fluidNInjia说明

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The flipbook on this level has been baked using the CIRCULAR preset.
The Material above is a preview, using the standard Ninja flipbook-player.
The VolumeCloud BaseMaterial utilizes the same flipbook-player,
set to use the same flipbook as this preview material.

Important: the two materials are independent - adjusting the preview
will not change the cloud-behaviour. To adjust clouds, you need
to edit the cloud material --- see instructions on the right!
All settings located in the VolumeCloud Material Instance,
available through the Volumetric Cloud Actor.

(1) Adjust Noise Flow Strength and Speed in the NOISE
group to influence the drift of SMALL structural details
(2) Adjust adjust "laySpeed" in the FLIPBOOK group to
incluence the tempo of LARGE structural changes
(3) Turn on - and adjust velocity based frame blending
in the FLIPBOOK group to support super-slow-down

Ninja could use baked simulation velocity data create smooth blending
between density-flipbook frames when playback is slowed down.
To enable this feat, set VelocityInterpolation: TRUE in the Player Material.
Velocity-based frame blending is "pushing pixels" towards velocity dir.
The amount of optimal "pushing" varies, depending on the playspeed.
Following the baking process, users are advised to manually adjust
VELOCITY settings in the player material (Strength, Floor, Ceil),
according to the playback speed.

Ninja stores flipbook frames in a compact, more-or-less square-like
grid structure (see the 4x2 grid on the left - storing 8 frames).
The default texture smoothing of video hardware (bi-linear interpolation)
is blending between adjecent pixels - too bad it does the same at
frame edges: border pixel values of a given frame are corrupted
by the values of the pixels from the surrounding frames.

This is not a problem, in case we only have useful information mid frame - eg. a candle flame sequence.
This is a problem, in case we would like to crate full-frame tiling patterns - typically needed to cover
large areas (eg. a cloudscape) with repeating flow patterns. Ninja uses a workaround to avoid
"corruption" caused by the video hardware interpolation - but, it is not a perfect solution:
frame edges are somewhat glitchy (see the mid-field edge on the left).
Simple solution: offset the tiled pattern until the artefacts are not visible )))))
Komplex solution: bake the sequence to a long, linear stream of images, so frames will not have
vertical neighbours (while horizontal neighbours are temporally close to the current frame).
The result is a flipbook with one row - the number of columns = the number of frames.
Ninja looks up grid-creation settings from a data table. By manually adjusting this table,
you could force ninja to create such long flipbooks: /Content/FluidNinja/Core/AtlasBuilder/DT_AtlasMatrices
Eg.: you'd like to bake a loop to 36 frames. Ninja, by default assigns a 6x6 matrix to this frame number.
You should set it to 36 x 1 in the atlasmatrices datatable before starting the baking process.
As a result, Ninja will generate a single row flipbook - somewhat resistent to tiling artefacts.

Sim quality depends on the number of pressure iterations.
More iterations result nice, turbulent flow.
Eg.: the baked flipbook used by the "atmoMED" preset has
been recorded using 16 iterations. Ninja default = 6.
You could adjust iteration number by going to the
NinjaTools Level / selecting FluidNinja Actor / locating
the NinjaTweak options on the Actor Details panel

Volumetric Cloud setups are using UE 4.26 technology,
lower UE versions are not supported.
According to this, NinjaTools 1.5 has been forked
to a 4.25 and a 4.26 branch. The two branches are distinguished
by 25/26 subversion element in their version number.