U Volume

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Fluid Ninja, Clouds

Obsidian: [[16-02-01-Rendering]] [[15-01-01-Shading]] [[11-01-01-U_Rendering]]

pxl.ink Unreal Rendering Features
pxl.ink Unreal Light - Lighe and atmosphere

Art

add different layers of clouds on diff heights to get paralax effect

  • HIGH cirrostratus / cirrus / cirrocumulus
  • MID altostratus / altocumulus /
  • LOW stratus / stratocumulus / cumulus / cumulonimbus

https://sergeneren.com/2019/08/21/creating-low-altitude-clouds/ https://gumroad.com/l/sFTCY/Clouds6m52fv

Unreal Volume

Control in Heightfog and material

Unreal CVars:

  • GridSizeZ - how many planes - 32 - 128 Can trade distance for quality
  • TemporalReprojection - Temporal smooth
  • HistoryWeight -0.1 -flickering layers / 0.9 - ghosting /== how smooth vs how responsive .6/.7 
    `r.VolumetricFog.GridPixelSize 8`   
`r.VolumetricFog.GridSizeZ 128`
`r.VolumetricFog.TemporalReprojection 1`
`r.VolumetricFog.Jitter 1`   
`r.VolumetricFog.HistoryWeight`   
&  r.SkyAtmosphere

Volumetric Clouds

Solved by using an approximation of realistic scattering by tracing multiple octaves. When near will be replaced with volume fog. Multiple scattering = albedo that is close to a value of 1

Setup

  1. Eneble volume plugin
  2. Drag Volumetric Cloud from actors
  3. In engine content: VolumetricsContent/tools/CloudCompositing
    • BP_CloudMask_Object - Scale and move away its asset with single cloud. Have debug plane to create shape
    • BP_CloudMask_Generator
  4. Assign Material: VolumetricsContent/Content/Sky/Materials
  5. Scene setup: Directional (w atmosphere sun light) / sky atmo / sky light with real time capture / height fog (insc and dircol to Black)/ setting: support atmo affect h fog.
  6. Unreal/Engine/Plugins/Experimental/Volumetrics/Content/Content - volumetric plugin content

M_volumetricCloud_02_Profiles_Soft

`r.VolumetricCloud.ReflectionRaySampleMaxCount`   
`r.VolumetricCloud.Shadow.ReflectionRaySampleMaxCount`  
`r.VolumetricCloud.ViewRaySampleMaxCount`
`r.VolumetricCloud.SampleMinCount`  
`r.VolumetricCloud.DistanceToSampleMaxCount`  
`r.VolumetricRenderTarget.Mode` - 0-2

[ Volumetric cloud ] Actor

Cloud Tracing properties enable you to scale the tracing quality of key cloud attributes, like clouds in reflections, shadowing samples for clouds and clouds in reflections, and the distance from the camera that cloud shadowing should stop. The cloud system doesn’t support Ray Tracing, only takes into account the clouds as rendered into the Sky Light.

Layer

  • Layer Bottom Altitude
  • Layer Height -
  • Tracing Start Max Distance -
  • Tracing Max Distance -
  • Planet Radis -

Cloud Tracing (balance visual nad perf) Sample Count - To optimize !!!

  • View Sample Count Scale - Clamped by: r.VolumetricCloud.ViewRaySampleMaxCount - Sample Count
  • Refraction Sample Count scale - rózowy ziomek miał na 1
  • Shadow View Sample Count - !! perf
  • Shadow Refraction Sample Count scale - Sky Light quality for reflections
  • Shadow Tracking Distance - !! perf - range of shadow

[ Directional Light ] Actor

  • Cast Cloud Shadows on an atmospheric light allows for the cloud volume to shadow scene elements
    • Cloud Shadow Map Resolution Scale drives the resolution and performance cost of the sunlight shafts. Reducing the radius of the cloud shadow map around the camera with the Cloud Shadow Extent property can help focus the shadow map resolution for sharper, better results.
  • Cast Shadows on Atmosphere and Cast Shadows on Clouds - Shadowing for large objects is achieved using a large enough Dynamic Shadow Distance or using Far Shadow Distance on the Directional Light to shadow objects that enable the Far Shadow flag in their details.
  • Cloud Scattering Luminance Scale provides a nice counterbalance to low light with low octaves count

And also

  • strength of shadows
  • distance that cloud shadowing happens from the current camera position (in kilometers),
  • whether clouds can self-shadow
  • whether clouds can cast shadows into the atmosphere

[ Sky Light ] Actor

The Sky Light component uses the Cloud Ambient Occlusion properties for soft ambient shadowing

  • When using secondary marching per sample, the cost is driven by values setup on the Volumetric Cloud component with Shadow View Sample Count Scale.
  • When the cloud samples the Directional Light Beer Shadow Map (which is also used to cast shadow on meshes), then a single evaluation of the shadow map is done at each ray marched position. The Beer Shadow Map generation is driven by information coming from the setup on the Directional Light component with Cloud Shadow Ray Sample Count Scale.

Ray Marching

paralax occlusion ray matching -
ray trace - array of features

Quality Modes

r.VolumetricRenderTarget.Mode 0 - recommended option for quality. It supports fast-paced gameplay that may have ground-to-space transitions, or flying through clouds. Clouds are fast to trace but can appear to have low resolution. Traces happen at quarter resolution, reconstruction at half resolution, and upsample on screen at full resolution.
r.VolumetricRenderTarget.Mode 1 balances quality with performance to fit a lot of types of gameplay that are good for ground views. This mode is more expensive but looks higher quality. Traces happen at half resolution, reconstruction and upsample on screen at full resolution.
r.VolumetricRenderTarget.Mode 2 focuses on higher quality while still supporting ground views for real-time gameplay. This mode is fast to trace and looks high resolution, but it does not support cloud intersection with opaque meshes.

Volume material

  • Material: Additive & Volume domain. Can be lit or unlit
  • Texture: Volume Texture, Created from source texture
    • Vector Displacement map (RGBA8)

Ground Contribution - if your frame budget allows.
Conservative Density attribute is used to accelerate the ray marching by skipping expensive material evaluation early on.

Material nodes

[Cloud Sample Attribute] material node

  • Altitude - Altitude relative to ground
  • AltitudeInLayer - Altitude relative Lowest cloud
  • NormAltitudeInLayer - 0-1 gradient
  • Shadow Sample Distance

[Advanced output] material output node

  • Phase G - [-1,1]
  • Phase G2 - [-1,1]
  • Octaves - [0,1]
  • Multi Scattering Contribution - [0,1] How much Contribution from every octave
  • Multi Scattering Eccentricity - [0,1] How much contribution will be removed
  • Multi Scattering Occlusion - How much became isotropic

To Fake Octaves: Contribution - high Eccentricity/Occlusion - low.

Set in Details

  • Octaves - 1- for real time
  • Gray Scale Material - Optimization
  • Ground Contribution - Add some cost
  • Volume Shadow - Handled by atmosphere lights and the volume material
  • Volume Ray Marching uses secondary ray marching to get sharp colored shadows
    • Limited in distance that shadows can be traced due to the limited number of samples that can be used
    • Good for ground to sky to space transitions even though they are more expensive.
  • Beer Shadow Maps (BSM) use to support far shadow distances for clouds and casting shadows on the ground.
    • Faster to render, but are less accurate and lack volumetric self shadow color.
    • Enough for clouds viewed from the ground.
    • Xbox One and PlayStation 4, Beer shadow maps are recommended for cloud shadowing.

Niagara

Fluid Ninja Live

Setup

  1. Add custom trace channel
    • Edit > Project Sengs > Collisions > TraceChannels (“TraceChannel” and “CollisionChannel” variables to “FluidTrace”)
    • “Set New trace channel” Name> FluidTrace, DefResponse> Ignore (all objects will be transparent for NinjaLive line tracers - except dedicated TraceMeshes in NinjaLiveComponent owners.), Trace Channel Index does not maer [if we have a trace channel: delete it add fluid trace and readd old trace channel]
    • For fps shooter: it have hidden trace channel !!! named Projectiles invisible in options : CHECK: FAQ issue5 Config/DefaultEngine.ini have + default channel responses should be game trace channel 1
  2. UV from Hit
    • Edit > ProjectSettings > Engine > Physics > Optimization - help convert 3d data to 2d fluid spcae
  3. Enable Apex Destructions
  4. Copy conternt - /Content/FluidNinjaLive to the /Content folder of the target project. (And recompile NinjaLive.uasset)
  5. In the level editor, select any NinjaLive Actor on a level. Select NinjaLiveComponent. Check the “Live Compability” group: the top 3 input fields should be set to “FluidTrace”.

Fluid Ninja (manula)

Inputs: Texture. Mat. Scene capture. geometry , (SM Bones sockets Phys Bodies Destructy) for real time: ~5 itterations for real time: 1-2 high res area fx and 3-6 character fx - 1k is high res
512x512 area = 6656 Kbytes, 1024x1024 area = 26624 Kbytes, 2048x2048 area = 106496 Kbytes.
6 buffers:

  • Paint Buffer - interaction
  • Divergence buffer - shockwave like
  • Pressure buffer - shockwave like
  • Velocity Buffer
  • Density

The rendering pipeline uses 8 RenderTargets for a single simulaon container by default:

  • 1 four-channel [ RGBA, for CollisionPainter ],
  • 5 single channel [ R, for Density and ScalarFields ] and
  • 2 bi-channel [ RG, for VectorFields ] All set to 16 bit precision.
    (te set resoluon, bit depth, channel usage)

2d fluid sim

  • using volume to track Pos and Vel > to Linetrace form cam to 2d
  • display on cam facing plane

  • Red are processing mat
  • Blue are outs to render target render buffer

Manual FAQ

TRACE LINES

use custom line trace:

  • normaly projecting from camera to billboard plane . for rotationali fixed sim contianers . !!!

use custome trace position on component. lvl 21

RenderTarget

  • this is what we call “Collision Painter”.

The switch is located at NinjaLiveComponent Details /Live General /SimplePainterMode (at the very bottom)

Parts

Ninja Live (RED)

Actor class object BP - “sim container” / “sim area”. Details: Activation, Interaction, Debug, ComponentOverrides.

Filter interactions, change material.

  • Activation volume (usually much larger than the sim area): the proximity of any user defined agent could switch the sim component between wake/sleep states. For example: a player pawn is entering the 1000 meter range of a sim area, area wakes up, initializes, acquires pre-generated render targets from the memory manager, and gets ready to encounter the player.
  • Interaction volume (usually same size as the sim area): detecting overlapping / colliding objects and forwarding the spatial information + velocity to the sim component. Using the interaction volume, anything could interact with the simulation: Static- and Dynamic Meshes, Skeletal Meshes, Physics Bodies.

Ninja Live Component

Actor Component class “sim component” - more parameters (sim presets / materials) Details: Activation, MemoryManagement, Performance, Compatibility, Debug, Generic, Interaction, BrushSettings, Raymarching

Ninja Live Memory Pool Manager (BLUE)

Ninja Live Utilities (GREEN)

Can add to actor

Ninja Live Preset Manager (BLACK)

“Collision Painter”

Custom GUI, Memory Manager, and Interface Controller.

Noise

A better strategy is stacking 3 layers of lower resolution 3D noises (128^3 for example) instead of 2 high resolution. And because the 3 layers have aggressively larger scale, they make up for low resolution:

    instr pre level lookup table     COST
Regular Texture           0
Fast Gradient 3d tex ~16 1 High quality but not for bumps (baked to a volume texture) Always tiles 0
Value Computational ~53-118   Low quality but computational yes 1
Gradient Tex Based ~61-74 8 High Quality always but <=128 1.5
Simplex   ~77 4 High Quality no 1.5
Gradient Computational ~80-143   High Quality yes 3
Voronoi Q1 8 cells x20 ~160       6
Voronoi Q2 16 cells x20 ~320       8
Voronoi Q3 27 cells x20 ~540       8
Voronoi Q4 32 cells x20 ~640        

Tiling Noise > Repeat Size (Repeat Size matches the sampled size that you will be baking out.)

High Quality Clouds

  1. Cloud Actor: Tracing section, increase the sample count scale for View, Reflections, and Shadows.
  2. Material node: Ground Contribution / up octaves to 2
  3. Light: Cast Cloud Shadow (+map Resolution Scale - heavy)/ Cast Shadows on Clouds / per Sample Atmospheric Light Transmittance / Light Shaft Occlusion
  4. Choose one of those:
    • r.SkyAtmosphere.FastSkyLUT 0 - Disabling this optimization is slower to render, but produces fewer visual artefacts with high-frequency detail that can appear in places like the earth’s shadow or scattering lobe.
    • r.SkyAtmosphere.FastSkyLUT 1
    • r.SkyAtmosphere.AerialPerspectiveLUT.FastApplyOnOpaque 0
    • Trace Sample Count Scale to adjust the number of samples used. If the max range isn’t enough, use the command r.SkyAtmosphere.SampleCountMax to choose a higher limit and manually enter a value in the property field.
    • r.SkyAtmosphere.FastSkyLUT.Width and r.SkyAtmosphere.FastSkyLUT.Height - mprove the quality of sunlight shafts
    • r.SkyAtmosphere.AerialPerspectiveLUT.Width - quality of fog on opaque and transparent surfaces

r.VolumetricRenderTarget 0 -
r.VolumetricCloud.HighQualityAerialPerspective 1 - aerial perspective for clouds to use high quality ray tracing instead of low resolution LUTs

##### Low Level Settings  
to the host actor class
in your Actors, apply the directly specified

- **Actor Details** - Activation, Interaction, Debug, Component Overrides.
- **Component Details** - Activation, Memory Management, Performance, Combability, Debug, Generic, Interaction,
Brush Settings, Raymarching


##### Spawn  
- Ninja Live fluid sim Actors at your levels -
- or add Ninja Live fluid sim Component to your own object classes. To make fluid sim Component work properly

Pseudo-Volume

SDF

VDB SDF Sparse volume that define distance to surface. (How far away from edge (positives outside cause its distance )). Black at 0. so can see if in/out.

  • ray matching Take big step and check how big next step should be. cause in fsd u know how far you are.

VOLUME FAKE 6 point lightmap

Cool! You can also output these directional lightmaps automatically in ue4 using the Volumetrics plugin along with the motion vectors. I have been meaning to post about that. https://twitter.com/Vuthric/status/1286796950214307840

pseudo volume smoke houdini
https://viktorpramberg.com/smoke-lighting

https://shaderbits.com/blog/ue4-volumetric-fog-techniques
https://www.youtube.com/watch?v=739NOjhLVnI, http://asher.gg/, Inside Unreal (Expand Your World With Volumetric Effects)](https://www.youtube.com/watch?v=R2RQm_Bu81I) - forum thread volume fog layers nice