Fast Stylized Procedural Sky

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Fast Stylized Procedural Sky is a unique dynamic sky material and advanced weather system that is perfectly balanced between quality and efficiency. Designed and optimized specially for Mobile, Virtual Reality, and stylized PC/Console games.

Features

• GPU friendly works efficiently even on VR/Mobile. Unlit material without blending uses one draw call
• Over 60 parameters to customize
• Network replication supported
• Clouds lighting with scattering and shadows changes depending on sun position
• Clouds shadow casting, height fog, and static and dynamic skylight cubemaps
• Configurable sun and moon, lens effect, eclipse and stars scintillation
• Atmospheric sky gradient with tilting in sun direction
• Customizable automatic clouds UV calculation
• Moon normal-mapping and lighting calculated based on relative sun and moon position
• Time of day curves and advanced preset system
• Multilayered clouds
• Wind direction and clouds speed
• Smooth transitions between weather states based on preset system
• Landscape backgrounds interleaved with clouds, static clouds, and stars layer
• Skydome and skysphere mode
• The material is based on the new unpublished before method for fast calculation of procedural clouds lighting. You will not find this solution anywhere else!

Technical details

• Sky material  (ONLY 150 instructions! and ONLY 4 texture samplers used!)
• Directional light shadow material.
• 1 blueprint that uses material and implements time of day and preset system
• 1 static skylight cubemap recapture helper blueprint
• 1 Sky shadow material
• 3 Skydome and Skysphere meshes
• 10 tilled clouds textures 512×512 with encoded four depth traces on channels
• 1 Moon normal map texture 512×512
• 1 Background equirectangular texture 2048×1024 (R-stars, G-Background clouds, B-Distortion clouds)
• 8 Color curves for simulating the day and night on Earth
• 12 presets of weather (sunny, cloudy, foggy, snowy, smoky, stormy, clean, rainy, half sunny, gloomy, blizzard, overcast)
• 3 time of day presets
• 3 Landscape backgrounds textures 4096×1024 for skydome (depth encoded as alpha)
• 1 Landscape background textures 4096×2048 for skysphere (depth encoded as alpha)
• 4 example static cubemaps for default skylight

Showcase

Release notes

Documentation

Get started

The easiest way to start working with Fast Stylized Procedural Sky is to For start watching the tutorial that shows how to use basic parameters of the blueprint:

1. Unpack FastStylizedProceduralSky into Content in your project.  
2. Open project and you should see a FastStylizedProceduralSky package with the following content:
3. Drag & Drop BP_FastStylizedProceduralSky on your scene. (Remember to remove the old  sky that you used before on your scene you don’t need this anymore)
4. Select FastStylizedProceduralSky blueprint that you just put on the scene and set up lights in the external tab:
   

   Actors
   Sun Light	External directional light used for lighting from the sun. The system will automatically change the direction and color of this light during the time update.
   Moon Light	External directional light used for lighting from the moon. The system will automatically change the direction and color of this light during the time update.
   Sky Light	External skylight used for global lighting on the scene. System recapture during the update. The frequency of recapture can be changed by.
   Height Fog	External fog used for cover the scene by fog. System changes the color of fog based on time of day.

5. Press play and enjoy the show.

Remember! Only movable light can be changed by Fast Stylized Procedural Sky. 

Remember! Enable dynamic lighting (no lightmaps) in projects settings to fully exploit the  abilities of the time of day cycle.

Sky system

Fast Stylized Procedural Sky is divided into a few basic systems that can work in cooperation as well as in separation either systems can stay inactive for manual customization.

All default properties of Fast Stylized Procedural Sky blueprint are editable only if Weather Preset System and Time of Day System is disabled. Three steps are needed to disable both systems:

• (Time Of Day) Use Time Of Day Curves = false, 
• (Time Of Day)  Time Of Day Change Mode = BlueprintDefaults
• (Weather Preset) Weather Change Mode = BlueprintDefaults

From this time all default properties of the sky can be manually customized for specific weather and time of day conditions.

External data

External options in Fast Stylized Procedural Sky blueprint allows stylizing final result for wide range types of games.

Fast Stylized Procedural Sky supports casting shadows from the sun on the ground.

This effect is implemented based on Light Function material that unfortunately is not supported on mobile.

Time of Day system

The time of day system is responsible for the passage of time calculations celestial movement and sampling curves of colors over time-based on sun height.

Time of day system changes a number of parameters of the sky based on time of the day like sun color, clouds colors, fog colors etc. The system can be updated in two modes:

• curve system
• preset system

Both modes exclude each other to change between these modes use flag Use Time Of Day Curves. Here is the list of  parameters that can be controlled by each of the systems:

Time of day curves

List of all Time Of Day settings can be controlled by curves. The curve system is active only when Use Time Of Day Curves = true. All defined curves are sampled based on the sun height. Mapping from time to sun height:

If the curve is not defined in the Time Of Day system then sky uses the default parameters from the time of day preset.

A simple example that shows how to change the horizon color using the time of day system:

1. Find curve to change in sky blueprint: Blueprint->SkyLowerColorCurve
   
2. You can edit the existing C_SkyLowerColor or duplicate the curve and replace a value of the SkyLowerColorCurve parameter in the blueprint.

Time of day presets

Basically the preset is a collection of predefined Time Of Day parameters that can be loaded to the sky. The preset system allows interpolating between these parameters and load custom settings for specific conditions. Time of day presets library can be found in TimeOfDay directory there are three basic examples presets BloodyMidnight, BlueNight, Pinky.

Time of day preset system is active only when Use Time Of Day Curves = false.

There are multiple methods to activate preset in the project that can be defined in Change Mode:

Adding a new preset to the library

The library of time of day presets can be easily extended. Few steps are needed to create and customize a new preset:

1. Open Select TimeOfDay directory and preset that will be extended.
2. Click right and select the option Create Child Blueprint Class.
3. Set the name and attributes in default properties of the newly created class.
4. Now preset is ready to use. Add preset to Time Of Day preset List in Fast Stylized Procedural Sky blueprint and start using as described in the section dedicated using a standard library of preset.
5. There is no preset editor. Just edit preset settings in the blueprint on the scene. Results of your changes you will see in the scene preview. After preset is finished just copy preset settings group and paste to your preset class.

Preset settings are stored in structure so you can copy current settings of the sky to your new preset. Change in preview and then copy to preset – It is the easiest way to tweak parameters for preset. The other method to updating the presets is by modifying a preset that is set as “selected” and click “reload selected” after finishing the modifications to see the result.

Event-driven time

Fast Stylized Procedural Sky has external functions that allow controlling the time of day for example from the level blueprint.

Weather system

Fast Stylized Procedural Sky comes with a library of presets for different types of weather: cloudy, sunny, clean, rainy, stormy, foggy, overcast, half sunny, glowy, blizzard, stylized. Each preset is just a list of predefined parameters that will be loaded to the sky after activation. The preset system manages the weather preset selection and interpolation between them.

There are multiple methods to activate preset in the project that can be defined in Weather Change Mode:

Event-driven weather

Fast Stylized Procedural Sky system can be configured to changing presets by events from the game. There are a few functions that can be used for steering presets:

• Set Preset Change Mode – Allow to change mode and duration of preset that is used in modes other than Blueprint Default.
• Set Preset External – Sets the preset from the library. Transition duration is how long the weather will be in transition.
• Set Preset External – Sets the preset from the list of presets by index. Transition duration is how long the weather will be in transition.

Example:

Adding a new preset to the library

Sometimes the game requires unique conditions for the specific situation in the game. The library of presets is expandable and weather designers can create their own presets and share parameters with other users of the system. Each preset is defined as Blueprint Class that extends from WeatherPreset class.

Creating a preset:

1. Select preset that will be extended.
2. Click right and select the option Create Child Blueprint Class.
3. Set the name and attributes in default properties of the newly created class.
4. Now preset is ready to use. Add preset to Weather preset List in Fast Stylized Procedural Sky blueprint and start using as described in the section dedicated using a standard library of preset.
5. There is no preset editor. Just edit weather preset settings in the blueprint on the scene. Results of your changes you will see in the scene preview. After the preset is finished just copy the weather preset settings group and paste it to your preset class.

Lightning effect

Fast Stylized Procedural Sky supports new lightning system since update 2.1. The example of using a lightning system is presented in the demo map Demo/Maps/AnimeLightningMap.

Basically, the BP_LightningController actor is responsible for controlling attributes like lightning source location/rotation/area/frequency and update of sky settings. 

Step by step explained how to use BP_LightningController:

1. Place BP_LightningController on your map. 
2. Setup the location of the actor to location above the scene (X=0.000000,Y=0.000000,Z=50000.000000). The volume of the actor presents the area of the lightning effect.
3. Change the External Parameter Sky to BP_FastStylizedProceduralSky actor from your map.
4. Select BP_FastStylizedProceduralSky to find Sky Material and open. Switch the UseLightning value in the material to true.
5. Run the game I watch the lighting effect.

Lightning Activation

The BP_LightningController is automatically active on the map but can be activated by events as well.  Set the activation loops value to 0 to control the activation by yourself. Then use Activate and deactivate events in your game to run the effect during the storm.

Lightning Fast

Lightning Fast is powerful combination materials and blueprints that implement a wide range of realistic and stylized electricity effects this external package can be easily integrated with Fast Stylized Procedural Sky.

Only a few steps are needed to integrate Lightning Controller with lightning Bolt from Lightning Fast:

1. Drag and drop LightningFast/Blueprints/BP_LightningBolt blueprint n the scene where Lightning Controller works.
2. Scale the lightning bolt actor to be visible from a large distance: Try to use Scale (50,50,50)
3. Set Activation Loops in Lightning Bolt blueprint to 0. It will disable auto-activation and allow you to control the lighting effect using a controller.
4. Implement your lightning effect trigger by binding to OnActivated delegate from Lightning Controller.

   

After these few steps lightning bolt effect will be shown at location and rotation randomized in Lightning Controller just after the lightning activation.

Lightning Fast use case is just an example, you can play sound or even spawn other effects/particles using activation event.

Skylight update

The Skylight actor captures the distant parts of the scene and using result data to compute lighting.  This actor can be very well integrated with Fast Stylized Procedural Sky. There are two methods to update the sky during changing the weather and time:

Fast Stylized Procedural Sky allows configuring skylight update to minimalize the costs.

Using sky spheres

Fast Stylized Procedural Sky supports rendering on skydome as well as sky sphere. Skydome is set as the default option. It is required to do a few important steps to switch sky into Skysphere mode:

1. Switch material to sky sphere UV: Open SkyData/IM_DefaultSky  and change UseSkydomeUV = False.
2. Set the sky sphere mesh in the blueprint:

   Open BP_FastStylizedProceduralSky and find SkyMesh component.  
   Change StaticMesh=SM_Skysphere or SM_SkysphereFlat (Flat is deformed but looks better with height fog).

3.  Change world layer texture used on the sky to the sky sphere:
   Select BP_FastStylizedProceduralSky
   Change WorldLayerTexture=T_SkysphereMoon

Additional material effects

There are few features in Fast Stylized Procedural Sky that are disabled in default material. It is because not all users need these advanced options and hitches on efficiency are not good enough to enable all of them by default.

To change these parameters you can create your own instance of sky material from M_BaseSky as well as modify SkyData/IM_DefaultSky. Reference to sky material instance can be set in sky blueprint parameter: External->SkydomeMaterial.

Moon movement

Shading of the Moon is always calculated based on the position relative to the  Sun it is hard to set up at first but results are very realistic. This is automatic so there is no need to care about the direction of shading on the Moon. There are a few important parameters that allow setting the moon movement:

Questions & Answers