBJ，OBJOpenGL(OpenGraphicLibrary)。OBJ、，OpenGL。：；OpenGL；OBJ；：TP391：A：1009-3044(2011)10-2393-04ObjThree-dimensionalModelFileFormatinOpenGL,InputandProcessingWANGJin-feng,YAOGuo-qing(ChinaUniversityofGeosciences,Beijing100083,China)Abstract:Introducedthethree-dimensionalmappingtoolsoftoday'spopularMaya,expoundstheMaya3dformatOBJgenerated,Thefileformatsof3DfilesOBJisintroducedandthewayshowtotransfer3DmodelfilestoOpenGLarediscussed.ThepaperlaysastrongemphasisonthefileformatsofOBJfileandhowtousecodetoformthemodelingdatastructureandhowtopainttheobjectmodels.ThenthepowerfulfunctionofOpenGLcanbeusedto3Ddisplayandinteractiveoperation.Keywords:3Dmodelfile;OpenGL;OBJfile;interact1OpenGL（OpenGraphicLibrary），。SGIIRISGL，，SGIOpenGL，19927OpenGL1.0。OpenGL，，。OpenGL，（Microsoft、IBM、DEC、SUN），OpenGL。，；OpenGLVisualC++，；OpenGL，。OpenGL、，:、、、、、。Windows。2MayaMayaAliaso/Wavafront，、、、、、、、、MTV、。MayaAliaso/Wavefront。，、、、。MayaWin-dowsNTSGIIRIX。，Maya。Maya，，。OpenGL，OpenGL[1]。3OBJOBJAlias/WavefrontMaya,。，3D。OBJ[2]，3D，Wavefront3D，。OBJ，ASCII，.mod，ASCII.obj。3.1OBJMayaMEL，DXF，Explore，Geo，OBJ，IGES，Aliaswire，Aiff，Image，RIB，MOV(Aaciimotion)，VRML2。OBJ，，，、，：2011-02-16：（1987-），，，，；，，。E-mail:[e-mail]，23992393ComputerKnowledgeandTechnology：710(20114)、。。obj[3]。OBJ[4]。OBJ(FileHeader)，。OBJ，“#”，。(Keyword)，。，(\)。(\)Tab，。OBJ。,，。（Vertexdata）：v：(Geometricvertices)。。3，X、Y、Z。Vt：(Texturevertices)。。。U、V。Vn：(Vertexnormals)。。3，X、Y、Z。Vp：(Parameterspacevertices)。(Free-formcurve)/(surfaceattributes):Deg：(Degree)。Bmat：(Basismatrix)。Step：(Stepsize)。cstype(Curveorsurfacetype)：(Elements):P：(Point)L：(Line)F：(Face)Curv：(Curve)curv22D：(2Dcurve)surf：(Surface)(Free-formcurve)/(surfacebodystatements):Parm：(Parametervalues)Trim：(Outertrimmingloop)Hole：(Innertrimmingloop)Scrv：(Specialcurve)sp：(Specialpoint)end：(Endstatement)(Connectivitybetweenfree-formsurfaces):Con：(Connect)(Grouping):G：(Groupname)S：(Smoothinggroup)Mg：(Merginggroup)O：(Objectname)(Display)/(renderattributes):Bevel：(Bevelinterpolation)c_interp：(Colorinterpolation)d_interp：(Dissolveinterpolation)lod：(Levelofdetail)usemtl：(Materialname)mtllib：(Materiallibrary)shadow_obj：(Shadowcasting)trace_obj：(Raytracing)ctech：(Curveapproximationtechnique)stech：(Surfaceapproximationtechnique)OBJ，，.mtl。mtllib[5]。(diffuse)，(ambient)，(specular)RGB()，(specularity)，(refraction)，(transparency)。usemtl，，usemtl。3.2OBJOBJ。OBJsquare.obj。2394ComputerKnowledgeandTechnology：710(20114)#square.objv0.0000002.0000000.000000v0.0000000.0000000.000000v2.0000000.0000000.000000v2.0000002.0000000.000000f12344v，f，。。#。#twosquare.objv0.0000002.0000000.000000v0.0000000.0000000.000000v2.0000000.0000000.000000v2.0000002.0000000.000000v4.0000000.000000-1.255298v4.0000002.000000-1.255298vn0.0000000.0000001.000000vn0.0000000.0000001.000000vn0.2765970.0000000.960986vn0.2765970.0000000.960986vn0.5316110.0000000.846988vn0.5316110.0000000.846988#6vertices#6normalsgalls1f1//12//23//34//4f4//43//35//56//6#2elementstwosqaure.obj：vn，ggroup，allgroup。facegroup，g。s，1groupall。1//1，1，1，，vt。2//2，3//3，4//4，[6]。3.3OBJOBJ，，。OBJ，、、。://typedefstruct_GLMnode{GLuintindex;GLbooleanaveraged;struct_GLMnode*next;}GLMnode;///*glmWeldVectors:eliminate(weld)vectorsthatarewithinan*epsilonofeachother.**vectors-arrayofGLfloat[3]'stobewelded*numvectors-numberofGLfloat[3]'sinvectors*epsilon-maximumdifferencebetweenvectors**/GLfloat*glmWeldVectors(GLfloat*vectors,GLuint*numvectors,GLfloatepsilon){GLfloat*copies;GLuintcopied;GLuinti,j;copies=(GLfloat*)malloc(sizeof(GLfloat)*3*(*numvectors+1));memcpy(copies,vectors,(sizeof(GLfloat)*3*(*numvectors+1)));copied=1;2395ComputerKnowledgeandTechnology：710(20114)for(i=1;i=*numvectors;i++){for(j=1;j=copied;j++){if(glmEqual(&vectors[3*i],&copies[3*j],epsilon)){gotoduplicate;}}/*mustnotbeanyduplicates--addtothecopiesarray*/copies[3*copied+0]=vectors[3*i+0];copies[3*copied+1]=vectors[3*i+1];copies[3*copied+2]=vectors[3*i+2];j=copied;/*passthisalongforbelow*/copied++;duplicate:/*setthefirstcomponentofthisvectortopointatthecorrectindexintothenewcopiesarray*/vectors[3*i+0]=(GLfloat)j;}*numvectors=copied-1;returncopies;}/*glmFindGroup:Findagroupinthemodel*/GLMgroup*glmFindGroup(GLMmodel*model,char*name){GLMgroup*group;assert(model);group=model-groups;while(group){if(!strcmp(name,group-name))break;group=group-next;}returngroup;},,。1OBJ，2。4OBJwindowsOpenGLglut。GLUTOpenGL，，。WindowsGLUT：1），5。2）“”“gl.h”，（VisualStudio2005，“VC\PlatformSDK\include\gl”）。glut.h。3）glut.libglut32.lib（VisualStudio2005，“VC\lib”）。4）glut.dllglut32.dllsystem32。（：C:\Windows\System32）。,，MayaOBJMaya[7]，。MayaOpenGL，OpenGL、、、、，、、[8]。2。5MayaOpenGL，OpenGL，。，OpenGL，Maya.OBJ，，、。，，，，LOD，，。3DMAX，AutoCAD，OpenGL，、、、。（2399）1OBJ22396ComputerKnowledgeandTechnology：710(20114)（2396）：[1],,,.OpenGL[M].:,1999.[2],.OpenGL[M].:,2001.[3]ShreinerD.OpenGL[M].5.:,2006.[4],.OpenGL[M].:,2000.[5]AngelE.OpenGL[M].2.:,2005.[6