This parameter set is used to apply a wave structure to a meshed Hybrido fluid, similar to the “Ocean Statistical Spectrum” modifier for RealWave. Before you start with the calculation of the displacement field, please visit the “Export Central” dialogue and check whether the appropriate resource is activated or not. All displacement data is stored as a sequence of TIFF files.
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If you want to learn how to preview and apply Hybrido's ocean statistical spectrum, please watch our "HyFLIP - Ocean Statistical Spectrum" video tutorial. |
Please bear in mind that Hybrido’s displacement is not visible during the simulation by default – even if it is activated. But, there are two three main methods to make it visible. The first one is based on RealFlow’s “Graphs” and very convenient, because we have already prepared an appropriate “Simulation Graph”. It can be found in RealFlow’s “scene” folder. You just have to add this graph to the “Simulation Flow” window. Please visit the “Simulation Flow” chapter to learn how to use graphs with a simulation. Please visit the “Simulation Flow (SF)” chapter to learn how to use graphs with a simulation.
Another way is to map the displacement onto an already existing Hybrido mesh. To make it visible, an appropriate shader is required:
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GridMesh node > Node Params > Shader > Source > Domain
Finally, it is also possible to use a RealWave surface in combination with an "Ocean Statistical Spectrum" modifier. The "Node Params" sections from RealWave and Hybrido share the same parameters and you can transfer the values between both panels. When you change any of the parameters, the complete displacement sequence has to be re-simulated, while the core fluid itself can be read from the already cached files. During the re-simulation process, the grid fluid domain's “Simulation” parameter under “Node” has to be set to “Cache”. Then it is possible to reset the scene, load the existing core fluid data and change only the displacement. To check the quality and look of the displacement you can use the previously mentioned graph again
Calculate displacement
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There are three methods to calculate the fluid's displacement:
Never | If you do not want to add displacement, please use the default option. |
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Always | When the displacement is created in a separate pass, for example after the simulation of the core fluid, you should select this mode. |
Use cache | Once the displacement has been extracted and you want to proceed with the splash, mist or foam passes, you can reuse the already generated data with “Use cache”. |
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If you have already worked with RealFlow's Graphs system or one of the demo scenes, e.g. “apply_stat_spectrum” then you have most probably already seen the “Time factor” setting. This parameter allows you to control the wave surface's speed. Values greater than 1.0 will accelerate the waves, while values smaller than 1.0 can be used to decelerate them. The advantage is that the waves' speed can be adjusted without changing any other parameter. Another plus factor is that the “Ocean Statistical Spectrum” settings from RealFlow Graphs, Hybrido, and RealWave have been unified as far as possible. This way, you will be able to get exactly the same results with identical settings in all three environments. "Time factor" is a dimensionless value and accepts floats – it works as a multiplier.
Quality
You can choose from 6 six different levels of quality. Of course, higher quality settings require longer simulation times, but also create more details. The chosen value is directly connected to the size of the final map – a “Quality” level of 4096 creates a squared image with 4096 x 4096 pixels. RealFlow's Hybrido displacement maps are stored as 16-bit TIFF files and can allocate more than hundred Megabytes per map with very high settings.
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To alter the height of the statistical waves, “Vertical Scale” is used. You normally have to adjust this parameter when you are changing the surface’s dimension value. “Vertical Scale” has a significant influence on the credibility of the entire simulation and can also be used for the creation of heavy storms with high waves. The parameter's unit is is metres per second [m/s].
Auto dimension
With this feature RealFlow specifies the horizontal dimensions of the grid fluid container which it uses for the calculation of the waves. By default it is set to “Yes”, but you can also specify your own settings if you change it to “No”.
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As shown above, the parameter is given in metres [ m m] and accepts floats.
Auto wind speed
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With this parameter set to “Yes”, RealFlow automatically reads the directions of existing wind daemons and translates their values into the direction the waves are travelling. With “No” it is possible to specify a custom wind direction.
Wind alignment
With small values only waves which are totally perpendicular to the waves' direction are removed. When “Wind alignment” is increased, RealFlow will remove more and more waves; waves which are less perpendicular. If the value is very high, only those waves which are absolutely parallel to the wind direction will remain.
@ wind direction
This is the wind direction in degrees [ deg deg]. Please note that in the case of using the linked daemons, the velocity vector is projected on the XZ plane and then converted to degrees. If you use another axis setup, where Y does not serve as a height axis, the orientation of the wind direction will change. By default (with YXZ orientation), RealFlow uses this notation:
- 0°: wind comes from the positive X axis (1,0) - positive wind directions are counter clockwise.
- 90°: wind comes from the positive Z axis (0,1)
Wind alignment
With small values only waves which are totally perpendicular to the waves' direction are removed. When “Wind alignment” is increased, RealFlow will remove more and more waves; waves which are less perpendicular. If the value is very high, only those waves which are absolutely parallel to the wind direction will remain.
Min Wave Length
With “Min Wave Length” the amount of details on the surface can be controlled. Higher values flatten the surface and create fewer ripples. Please keep in mind that the parameter is connected to “Dimension”. When entering lower values, this parameter should be decreased, too, to guarantee that the RealWave object still shows enough structures.
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Since the displacement is calculated from a texture map it is also possible to define the number of repetitions both in U and V direction of the mesh grid. U and V coordinates are related to the UV grid that is created with the mesh. Displacement maps are seamless, though very high values are very likely to create regular patterns on the surface. This value is dimensionless and accepts integers.
Evaluation UVW mapping
In RealFlow's grid fluid simulation, displacement is used to create a wide variety of different secondary effects, for example for adding foam particles. To take the current displacement value into consideration this parameter will be read.
You have several options: “UV particle” evaluates the texture coordinates of the fluid particles to access the displacement data. With “Top projection”, the coordinates will be taken from a projection plane. “Top projection (Average velocity)” works exactly like the previous function, but here, the projection plane moves with the fluid based on its average velocity.