Blender 3D: Noob to Pro/Creating Basic Water animation

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A low resolution, high viscosity fluid test

Water and Other Fluids[edit]

Water is without a doubt one of the most important compounds in our lives; It covers about 75% of the earth and is therefore incredibly important in quite a few blender animations. Wouldn't it be great if we could get an accurate physical representation of this liquid in blender? We can, using a tool called Fluid Simulation. This tool looks unnervingly complex at first glance, but this tutorial should clear it up for you. At least to a basic level.

The Domain[edit]

One can imagine how much time it would take Blender3D to think about everything in the infinite space of a 3d world in terms of fluid objects and deflection, so we obviously need to cut down on that size. Create a fairly large cube. This will eventually be set as the volume in which all of the fluid simulation occurs. Don't make it too large, but not too small either, let's say 10 times bigger. With this cube selected, go to to the physics screen. Find the button that says "Fluid", and click the "Fluid" button to enable the function. Set type to "Domain". All the fluid physics will be calculated inside this cube. Also in that tab, you'll see 3 sub-sections, "Fluid World", "Fluid Boundary" and "Fluid Particles". Each one opens a different set of settings. These will be explained as they become important.

Under "Time" you can adjust how much seconds the fluid animation will take. Due to this you should change the "End" frame to "96", under the "Timeline", because the standard setting is "4". You can also change it how you like.

To make the other objects go into the "Wireframe" viewport.


The Fluid[edit]

As a basic start up for your experiments with fluid simulation, I am going to take you through a small demo in which we drop an object into a pool of water, creating a splash. To do this, we need a fluid object and an obstacle object. For the fluid, create another cube, scaled down to cover the bottom of your domain. Make a rectangle, that hovers just inside the domain and is half as high as the domain. Enable this object in fluid simulation also and set type to "fluid". When we start to bake the fluids, this will be set up as your liquid.

Let us go over what you have now. You have your starting cube, with fluid physics and type "domain", and will be referred to as "Domain". Inside this is the rectangle that will cover the bottom of your Domain , which is the liquid. The liquid will be a different object with the type "Fluid".


The Obstacle[edit]

Create a third object which we will call "Obstacle". This will be the object dropped into the water, and will be described further in the explanation. Give it an IPO/Animation to drop into the water, and enable it as --you guessed it-- an obstacle (click the "fluid" button, in physics, and set type to "obstacle").

Set up the animation in the front/side views, not the top view. The z-axis is where gravity works.


Baking Fluids[edit]

Now we get to see what it all looks like. Select the domain object, and find the big button that says "BAKE" under "Physics" - "Fluid". If you want to use a bake again, don't choose a temporary location, otherwise you'll have to bake it all over again. Press it. Be patient, blender has to bake this simulation, something like it would render the final product. The loading bar of this baking will stay in the bar at the top of the screen with the blender logo. If at any time you feel that you want to abort this process, press "Esc". Once the bake is finished, click under the "Timeline" on the play button. You should be able to view the full simulation.


Finishing touch[edit]

Blender will make your water its default opaque grey, unless you set its color. A good way to make realistic, clear water (as well as glass for that matter) is to edit the color, then apply a simple mirror effect plus transparency effect. After your water has rendered, select the domain in object mode. This selects the liquid in the frame you have just added. in the "Materials" tab (if when you click on this, the colors settings are not up, just press add new under the only panel there). Go to the "Mirror" section, play around with the settings until you get what you fancy. Suitable settings include Reflectivity to 0.1 for water, 0.15 for glass, set depth to 7; Under the Transparency section, click on Ratrace and set IOR to 1.3 for water, 1.5 for glass; Then set the Alpha value to 0.1 while adding an appropriate color under the "Diffuse" section, like: "6279E7". I should do the same for the "Fluid"


Other Fluid Objects[edit]

There are other incredibly useful types of fluid objects like "inflow" and "outflow". The both of these do exactly what they sound like. Inflow objects pour more fluid into the scene, and outflow objects drain it away.