OpenGL with PyOpenGL tutorial Python and PyGame p.1

OpenGL with PyOpenGL introduction and creation of Rotating Cube ... to your perspective, not in relation to your actual location within the 3D environment. search Home +=1 SupporttheContent Community Login Signup Home +=1 SupporttheContent Community Login Signup OpenGLwithPyOpenGLintroductionandcreationofRotatingCube WhenIfirstbeganlookingintoOpenGLwithPython,mymaingoalwastofigureouthowtomakearotatingcube.Idon'tthinkIamalone,sincethisseemstobethepinnacleofunderstandingthebasicsofOpenGL.Assuch,IhavecompiledthisfirstvideotoincludeeverythingfromacquiringPython,PyOpenGL,andPyGame,tocreatingthenecessarycodetomakearotatingcube.Thisfirsttutorialisquitelong,butIwantedtogoaheadandputeverythingintothisvideo.IhadaveryhardtimefiguringoutOpenGL,mainlybecausemostoftheOpenGLwithPyOpenGLtutorialsthatIcouldfindwereclearlywrittenforsomeonewhoalreadyknewOpenGL.Ididnot,sothiswasamassivehurdleforme.HopefullyIcanhelpyoualllearnitmuchfasterthanIdid. Firstoff,PyOpenGLisjustsomePythonbindings(somePythoncodethatactslikeasortofwrapperaroundnativecode),soyoucanmanipulateOpenGLwithinthecontextofPython.OpenGLisacross-languageAPI,soyoucantakeyourknowledgeofOpenGLtootherlanguages. So,thewayOpenGLworksisyoujustspecifytheobjectswithinspace.Foracube,forexample,youspecifythe"corners."Cornersarereferredtoasvertices(plural)orasavertex(singular).Youmayalsoseethemreferredtoasanode(singular)ornodes(plural). Onceyoudefinethevertices,youcanthendothingswiththem.Inthisexample,wewanttodrawlinesbetweenthem.DefiningtheverticesisdonewithasimplelistortupleinPython.Youcanthenpre-definesomeruleslikewhatverticesmakeupa"surface"andbetweenwhatverticesarethe"edges,"orlinesthatwewanttohavedrawnbetweenthevertices. Onceyoudothat,thenyou'rereadytowritetheOpenGLcode.Todothis,youhaveglBeginandglEndstatementsthatyoucall,andbetweentheseiswheretheOpenGL-specificcodegoes.IntheglBeginstatement,youspecifythe"type"ofcodethatyouareabouttopass.Theseareconstants,andcontainthingslikeGL_QUADSorGL_LINES.ThisbasicallynotifiesOpenGLhowyouwantittohandleyourstatements. Sothat'stheabstractconceptofhowOpenGLworks,let'sgoaheadanddoit! First,youwillneedtohavethefollowing: Python PyOpenGL PyGame IfyouareaWindowsuser,thenIhighlyrecommenddownloadingPyGameandPyOpenGLfromthissourceofWindowsbinariesforPythonModules.Justsavethatlinktoyourbookmarks.Superusefulwebsite. Onceyouhaveeverything,goaheadandopenupIDLEandtypein: importpygame importOpenGL Ifyoucantypethosestatementsandrunthemwithoutanyerrors,thenyouarereadytoproceed.Ifyouaregettingerrors,somethingwentwrong.Mostofthetime,theerroriseitheryou'vedownloadedthewrongPythonversionofPyGameorOpenGL,orthewrongbitversion.So,ifyouareusing32bitPython,youneedtouse32bitmodules,andsoon.Evenifyouroperatingsystemisa64bitOS,youmaystillfindyou'rerunninga32bitversionofPython.Ihighlyrecommendusing64bitPythonifyoucan,32bitislimitedto2GBofram,whichisquitethelimitation.Ifyouhavea32bitOS,thenyoucannotuse64bit. Alright,nowlet'sgetintothecode!IfyoustillhavetheimportpygameandimportOpenGLcode,erasethatandstartcompletelyblank. First,we'regoingtodosomeimports: importpygame frompygame.localsimport* fromOpenGL.GLimport* fromOpenGL.GLUimport* We'reimportingallofPyGamehere,andthenallofthePyGame.locals.ThisissometypicalPyGamecode.IfyouwanttolearnabunchmoreaboutPyGame,checkoutthePyGamePythonprogrammingseriesIofferhere. Next,weimportOpenGL.GLandOpenGL.GLU.OpenGL.GLisjustyourtypicalOpenGLfunctions,thenOpenGL.GLUissomeofthemore"fancy"OpenGLfunctions. Forthefirstfewvideos,Igoaheadandmiss-spellvertices.Oops. vertices=( (1,-1,-1), (1,1,-1), (-1,1,-1), (-1,-1,-1), (1,-1,1), (1,1,1), (-1,-1,1), (-1,1,1) ) Here,we'vedefinedthelocation(x,y,z)ofeachvertex.Ithinkitisbesttoenvisionthisin"units."Trytothinkoftheselocations"spatially."Withacube,thereare8"nodes"orvertices. Next,we'rereadytodefinetheedges: edges=( (0,1), (0,3), (0,4), (2,1), (2,3), (2,7), (6,3), (6,4), (6,7), (5,1), (5,4), (5,7) ) Eachoftheabovetuplescontainstwonumbers.Thosenumberscorrespondtoavertex,andthe"edge"isgoingtobedrawnbetweenthosetwovertices.Westartwith0,sincethat'showPythonandmostprogramminglanguageswork(thefirstelementis0).So,0correspondstothefirstvertexwedefined(1,-1,-1)...andsoon. Nowthatwe'vegotthat,let'sworkontherequiredcodetoworkwithOpenGLtoactuallygenerateacube: defCube(): glBegin(GL_LINES) foredgeinedges: forvertexinedge: glVertex3fv(vertices[vertex]) glEnd() First,westartoffourfunctionaswewouldanyotherfunction. Next,sincethisisjustafunctioncontainingOpenGLcode,wegoaheadandopenwithaglBegin(GL_LINES),thisnotifiesOpenGLthatwe'reabouttothrowsomecodeatit,andthentheGL_LINEStellsOpenGLhowtohandlethatcode,which,inthiscase,meansitwilltreatthecodeasline-drawingcode. Fromthere,wesayforedgeinedges,whichcorrespondstoeachpairofverticesinouredgeslist.Sinceeachedgecontains2vertices,wethensayforvertexinedge,doglVertex3fv(vertices[vertex]),whichperformstheglVertex3fvOpenGLfunctiononthe[vertex]elementoftheverticestuple. Assuch,whatendsupbeingpassedthroughOpenGLwiththeconstantofGL_LINESis: glVertex3fv((1,-1,-1)) glVertex3fv((1,1,-1)) ...andsoon.OpenGL,knowingthatwe'redrawinglinesherewilldrawlinesbetweenthosepoints. Afterrunningthroughalledges,we'redone,sowecallglEnd()tonotifyOpenGLthatwe'redonetellingitwhattodo.Foreach"type"ofOpenGLcodethatyouplantouse,youwillneedopeningandclosingGLcommandslikethis. That'sitforourcubefunction.Thisfunctionwillcreatethecube,butnowwewanttodisplaythecubeandspecifyourperspectiveintheenvironment: defmain(): pygame.init() display=(800,600) pygame.display.set_mode(display,DOUBLEBUF|OPENGL) ThisismostlytypicalPyGamecode.Ifyouwanttounderstanditmore,checkoutthePyGamePythonprogrammingseries. Theonlymajordifferencehereiswe'readdinganother"parameter"lookingthingafter"display"inthepygame.display.set_mode.Theseareactuallyconstants,notifyingPyGamethatwe'regoingtobefeedingitOpenGLcode,aswellasDOUBLEBUF,whichstandsfordoublebuffer,andisatypeofbufferingwheretherearetwobufferstocomplywithmonitorrefreshrates.Takenotethatpipe("|")thatisusedtoseparateconstants.Itwillbeusedagainlatertoseparateconstants. Next,withinthismain()function: gluPerspective(45,(display[0]/display[1]),0.1,50.0) gluPerspectiveiscodethatdeterminestheperspective,asitsounds.Thefirstvalueisthedegreevalueofthefieldofview(fov).Thesecondvalueistheaspectratio,whichisthedisplaywidthdividedbythedisplayheight.Thenexttwovaluesherearetheznearandzfar,whicharethenearandfarclippingplanes. Whatintheheckisaclippingplane?Ifyou'relikeme,thatmeansnothingtoyouatthispoint.Basically,aclippingplaneisatwhatdistancedoestheobjectappear/disappear.Sotheobjectwillonlybevisiblebetweenthesetwovalues,andbothvaluesaresupposedtobepositive,becausetheyareinrelationtoyourperspective,notinrelationtoyouractuallocationwithinthe3Denvironment. So,we'rehavingthecloseclippinghappeningat0.1unitsandthefarclippingplaneas50.0unitsaway.Thiswillmakemoresenselater,oncewe'vedisplayedthecubeandwecancontrolwhereweareinthe3Denvironment,thenyouwillseetheclippingplanesinaction. Nextup,wehave: glTranslatef(0.0,0.0,-5) glTranslatef,officially"multipliesthecurrentmatrixbyatranslationmatrix."OKcool,againthatmeansnothingtome.So,inlayman'sterms,thisbasicallymovesyou,andtheparametersarex,yandz.Soabove,we'removingback5unites.Thisissowecanactuallyseethecubewhenwebringitup.Otherwise,we'dbeabittooclose. Nowlet'swriteourtypicaleventloopforPyGame.Again,ifyouwanttolearnmore,checkouttheaforementionedtutorial. whileTrue: foreventinpygame.event.get(): ifevent.type==pygame.QUIT: pygame.quit() quit() ThisisasimplePyGameeventloopthatisonlycheckingforanyexit,whichisonlylookingfortheliteral"x"out.Continuingunderthis"while"statement: glRotatef(1,3,1,1) glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT) Cube() pygame.display.flip() pygame.time.wait(10) glRotatefmultipliesthecurrentmatrixbyarotationmatrix.Theparametershereareangle,x,yandz. ThenwehaveglClear,whichislikeanyotherclearingfunction.Wespecifyacoupleofconstantshere,whichistellingOpenGLwhatexactlywe'reclearing. Oncewehaveaclean"canvas"ifyouwill,wethencallourCube()function. Afterthat,wecallpygame.display.flip(),whichupdatesourdisplay. Finallywethrowinashortwaitwithpygame.time.wait(10). That'sitforourmainfunction,andnowwejustcallamain()attheendtomakeitallwork.Justincaseyougotlostsomewhere,here'stheentirescriptputtogether: importpygame frompygame.localsimport* fromOpenGL.GLimport* fromOpenGL.GLUimport* verticies=( (1,-1,-1), (1,1,-1), (-1,1,-1), (-1,-1,-1), (1,-1,1), (1,1,1), (-1,-1,1), (-1,1,1) ) edges=( (0,1), (0,3), (0,4), (2,1), (2,3), (2,7), (6,3), (6,4), (6,7), (5,1), (5,4), (5,7) ) defCube(): glBegin(GL_LINES) foredgeinedges: forvertexinedge: glVertex3fv(verticies[vertex]) glEnd() defmain(): pygame.init() display=(800,600) pygame.display.set_mode(display,DOUBLEBUF|OPENGL) gluPerspective(45,(display[0]/display[1]),0.1,50.0) glTranslatef(0.0,0.0,-5) whileTrue: foreventinpygame.event.get(): ifevent.type==pygame.QUIT: pygame.quit() quit() glRotatef(1,3,1,1) glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT) Cube() pygame.display.flip() pygame.time.wait(10) main() Theendresultshouldbe: AwesomeandcongratulationsonyourPyOpenGLcube!Thereisobviouslyalotmoretolearn,andsomeofthesefunctionsmaynotmaketoomuchsensejustyet.I'llbegoingoverthoseabitmoreindepthsoon. Thenexttutorial:ColoringSurfacesaswellasunderstandsomeofthebasicOpenGLcode OpenGLwithPyOpenGLintroductionandcreationofRotatingCube ColoringSurfacesaswellasunderstandsomeofthebasicOpenGLcode Go Understandingnavigationwithinthe3DenvironmentviaOpenGL Go Movingtheplayerautomaticallytowardsthecube Go RandomCubePosition Go AddingManyCubestoourGame Go AddingagroundinOpenGL Go Infiniteflyingcubes Go Optimizingtheprocessingforinfinitecubes Go