Fluid Simulation 0.6.6 with Art of IllusionPlugin made by Delt()r Made by Troy, traduced from german to english by Runnerblood April / May 2009 http://www.uninformativ.de http://www.aoi-board.de This document is under the Creative Commons Attribution-Noncommercial-Share Alike 3.0 Germany License

http://creativecommons.org/licenses/by-nc-sa/3.0/de/ . http://creativecommons.org/

Page 2 Contents 1.0 Introduction 1.1 Installation 1.2 Function and purpose of the simulation 2.1 Animation and Baking 2.2 Time steps and particle size 3 Flussigkeitssimulation 3.1 The Stuffed Basin (Boundaries and fluids) 3.2 Extended options to the previous example 3.2.1 Fluid 3.2.2 Boundary 3.3 Targeted pour liquid (emitter) 3.4 Advanced options the previous example 3.4.1 Emitter 4 simulation of deformable bodies 4.1 Background 4.2 Using 4.3 Advanced options 5 Global Options 1.5 previews and Views 2.5 Fluid Params 6 Going Further techniques 6.1 Baking continue 6.2 Selection Sets for grouping

Page 3 Initiation Since 2005 delt0r works on a plug-in for physical simulation of what a pure plug-in for the start of should be Blender. Although he discovered quite soon that in this respect already available from other programs grammers were at work, but decided nevertheless Darfur, develop its own plug-in to the benefit for users of Art of Illusion. Because on our already delt0r program was only in early 2007th, the core of its simulation was always written in Java, since what the integration with Art of Illusion very naturally came to meet. So things are then took its course. Delt0r's plugin is indeed still in a very early development phase, but it is certainly to usese and if only to have fun. The current version is linked in his blog: http://delt0r.blogspot.com/ It should be noted that this is no official documentation. However, I will try the procedure as accurately as possible and to present all possible options to address. Installation The installation is quite simple: you visit delt0r's blog searches, the current link and loads a file called Physics.jar down. This file must then in the subfolders of the plugins Art of Illusion directory will be copied. Done. For the 0.6.6 version of the plugin, you should use the 2.7.2 version of Art of Illusion. For the case that Art of Illusion is not installed yet, it can be found at the following URL: http://www.artofillusion.org Function and purpose of the simulation As the name lets suggests, is the primary purpose to simulate fluids. These arise in a so-called emitter and then interact with boundary defined as objects in the scene. The plugin is also actually a simulation.

Page 5 Basics Animations and Baking Key word: animation. The fluid simulation describes Precedent, together with the time the alter. One therefore can not avoid an animation - Also create one on a single image rendering might end if. That would indeed not too much Work (animation is finally one of the main tasks of Art of Illusion), but the fluid simulation takes us from even the most part. The minimum is, however, to make accessible to the timeline. In Normalfall you have to do anything more than the margin at the lower end of the Art of Illusion main window Stuck up a mouse to draw with the. With this bar, it is possible within an animation . Navigate Figure 1 - Art of Illusion with a visible timeline. At the point marked in orange must be drawn, the green slider is used to set the timing. Since the calculations, which hires the fluid simulation, expenses are pretty, they can not in Real place. The simulation must therefore be precomputed before the actual rendering. This Process is called Baking and will be launched from the plugin out. Only after it has also really has an impact when the current point in the timeline changed to, and the objects move. The data is temporarily stored in a file here. It should not be stingy here and an almost full with data carrier begnugen: This file may be in long simulations of several hundred Megabytes in size. Time steps and particle size A physical simulation is running on the computer always discretized " from, that is, there is only one finite number of fixed dates, which are calculated. In between, there are compulsory Lucken " . This follows naturally that a simulation is precisely when these dates are near beeinander. The Distance between two of such dates is referred to in the plugin Step Size. Page 6 Basics 6 Here one needs to find a good compromise: If the step size too large, then the simulation is indeed very quickly calculated, but highly inaccurate. It may then happen that Flussigkeitspartikel their obstacles erspringen " . If the step size chosen is too small, however, it simply takes too long to the Baking-

Process is complete. 2 Figure 2 - A simulated Partikelubersieht an obstacle by a large step size. The liquids are internally modeled as small particles of solid Large, based on the Particle Parameters Size. As you can guess already, is here A similar context: If the particles are very small, then the simulation is very detailed, but slowly. If they are too big, we simulated some football. Both parameters are preset, for the simple examples will suffice. You must know that here there is a loose connection. Reducing the particle size, it should they also reduce the time steps. A fixed formula specified hierfur ware, but not very practical cable. The reason for this relationship is that smaller particles more easily Hindernisseuberspringen can penetrate into each other or each other, as is the case with large particles. Grob let themselves say you Halves Particle Size, then you should also halve the step size. Figure 3 - In-larger particles is a collision detected yet, while smaller parparticles in the same simulation by the object tunnel again. Figure 3 Size is also once again the principle means of Step clear: The large particles were tunneling through the barrier if they were moving faster. A higher Speed means that particles per time step, a bigger distance to zurucklegen, which of course Large gaps between them, the. This increases the chance that a particle is not an obstacle responsible. We need, therefore, even if one has high speed in a simulation, a Small Step Size elections. In the distant future there will be a solution of Darfur and that an adaptive step size. How the functional kidney and is incorporated esuberhaupt when is still open. 2 A beautiful story on this subject is sichubrigens here: http://xkcd.com/505/ Page 7 Flussigkeitssimulation 7 Flussigkeitssimulation The practical application of the fluid simulation can be best explained with an example. In the first Part should be our goal, 1st Filled to create a pool of water, 2nd flow out to be a source of water. The Stuffed Basin (Boundaries and fluids) First we will define the boundary as the basin. For some time supported the so-called plug-in Poly Boundaries, ie objects whose surfaces can be used as an obstacle. 3 This means for us, that we are comfortable POLYMESH an object in the scene and bring the whole unchanged can use this. If we do this, therefore, and make us a very rudimentary pelvis. Respect The overview, we call it into Pool " . To study the dimensions 6 6 2 have approximately. A quick side note: Primitive Art of Illusion-objects, ie cubes, spheres or cylinders can, Obstacles in the fluid simulation can be used than not.

Figure 4 - A simple tank. As initially mentioned, objects can be defined as a fluid and are thus completely wing Exactly we now want to use: we create an additional, simple POLYMESH-cube, which we in the basin . Share He is still solid, but that will be Baldanders. We call it Stuffing " . In order to be able to assign physical properties of objects, it must first instance of the fluid-ins be added to the scene. One simply chooses blue droplets from the Toolbar and draws a Rectangle. What one sees in the next step, the wire mesh of a cube. This area is important: He defines where liquids can not exist and where. Leave these particles are cubes, 3 Inalt versions it was different. In earlier times were the points of an object as limits to what a lot of Zwischenarbeit required. Page 8:00 Flussigkeitssimulation 8 Figure 5 - The pool is (still) sound refilling. they disappear automatically. It is not a problem, the area later with the usual simple scaling tool to expand. Double-click the newly created object in the Objektlisteoffnet its properties. This will now play the whole magic. We select the object Pool " in the middle list. To assign an object properties, Boundary we have to it only in the current Selection " ernehmen. The terms conflict unfortunately something because this choice has nothing to do with the selection sets in the left half of the dialogue to do - to which we only come later. The selection, to this one is determined, only those objects to which the set Parameters contribute. It was in the middle list, therefore, several objects at once and also mark so this process simultaneously. From the right drop-down list, we choose now Boundary " 4 and click

Set To Selection " . There are Now a few more options accessible, for our example but these are optimal. Next we explain the inner cube to the liquid. This process is designed quite Fluid simple: the object called Stuffing " the middle list choose from, to Set To Selection " and click This time we assign it the type Fluid " to. That's it. Now we can also reach the first Baking " . Start Therefore we switch to the tab Baking " . Baking Here you can specify the destination for the file temporarily by one, the default value should be but temporarily Should be sufficient. Important: if you want to start with the simulation of the front, you should always have two Buttons Press for: Clear Cache Object " : This button signals the plugin that it use all-buffered sured information about the correct password MOGE existing objects, especially their geometry. The means this button you had to Betat even if you subsequently of the Great Basin others wanted. Reset Simulation " : On the other hand knob ensures that second Darfur, that both the time reset to zero

as well as all previously calculated movements are deleted. This must be one that is additionally draw lots; 4 The spelling errors are further down the TODO " List ... Page 9 Flussigkeitssimulation 9 Figure 6 - The first two objects are defined in the plugin. if you want to ensure that the simulation of the front begins to count really. In the lower field, we can still enter the time the simulation is what to. This date is absolute, that is, he does not determine the duration of the simulation. We therefore write a 2 " in the field, 0 to 2 seconds because we want to simulate a second from. After clicking on Bake " displays a progress bar, but soon disappears. Abandon If now plugin by clicking on the OK " and then move the slider in the timeline a bit, You should also have the first signs of life in the fluid can discover. Before one can reasonably render a meaningful picture, it states: Light must be in the scene. This step is trivial and we need to suggest in the manual 5 after. ;-) You probably want the object POLYMESH Stuffing " . Hide The reason is that setting of the object on Fluid " the original object is not affected. It serves only as a quasi-particle source and is therefore usually in your way. Do not worry, the fluid does not become invisible, because this is part of the object

PhysicsObject 1 " . So it was actually the fluid does not want to render, so you had the whole Physics object hiding. At the moment it is not possible, only parts of the Physics Building to hide. Figure 7 then shows can look like a possible outcome. Advanced options for the previous example Fluid An object as in Figure 6 as Fluid " is defined, offers in addition the following options: Fill ratio " the directions X, Y and Z: this can be specified in such full " an object. Hat is a tall cylinder to the fluid object is declared, for example and did this but only for Half filled with water have, then X fill ratio " on 0.5 " be set. The range of values goes from here 0 " to 1 " . Initial v " stands for

initial velocity " , Determines the initial velocity, and here are 5 Here the deutscheUbersetzung by Vidiot: http://www.uninformativ.de/tutorials/Vidiot/AoI_Manual_2_6_ger/contents_de.html Page 10 Flussigkeitssimulation 10 Figure 7 - A first test render the scene with a transparent background. again separate values for the X, Y and Z. If one wants to so that the water block to Only a second after the start up and then flies back herunterfallt, we must Initial vy " on 9.81 " . Share The range of values is arbitrary, it can therefore also negative numbers can be entered. Dither ratio " : Here it is possible the fluid at the beginning of something durcheinanderzuwirbeln But to put it at top speeds. Again, the range of values almost at will, we must But remember that fluid particles outside of the object are never placed. Substituting dither reason " So for example, 1000 " , Then probably no more fluid appear at all. In the Area 1-5 " But if we ride very well. Boundary Boundaries are more complex objects. Let us in turn by: Is static "

: This property determines whether an object is moved " or not. This is true Animations meant, of course you can also create (rather than just individual images). Once you manually, outside of the simulation using keyframes or procedural tracks, moving objects, then, This hook must be set absolutely. Otherwise the fluid simulation gets away with anything. For more details about animation in general was once even referred to the Handbook: http://www.uninformativ.de/tutorials/Vidiot/AoI_Manual_2_6_ger/animation_de.html Is PolyBoundary " : Determines whether the surfaces of the body should be regarded as limits or whether the old vertexbasierte method should be applied. Usually you want to hook this schatzungsweise will not remove this option obsolete soon disappear. Calculate Boundary outside poly (gon) " : Since each mesh is a barrier, there is inevitably of a set of polygons, in a louder TriMesh are triangles. A step in the recognition, if a particle collides with an obstacle or he is near, is that particles in the plane Page 11 Flussigkeitssimulation 11 to project that such a triangle spanned by. Then is examined if these projectstion lies within the triangle or not. This means that, roughly outlined in full, a collision test of a Be performed with a triangular particle. Figure 8 Sun 'll illustrate this idea again. Figure 8 - The projections of two balls in the plane of a triangle. The projection of the orange ball now lies within this triangle, but the green ball not - they can collide with the triangle was never so, even if them so it was hochuber are not. Some body can occur with this method, the problem that fluid expiring " , the obstacle is not quite so close. The main option here tried this problem entscharfen. She makes sure that the force which acts on a particle if its projection into the Plane outside the triangle, is not zero is abrupt. Instead, works outside a small Force on the particles, provided it is in the neighborhood. Hierfur is the distance to the point nachstliegenden polygon in question as a measure taken in, as Figure 9 v is erdeutlichen. Figure 9 - Even particles whose projection outside of a polygon is learned by the distance to nachstliegenden point on the polygon a corresponding

Rejection, if Calculate boundary outside poly " enabled. This solution is however not perfect. It also makes sure that often too great a distance between obstacle and fluid there - which of course is not realistic. The option is therefore also disabled by default. If you have a Leak " , But it may in certain circumstances be worth it test, to enable. Page 12 Flussigkeitssimulation 12 Velocity Bias " : An alternative remedy for this task (body licking). This is active energy, the system brought in and near strong repelled particles. The entered This value controls the strength of this additional repulsion. This should be used only if Calculate boundary outside poly " Off. This conservation of energy is of course the injured. This leads to the fact that starting fluids to cook " . If one wants to stop a leak, this option only with a very low value may be a solution. On the other hand it can of course also be that just the effect Cooking produce the like. :-) Too high but this value should not be. Even at 2 " it may happen that the Simulation to aufschaukelt and very explodes " .

Boundary Factor " : This factor influences the Abprallverhalten of particles and provides that in certain contexts, another alternative to combat leaks. Unlike the Velocity Bias " here is not constant but energy put into the system, but only in Contact the moment. The higher this factor, the strong bounce particles off of the surface. But beware: If the Factor is too high, can also be placed on the simulation hereby explosion. Boundary Clamp " is directly related to the just mentioned Boundary Factor " , namely, he is a maximum for this factor. That is, you can prevent a fast impinging particles an exorbitantly high reflectivity learn. Will I enable it, however, that particles bounce off very strongly indeed, so this value must be set quite high (in the Doubt on 1000 " or more). Boundary Friction " This value does exactly what its name suggests, let - it controls the Friction that acts on this Oberflhe. This is not too much to consider. The higher this Value, the greater the friction. However, one has to experiment even if the spotlight will simulate certain materials, for a real " physical meaning is not the value. That is, unfortunately, that moment is not possible, reference values of real materials for Specify the friction. Targeted pour fluid (emitter) An emitter is a possibility as a fluid, to allow fluid to emerge. An emitter can rather than Tap "

be considered: For liquid pours them with a fixed rate in a certain direction. It is now such that the emitter program parts are nochaltere vertexbasiert and therefore work. For us Normal this means, first, that we have a bit more work and at first a very short trip the geometry have to make. For must be geklart advance the importance Normal " in the and for the fluid simulation in particular have generally. Figure 1 0 shows a simple cylinder. You can see a little blue lines are the normals also: The normal of a surface is a vector that is perpendicular to this surface. However, can only Triangles Flachennormalen useful to define, since only points in triangles are all always in a common plane. A square, for example, can are curved in " be, thus not all of his Vertex in a plane - therefore not clear Flachennormale definable. We will immediately create the first emitter, which will be TriMesh simple one. As already mentioned, Emitter vertexbasiert work. This means that each point TriMesh produce liquid is in our. But in which direction? Here normal now come into play. Normal, although in fact Flat defined, but can be relatively easy to adjacent Punkteubertragen. One can Normal form for a point, for example, by normals of all adjacent surfaces of the averages. Page 13 Flussigkeitssimulation 13 Figure 10 - A screenshot from Wings3D to leave here on the normals of a body displayed directly. Thus we have defined an approximate direction, which our water will flow along. Art of Illusion controlled mechanisms to a mesh vertex normals automatically from Flachennormalen can generate. Darfur, there are different approaches, but only one of which will guarantee maximale control: We must with a TriMesh Shading " as Smoothing Method " . Create The quickest way to do that is the following: We double-click the icon POLYMESH (sic) and then choose a template as Flat Mesh "

out. The Great, we use here, for example, to 5 5, the created object should be about the expansionRegulation 4 4 in AOI units possess. The Smoothing Method " in this dialogue has yet to None " be set. After we have created such an object, we convert it by right in the object list TriMesh into one. Now we can under the object list in the properties of the Smoothing Method " on Shathing " . Share Since we want to set this object equal emitter as we call it like this: Emitter " . The point of this detour is as follows: Only shading calculates vertex normals without the correct geometry of the body to alter. 6 In principle no objection language, instead of one's TriMesh POLYMESH to 6 If you are interested in Darfur can more precisely, once the method getWireframeMesh () in the Art of TriangleMesh.java Illusion source code view. Page 14 Flussigkeitssimulation 14 - Use the latter result, unfortunately, sometimes incorrectly calculated vertex normals, what's in TriMesh is not the case. If this object is finished, we must again notify the fluid simulation. For this we create Objects draw up only one physics object to the emitter around undoffnen then its properties. As always choose

we object Emitter " in the central list, and this time also set its type to Emitter " . Then click on Set To Selection " . Now options are more visible, in which I Moment one wants to address only the Normal factor " . This is the initial velocity in the direction the above-described normal to. If we want so that our water is not just straight to flows down to start in direction of the normal pours but (before the gravitational zuschlagt), then we should this factor as to 5 " . Share To the scene before the Baking just got a little more interesting, we create just below the Emitters have a ball as an obstacle. We also can use the fluid simulation in this, have to we convert it into a TriMesh before, not since the plugin with Art of Illusion primitives can handle. We then define this object in the simulation than in the previous section Boundary " . Now we can start as had the baking, it takes only hierfur should first 3 seconds to simulate only. Figure 1 1 shows again the setup of the emitter and Figure 12, the finished rendered scene. Figure 11 - Exemplary emitter setup along with a ball as an obstacle. The Ball was previously converted into a TriMesh. Advanced options for the previous example Emitter The advanced options for emitters are rechtuberschaubar and also explain almost by itself: Negative Emitter " : Normal emitter emit liquid. Whether a man but targeted Fluids be removed from the simulation, it must set these hooks you. Particles, a negative Emitters are close, are simply deleted. Do not forget: emitter vertexbasiert always work - as well as the negative of its genus. Will

So we hereby groflhig particles Clear, then the mesh of the negative emitter very fine be divided. Normal Factor " : At this value was already near the top received more. It regulates the Velocity along the normal. The Velocity Factor " concerns only animated emitter, more precisely, it concerns only moved. The Simulation usually created simply to those of the present vertex positions to new particles. Moves Page 15 Flussigkeitssimulation 15 Figure 12 - The scene rendered with the setup of Figure 11th is an emitter, however, this is not necessarily physically correct - who by a moving Train jump off, did not immediately a speed of 0 " Just because he has left the train. If one factor that is to 2 " , So the particles get twice the speed of the emitter as initial velocity. In general, here was a value of 1 " be desirable, because the regulars The initial velocity sollteuber Normal Factor " be controlled. Is static " Boundaries relevant field is like when a animation will be created. If this hook not set, get the fluid simulation with not that the emitter is moving.

Density Factor " : A very selbsterklarende option. This can be controlled, how much fluid emitted from the emitter. The smaller the value (there are only large positive values to zero) allows more dunnfl is the particle flow. It tropfelt. Page 16 Simulation of deformable bodies 16 Simulation of deformable bodies Background Soft Bodies are known as spring-mass systems modeled. That is, there are several mass points, which are connected by springs. a certain framework and with a suitable geometry can in order soft, swirling body can be simulated. Figure 1 3 a simple, two-dimensional version of a spring-mass system: the green points are moving mass points, the red dot in the middle is fixed and the connections between the points are the springs used dar. There are two dominant factors that influence such a simulation: the spring constant (Spring Constant) and the mass of a particle (particle mass). In Figure 13 are the same number of simulations shown, the spring constant varies. A smaller constant makes sure that the object weicher " - is this constant is chosen but small, then simply breaks the object up in. Figure 13 - Two-dimensional simulation of a spring-mass system with different Spring constant (in descending order from top left to bottom right). Is this to low, breaking the system together. Goods too high, but it was by numerical instability explode " . If you declare an object in Art of Illusion as a soft body, then all points of TriMesh's to Mass points and the edges between them to springs. It is instead a uniform distribution, ie Springs is all the same constant and all mass points assigned to the same mass. Use In the following we will simulate a simple scenario: two slightly offset up opposite cube will slide down a ramp and then collide. We first create the ramp. Since this is a boundary later be designed with a perfect object POLYMESH suitable. How exactly is such a simple ramp created one, I did not describe precisely, because Page 17 Simulation of deformable bodies 17 it is sufficiently different tutorials for this. 7

In a certain high hve we then create two simple Cube, which we then convert into TriMesh'es (located to the bottom of the ramp in Y-direction at 0, then we set the cube around to High 8). This cube itself should be about the size 2 2 2 AOI units have. So that the body already soft " Look, we share their Smoothing Method on Approximating " - And thus we can easily distinguish well, they get two underdifferent textures. Finally, we turn the two still quite easy to introduce some Anfangsstorung System to bring in the (it is usually quite boring, objects to drop down to perfect). Figure 1 4 z shews such a setup. Figure 14 - The finished setup with ramp and two smoothed cubes. Texture is important for Soft Bodies: This should be less than in Texture Mapping " in the normal way of Illusion options necessarily the hook Bind to Surface Texture Coordinates " be activated, otherwise shifts later, the texture. 8 Now we can a physics object in the scene to bring that includes all these objects. There we like had the ramp Boundary " (To put it to something more interesting, you can see directly the friction for example, 250 " set) and this time the two cubes on Soft " . At their settings Second, we only Internal Reps " on

3 " , All else being at the default settings. Now already be baked - this process should be done a few seconds in. Moving hereafter the time bar should drop the two cubes and then collide - as in Figure 15 to . See It should be soft at a few things to keep in mind Bodies: They are really not intended for objects such as cubes, but for really soft objects. As you see, you can indeed with correspondingly large spring constants also apparently hard objects simulate, but they will always collapse, large forces act on them when. It can be For example, from whatever high Do not drop. Many objects are not stable - for example, a long board. This was more like a piece of Fabric and lax in the collapse behavior. The attempt to simulate a catapult was allowed, so probably fail. 9 7 See for example: http://www.aoi-board.de/index.php?action=posts&fid=26&tid=16 8 The objects are the simulation in their local coordinate system moved through. 9 But I was glad sehruber possible solution. :-) Page 18 Simulation of deformable bodies 18 Figure 15 - Figure 14 en tstandene simulation of the two covered cube. There are no Selbstkollision, a soft body that is never in conflict with itself one hand, favored unfortunately the frequent collapse, the other, are thus also substances (Clothes) is not realistic simuscalability. We must never forget in TriMesh'es to convert the objects. :-) Advanced Options Soft Bodies also have a couple of settings in addition: Constant Spring " and Particle Mass " : These are the two main parameters, which already Were addressed in the introductory section. The spring constant determines how stiff " the feathers between the mass points are, and the particle mass is to the weight of such a point.

As a reminder, a Dreiecksmeshes vertices to be mass points and the edges between them to Springs. It is easy to see that the spring constant must be increased if the mass is increased. This is clear because the springs have to be more weight tragen.Uber the mass can also be Collision control. For a bowling-ball scene, the higher mass corresponding to a given are conceivable ware the following setup: - The cone will have a mass of 0.5 " with the standard spring rates. - The bowling ball against the mass-preserving 10.0 " and a spring constant of 10,000 " . Damping " : Objects to tremble at the start, the damping (the feathers) be increased to counter it. Actually, the default value 0.5 " relatively low and are often more 1 " or 2 " Needed. Boundary Force " : Soft Bodies two consecutive meetings, collision detection takes place after the Scheme Points versus surfaces " . That is, for all points of a Soft Bodies will be tested if they

the wing of another soft touch upon Antibodies. If so, then there is a collision. It may happen that penetrate objects. The Boundary Force is an attempt to this Counteract some effect. Internal Reps " : The time steps of simulation of Soft Bodies were slightly from those of the Page 19 Simulation of deformable bodies 19 remaining simulation decoupled. This factor regulates how many additional dates for this body considered to be - a global per time step. If, for example, the global step size to 12:01 " and Reps on the Interal 5 " , Which runs on an effective step size of 0002 " out. You should use this function but only cautiously. Especially when the message becomes, we MOGE for Soft Bodies steps to reduce the time to fill it - then lost it on the bestenuber the Internal Reps and let the global step size, without prejudice. Page 20 Global Options 20 Global Options Previews and Views We briefly present the options in that tab through. It should be noted that a Vidiot schoneUbersicht the results posted for the various iso-surface parameter has created: http://www.aoi-board.de/index.php?action=redirect&loc=show_post&id=1731 But after the series: Preview Particles " : Solluberhaupt a preview of particles are created?

Preview Boundary " This option seems more to have no effect. Use Isosurfaces for Raytracing " : Iso-Surfaces (sometimes implicit surfaces, blobs or Metaballs called - even if not all exactly the same thing) are a fundamentally different way to describe Oberflhen to. Unlike triangulated meshes, which consist only of triangles and the desired body often can sew, therefore, offer a much more compact Iso-Surfaces Form of storage and description of objects. The simplest iso-surface is the ball: " All points in space, the distance from the center have five belong, to the surface. " This is a five Kugeloberflhe with radius accurately described mathematically - Delta had a net contrast, have infinitely many triangles to achieve this accuracy. Of course, as always, there are disadvantages as the one needs the rendering of iso-surfaces more Time and secondly, they are rather poorly in the general modeling. Darfur but the more better to render fluids, because triangulated Fluids " were inevitably fairlyLich look edgy. Iso-Surfaces As they appear on the other hand completely smooth " Because many small hierfur Balls are used to gently ineinanderuberflieen. To disable this option, but may also be desired: namely then renders's Art of Illusion Raytracer only the pyramid, pointed particles, as in the preview shows. This is of course much faster. It is also strongly recommended to disable this option, if you only renders Soft Bodies. Metaball size ratio " : Iso-surfaces are used, this option provides the Large " the balls. That is not to be confused with actual particle size, however. This is only is a pure representation of parameters - Metaball is smaller than the size, the individual Flussigkeitspartikel be smaller rendered, but still calculated as before. The result is unrealistic. Implicit Surface Threshold

" : Iso-surfaces are not as usual with direct cuttests ( Cuts the current Ray a triangle? If so, where and how? " ) Rendered, but it is usually on a Ray entlanggetastet " . In theory, the distance between two distancepoints to be infinitely small. In practice this is of course not, so you put a certain Fixed step size, which is now done. The higher the value, the faster the rendering, but also the less accurate is the result. A smaller value, for example 0.5 " needs more time, but it looks better. Mesh Preview " and Mesh Size " : This is a triangulation of the fluid made and the resulting TriMesh without rendering directly - in the scene depicted -. This process is allerdingsauerst effort and hardly useful as a preview. Page 21 Global Options 21 The Great determines the accuracy of the mesh previews. The higher the value, the less accurate is the result. Attention: Small values can kind of fast to his knees to force illusion, so that there abwurgen can. Velocity Factor " : Preview Is Mesh (default), then small pyramids appear, Welche and the current direction (in the form of their height) velocity each particle represent one. The Velocity Factor now control how much current flows, the velocity in this representation larger values mean more influence. In general, we will here retain the default value.

Ratio particles displayed " : This option seems more to have no effect. Use Sample Grid " and Sample Grid Factor " : This is an option to accelerate the Rendering process by the space lattice is divided into a uniformly. In this grid Results of ray tracing cached, so de facto no longer pursuing any Ray completely - will he end up in an already visited lattice nodes, preserving the value stored there. This is the picture of course again inaccurate and can lead to artifacts come. The smaller the value, the less accurate the result. It is worth but little more, this option to activate the plugin as better optimization anderweitiguber grouted. Fluid Params Step Size " : Sets the time interval between two simulation steps. This point was already in the principles discussed in more detail. Bake Frame Size " : This frame can be combined, while the underlying Simulation with the same step is calculated. A value of 1.0 " causes for example, that only every second, a new simulation step is visible. If you want to increase cleavage, temporal resolution, with more frames per second rendering, then, must-Gege appropriate, this value can be changed. He let be calculated as size = 1 fps , with the desired frames per second fps are being called. For 200 images per second must this value is set 0005 to be so. Otherwise, the animation is jerky. Of course may need to be reduced and the step size at. Particle Size

" : The size of a particle. Was treated with the basics. Density " : The density of the fluid or coherence. If this value is reduced, it tends to Simulation to individual Blots " to produce, while for large values it more of a together mengehoriges structure forms. Body Acceleration " : This is simply the gravity meant. Therefore, the middle earth acceleration in the negative Y-direction also the default. Page 22 Going Further techniques 22 Going Further techniques Baking continue It is possible at any point to interrupt the Baking. But even if the beacon process regulares be reached end, it can be later this point continue to. Dazuoffnet simply the Settings of the physics object, changes to the Bake " Tab and there is a one time, the the future is. The simulation is then continued at the current time. In this way can the parameters of the simulation during operation " be changed. For example, between one emitter may be disabled - that's as easy as it sounds, it be simple in the object definitions in the tab Object Management " on None " be set.

For your safety, but at solchenAnderungen before continuing with the process of bake-button Clear Object Cache " will Emitter, alleAnderungenubernommen be so. Should not Betat the knob Reset Simulation " - Herewith is reset everything and started at zero. Selection Sets to group With version 0.6.6 of the fluid simulation is a plug-in integration with Selections from Art of Illusion created. This will be a major simplification, so as mass values assigned to objects can be. It also significantly increases The overview. Therefore, it is worth a quick look at to throw this plugin. If it is not installed yet, can the esuber Scripts and Plugins Manager be installed easily. The basic idea of Selections plugins is to objects in logical groups together. There may a bit more, for example, locking or hide the objects for our purposes, but not quite as interesting - unduberdies selbsterklarend. The operation is quite simple: the objects, we will summarize the marked one, and then under Selections " on New " . This creates a new group that automatically contains all these objects. However, since no obvious is that this is the case, you can double click on the name Selection of the sets a new dialog window with einerUbersichtoffnen. In this new dialogue can also Objects are removed from the group. More specifically, what is highlighted here belongs to the group. A possible use case: You have a lot of pins and did all this later in the same way as Soft Body use. These sums they advance together in a Selection Set. The plugin itself appears then in the left table a new record. If we choose from them are automatically all the objects in the Center marks the belong to this set. Now you can add it to the current selection and thus them to give an impact properties at all (see Figure 16) . Page 23 Going Further techniques 23 Figure 16 - A Selection Set in the application. Here the state after the button Set To Selection " Emitter was.