Nicole Kennedy Design

Ideation, Creation & Everything In Between

Flip Fluid Waterfall – Particles, Part 8

At this stage in the process I am wanting to create a more realistic look for the waterfall for example where the water crashes and impacts with the rocks this is not random and I need to set up my velocity in order to show this properly. The next thing that needs to be taken into account is the water is whiter in appearance when it has more velocity and this is another parameter that will need to be played about with in the next stages of the tutorial.

A new emitter needs to be created for the splashing and spray effect of the waterfall. I am going to create A VOP SOP node by using the tab menu and typing in vop and then selected the relevant node and placing it in the network view. This is shown in the screenshot below. Screen Shot 2014-01-09 at 15.48.26When I dive down into the VOP_SOP node this is what I see I have a global1 and an output1 options box as default but I now need to make changes to include more options the first thing I need to do between output1 and global1 is to add a length node using the tab menu and placing the node in the middle of the connecting line.

The velocity option from global one was connected to the vec option of the length node  at this stage.

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The next stage in the process was to create a fit range node this was done by using the tab menu and typing in fit I was then able to place the node between the length1 and output node.  The len option was then connected to the val option of the fit range node. Followed by the shift option connecting to the Cd option of the output1 node.

You can also see that the Source max of the fit1 node has been increased from 0 to 6.9.

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The next stage was to back out to the object level and  include what is known as the timeshift node into the network this is done by again using the tab menu and typing in time which brrings up all the options of time I then had to select the timeshift node and place it outside the VOP SOP. Screen Shot 2014-01-09 at 15.57.06The window on the right hand side of the screenshot below is shown whenever a timeshift has just been created or is selected. You may notice the Frame option in green, This option allows me to include an expression from $F to $F-1.This allows us to look at the frame previous to the one shown for example 68 the minus one allows us to see frame 67. Screen Shot 2014-01-09 at 15.57.48The next stage is to create an import attribute node which is done using the tab menu however as the lecturer explains in the video we cannot use this import attribute as we cannot rely on our point attributes not changes therefore we must use something called a point cloud. Screen Shot 2014-01-09 at 16.01.03In these images below the point cloud node is created using the tab menu and typing point which brings up all relevant nodes with the word point in them I then selected point cloud node and placed the node within the vop sop in the network view.

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The next stage is to create a point cloud filter using the tab menu and then connect it from the point cloud handle to the point cloud filter handle. In the point cloud filter options there is an option for channel which is by default set to P I change this to V so that the velocity is now the channel.

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The next stage as shown in the images below is the creation of a subtract node done by using the tab menu and typing in subtract and then placing the node on the VOP SOP network view.

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This part of the tutorial slowed me down an awful lot I encountered a few problems which I will show in a slideshow at the end of this post I had to promote a parameter and promoted the wrong parameterI also changed the position channel value which I wasn’t meant to do and messed up the VOP SOP network I have spent all this time creating. The solution to this problem was to load an older save an redo this particular chunk of the tutorial again in order to get it right this time. When there is an error in your network on Houdini the node will show red crossed lines across it from what I could determine nothing else had been affected but I didn’t want to continue through the tutorial to run into a problem due to the error at a later date.

In the screenshot below I had to promote the parameter of the Point Cloud Texture value which showed the point cloud texture option in the particle_fluid level.Screen Shot 2014-01-13 at 18.41.06 I was then able to see the point cloud texture option in the particle_fluid level parameters which now shows /obj/particle_fluid/timeshift1.  This now indicates that my timeshift1 node is connected to my particle_fluid node now. Screen Shot 2014-01-13 at 18.41.36


Errors, Promoting the wrong parameter and removing the position channel when I should not have I could not find an option to unpromote a parameter and typing the letter P back into the position channel had no effect so I must have deleted an expression that was required.

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This entry was posted on January 13, 2014 by in Creative Experimentation, Creative Strategies, Houdini, Special/Visual Effects and tagged .
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