Read depth values while stencil testing(same texture) - Stack ...

In my opinion there should not be any problems, because i'm not reading the stencil buffer values in the shader. 2022DeveloperSurveyisopen!Takesurvey. Home Public Questions Tags Users Companies Collectives ExploreCollectives Teams StackOverflowforTeams –Startcollaboratingandsharingorganizationalknowledge. CreateafreeTeam WhyTeams? Teams CreatefreeTeam Collectives™onStackOverflow Findcentralized,trustedcontentandcollaboratearoundthetechnologiesyouusemost. Learnmore Teams Q&Aforwork Connectandshareknowledgewithinasinglelocationthatisstructuredandeasytosearch. Learnmore Readdepthvalueswhilestenciltesting(sametexture) AskQuestion Asked 6years,1monthago Modified 6years,1monthago Viewed 779times 0 Iknowthatitisaverybadideatoread/writefrom/tothesametexture/location,becausethiswouldresultinundefinedbehaviour. Butinmycase,ifdepthtestingisdisabledandIreadthedepthvaluesinashader,isitoktodothestenciltestingatthesametimeasreadingthedepthvalueswithinthesametexture? Inmyopinionthereshouldnotbeanyproblems,becausei'mnotreadingthestencilbuffervaluesintheshader.Or,couldtherebyanyhardwarerelatedproblemswhenthetextureisboundforreadinginashaderandOpenGLusesittodothestenciltesting? Thistextureisfilledwithdepth/stencilvalues.Iwan'ttoavoidsomeheavyBRDFlighting(Directionallight)calculationsonspecificpixels(thesky). Examplecode: //Containsthedepth/stenciltexture(deferredDepthStencilTextureID). //TwoFBO'saresharingthesamedepth/stenciltexture. lightAccumulationFBO->bind(); glEnable(GL_STENCIL_TEST); glStencilFunc(GL_EQUAL,1,0xFF); //Disablewritingtothestencilbuffer,i.e.allthebitsiswrite-protected. glStencilMask(0x00); glDisable(GL_DEPTH_TEST); glEnable(GL_BLEND); glBlendFunc(GL_ONE,GL_ONE);//Additiveblending.Lightaccumulation. glActiveTexture(GL_TEXTURE0); glBindTexture(GL_TEXTURE_2D,deferredDepthStencilTextureID);//GL_DEPTH24_STENCIL8 //Bindothertextureshere... shader.bind(); //Uniformshere... postProcessQuad->renderQuad(); shader.unbind(); //Unbindallthetextureshere. ... glDisable(GL_BLEND); glEnable(GL_DEPTH_TEST); glDisable(GL_STENCIL_TEST); lightAccumulationFBO->unbind(); opengltexturesshaderdepth-bufferstencil-buffer Share Follow editedApr22,2016at3:47 karl88 askedApr22,2016at0:45 karl88karl88 31111silverbadge1111bronzebadges 2 Doyouonlydostenciltestinginthisrenderingpass,ordoyouuseastenciloperationthatmodifiesthestencilvaluesaswell? – RetoKoradi Apr22,2016at2:52 Ihaveupdatedmypostwithexamplecode.Ihavenotincludedthestenciloperationinthisrenderingpass.Ihavealsosetthestencilmasklikethis:glStencilMask(0x00); – karl88 Apr22,2016at3:44 Addacomment  |  1Answer 1 Sortedby: Resettodefault Highestscore(default) Datemodified(newestfirst) Datecreated(oldestfirst) 1 Butinmycase,ifdepthtestingisdisabledandIreadthedepthvaluesinashader,isitoktodothestenciltestingatthesametimeasreadingthedepthvalueswithinthesametexture? No.WhetheranoperationisdefinedornotisbasedontheimagesattachedtotheFBOandreadfrom.Notthecomponentsofsaidimages.Andno,writemaskingwillnotsaveyoufromundefinedbehavior. Sounlessyourstenciltextureisseparatefromyourdepthtexture,that'snotgoingtowork.Andgoodluckfindinghardwarethatwillallowyoutoseparatedepth/stencilimages. EvenwithGL4.5/NV/ARB_texture_barrier,theanswerisstillno.Thatfunctionalitymakescertainexceptionstotheaboverule,butonlyforoperationsthatareduetofragmentshaderoutputs.Stenciltestoperationsarenotfragmentshaderoutputs,sotheydon'tapply. Share Follow answeredApr22,2016at4:49 NicolBolasNicolBolas 412k6161goldbadges709709silverbadges901901bronzebadges 1 ok,thanksfortheinfo.So,whataremyoptions?Renderaquadandcopyingthedepthinfo.toanotherfbo/texture?Blittingfbos?Whichmethodisbestwhenitcomestoperformance? – karl88 Apr22,2016at5:38 Addacomment  |  YourAnswer ThanksforcontributingananswertoStackOverflow!Pleasebesuretoanswerthequestion.Providedetailsandshareyourresearch!Butavoid…Askingforhelp,clarification,orrespondingtootheranswers.Makingstatementsbasedonopinion;backthemupwithreferencesorpersonalexperience.Tolearnmore,seeourtipsonwritinggreatanswers. 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