Description

Volumetric Glass is an advanced and efficient master material designed for rendering volumetrics and glass. The package is useful for creating sci-fi stylized environments like water tanks, aquariums, and underwater tunnels even glass in submarines. The package is perfectly balanced between quality and efficiency. Designed and optimized specially for Mobile, Virtual Reality, and stylized PC/Console games.

Features

• Two types of material underwater volume  and shaped glass
• GPU friendly and very efficient can be used on mobile as well as in the VR
• Multiple shapes (box, sphere, ellipse, cylinder, mesh)
• Spline based tunnel blueprint
• GPU friendly very efficient (only 150 instructions)
• Over 70 parameters to setup: light shafts, volumetric, scattering, glass color, fog density, wet color, reflections, etc.
• Animated clip plane surface
• Vertex color based texture masking
• Example map contains underwater world and sci-fi laboratory
• High-quality fast scattering
• Fast box projected reflections
• Custom multi-channeled point lights
• Easy for integrating with other water surfaces like Aquatic Surface.

Documentation

Get Started

The most important think about the Volumetric Glass is that the package is divided into two materials specialized for use in different cases:

1. Glass Volume (Materials/M_GlassVolume) – Supports rendering of glasses from the inside of the fluid volume. Represents underwater windows, tunnels, glasses, and world rendered from the inside of the water. Material is called M_GlassVolume.  
2. Glass Shape (Materials/M_GlassShape) – Supports rendering shapes from the outside of the fluid volume. Useful for water tanks sci-fi stylization, volumetric fog used as an environmental effect.

Both materials should be instanced before using on the meshes. To create material instance from the base material click right button on the chosen material and select “Create Material Instance” option.

Glass Shape

Glass Shape material can be used on different geometric objects like a box, cylinder ellipse. 

 

Basically, the system requires to use of meshes with unified size (100cm,100cm,100cm) and pivot in the center. The mesh can be scaled properly in actor properties. Example shapes can be found in the Package/Meshes folder.

Example of use:

1. Chose the shape and place on the map. For example SM_Box
2. Create a material instance from M_GlassShape
3. Open newly created material instance and set up the parameters. Find the Shape tab and select the shape that you want to use:
   
4. Setup the Reflection Texture cubemap in the material. It should be the texture cached from the scene using the Scene Capture Actor. If you don’t know how to prepare a cubemap read the Capture Reflections chapter.
5. Apply glass material on your glass on the meshes and see the magic 🙂

It is not possible to use Box/Sphere shaped meshes on the characters props or customization elements because it is not geometric compatible. There is additional UseShapedMesh mode in the M_GlassShape material that implements approximated shape for the undefined shapes.

Base parameters

M_GlassVolume
Use Fog Exp2	Use exponential fog or linear if false.
Fog Base	Base depth of the fog effect.
Fog Density	The density of the fog effect.
Fog Color	Color of the deep fog.
Use Wet Color	Enable wet color functionality.
Wet Color	The color multiplier applied to geometry inside the shape.
Use Translucency	Whether the translucent effect should be active.

Clipping plane surface

Clip plane surface is the effect of clipping the geometry by plane filled by an animated fluid surface.

Clip plane
Use Shape Clip Plane	Whether the clipping plane effect should be active
Shape Clip Plane	Equation of clipping plane RGB-normal, A-translation
Use Surface Normal Map	Use the surface normal map
Surface Normal Map Texture	The texture used as a normal-map.
Surface Normal Map UV	UV scale and translation in an animation of normal maps on two layers. R – Layer 1 scale,  B – Layer 2 scale,  G – Layer 1 move,  A – Layer 2 move,
Surface Normal Scale	Surface normal z value multiplier before normalization. Allow changing height ow wave.
Surface Normal Flatness	Surface normal flatness. Allow changing height ow wave.
Use Surface Normal Scale	Whether to use Flatness or Scale
Use Surface Normal Map	Use the surface normal map
Use Clip Plane Reflection	Allow using clip plane reflection effect
Use Water Line	Allow rendering waterline on the glass. (experimental)

Lighting

System supports multiple methods of lighting the meshes:

• coloring edges of the mesh at lower depth (simple and fast) Use Light Color Edge = true
• simplified directional diffuse light UseLighting = true
• advanced subsurface scattering (very complex slowest) UseSubsurfaceScattering = true

All of these methods can be used separately or combined at the same time. The only single light source can affect the glass and it can be point light or directional light.

Use Directional Light	True – Use Directional Light	False – Use Point Light
Use Channel = true	Reads the directional lighting values from global settings Materials/UtilsPC_VolumetricGlass DirLightChannel0	Reads the directional lighting values from global settings Materials/UtilsPC_VolumetricGlass  PointLightChannel0-2.  Point light channels can be controlled by the BP_ScatteringLight blueprint placed on the level with the selected channels to set.
Use Channel = false	Reads the directional lighting values from local variable Light Direction in the material.	Reads the directional lighting values from the local variable Light Position in the material.

 

Lighting
Diffuse Power	Diffuse lighting color.
Light Color	Color of light inside the volume.
Use Directional Light	Whether to use directional or point light.
Light Direction	If Use Directional Light = true then uses this value as light direction. Length of vector changes fading.
Light Location	If Use Directional Light = false then this is the default location of the light relative to the actor. Alpha channel contains Attenuation.
Use Light Color Edge	Use the light color as the edge of the shape. The shape will be lightened in depth. The scale of depth can be changed in the alpha channel of the Light Color parameter.
Use Channel 0/1/2	Select which channel will be used as a global point light.

Scattering

Scattering
Scattering Ambient	Scattering ambient value
Scattering Depth	Scattering depth scale
Scattering Depth Block	Scattering blocked by mesh depth inside the volume
Scattering Distortion	Light distortion inside the scattering inside the volume
Scattering Power	Exponential power scattering effect inside the volume
Scattering Sale	The scale of scattering effect inside the volume
Use Lighting	Whether the lighting and scattering effect should be active.

 

Glass Volume

First, you have to place the BP_GlassVolume blueprint on the scene. BP_GlassVolume represents the shape of the fog volume that will be used for volumetric glass.

1. Volume is visible only throw the glasses that use specialized material called M_GlassVolume.
2. Create a material instance from M_GlassVolume and set up the parameters.
3. Apply glass material on your glass meshes and see the magic 🙂

 

Base parameters

M_GlassVolume
Use Fog Exp2	Use exponential fog or linear if false.
Fog Base	Base depth of the fog effect.
Fog Density	The density of the fog effect.
Fog Color	Color of the deep fog.
Fog Scattering Clamp	Maximum scattering power.
Fog Scattering Scale	Scale config of the scattering color effect.
Fog Scattering Shift	Shift config of the scattering color effect.
Fog Scattering Width	Width config of the scattering color effect.

Light shafts

Glass material supports simplified optimized light shaft effect settings and configuration listed below.

Light shafts
LightShaftColor	Light shaft color in scattering.
LightShaftDistance	The distance of the light shaft effect from the camera.
LightShaftIntensity	The intensity of the light shaft effect.
LightShaftPosition	Camera position scale when moving light shaft.
LightShaftSpeed	Light shaft animation speed.
LightShaftTexture	The texture used as a light shaft.
UseLightShaft	Activates light shaft effect.

Tunnel Spline

BP_TunelSplineActor is an additional blueprint useful for creating underwater tunnels. To start using this actor just place the BP_TunelSplineActor  on the scene and setup parameters.

BP_TunelSplineActor
Static Mesh	Looped mesh used for tube
Forward Axis	The forward axis of the mesh.
Translucency Sort Priority	The priority of mesh rendering. Can fix some translucency bugs.

Hold Alt+Drag the point of spline to create duplicate of spline point.

Capture Reflections

The Volumetric Glass system renders reflections based on the cube maps cached from the scene. It is really efficient method but requires some additional effort to cache the reflection.

1. Place Blueprints/BP_SceneCaptureCube on your map and set up a proper position to capture the scene (center f the room would be great).
2. Open Material/Textures and find the render target (RT_SceneCapture).
3. Click right on the RT_SceneCapture and select “create static texture” newly created texture is ready to use in the volumetric glass system.

Reflections Settings

The reflection effect is based on a prerendered cubemap. Volumetric glass supports two types of reflection mapping. Spherical reflections and box projection mapping.

• Spherical mapping – Very fast but inaccurate. Works out of the box.
• Box projection mapping – Very accurate in box-shaped rooms. Requires additional room size pieces of information in the materials.

Box projection mapping
UseBoxProjection	Allows using box projection mapping. If disabled then the system uses standard spherical cube-map projection.
ReflectionBoxExtend	half size of the room cached in the reflection map.
ReflectionBoxPosition	Position camera where the reflection was cached.
UseReflectionBoxLocal	Forces system to use reflection box capture in local space of actor position. Useful when the mesh is connected to the same actor as the reflection capture component.

Other reflection parameters:

Reflections
ReflectionColor	Color of reflection allows adjusting the cubemap to underwater conditions. Alpha channel represents the power of fresnel.
ReflectionTexture	Prebaked cubemap reflection texture should be cached in the place where the glass is rendered.
Use Shlick Reflection	Enables physical-based Shlicks fresnel calculations. Otherwise uses a fast simplified dot(camera, normal) fresnel.
UseReflectionBoxLocal	When true then ReflectionBoxPosition will be added to the actor position.

Glass Settings

Volumetric glass materials support advanced glass surface configuration that allows customizing appearance to specific requirements. Glass surface is rendered before the volume and can cover the objects behind the glass.

M_GlassVolume
Glass Color	Color of glass mesh (with translucency).
UseGlassTexture	Allow using glass texture instead of flat color.
UseGlassTextureColor	Glass texture color multiplier.
GlassTexture	Glass texture used when UseGlassTexture = true
GlassTextureU	Scale glass texture on U axis
GlassTextureV	Scale glass texture on V axis
UseGlassTexturVertexAlpha	Uses vertex color alpha channel as a multiplier for glass texture. Broken glass example.

 

 

Aquatic Surface is a well optimized advanced material that implements configurable water effect.

Features

• Water clip line effect 
• Underwater and over water surface
• Underwater post-process volume
• Two types of static reflection/refraction projections (box projection. spherical projection)
• Translucency effect support for underwater particles and meshes
• Water holes for boats
• Example 4 types of basic configurations: lake/reef/pool/waste
• Animated caustics based on decals
• Standard UV mapping, vertex color flow, and texture color flow maps
• Over 100 parameters like translucency, fog depth, mapping, reflective, refraction, scattering, wet color.
• Multiple material switches enable/disable some of the effects to increase quality/efficiency
• Separated onto 4 materials: overwater surface, underwater surface, in water post-process volume, caustics decal. Each of them can be used with other water systems.
• Very fast and GPU friendly. 120-160 instructions depend on used effects.
• Quality/Efficiency adjustment. cinematic (realistic reflections) and standard (fast static box projected cube-map)
• Water edge implemented without using the distance fields
• Specular effect and glittering on waves
• Simplified underwater scattering
• Implemented as the unlit translucent material
• Interactions & Buoyancy components
• Fast simulated interactions with moving area
• More options and switches to customize/optimize than you can try during your whole life 🙂

Gallery

Release changelog

Documentation

Get started

In Aquatic Surface package the water visualization is divided into multiple specialized material effects. Each layer of the effect can be separately configured to achieve incredible effects and can be used individually.

• Overwater surface (M_AquaticOverWater)
• Underwater surface (M_AquaticUnderWater)
• Pre-translucent volume water (M_AquaticVolume)
• Post-process screen water (M_AquaticScreen)
• Caustics decal (M_AquaticCaustic)
• Waterplane holes for boats (M_AquaticHole)
• Material function fo translucent meshes (MF_AquaticTranslucent)

Demo folder contains all assets prepared to showcase the example Maps. Check the example maps to see the possibilities of the Aquatic Surface system.

Each example map uses its own template of water materials located in Template folder like Like/Reef/Pool. A template is a group of material instances created from Aquatic Surface master materials. For example, in folder Demo/Lake you can find material instances of materials used on LakeMap. Those materials can be easily edited to achieve another visualization of lake water.

You can create your own material instances of water by duplicating the chosen template content or by using the editor option “Create Material Instance” on master materials located in Material directory.

Few simple steps to start using Aquatic Surface:

1. Chose the template of Aquatic Surface water that you want to use on your map. For example AquaticSurface/Demo/Templates/Reef.
2. Drop the blueprint (/Demo/Templates/Reef/BP_AquaticSurface_Reef) of water on your level.
3. Modify the parameters of the blueprint to adjust the water to your map. Especially it is important to set up bounds of reflection overwater/underwater and post-process volume size. A detailed description can be found in Aquatic Surface Blueprint section.

Aquatic Surface Blueprint

The BP_AquaticSurfce is a combination of underwater overwater and post-process materials that provides a user-friendly interface to configure water.

BP_AquaticSurface
Reconstruct	Click to refresh the reflection texture and material parameters. Reconstruct the object.
Over Water Material	The material instance used on over the water surface.
Under Water Material	The material instance used on under the water surface.
Volume Material	Material instance used as fog volume of water.
Near Plane Distance	Clip plane distance. By default 10.
Volume Box Extend	Underwater pre-translucent volume box size.
Volume Box Location	Underwater pre-translucent volume box location.
Volume Fog Density	The density of the underwater fog
Volume Fog Base	The distance of underwater fog near plane
Reflection External	External blueprint of reflection that can be shared between multiple water surfaces.
Reflection Cubemap	Static cube map reflection.
Hidden In Reflection	List of actors not rendered to reflection.
Reflection Capture Delay	Allows capturing reflection after start witch some small delay (after the content is loaded). The -1 value – never recapture.
Reflection Source Location	The point where the reflection capture was taken.
Reflection Box Over Extend	The size of the box used for surrounding cubemap used as over water.
Reflection Box Over Location	The central location of the box used for surrounding cubemap used in the underwater material.
Reflection Box Under Extend	The size of the box used for surrounding cubemap used as over water.
Reflection Box Under Location	The central location of the box used for surrounding cubemap used in the underwater material.

Pay attention that M_AquaticScreen material should be set in PostProcess component in PostProcessMaterials array.

Over Water Surface

The M_AquaticOverWater is the material effect visible from over the water reflection refraction fresnel and depth. This material should be used on plane meshes aligned horizontally with normals directed upward.

1. Find the M_AquaticOverWater* material that you want to modify from the example library of materials.
2. Click right select duplicate option on the material. Rename to your water. It is good practice to have a clean naming convention like M_AquaticOverWater+River/Lake/Ocean.
3. Put on your scene flat plane surface and apply the newly created material.
4. Open created material and edit parameters to customize for your scene.

 

Overwater Base Color
Fog Base	Specifies the covering at which fog should starts.
Fog Density	Cover by fog depending on depth change.
Fog Color	Fog color when a mesh is fully covered.
Use Fog Exp 2	The exponential types provide more depth, more natural-looking fog, and make the edges appear smoother. When disabled fog works in linear mode.
Scattering Color	Fog color near the coast
Shadow Color	The color multiplier on the ground from water shadow.
Wet Color	The color multiplier on the ground for simulating the wet material.

Overwater Refraction
EmissiveReflection	0.0 Reflection will be applied to the base color when 1.0 it will be added to emissive. Parameter allows controlling how much sun color can affect the reflection.
Refraction Color	Surface refraction color multiplier.
Use Shlick Reflection	Enables physical-based Shlicks fresnel calculations. Otherwise uses dot(camera, normal) based scale.
Reflection Exp	Exponential reflection. In the Shlick’s model of reflection, it is 5.
Box Projection Extend	Size of box projection.
Use Box Projection	Allows using box projection mapping. If disabled then the system uses standard spherical cube-map projection.
Cubemap	Cubemap texture used on objects. By default connected to render target. Textures should be prebaked and saved in content.
Use Multireflection	Blocks reflected rays from sampling the cube-map under the water, reflects the ray again. It gives better results when using very high waves.

Overwater Sun
Use Sun	Allows using second normal texture source.
Use Sun Half Vector	An alternative method of calculating specular reflection based on half vector instead of reflection. Little different result.
Sun Color	Color fo highlights.
Sun Intensity	The intensity of highlights.
Sun Shininess	The shininess specifies how small the highlights are: the shinier, the smaller the highlights.
Glittering Power	High power of glittering increases lighting points intensity.
Glittering From Sun	How the position of the sun affects the Glittering effect.
Glittering Clamp	Max glittering emissive value.

Overwater Translucent
Refraction	Simplified refraction effect based on UV shifting on waves.
Translucency	Alpha blend translucency on the coast. Should be very low it conflicts with the refraction effect.
Use Coast Foam	Activates additional coast foam effect.
Coat Foam Color	Coast foam color multiplier. Width in the alpha channel.
Use Distance Fade	Activates translucent fade effect on the horizon.
Distance Fade Min	Minimum distance from the camera to start fade.
Distance Fade Width	The width of a fading area.

Under Water Surface

The M_AquaticUnderWater is a waterplane surface rendered from under the water. This material mainly represents the effect of refraction and reflection under the water. This material should be used on plane meshes aligned horizontally with normals directed down.  

1. Find the M_AquaticUnderWater* material that you want to modify from the example library of materials.
2. Click right select duplicate option on the material. Rename to your water. It is good practice to have a clean naming convention like M_AquaticUnderWater+River/Lake/Ocean.
3. Put on your scene flat plane surface and apply the newly created material.
4. Open created material and edit parameters to customize for your scene.

Underwater Refraction
Refraction	Refraction coefficient <1.0, 2.0>.
Refraction Color	Surface refraction color multiplier.
Box Projection Extend	Size of box projection.
Use Box Projection	Allows using box projection mapping. If disabled then the system uses standard spherical cube-map projection.
Cubemap	Cubemap texture used on objects. By default connected to render target. Textures should be prebaked and saved in content.
Screen Refraction	A coefficient of screen color refraction. Makes that meshes close to the camera can be seen from underwater.
Use Sun Specular	Allows using sun specular effect.
Sun Specular Shininess	Shininess parameter of the sun.
Sun Color	Sun color multiplier. Scale encoded in the alpha parameter.

Pre-translucent volume water

The M_AquaticVolumeWater is a custom post-process effect rendered before translucent. Ths material visualizes the underwater ‘fog’ and wet surface.

The fog parameters should be set in BP_AquaticSurfce blueprint because these parameters are shared between multiple materials (like translucent).

Post-process fog
Use Fog	Allows using the build-in fog effect.
Fog Color	Sets the color of fog.
Fog Density	Cover by fog depending on depth change.
Fog Base	Specifies the covering at which fog should starts.
Use Fog Exp 2	The exponential types provide more natural-looking fog and make the edges appear smoother. When disabled fog works in linear mode.
Use Fog Scattering	Allow to using the second color of fog near the water surface.
Fog Color Scattering	The second color of fog near the water surface
Fog Scattering Scale	Scale config of the scattering color effect.
Fog Scattering Shift	Shift config of the scattering color effect.
Fog Scattering Width	Width config of the scattering color effect.
Use Fog Wet Surface	A color multiplier of the wet geometry near the surface fo water.
Fog Wet Color Surface	A color multiplier of the wet geometry near the surface fo water.
Fog Wet Color	Color multiplier f the wet geometry.

Post-process water

The M_AquaticScreenWater a post-process effect that visualizes the distortion vignette and water plane clipping line. This material should be used in the post-process volume.

Post-process waterline
Use Water Line	Allows displaying waterline effect. Can be disabled to optimize if you are not going to display the waterline (for example when the game is located fully underwater).
Use Water Line Refraction	Allows displaying water line distortion effect.
Use Water Line Exp	Allows using exponential waterline cover and distortion.
Use Water Line Noise	Additional noise from full-screen texture can be used on the waterline (experimental).
Water Line Color	The color multiplier for waterline effect.
Water Line Refraction	Waterline refraction scale (better results with small negative values).
Water Line Refraction Width	The width of the refraction effect. Fade in distance from the waterline.
Water Line Width	The width of the water line on the screen.

Post-process Screen
Use Texture Distortion	Allows using underwater full-screen distortion effect.
Use Vignette	Allows using underwater vignette effect.
Use Vignette Distortion	Allows using underwater vignette distortion effect.
Vignette Distortion	Vignette distortion scale.
Vignette Dark	The scale of vignette dark color.
Vignette Edge	Hard/soft edge of vignette color

Caustics decal

The M_AquaticCausticDecal material is the effect of caustics projected on the ground. The effect is animated using a simplified method based on animated textures. Caustics animation using a looped cycle based on 16 frames. Caustics decal should be used wich blueprint BP_AquaticCausticDecal prepared especially to update the animation.

1. Find the M_AquaticCaustic* material that you want to modify from the example library of materials.
2. Click right select duplicate option on the material. Rename to your water. It is good practice to have a clean naming convention like M_AquaticUnderWater+River/Lake/Ocean.
3. Drag and drop Blueprints/BP_AquaticCausticDecal on your scene.
4. Set created material to the Dynamic Material parameter in BP_AquaticCausticDecal on your scene.
5. Open created material and edit parameters to customize for your scene.

 

BP_AquaticCausticDecal
Light source	Decal casting direction. Directional light from the scene.
Textures	List of textures used in decal animation. Animated caustics.
Animation Speed	Caustics animation speed (frames per second).
Dynamic Material	The material of caustic M_AquaticCaustic to use.
UV Scale	Caustics texture UV scale.
UV Move	Caustics texture UV movement in time.

M_AquaticCaustic
Color	Caustic color multiplier. Saturation power encoded in the alpha channel.
Blur Max	Castaic maximal mipmap level used near the coast.
Blur Width	Caustics blending width from Max (near water plane) to 0(deep in water)
Emissive	Additional emissive lighting effect in the shape of caustics.
Shadow	Darkening around the caustics (water plane shadow)
Shadow Fade Width	Transition length from No shadow(near water plane) to shadowed (deep in water).
Sun Fade Scale	Only faces directed in front of the sun will be covered by caustics. This parameter allows scaling the disappearing.
Sun Fade Shift	Only faces directed in front of the sun will be covered by caustics. This parameter allows shifting the start point of disappearing.
Saturation	The saturation of caustics texture.
Use Wet Reflection	Allows using specular reflection on the wet ground.
Wet Reflection	The intensity of specular reflection on the wet ground.
Use Water Hight Clip	Allows using clipping the decal effect by water plane. Fixes visibility when the decal projection is the higher than the water plane.
Water Height	Waterplane height on the scene.
Water Height Fade	Fade of decal near the water plane.

UV mapping and normals

Wave effect is based on two moving normal maps. The system supports two types of wave effect animation in UV Transform and Water Flow. To switch between these two types of UV just change Use Flowmap option in the material. UV animation is supported by overwater surface as well as the underwater surface.

UVMapping parameters
Use Flowmap	Refraction coefficient <1.0, 2.0>.
Use Flowmap Texture	Use the flow-map texture instead of vertex colors.
Flowmap UV Config	R and G is an X and Y axis speed of layers. The directions can be inverted as negative. Parameter B is the time scale of a flow map cycle. Parameter A scales the flow map UV.
UV Move Sale 1	The parameters R and G represent the movement on axes X and Y of UV map 1. The parameter B scales the UV.
UV Move Sale 2	The parameters R and G represent the movement on axes X and Y of UV map 2. The parameter B scales the UV.
Use UV Tex Coord/Use UV Tex Coord 1	Use UV Texture coordinates instead of world space position. Can be useful for rivers witch specific mapping.
UseBlendNormalAdvanced, UseBlendNormalUDN	Changes the normal map blending types. There are three types of normal map waves blending. Standard linear (fast), advanced whiteout /UDN. Read more: Blending modes.

Normal mapping
Normal Scale	Scales the normal vectors. Allow making waves higher or more flat (change B value to higher to make it flat).
Normal Texture	Normal texture source.
Use  Normal Texture 2	Allows using second normal texture source.
Normal Texture 2	Second normal texture source.

UV transform

UV Transform mode is the fastest and simpler method just moving and scaling the normal map layers UV coordinates in time. This mode is enabled when UseFlowMap is set to false. In this mode, two scaled layers of normal maps are moving linearly in a defined direction. The configuration of movement speed and scale can be changed in UV Move Sale 1 and UV Move Sale 2 parameter.

Water Flow

Water flow is one of the coolest methods of water animation, first introduced in Portal 2 presented on SIGGRAPH 2010.
The basic idea in this method is to move the UV of the water textures according to direction vectors drawn on the surface.

This package supports rendering water witch two methods of flow colors, vertex color, and flow map texture. Each method has some advantages and disadvantages described below:

	Vertex-based	Texture-based
Efficiency	High	Low
Requirements	Additional mesh divisions	Additional texture per object
Editor	UE4 vertex painter -it is not	External Tool

Flow-tools

Texture-based flow mode uses textures that can be prepared in an external tool like FlowMap Painter. Those textures should be loaded as vector displacement maps because of data precision that is important to achieve the best possible visual effect. There will be a special tool for creating flow map textures in Unreal Engine Editor in the future version of the Aquatic Surface package.

Vertex-based flow mode is the more interesting feature because does not require any additional textures only mesh used for effect should be tesselated (divided on multiple triangles). You have to decide how many verticles do you need to draw your flow on the mesh.

Editing vertex flow

The process of editing water flow per-vertex is a little inconvenient because there is no tool for this in UE4 editor. I didn’t want to transform this package into a vertex-flow editor plugin because it’s not the idea of Aquatic Surface. I’ve decided to use Vertex Paint editor and create additional tools for previewing the results of changes that make the whole process a little more convenient.

1. Switch the option UseFlowMap to true to use the flow map feature on water.
2. Change mesh density according to your requirements of precision. If the material is not reacting on vertex color brush then probably you should use mesh with higher density and select the mesh component to paint.
   
3. Switch the option UseFlowmapToolthe to true in the overwater material to see debug vertex flow preview.
4. Select the mesh to paint on.
5. Chose Vertex Paint tool in the UE4 editor
6. Setup the paint color R and G according to the table of vectors below:
   

   (0.0, 1.0,)	UP (0.5, 1.0)	(1.0, 1.0)
   LEFT (0.0, 0.5,)	ZERO (0.5, 0.5)	RIGHT (1.0, 0.5)
   (0.0, 0.0)	DOWN (0.5, 0.0)	(1.0, 0.0)

7. Paint on the mesh
8. Use random  value on the blue channel to force noisy transition between normalmaps.
9. After finished work, you have to propagate changes to mesh to save the data.
   

   Unreal Engine 4 has some troubles with using dynamic vertex colors on actors so propagation is required to run vertex colors in the standalone version of the game. It’s inconvenient because you will have to do copies of every water surface that using vertex flow. You can speed up resolving this issue by voting on my bug fix request: https://issues.unrealengine.com/issue/UE-64354

Translucent under the water

The Aquatic Surface package supports translucent materials. This effect is very limited by the material system and requires to add special material node MF_AquaticSurface to the translucent material that will be used on an object in the water. This effect is implemented by fading the translucent objects depends on the distance from the camera.

There are three examples of material created for use under the water:

• M_TranslucentAdvanced – Advanced translucent effect calculated per pixel. It can be slow but very accurate.
• M_TranslucentFast – This material is using Vertex Interpolation. It’s a fast method to implement this effect.
• M_TranslucentDither – Traditional dither material used in UE4.
  

  

Reflections

Aquatic Surface supports multiple types of reflections. Table below shows differences between all approaches:

Reflection type	Efficiency	World	Scene type	Material type
Cube-map	Very fast	Static	closed area, lakes pools	M_AquaticSurface_Unlit, M_AquaticSurface_LIT
Reflection capture	Fast	Static	all	M_AquaticSurface_LIT
SSR	Slow	Dynamic	all	M_AquaticSurface_SSR
Planar reflection	Slow	Dynamic	all	M_AquaticSurface_SSR, M_AquaticSurface_LIT

The type of material is specified in the Parent attribute of the material used as OverWaterMaterial in BP_AquaticSuraface.  It’s good practice to use _Unlit, _Lit, _SSR post-fix in water surface material names.  

Static cube-map reflections

All BP_AquaticSurface actors use the same shared Render Target reflection texture so it is not possible to generate the textures for multiple water reflections at the same time. However, the system can be set to use static pre-baked cube maps and it solves that problem.

Step by step how to create and use the static cubemaps:

1. Select the water actor on the scene.
2. Find the reflection tab in the properties of water actor
3. Clear the Static Reflection Cubemap value if is set. This will force the system to render reflection into the cube-map texture.
4. Click reconstruct button to refresh the texture.
5. Find /Game/AquaticSurface/Textures/Cubemaps/RT_AquaticCubemap
6. Click right button on the RT_AquaticCubemap and from the context menu chose the Create Static Texture
7. Set the newly created texture into the Static Reflection cube-map parameter in an Aquatic Surface actor.
8. Repeat all steps for all Aquatic Surface actors on the scene.

Probably you have some questions. For example WHY the hell I have to do this? Thanks to using static cube map textures your game will load and work very fast even on mobile and VR. It’s far better solution than dynamic reflections used in other water systems.

Dynamic planar reflections

Aquatic Surface can be easily set to use dynamic planar reflections.

1. Select BP_AquaticSurface on your map.
2. Switch UsePlaneReflection attribute to true.
3. Change OverWaterMaterial attribute to material that supports dynamic reflections (with post-fix _SSR or _LIT (for example MI_AquaticOverWaterOcean_LIT)
4. Open project settings and search for “Planar Reflections” switch the  “Support global clip plane for Planar Reflections” to true.
5. Save and restart the editor.

Hole in water plane

There is a simple solution for holes in water planes that can be used for boats. You just have to create a mesh that will be rendered inside the boat and use material M_AuaticHole. Check the example boat.

This feature requires screen color sampling so it is not supported on mobile platform.

Interactions

Aquatic surface supports the interactive surface effect based on physics simulation in a quality comparable to current-gen games. The basic configuration is presented in the video below (LakeMap):

1. Set UseInteraction=true parameter in the overwater/underwater material used in the water surface. 
2. Drag and drop BP_AquaticSimulation actor on the scene.
3. Set parameters of the BP_AquaticSimulation. Add the BP_AquaticSurface from the scene to the AquaticSurface list.
4. Add the BP_AquaticInteration component to the actor that is going to interact with water.

BP_AquaticSimulation
AreaSize	Size of simulation area.
AquaticSurfaces	List of surfaces managed in the simulation.
Interp Speed	The speed of simulation area interpolation to important place on the map (where something is moving in water).
DrawDebug	Preview the are of simulation.
Animation Rate	FPS of simulation.
Wave Travel Speed	Simulated wave speed.
Wave Damping	Simulated wave sampling
Wave Normal Scale	Normal-map wave vector scale.
Materials	Three render target textures used for rendering the simulation. Can be replaced by textures with a higher resolution.

Aquatic simulation reacts on two types of interactions:

1. Component-Based – Actors that contains BP_AquaticInteration will be registered in the water surface and make waves when moving. Check the example Character blueprint with left/right foot interactions connected to the foot bones in the construction script.
2. Event-Based – Interaction can be generated on the event for example hit/explosion by executing the AddInteraction function on Simulation blueprint. The simple example presented in LakeMap level blueprint.
   

BP_AquaticInteraction
Dynamic	Noise added when actor stays in place.
Force	How much location change generates waves.
Torque	How much rotation change generates the waves.
Radius	The radius of the interactive object
Height Fade	Fade out of interaction when it is far from the surface.
Importance	Bigger importance means that the region should be moved to show the effect.
Max Velocity	Max velocity of waves generated from this interaction. Allow clapping the forces.
Max Distance	Max distance from interaction to the center of the simulation area. Useful for a player that should always interact with water.

How fast it is where is a bottleneck? It takes about 0.06ms per frame for render the simulation in 256×256 texture that result is reasonable even for VR games. Update of the interaction component is the biggest bottleneck of the algorithm because of the slow math evaluation in the blueprints. That is why you should consider minimization the number of interaction components in actors or aquatic simulation blueprint nativization.

Buoyancy

Aquatic Surface supports a fast simplified buoyancy system for physics actors.  An example of using buoyancy is presented in the BP_AquaticBuoyancyActor.

1. Add BP_AquaticBuoyancy  to your physics-based actor
2. Set the parameters of an added component

BP_AquaticBuoyancy
Shape	The shape of the object that will be reacting to water.  Cone shape is the best choice for Boats – if deeper is object the force of buoyancy will be higher.
Shape Radius	Used for calculating the density of the object.
Linear/Angular Damping	Allow controlling how much object is slowing down in the water.
Center of mass	The position where the force is applied to the object. Boats should transfer the center of the upper higher to be more stable.
Force scale	Scales the force applied to the physics object.