RealFlow在线教程翻译（4）——Calm Fluid Surfaces （静态流体表面）

（以下英文部分及图片皆来源于RealFlow官方文档：http://support.nextlimit.com/display/rf2014docs/Calm+Fluid+Surfaces）

    When a fluid is poured into a glass or any other container you will see an up and down motion for a certain amount of time. A little later, the fluid comes to rest and forms an even surface. RealFlow mimics this behaviour, but it can take some time before the fluid is totally calm. During this time you can observe the fluid sloshing and moving. One method is simply to sit and wait until the fluid has relaxed, but this can be a very time consuming task. It is much better to support this process with RealFlow's “k Speed” daemon. Please bear in mind that this approach is suited for standard particle emitters. Hybrido fluids do not have to be relaxed.

    当液体被倒入杯子或其他容器中，你会看到液体在一段时间之内将上下波动。一段时间后，液体静止下来并形成一个水平表面。RF可以模拟这种行为，但在液体静止之前需要一些时间。在这段时间里你可以观察液体的晃动。一种简单的方法是坐下来并等待液体静止，但是这有些浪费时间。更好的方法是使用RF的 “k Speed” daemon（速度控制场）处理这一进程。请记住该方法只适用于标准粒子发射器，混合液体没必要静止。

 

A sloshing fluid and its relaxed state created with the method described here.

使用以上介绍方法仿真的晃动液体和其静止状态

    All scene elements can be added from RealFlow's “Edit” menu:

    所有场景元素都可以在RF的“Edit”菜单中添加：

• Add > Emitters | Objects | Daemons

• RealFlow nodes can be moved, scaled, and rotated with the W, R, and E keys.

• Imported objects from SD files have to be unlocked before they can be transformed with Selected object > Node Params > Node > SD ↔ Curve

• Viewport perspective is changed with the 1, 2, 3, and 4 keys.

• Shading modes are toggled with the 7, 8, 9, and 0 keys.

The Relaxation Process（静止过程）

    To create a calm and even surface, please follow these steps:

    为创建一个静止与水平表面，请进行以下操作:

    Start the simulation without the influence of the “k Speed” and "Drag Force" daemons.

    在不受“k Speed” 与"Drag Force" daemons影响的情况下开始仿真。

• Fill the object until the desired water level has been reached and let the simulation run for a few more frames.
• 填充容器直至达到所需水位，让仿真多运行几帧。
  
• Set the emitter's “Speed” parameter to 0.
• 将emitter的“Speed”参数设置为0
  
• Create an initial state and activate “Reset To Initial State”; reset the scene.
• 创建一个初始状态然后激活“Reset To Initial State”（重置到初始状态），重置场景。
  
• Add a “k Speed” daemon.
• 添加“k Speed” daemon
• Node Params > k Speed > Limit & Keep > Yes
• Max speed > 1.0
• Max speed > right-click > Add key
• Shift the timeline slider to frame 200 (the fluid disappears).
• 将时间轴调至第200帧（液体不见了）
  
• Max speed > 0.01
• Max speed > right-click > Add key
• Reset (the fluid reappears).
• 重置（液体重现）
  
• Add a “Drag Force” daemon.
• 添加“Drag Force” daemon
  
• Under Drag Force > Drag Strength create two keys with values of 0 (f = 0) and 75 (f = 200).
• 在Drag Force > Drag Strength（阻力值）新建两个值,第0帧值为0，第200帧值为75。
  
• Simulate. At frame 200 the fluid should be calm and relaxed.
• 仿真。在第200帧处液体静止。
  
• Create a new initial state for your final simulation as described above.
• 按照以上所述为最终仿真创建一个新的初始状态。
  
• Reset.
• 重置
  

    An initial state can be saved easily:

    初始状态很容易被保存：

• Make an initial state with Node Params > Initial State > Make Initial State.
• 通过Node Params > Initial State > Make Initial State创建初始状态。
  
• Set “Use Initial State” to “Yes”.
• 将“Use Initial State”设为“Yes”。（即设置使用初始状态）
  
• Activate the “Reset To InitialState” option with a click on the triangle next to the “Reset” button.
• 点击“Reset”按钮旁边的三角形激活“Reset To InitialState”选项。
  
• Optional: backup your previous data or apply a new export name for the emitter.
• 任选：备份之前的数据或为emitter应用一个新导出名。
  
• Reset the scene to load the initial state at frame 0 (or any other specified frame).
• 重置场景以载入第0帧处的初始状态（或其他指定帧处）。
  
• Simulate, using the initial state.
• 仿真，使用初始状态。
  

 

 

    This procedure will help you get an even fluid surface you can use as a starting point for a new simulation. Depending on the number of particles, this process can take a while. We therefore recommend disabling the viewport during simulation (Alt + D) or using the Command Line version:

    以上过程可以帮你得到一个可以用作其他仿真开头的水平液面。基于粒子数量，运行需要一段时间。所以我们建议在仿真时关闭视口或使用命令行版本。

• Simulation button context menu > Command line