HYBRIDO REALFLOW 5 TUTORIAL BASIC 2


Uploaded by hdlect on 22.09.2010

Transcript:
Welcome, this is JCO with the second part of the high
definition tutorial on HYBRIDO in Realflow 5.
In the last video I explained the basic concepts of HYBRIDO
and how to navigate the interface. I also talked about how
to prepare all the elements for simulating a scene with
HYBRIDO and we simulated the scene to produce the core
fluid.
The core fluid has to be created first before attempting to
generate secondary particles.
Now I will continue with the creation of secondary particles
in the following order:
Splash particles first, foam second and mist third.
To see the result of the simulation I created in the first
video, I hit the rewind button at the bottom of the window .
This moves the cursor to the beginning of the simulation. At
this point, it is very important to keep the simulation we
have so far.  
To do that, I have to save  and convert the simulation from
active mode to cache mode in the nodes pane . Cache mode
puts data onto the disk that can be used over so to avoid
having to simulate again. When a simulation has been ran,
the frames in the timeline change to yellow, this indicates
that the behavior of the particles are now located in memory
or cache, so to see the simulation we just have to use the
play button and the result will be presented in a faster
smoother way. Let’s hit play and observe the simulation.
While the simulation is running I would like to make a
comment about the type of fluid you can use.
In our current example the water is generated by an object
that is affected by gravity. Like in the real world, if you
release a liquid, it will fall and when it hits a surface it
will bounce a produce splash. Eventually, the liquid will
come to a stop as the energy dissipates with time. If the
intention is to create a liquid that runs continuously, the
Grid Fluid Emitter should be set up to flow constant.
To do that you have to select the Grid Fluid Emitter first
Then in the Node Parameters under emitter, change the option
Stream from No to Yes,
In addition you have to change the default number for
initial speed from 0 to any value that you want. If the
initial speed is not modified, the stream will not run.
In this case I will use 3.
This will generate the type of liquid that runs
uninterrupted like a waterfall or a hose.  
Let’s go back now to our original simulation.
The result we obtained shows the core fluid. This is the
backbone on which the secondary particles are created by
Realflow.
We will continue now with the creation of splash. Make sure
the animation is in the first frame and also that in fact  
cache mode has been activated for the Grid fluid domain.
Also, global links and exclusive links have to be prepared.
For those new to Realflow I will give a quick overview so we
can proceed. This is not intended to explain in detail what
exclusive and global links are. It is just an introduction
and a roadmap for the HYBRIDO workflow.
Later, I will post a detailed tutorial that will help you
understand this very important aspect of Realflow animation.
By default, every item created in Realflow will be located
in the global links category. This means that those items
can interact with each other, and forces will affect all
elements that share that category, as long as these forces
are also located in the global links.
Very frequently, it is necessary to break the connection
between elements or between forces and elements to achieve a
better simulation.
I will demonstrate the concept with two simple circle
emitters and a  force acting on them. In this case, Gravity.
These 2 liquids are interacting with each other; in
addition, gravity is affecting both simultaneously. This is
the default setup how Realflow manages objects at the moment
of creation.  
To create exclusive links, the Global links have to be
deleted first. To do that, select the first item in the
Global links, then hold the SHIFT key on the keyboard and
select the last item on the Global links, then either hit
the DELETE key on the keyboard or right click and select
remove.
Now that Global links have been removed, Exclusive links can
be created by dragging items to the Exclusive links box.
First move the Grid Fluid Domain or the emitter and then
drag directly on top them the items that you want to be
associated with this emitter, in our case is gravity. Then
drag the second emitter to the exclusive links pane and
gravity on top of it. The name shows a plus sign on the left
that indicates that that item is a group that contains sub
objects. To see the sub objects, click on the plus sign and
this will expand the view.
Let’s take a look now to the animation.
The liquids are affected by gravity, but when their paths
cross they do not interact. Let’s remove gravity from one of
them by selecting it and removing it by using the right
click mouse and then selecting remove.
Let’s simulate again. Like before, the liquids do not
interact but now one of them is not  affected by gravity and
that is why there is not bending of the path that the fluid
follows.
After this brief explanation of Global and Exclusive links,
let’s continue setting up Exclusive links for HYBRIDO for
the Grid Fluid Domain and for each one of the secondary
particles.
The first secondary particle is Splash.
To add splash to the simulation I have to hit the Grid Fluid
Menu from the top, or by right clicking in the nodes pane
and selecting … Add…  Grid fluid…  Splash.
By default, splash is created as a small green box in the
center of the Grid Fluid Domain. This box represents the
location where the core fluid will actually produce splash.
There will not be generation of splash particles outside
this box.
Splash can be resized  and moved, with the purpose of
restricting the generation of splash just to areas we choose
like in places in which intense turbulence occurs, or just
to places where the water collides with an object, or it can
be located in places that are close to any camera with the
purpose of avoiding to generate splash globally which
consumes time and memory. If the camera will not see it
there is no need to generate splash.
I can create splash in more than one location to allow very
precise control and optimization of the rendering time and
computer memory.
In this picture we can appreciate that the fluid will hit
several rocks, therefore splash was added selectively to
each one of the rocks.
For the current simulation, for purposes of demonstration, I
want to produce splash in the whole Grid Fluid Domain so I
will resize the Splash to fit the scene accordingly by
selecting the scale button, or by using the shortcut R in
the keyboard and dragging its handles until it is of the
appropriate dimensions.
Something to keep in mind is that secondary particles are
not bound by the domain and they can be affected by Daemons.
This means that they will persist beyond the boundaries of
the domain and will continue moving outside from the Grid
Fluid Domain according to the forces that created them.
Let’s see how that happens. (movie)
This puts a heavy strain on your system because every single
particle that falls into infinity is still accounted for and
calculated by Realflow in the simulation , which  very
likely will drain the computer memory and make it crash.
To stop these particles we will use a Daemon that destroys
any particle that is located outside its borders. The tool
for that job is the kill volume Daemon.
To add a kill volume Daemon click on the Daemon menu  and
select k volume. This will place the k volume daemon in the
center of the screen.
Next, it has to be resized to include the Domain and
everything on it. To do that, select the fit to scene option
from the Node parameters.
 It can also be resized manually with the scale option from
the top menu and dragging the handles until you get the size
you want.
Now, that we have created the k volume and we have resized
it to accommodate all the items in the animation, delete all
elements from global links by selecting the first, then hold
the SHIFT key, select the last right click and select
remove.
Move Grid fluid domain to exclusive links, add on top of the
newly created grid fluid domain in the exclusive links the
following elements:
* The emitter, in this case is the cube 01
* the Grid fluid emitter
* the grid fluid splash
* and gravity.
You also have to add an additional copy of grid fluid splash
to the exclusive links pane  and on top of that the
following elements:
* The kill volume daemon
* The gravity daemon
Now hit the simulate button…
I will fast forward to the end of the simulation and show
the result in the next video.