rfrk-mentalray-3dsmax

REALFLOW RENDERKIT V2.0 FOR MENTAL RAY FOR 3DS MAXMANUAL VERSION 0.42

1 INTRODUCTION Introduction Pag. 3

2 FlowerMesher Overview 2.01IncludingfluidsforMeshingPag. 6 2.02MeshingPag. 8 2.03MeshFiltering,ClippingandOptimizationPag. 8 2.04ThemagnitudesPag. 9 2.05LoadingandsavingRFRKmeshesPag. 9

3 RFRK Particler Overview 3.01FluidSequencesPag. 11 3.02Multipoint,Clipping,FiltersandMotionBlurPag. 11 3.01SizePag. 12 3.01ParticleprimitivesPag. 12 3.01MagnitudesPag. 13

4 RFRK Cloud Overview 4.01FieldandParticlesSequencesPag. 15 4.02LightingandShadingPag. 15 4.01ColorsandOpacityPag. 17

5 RFRK Displacement Overview RFRKDisplacementOverviewPag. 18

6 MENTAL RAY: 3DS Max Plug-in 6.01Plug-inInstallationManualPag. 20 6.02Plug-inManualPag. 21

©NextLimitTechnologies2010

RealFlow RENDERKIT v2.0 for mental ray for 3ds Max - Manual Version 0.42

Introduction | 3

1 INTRODUCTION

TheRealFlowRenderKit2.0(RFRK)isasetoftoolsthathasbeendesignedtofacilitatethecomplextaskofrenderingRealFlow™fluids.

Forthepastdecade,simulationtoolslikeRealFlow™havebeenusedtoachieverealisticfluid simulations. Nowadays RealFlow™ can be used to compute fluid dynamics shotsatawiderangeofscales,fromabigpieceofoceanofseveralhundredsofmeterstomillimetricalwaterdrops.Forexample,ifwesimulateastormyseanearthecoastwewillhaveamassofsea,splashes,spray,mist,foam,etc...andforeachoneoftheseelementsthewaterbehaviourshouldbesimulatedatdifferentscales.

Thenexttaskafterthesimulationistheshadingprocess.Atthisstagewehavetouseandcombineallthefluidelementsinsideoursimulation,chooseashadingstrategyforoneofthemandpassthemtotherenderer.

Duetotherenderer’slimitations,rightnowwecannotusethesamematerialforallthefluidsofoursimulation.Soitisveryimportanttohavealltheseelementsseparatedforshadingpurposes.Theappearanceofabigoceansurfaceisverydifferentfromthatofamistwaterdrop,whilebotharemadeofwater.

ForthestormyseascenethatwehavedescribedaboveRealFlowwilloutputthefollowingfluidelements:abigmeshwiththeseadynamicswithananimateddisplacementtexturetocapturethehighfrequencyandchoppywaves;fluidparticlesormeshesforsplashesandfoam;andwaterdensityfieldsformisteffects.

Assaidbefore:theshadingstrategyisnottrivialanditcanbedoneinseveralways.Forexample,splashparticlescanberenderasmesheswithadielectricshader,asspriteswithsemitransparenttextures,orasaselfshadowvolumecloud.Therearealotoffactorsthataffectwhichapproximationweshouldchoose,suchasthedistanceofthesplashtothecamera,thevelocityofthesplash,etc..Thekeyideaisthateachapproximationwillgiveourfluidsadifferentlook.

TheRealFlowRenderKitcanhelpusinthiscomplextaskwithdifferenttools:



Introduction | 4

RFRK Mesher:thisproceduraltoolhastwomainfeatures.Itcancreateamesh,whichwillrepresentthesurfaceofourfluid,fromourparticlesbinfilesatrendertime.Oncethefluidsurfaceiscomputeditwillbesentdirectlytotherenderer.ThesecondfunctionisthepossibilitytoimportourBINorMDprecomputedmeshesandpassthemtotherendererdirectly.Using these featuresweskip theproblemofhaving to loadahugegeometrymeshinour3Dplatformviewportwithalltheconsequencesthisbrings.Also,withthefirstfeatureweavoidsavingallourmeshestodiskbecausetheyarecomputedonthefly.Thesefeatureswillgreatlyimproveourcurrentpipeline.

RFRK Particler:thistoolcanbeofmuchhelpifwewanttouseourparticlesasdifferentprimitives types like points, spheres, sprites, instances of certain geometry, etc... Thistooloffersalotofpossibilitiessuchaschangingtheparticlesizeaccordingtothecameradistanceoraccordingtoaparticlemagnitude,multipointcloudswithvelocitydeformation,camerafrustumclipping,etc..

RFRK Cloud:wecanusethisshadertorenderourfluidparticlesandourmistdensityfieldsandobtainavolumetriccloudasanobject.

RFRK Displacement: is used in combination with statistical spectrum displacementtexturestogetahighlevelofdetailinseasurfaces,capturingthehighestfrequencyandchoppywaves.Itoffersthepossibilitytocombinemorethanonetexturelayeratthesametime.



Introduction, FlowMesher Overview | 5

2 FLOWMESHER OVERVIEW

RFRKMeshercanextractageometryfluidsurfacemesh implicitlycontained insideourfluid particles. It offers the possibility to be configured with a lot of parameters likepolygonsize,smoothness,radiusoftheparticles,etc…Alltheseparametersmustbesetaccordinglytoobtainthefluidsurfaceshapethatwearelookingfor.

Ifwehavealreadyprecalculatedourmeshes inRealFlow,wecanuseRFRKMeshertoinsertthemintoourrenderingenginedirectly.Normallya3Dplatformviewportcannotworkverywellwiththousandormillionsofpolygons.WithRFRKMesherwecanoverridethisissueanddoalltheshadingtasksinaneasyway.




2.01 Including fluids for MeshingAs we said above the surface of our fluid is computed with fluid particles from oursimulation.So thefirst step toobtainafluidsurface is toselect theparticles thatwilldefineourfuturemesh.

Howeverthesefluidparticles,bythemselves,onlyrepresentaposition,oralocationinspaceandnothingelse.Itisnecessarytogivethemsomepersonality.

Oneofthepropertiesoftheparticlesthatwecanconfigureistheirvolume(orradius).Dependingonhowmuchvolumewegivethemwewillobtainamoreorlesscoarsemesh.

Theimagesbelowgiveyousomeexamplesofthesamefluidwithdifferentvaluesforitsparticlesradius.

F.01Radius=0.025 F.02Radius=0.05 F.03Radius=0.1

Anotherinterestingpropertyoftheseparticlesisthepossibilitytofilterthemaccordingtotheirnumberofneighbours.Inthiswaywecanobtainonlythecoreorsplashesofourfluids.Intheimagesbelowweseehowthesefiltersactwithfluidparticles.

F.04core=0 F.05core=0.5 F.06core=0.8

F.07splash=0 F.08splash=0.5 F.09splash=0.8

BooleanoperationsarepossiblewiththeRenderKit.Youcanaddasmanyfluidstothesceneasyouwant.Theappearanceofcontinuitywillbecreatedbymixingthedifferentfluidsinthescenesothattheymakeupthesamemesh.Inthenextimagewehavetwofluidemittersworkingtogether.




Theresultisauniformandsmoothmeshwithoutdiscontinuitiesandedges.

Nextwecanseehowthesubtractivefluidsoptionworks.

F.10FluidAMuteOn F.11FluidASubstractOn

F.12FluidBMuteOn F.13FluidBSubstractOn

RealWave objects exported in RealFlow can also bemeshed by the RenderKit, in thesamewayasRealFlowfluidparticles.TheRFRKMeshertessellatestheRealWavemeshinternally, inserting particles inside each polygon, transforming RealWave meshes inparticleemitters,andcouldbeusedtoobtainthesamesmoothandcontinuitybehaviourthatwehavedescribedabove.

Another way to include fluids inside RFRKMesher is loading precalculated and savedRealFlowmeshes.Beforebeingabletoshadeandrenderthem,wehavetoimportthemintoour3Dplatformviewport.Asdescribedabovethisgivesalotofworkflowproblems.WithRFRKMesherweskiptheseissuesandpassthemeshtotherendererdirectly.




2.02 MeshingOncewehavedecidedwhichfluid elementswill formour final fluid surface,wemustdeterminewhatwewantourmeshtobelike.Severalglobalmeshpropertiescanbesetuplikeitsdetail,smoothness,fieldtype,etc…Thedetailofourmeshisrelatedtoitsresolutionandtheresolutionisrelatedtothesizeofourpolygonsandfinallytothetotalnumberofpolygons.Whendecreasingthesizeofourpolygonswewillgetmesheswithmoreresolutionandallthefinefeaturesofourfluidwillbecaptured.Howeverthemesheswillalsogetmorepolygons.Belowwehavesomeexamplesofthesamefluidwithdifferentpolygonsizes.

F.01PolygonSize=0.025 F.02PolygonSize=0.05 F.03PolygonSize=0.1

Anotherkeyaspectinvolvedinthefinalappearanceofthemeshisthelevelofsmoothnessused–i.e.whetheryouarelookingforsmooth-orblobby-lookingfluid.Toobtainaspecificlookyouwillhavetoconfigurethemesh.Thesmoothnesstellsthealgorithmhowfaritshouldgotogatherenvironmentinformationtocomputeagivenpointofthemesh.

F.04Smooth=0 F.05Smooth=80

2.03 Mesh Filtering, Clipping and OptimizationOncewe have depicted ourmesh properties,we can apply some filters, clipping andoptimizationalgorithms,withtwoobjectives:wewanttofine-tuneoursurfaceorweneedtoreducethenumberofpolygons.

Somefilters,likesurfacetensionandsurfacerelax,canbeappliedtooursurfacetoget,finally,thefluidsurfaceshapethatwearelookingfor.

F.01R=0.15,T=0.6,S=1 F.02R=0.15,T=0.6,S=16 F.03R=0.15,T=0.6,S=64

R=RelaxT=TensionS=Samples

Sometimesourmesheshavemillionofpolygonsandtherenderercanhavedifficultiestoworkwiththem.RFRKMesheroffersthepossibilitytoremovepolygonsandredundant




informationinseveralways:removingpolygonsinareaswherethemeshisn’tevergoingtobedisplayed(liketheinternalorexternalsideofobjects),moreover,wecandiscardtheparticlesoutsidethecamerafrustumtocomputeameshthatadjuststothecameraprojection.

Anotherwaystoreducethenumberofpolygonsisaccordingtothecurvatureofthemesh.Thiswaythealgorithmwillkeepthehighcurvatureareasandwillstartremovinghighflatareas.Youcanalsodothisaccordingtothedistanceofthepolygonfromthecamera.Thismeansthatpolygonsthatarefurtherawaythanagivendistancewillberemovedaccordingtothesurfacecurvatureandcloserpolygonswillbekept.

F.04Nooptimization F.05Optimizationbasedoncurvature

2.04 The magnitudesFluidsolversnotonlycomputethepositionandvelocityofourfluids,thereisinformationofotherphysicalmagnitudes inoursimulationstoo.Magnitudes likevelocity,age,andvorticity,whichcanbevery important forshadingpurposes,arestored insideourBINfluidparticlesfiles.RFRKMeshercanaccessthisinformationandexportthesemagnitudestotheverticesofthepolygonsofourfluidsurface.Now,themagnitudescaneasilybeconnectedtotexturerampsandshaderparameters,andcanbeincludedquicklyinourshadernetworks.

F.06ShadingVelocities F.07ShadingPressures

2.05 Loading and saving RFRK meshesWhenyouareworkingwithheavymeshes, it canbe time-consuming to compute thewholefluideverytimeyouwanttomodifyaparameterofyourmaterial.Wenowhavethepossibilitytoexportandimportthesurfaceofafluidthatwehavejustcomputed,asMDorRIBfiles,withalltheavailablemagnitudes.



Introduction, Particler Overview | 10

3 RFRK PARTICLER OVERVIEW

Theremaybecertaincaseswherewedon’twant to render thefluidsofoursceneasfluid-likesurfacesandwearemoreinterestedinamorechaoticandblurredsurface,aswithhighspeedandsparsefluids.Othertimesthefluidcouldbesofarawayfromusthatwewouldnevernoticethedifferencebetweenafluidgeometrymeshandanyotherlowcostgeometry.

RFRK Particler uses the fluid particle positions to place other geometry primitives likepoints,sprites,spheresorothergeometryinstances(*pointsprimitiveonlyavailableforRenderManandinstancesonlyavailableformentalray).




3.01 Fluid SequencesAswithRFRKParticler,thefirstthingthatweneedtoknowiswhichfluidsequenceswewanttoinclude.Wealsohavethepossibilitytoaddmorethanoneparticlesequence.

3.02 Multipoint, Clipping, Filters and Motion BlurOncewehaveincludedthefluidparticlestoparticipateinthescene,itcouldbeinterestingtoincrease,decreaseorfilterthenumberofparticlesaccordingtocertaincriteria.

Withthemultipointoptionwecanmultiplythenumberofparticles.Wecangenerateasphericalcloudofparticlesaroundeachparticle.Thereisanoptiontodeformthesphericalcloudofparticlesalongthevelocityvectoroftheparticles.

Wecandecreasethenumberofparticleswithcameraclipping,soalltheparticlesthatareoutsidethecamerafrustumprojectionwillberemoved.

Andfinallywecanfilterourparticlesaccordingtothenumberofneighbors,aswedowithRFRKMesher.

F.04Core=0.0 F.05Core=0.5 F.06Core=0.8

F.07Splash=0.0 F.08Splash=0.5 F.09Splash=0.8

Motionblurdependsonseveralcameraandsceneproperties.Moreover,thereisanoptiontoclampthemaxvelocitiesoftheparticlestohavemorecontrolovermotionblur.




3.03 SizeUsuallywewould notwant all the particles of our fluids having the same size. RFRKParticlerhasanoptiontocontrolthesizeoftheparticles,accordingtotheirdistancetocameraorcertainfluidmagnitude.Havingagoodcontroloverthisparameteriscriticaltoachievetheresultthatwearelookingfor.Therefore,RFRKParticlerfeaturesacurveeditortohaveagoodcontroloverthisproperty(**Mayaand3dsMaxplug-insonly).

3.04 Particle primitivesInthenextstepwehavetodecidewhichprimitivetypewewanttoattachtoourfluidparticles.Dependingonwhichprimitivetypeweuse,wecanachieveaspecificlookforourfluid.

F.01Sprites F.02Spheres

F.03Cubes F.04Instances




3.05 MagnitudesTheRFRK Particler can also read the particle properties fromRealFlow fluids. As saidabove in the RFRKMesh section, you can read them in yourmaterials (for instance,mappingtheopacitybasedontheageoftheparticle)tohavemorecontrolovershading.

F.01ShadingVelocities F.02ShadingPressures



Introduction, Cloud Overview | 14

4 RFRK CLOUD OVERVIEW

Itoftenhappensthatwecannotcreateaspecificfluidlookusingjustgeometry,andweneedtofindothersolutions.Forexample,creatingtheeffectofthesplashofabreakingwaveorthewatercollidingagainsttherocksisveryhardtoachievewithjustgeometryand a surface shader.One of themain difficulties iswith thematerial displaying lightscatteringandattenuationwhenittravelsinsideavolume.

This effect can be handled easily with volumetric approximations. RFRK Cloud is avolumetricshaderthatwecanuseforthispurpose.




4.01 Field and Particles SequencesRFRKCloudcanreadstandardfluidparticlesfilesandmistfields.

Aswehavepreviouslyexplainedwiththeothertools,wecanmodifytheinputfluidsandcontroltheircontributiontoourdensitycloudstorender. Thesefieldsaresavedtomemoryinavoxelizationstructure,sothesizeofthevoxelsisdecisiveforourfinalcloudappearance.(**theCellSizeandradiusareonlyconfigurableforBINparticlefiles.FormtcfilesthesepropertiesaredefinedinRealFlow).

F.01CellSize=0.06 F.02CellSize=0.03 F.03CellSize=0.01

Wecangiveourparticlesmoreorlessvolume.**

F.04RadiusScale=0.02 F.05RadiusScale=0.04 F.06RadiusScale=0.09

Wecaneasilyincreasethedensityofourdensityfields,obtainingamoreopaquevolume.

F.07DensityScale=1 F.08DensityScale=3 F.09DensityScale=6

4.02 Lighting and ShadingRFRKClouddoesn’tonlyallowustocontroltheshapeanddensityofourfluidcloudfield.Wecanalsomanagehowmuchandinwhatwaythelightofourscenewillinteractwithit.

Somebasicchangescanbemade,likeincreasingtheintensityofthelightthatreachesourfluid,oraddingambientlightingtoremovehardshadowsareas.

F.01LightIntensity=10 F.02LightIntensity=20 F.03LightIntensity=30




F.04Ambientcoloured F.05AmbientTexture

Wecancontrol theamountof light that is scatteredandabsorbedas the light travelsthroughthecloud.

ExtensionCoefficient0.1(Left)and1.0(Right)

Albedo0.1(Left)and1.0(Right)

Lightanisotropycanalsobecontrolled.Thelightanisotropytellsusinwhichdirectionthelightisscatteredaccordingtotwovectors.Thefirstvectoristhecameratothepointofthecloudthatwearesampling,andthesecondvectorisfromthatpointtothelightposition.

F.06Anisotropy=-0.5 F.07Anisotropy=0.1

F.08Anisotropy1=0 F.09Anisotropy1=0.7 F.10Anisotropy1=0.3




4.03 Colors and OpacityThecolorandopacitycanalsobechanged.

Cloudcolored

ColorandOpacitytextured

F.01Notusing3DopacitytexturesF.02Using3Dtextures



Introduction, Displacement Overview | 18

5 RFRK DISPLACEMENT OVERVIEW

Using this shader we can get full 3D displacement. This is 3D displacement becausewearenotonlymodifyingthegeometry in itsnormaldirection,butalso in twootherdirectionsdefinedasbasisperpendiculartothenormaldirection.ThiswaywecanimportimageswithdisplacementtexturesgeneratedinRealFlow(especiallyusefulforstatisticalspectrumwithchoppywaves).Youcanusethiswithanytexture.

It is important to understandhow the shader interprets theRGB channels: thegreenchannel indicatesthedisplacement inthenormaldirectionofthesurface.Theredandbluechannelswilldisplacethegeometryinthetwootherdirections,asexplainedabove.For example, you can specify that a colorwithRGBvalues0.50.50.5 is equal tonodisplacement.Thismeansthatvaluesbelow0.5giveanegativedisplacementandabove0.5apositivedisplacement.Tojustgetadisplacementinthenormaldirection,theredandbluechannelsshouldbesetto0.5.



Introduction, Displacement Overview | 19

YoucanusethedisplacementsexportedfromRealFloworcombinethemwithtexturesfromyour3dplatform.



MENTAL RAY: 3DS Max Plug-in, Installation Manual | 20

6 MENTAL RAY: 3DS MAX PLUG-IN

6.01 Plug-in Installation Manual

a. Windows 64 bitsLet’slookintothe“RFRenderKit_Max_2”plug-inmadefortheRFRKand3DStudioMax.Themainareasthatwehavefocusedonareworkflowandperformance.

Theplug-inhasaninstallerwizardsothatusersarenolongerrequiredtomanuallycopyfiles into the3DStudioMaxdirectory.The installerauto-detectswhich3DStudioMaxversionsareinstalledandwhere.Allversionsof3DStudioMaxstartingwithv.8.0to2010aresupported,with64-bitbuildswhereapplicable.



MENTAL RAY: 3DS Max Plug-in, Manual | 21

Thewizardauto-detects3DStudioMaxversionsandinstallationlocations.

u Note:TheRFRKisdesignedtoworkwithmentalray;thereforementalraymustbeactivatedin3DStudioMaxinordertousetheRFRK.Toactivatethementalrayrenderin3dsMax,gototherenderdialogandselectmentalrayRenderer.

Mentalrayrendererin3DStudioMax

6.02 Plug-in Manual

a. ToolbarTheRFRKfunctionalitiesareaccessibleviaafloating/dockabletoolbarandamenu.

RFRKtoolbar

Thefunctionofthebuttons(fromlefttoright):

• RFRK Mesher:CreatesageometryshaderintheviewporttoloadtheBINsequencetogeneratethemesh.

• RFRK Particler:CreatesageometryshaderintheviewporttoloadtheBINsequencetogeneratetheparticles.

• RFRK Cloud:CreatesacloudobjecttoloadtheBINandMTCsequencestogenerateavolumetriccloud.

b. RFRK Mesher ParametersRFRKMeshergeneratesageometryshaderintheviewportsothatyoucanselectRealFlowBINparticlefilestogenerateapolygonalmeshatrendertime.WhenyouclickontheRFRKMesherbutton,itwillasktoyoutoselecttheBINsequencefiles.

F.01Binsequencefiles F.02Particlesloadedintheviewport

Whenyouselectafilesequence,thegeometryshaderwillberepresentedbyarectangleintheviewport.Ifwemovethetimelinetheparticleswillbedrawnintheviewport.Thecontentsofthegeometryshaderwillberenderedwithmentalray.

ThegeometryshadergeneratedbyRFRKMesherbehavesinthesamewayasstandardgeometryin3DStudioMax.ThegeometryshaderwillbelocatedinthesameplaceasitwasintheoriginalsceneinRealFlow,butitcanbemoved,scaledorrotatedifyouwant.

Ifyouselectthegeometryshaderyoucanseeitspropertiesinthecommandpanel.




F.03GeometryshaderparametersF.04InstancingtheRFRK_Meshermapinthecommandpanel

Viewportrepresentationgivesyoutheoptiontoviewtheparticlesintheviewport.Ifyouuncheckthisoption,arectanglewillshowthepositionoftheparticles.

F.05ViewportrepresentationforRFRK_Mesherobject

The Parameters tab is represented by a RFRK Mesher map button which shows theparameters tocontrol thepropertiesof thefluid.Thereare twoways tomodify theseparameters:Bydefaultthegeometryshader iscreatedwithaRFRKMeshermap.ThismapcanbemodifiedbydraggingitfromthecommandpanelintotheMaterialEditorandcreatinganinstance.WhenyoumodifythemapintheMaterialEditor,itwillbemodifiedautomaticallyinthegeometryshader.(Seeimage“instancingtheRFRKMeshermap”above).Themappropertieswillbedisplayedwhenyouselectthemapslot.

ThesecondwayistocreateamapintheMaterialEditorbyselectingtheiconandchoosingtheRFRKMeshermap(asshownintheimagebelow).

RFRKMesher map:Inordertoassignthenewmaptothegeometryshader,dragthemapfromtheMaterialEditortothemapbuttoninthecommandpanel.

u Note:InordertobeabletochoosetheRFRKMeshermapintheMaterialEditor,thementalrayRenderermustbeactiveintherenderdialog.

TheparameterswillappearifyouclickontheslotoftheRFRKMeshermapintheMaterialEditor.




RFRKMeshermappropertiesinMaterialEditor

Particle Sequences Parameters• Add/Remove:AllowstheusertoaddorremoveseveralBINsequencesonthesame

RFRK_Meshernode.• Filename:Browsetothepathandfilenameofthesequenceyouwanttoload.• Offset: Thisparameterallowsyoutogivepositiveandnegativeoffsetstotheloaded

sequence.• Radius (new):Radiusoftheparticlesforthesequence.Thisallowsustodetermine

howcoarsethemeshofourfluidisgoingtobe.Normallytheparticlesofthefluidshaveanoptimumradius.Ifwegoveryfarawayfromthisradiuscomputingtimescanincreasealotandthefluidmaynotlookrealistic.

• Core and Splash(new):Itcanoftenbeinterestingtofiltertheparticlesofourfluidtoonlykeepitsmostdenseorisolatedregions.ThenumberofneighborsmustbeavailableinsidetheBINfile.

u Note:TherearesomesimulationmodesinsideRealFlowforwhichthisinformationcannotbesaveinsidetheBINfiles.IftheBINparticlesfileshavebeenexportedfromanyother3Dplatformyoumustensurethatthisinformationiswell-definedinsidetheBINparticlesfiles.

• Max Velocity (new):Clampthevelocitytothisvalue.Sometimesduetowronglydefinedsimulationsettings,theparticlesofthefluidcancontainveryhighvelocities.Togetgoodmotionblurresultsitisnecessarytoclamp the velocities. Thisparameterwillclampallthevelocitieshigherthanthisvaluetothesetvalue.

• Subtractive (new):Useifyouwanttousethesequenceasanegativefield.• Wait (new): Waituntilthenextframeexists.Sometimeswearerenderingwhilethe

simulationisstillbeingcalculated.Byactivatingthisoption,wetelltherenderertowaituntilthenextsimulationframeiscomputedandwritten,toensurethattherewillbeafiletorenderwhenlaunched.

• Mute (new): Ignorethesequence.• Viewport Color (new): Allows the user to select the color to represent the

sequence’sparticlesintheviewport.

Global Mesh Parameter• Polygon Size: Here you can enter a custom value for themesh’s polygon size.

Smallervaluesleadtolargermeshfiles,butalsotomoredetail.Lower“Polygonsize”valuestakelongertocalculateandneedmoreresources.Pleasenotethat“Polygonsize” is not responsible for the rounded look of a fluid’s borders. If youwant toavoid roundedborders,filtersand radius settingsareofmuchhigher importance.Additionallyasufficientamountofparticles isneeded.Finally, the lookofameshstronglydependsonyourscenescale.

• Smooth: Blendstheindividualspheresandmetaballstogethertoachieveacoherentmesh. Without an adequate “Smooth” value you can see the individual spheresaroundtheparticles.Theradiusofthesespheresisexactlythevalueyou’veenteredundertheemitter’sfieldsettings.

• Surface proximity: To decrease or increase the distance between the mesh’spolygonsandtheemitter’sparticles,thisvaluemustberaisedorlowered.

• Auto Polygon Size:RenderKit2meshengineautomaticallyadjuststhepolygonsizeto get the best balance between quality and number of faces. You can activate/deactivatethis featurebysimplyswitchingto“Yes”or“No”.This isuseful todoaquicklowresolutionstartup.IntheoutputrendererlogswecanseewhichvalueofPolygonSizehasbeenused.With“No”,the“Polygonsize”fieldisunlocked.

• Field Type:Wecanusetwodifferentfieldstocomputethemesh:metaballsandspheres. The standard type for RenderKitmeshes is “Sphere”.With “Sphere” themeshiscalculatedveryfast,butcansometimesshowroundborders.Tocompensate




forthis,the“Smooth”parameterandtheparticleemitter’sFieldsettingsfor“Radius”canbeadjustedtoachieveabetterresult.Withoutsmoothingandenoughresolutionyoucanseetheindividualspheresaroundtheparticles.

• Axis: Allowsyoutochoosetheaxiscoordinatesystem.

Camera Parameters

• frame:Actualframe.• fps:Framepersecond,veryimportanttocomputethecorrectmotionblur.Itshould

bethesameasinyoursimulation.

u NOTE:InordertouseMotionBlur,theMotionBluroptionmustbeselectedinthepropertiesofthementalrayrenderer.

Filters Parameters• Filter Mesh:Youcanchoosewhetheryouwanttoapplythefilters(“Yes”)ornot

(“No”).Filteringisaveryfastmethodanddoesn’tincreasemeshingtimetoomuch.Theresultisalwaysworththeslightlylongercreationprocess.

• Relax:Thistypestretchesandsharpensthemesh’sedgesandgivesamuchmorenaturallook.Theresultisamorewateryandrealisticappearance.“Relaxation”helpsyou togetqualitymesheseven from lowresolutionemitters.Thedefaultvalue isaverygoodstartingpointand it’svery likelythatyoudon’thavetoalter itatall.“Relaxation”isverysensitiveandinsteadofchangingthefilter’sstrength,it’softenbetter to loweror raiseSteps.Though“Relaxation” isveryeffective, ithas limits:Emitterswithjustafewhundredorthousandparticlesareusuallynotsuitedtocreateaperfectmesh–evenwithfiltering.

• Tension: Ifyoucanseeunwantedhighfrequencystructuresonyourmesh, thenit’sagoodideatoactivatethisfiltertype.“Tension”flattensthemeshsurfaceandremovestheseartifacts.Similarto“Relaxation”,thistypeisalsoverysensitiveandstronglydependson theaccording“Steps”settings.High-frequencypatternsdon’toccurveryoften,sothe“Tension”filterisrarelyused.

• Steps: Each filter is affected by this parameter. Higher settings strengthen theinfluenceof“Relaxation”and“Tension”,andtheycanleadtocompletelyover-filteredmeshes.Highvaluesmayproduceunrealisticresults,unlessyouwanttoachieveacertaineffect.Anotherissueisthatveryhighsettingswillreducetheamountofdetail.

Clipping Parameters

• Object Clip:Clippingisaveryeffectiveandconvenientwaytoreduceamesh’ssize.Wheneverthereareinvisiblepartstheyshouldbeclipped.Trytousesimpleobjectswithevensurfaces,forexamplecubes,becausecomplexobjectswillonlyincreasemeshcreationtime.

• Camera Clip: Cuts away everything that’s outside the currently adjusted field ofview.

• Out Inside: You can decidewhich “side” of the clipping object should be used.“Inside”usestheobject’svolumeandeverythinginsideitwillbecutaway.“Outside”clippingdeletesallpolygonsoutsidetheusednode.Openpartsorholesarefilledwithpolygonsandtheresultisaclosedmesh.

• Clip Files:Useifyouwanttoactivateclippingwithgeometry.YouneedtospecifytheSDfilewherethegeometryisstored.Seethefollowingparameter.

• Add File:AnSdfileisneededtocomputetheclipping.Thisoptionshowsabrowsertochoosethefile.Allthegeometrydefinedinsidethisfilewillbeusedforclipping.

Optimize Parameters• Optimize: Thisentryprovidesthreeoptions:“No”,“Curvature”and“Camera”.“No”,

ofcourse,disablesanyoptimization.The“Curvature”and“Camera”settingsunlockfurther settings tocontrol themeshquality.The “Camera”optiondependson thecurrentview.Areasclosertothecamerahaveahigherresolution,whiledistantpartsshowreducedquality.“Curvature”analysesthemesh’sgeometryandpolygonsinflatareaswillberemovedfirst.Inaddition,highervaluescanbeusedtodeletepolygonsfromareaswithmorecurvature.

• Merge QualityFactor:Tospecifyamesh’squality,youcanenteravaluebetween0and1.Highersettingsyieldtobettermeshes,butdecreasecalculationspeed.

• Polygon Reduction Percent: You can easily reduce the number of polygonsbydeterminingacertainpercentage.Anexample:Byenteringavalueof75, thisfunctionkeepsapproximately75%oftheoriginalpolygonsanddeletestheremaining25%.So, ameshwith 100,000 faceswill have around75,000polygons left afteroptimization.

• Camera Distance: This value represents the distance between the camera andtheareawherethefirstpolygonswillberemoved.Withgrowingdistance(=highervalues)thenumberofpolygonsdecreases.Theareawiththehighestresolutionis




alwaysnexttothecamera.

RealWave Parameters• Insert RealWave:YoucaninsertRealWaveobjects inthemeshandrenderwith

yourfluids.• RealWave: BrowseforaRealWaveSDmeshfile.• Polygon Size:PolygonsizeoftheoriginalRealWavemesh.• Resolution: Resolution of the particles that youwant to insert in the RealWave

mesh.• Radius:Radiusofthenewparticlesincluded.

RealFlow BIN MESH• Insert Bin Mesh:This is an interesting settingwhenyouareusingbigmeshes.

ThemeshisnotloadedintheMayascene,butsentdirectlytotherenderengine,OverridingwhateversequencesofBINfilesareloadesandingnoringtherestofthesettings.Itwillactasalazycompute,justloadingaprecalculatedmeshfromdisk.Magnitudescanstillbeusedintheshadingifthemeshhasthenecessaryinformation(eg.Velocity)

• Bin File: BrowseforaBinmeshfilename.• Offset: Thisparameterallowsyoutogivepositiveandnegativeoffsetstotheloaded

sequences.• Wait: Wait until the next frame exists. Sometimes we are rendering while the

simulationisrunning.Withthisoptiontherendererwaitsuntilthenextsimulationframeiscomputedandwritten.

System ParametersTheseparametersconfigurecertainoperativesystemsettingsandthewaywewanttopassthemeshtotherenderer.• Threads:Numberofthreadstouse.• Max Memory: Maximumsizeinmegabytesofeachsubvolumeofmesh.• Number of Polygons Per Group:Numberofpolygonsofeachsubmesh.Formental

raythisisacriticalparameter.Itisnotthesametosendanobjectwithafewmillionpolygonsthantosendseveralobjectswithafewthousandpolygons.Therendertime

decreasesalotifweonlyuseobjectswithafewthousandpolygons.

Lazy Compute• Actioninthiscomboyoucanchoosetosaveorimportthegeneratedmeshtoor

fromdisk• MD Mesh: thefilenamepathwheretosaveorlookforthestoredmesh(format/

mypath/rfrkmesh#####.md)• Offset: numberofframetooffsettheloadedmesh.

Magnitudes• Channels: Indicates the channels of the particles that can be transferred to the

vertexofthemesh.ChannelscanbeVelocity,Density,Force,Pressure,Neighbors,Mass,Age,Temperature,Isolation,VorticityandViscosity.

Theappearanceofthematerialwilldependonthechannelyouhaveselected.Forexample,ifyouwanttorelatetheopacityofthemeshtothechannelAgeyouwouldhave to apply theRealFlow Texture Magnitudemap formental ray. ThemapshaderwillthenhavethevaluesetinthechannelfieldintheRealFlowMeshershader.Seetheexamplebelow.

RenderwithMagnitudeeffect RFRKMesherAgechannelmappedtoOpacitychannel

Toapplythemagnitudetotheopacitychannelastheimagesshow,selecttheAgechannelintheRealFlowMeshermapandthenapplytheRealFlow Texture Magnitudemaptothedesiredproperty.




F.01RFRK_Meshershader F.02StandardmaterialwithRealFlow

F.03RealFlowTextureMagnitudegetthevalueinRFRKMeshershaderF.04TextureMagnitudeappliedtoOpacity

u NOTE:Bear inmind that you should check if theparticleshave the correctnormalizedvaluesforeachmagnitude.

c. RFRK Particler ParametersRFRKParticlergeneratesageometryshaderintheviewportwhichenablesyoutoselectRealFlowBINparticlefiles.Thesefilescanberenderedwithmentalrayintheshapeofaninstancedobject,spheres,cubes,orsprites.InthesamewayasinRFRKMesher,whenclickingonRFRKParticleryouselectthefilefor thesequenceofparticles thatwillbe loaded in theviewportandrepresentedbyarectangle object. This objectwill be the geometry shader to renderwithmental ray.Particleswillbeshownintheviewport.

F.01BINsequencefiles F.02Particlesloadedintheviewport

F.03Viewportrepresentationforparticles




Bydefault,theloadedparticleswillappearinthesameplaceasintheRealFlowsceneandtheycanbemoved,rotatedandscaledasintheRFRKMeshergeometryshader.Whenyouhave created thegeometry shader, select it andgo to its properties in thecommandpanel.

F.04GeometryshaderinthecommandpanelF.05InstancingtheRFRKParticlermap

Max Particles indicates the maximum number of particles that can be viewed in theviewport.Itisagoodideatolimitthenumberofparticlesintheviewportrepresentationwhendealingwithheavysceneswhichcouldbecostlyforthesystemtomanage.TheParameterstabinthecommandpanelisrepresentedbyaRFRKParticlermapbuttonwhichcontainstheparameterstocontrolthepropertiesofthefluid.AsinRFRKMesher,we can drag themap button into the Material Editor to be able to access the RFRKParticlermapproperties.YoucanalsocreateanewRFRKParticlermapusingtheiconandchoosingtheRealFlowRFRKParticler2map(asshownintheimagebelow).

F.06RealFlowRFRKParticler2map

Toassignthenewmaptothegeometryshader,dragthemapfromtheMaterialEditortothemapbuttoninthecommandpanel.

u Note:TobeabletochoosetheRFRKParticlermapintheMaterialEditor,thementalrayrenderermustbeactivatedintherenderdialog.

TheparameterswillappearwhenyouclickontheslotcontainingtheRFRKParticlermapinthematerialeditor.

RFRKParticlermappropertiesinMaterialEditor




Particle Sequence Files• Filename:PathandprefixoftheBINsequence.• Offset: Offsetforthissequence.• Wait (new):Waituntilnextframeexists.• Mute(new):Ignorethisfile.• Viewport color (new):Colortodisplaytheloadedsequenceintheviewport.

Particle Size Parameters• Size:Sizeoftheparticles.• Random Variation:Randomsizevariationpercentfromtheoriginalsize.• Scaled By Magnitude (new):Thesizeof theparticleswill becontrolledwitha

magnitude.• Magnitude:Choosethemagnitudetocontrolthesizeoftheparticles.

Magnitude CurveMin / Max:Thesetwovaluesareusedtonormalizethevaluesofamagnitude.

Camera Curve• Scaled By Camera Distance:The sizeof theparticleswill be controlledby the

distancetocamera.• Min / Max: Particles with a distance to camera between these values will be

controlledwiththecurveeditor.

Other Parameters• Render Type:Theparticleswillbereplacedwiththegeometryprimitivethatyou

select:sprites,spheres,cubesorinstancesofgeometryalreadydefined.• Instanced Object:Ifyouwanttorenderinstancesyoumustselectedanobjectin

thescene.• Core:Removetheisolatedparticlesandonlykeepthecoreofthefluid.• Splash:Removethecoreofthefluidandonlykeepthemoreisolatedparticles`.• MaxVel: Limits the velocity of the particles to this value. Limiting the speed of

particlescanlimitthemotionblurintherender.

u NOTE:Inorder touseMotionBlurwithRFRKParticler, theMotionBluroptionmustbeselectedinthepropertiesofthementalrayrender.

• Axis: Selectthecoordinatesystemwhereyouwanttowork.• Percent Total Particles:Itispossibletorenderjustapercentofthetotalnumber

ofparticles.

Clipping Parameters• Camera Clip:Removealltheparticlesthatareoutsidethecamerafrustum.

Multipoint Parameters• is Multipoint: Booleansettingthatenablesthisfeature.• Density:Indicatesthenumberofnewparticlesthatwillbecreatedforeachparticle

intherender.• Dispersion: Indicates the dispersion of the new particles around the existing

particle.• Deformation: Deformation of the cloud of multipoint particle sphere along the

velocitydirectionoftheoriginalparticles.• Seed:Indicatesaseedtosetthepositionfortheparticlescreated.

Other Attributes Parameters• FPS: Indicatestheframespersecondinthescene.

ChannelsYoucanselectthemagnitudesthatyouwanttoattachtotheverticesofthemesh.Thisisusefulforshadingpurposes.Youcanchooseseveralmagnitudestotransfer intotheshaderpropertiesofthebuiltmesh.

d. RFRK Cloud ParametersRFRKCloudgeneratesageometryshader in theviewportwhichenablesyou toselectRealFlowMTCparticlefiles.Thesefilescanberenderedwithmentalrayintheshapeofaninstancedobject,spheresorsprites.InthesamewayasinRFRKMesherorRFRKParticler,whenaddingasequenceforCloud,youselectthefileforthesequenceofparticlesthatwillbeloadedintheviewportandrepresentedbyarectangleobject.FilestoloadwillbeeitherBINfilesorMTCfiles.Thisobjectwillbethegeometryshadertorenderwithmentalray.Aboxwillbeshownintheviewportwhentheparticlesareloaded.




F.01MTCsequencefiles

F.02Particlesloadedintheviewport F.03Viewportrepresentationforparticles

Bydefault,theboxwillappearinthesameplaceasintheRealFlowsceneanditcanbemoved,rotatedandscaledasintheRFRKMesherorRFRKParticlergeometryshader.Whenyouhavecreatedthevolumegeometryshader,selectitandgotoitspropertiesinthecommandpanel

F.04VolumeshaderinthecommandpanelF.05RFRKCloudmap

LODindicatesthepercentnumberofparticlesthatcanbeviewedintheviewport.Itisagoodideatolimitthenumberofparticlesintheviewportrepresentationwhendealingwithheavysceneswhichcouldbecostlyforthesystemtomanage.

Togettheshaderinthematerialeditor,we’llselectthe“PickmaterialfromObject”andwe’llthenclickontheRFRKCloudObjectintheviewport.




F.05mentalrayshaderinthecommandpanelF.06SurfaceandShadowparametersF.07CloudmapfromVolumeparameter

WecanalsoselectaRealFlowCloudmapfromthemapsselector.

F.08RFRKCloudmapF.09RFRKCloud2mat

ToassignthenewRFRKCloudmaptothegeometryshader,wemustcreateamentalraymapandincludeitintotheVolumeparameterandaddarfrk_cloud2_matintheSurfaceandShadowParameter.TheparameterswillappearwhenyouclickontheslotcontainingtheRFRKCloudmapincludedintheVolumeparameter.

F.09RFRKCloudmappropertiesinMaterialEditor

Sequence FilesWecanimportseveralemittersandmistfieldstogetaninhomogeneousparticipantmediainthespaceofourscene.

• Filename:NameoftheBINorMTCfilethatyouwanttoimportforgeneratingthedensityfield.




• Offset: Offsetforthefile.• Cell Size:Sizeofthecellsofthedensityfield(onlyforBINparticles).• Radius Scale: Radiusoftheparticles(onlyforBINparticles).• Density Scale:Theamountthatyouwanttoscalethedensityofthefieldofthis

sequence.• Min Density:Setallthedensitiesbelowthisvaluetozero.• Max Density:Setallthedensitieshigherthanthisvaluetothisvalue(clamp).• wait:Therendererwaitsuntilthenextframeexists.• mute:Ignorethisfile.

Parameters• Light Intensity:Setyourlightintensity.• Light Ambient:Setambientlight.Thisisusefultonotgetblackself-shadowareas.• VolumeColor:colorofthecloud.• Density Color:Colorortexturescalefactorfordensityfield.• Ext Coeff:Extinctioncoefficient.Theamountoflightthatisabsorbedbythecloud.• Albedo:Ratiobetweentheextinctioncoefficientandthescatteringcoefficient.• Anisotropy 1:Controlstheshapeofthefirstlobethatdefinesthescattering.Ranges

between[-1,1]Azerovaluemeansanisotropyscattering.Minusonefullbackwardscattering,andonefullforwardscattering.

• Anisotropy 2:Controlstheshapeofthesecondlobethatdefinesthescattering.• Weight 1:Scalefactorforanisotropy1.• Weight 2:Scalefactorforanisotropy2.• Integ Start:Specifywhenyouwanttostartintegratingtheray.• Integ End:Specifywhenyouwanttostopintegratingtheray.• Step Size: This is the integration step sizewhich is related to thequality of the

volumetric.Thisparameterhasabiginfluenceontherendertimes.

u Note:TorenderRFRKClouds,“UseAutovolume”mustbecheckedinthementalrayrenderer.

F.01UseAutovolumecheckedtorenderwithCloud.

e. RFRK Displacement Parameters

RFRK Displacement using an RGB mapIn3DStudioMaxwecanapplyadisplacementshadertotheDisplacementslotofamentalraymap.

F.01RFRKDisplacementmapappliedtothementalrayshader




ToassignthenewRFRKDisplacementmaptothedisplacement,wemustcreateanewmentalrayshaderandclickonDisplacementSlot.TheRealFlowDisplacementcannowbeselected.TheparameterswillappearwhenyouclickontheslotcontainingtheRFRKDisplacementmapincludedinDisplacementslot.

ParametersAllowsyoutoloadmultipletexturesequences.

Sequence• Intensity:Theheightthatthegeometrywillreach.• Map:Mapusedforthedisplacement.• Mute:Ignorethistexture

f. RFRK Texture Magnitude

F.01RFRKParticlerAgeMagnitude

F.01RealFlowTextureMagnitudeappliedtotheAgeParameters

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