What is the fastest way to pass around values in GLSL?

I can think of at least three ways to pass around such values for modification: Use inout parameters for every function. Pass the value as an in ... Home Public Questions Tags Users Companies Collectives ExploreCollectives Teams StackOverflowforTeams –Startcollaboratingandsharingorganizationalknowledge. CreateafreeTeam WhyTeams? Teams CreatefreeTeam Collectives™onStackOverflow Findcentralized,trustedcontentandcollaboratearoundthetechnologiesyouusemost. LearnmoreaboutCollectives Teams Q&Aforwork Connectandshareknowledgewithinasinglelocationthatisstructuredandeasytosearch. LearnmoreaboutTeams WhatisthefastestwaytopassaroundvaluesinGLSL? AskQuestion Asked 10years,10monthsago Modified 8years,8monthsago Viewed 1ktimes 4 1 InGLSLshaders,Ioftenwantacoupleoffunctionstomodifyasinglevalue,forvariousreasons(e.g.afragmentshaderthatusesfourfunctionstoapplylighting,texture,specularsandfog,say).Icanthinkofatleastthreewaystopassaroundsuchvaluesformodification: Useinoutparametersforeveryfunction. Passthevalueasaninparameterandusethereturnvalue(whichhastheobviousdisadvantagethatIcanonlyuseonevalue). Useaglobalvariablethateachfunctionmodifies. ShouldIexpectanypracticaldifferencesbetweenthesemethods?Aresomemoreprobablyfasterthanothers?Aresomemorecompatiblethanothers?Arethereanyotherdifferences?Orothermethods,forthatmatter? OrcanIsimplychoosetheoneIlikebest,stylistically? glsl Share Improvethisquestion Follow askedOct31,2011at17:53 Dolda2000Dolda2000 24.5k22goldbadges4949silverbadges8989bronzebadges 3 4 Optimizeyouralgorithm.Thenoptimizeanyotherbottlenecksyoufind.Afterdoingallofthat,thenyoucanthinkaboutwhatmethodsofmodifyingparametersworkbestonagivencompiler(becauseitwillbecompiler-dependent).Ingeneral,youwillgetpreciselyzilchoutofthis. – NicolBolas Oct31,2011at18:45 1 Thethreemethodsyoudescribearelikelytoendupbeingthesameifyouhaveonlyasingleshaderinanygivenprogramstage.Ifyoulinkmultipleshadersintoasinglestage,thenusingaglobalmightbedifferent(betterorworse).Asalways,youneedtoprofiletofigureoutwhat(ifanything)isdifferentandwherethebottlenecksare. – ChrisDodd Oct31,2011at20:17 1 Also,for#2,youcanuseoutparameterstoget(effectively)extrareturnvalues. – ChrisDodd Oct31,2011at20:18 Addacomment  |  1Answer 1 Sortedby: Resettodefault Highestscore(default) Trending(recentvotescountmore) Datemodified(newestfirst) Datecreated(oldestfirst) 0 ThiskindofoptimizationdependsmostlyontheunderlyingGLSLcompiler.ProfileyourshaderondifferentGPUs:AMD,nVidia,Intelandselectthebestcodepath. Share Improvethisanswer Follow answeredDec8,2013at12:20 SergeyK.SergeyK. 24.3k1313goldbadges101101silverbadges173173bronzebadges Addacomment  |  YourAnswer ThanksforcontributingananswertoStackOverflow!Pleasebesuretoanswerthequestion.Providedetailsandshareyourresearch!Butavoid…Askingforhelp,clarification,orrespondingtootheranswers.Makingstatementsbasedonopinion;backthemupwithreferencesorpersonalexperience.Tolearnmore,seeourtipsonwritinggreatanswers. Draftsaved Draftdiscarded Signuporlogin SignupusingGoogle SignupusingFacebook SignupusingEmailandPassword Submit Postasaguest Name Email Required,butnevershown PostYourAnswer Discard Byclicking“PostYourAnswer”,youagreetoourtermsofservice,privacypolicyandcookiepolicy Nottheansweryou'relookingfor?Browseotherquestionstaggedglsloraskyourownquestion. 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