Shaping The Cloud With 3D Noises Author 3D Noises I’ll try to sum up what I’ve learned in next sections. It’s a very challenging task, fortunately this is a topic that has been experimented with by a lot of super awesome FX artists. To make natural looking cloud of fog, we need to stack multiple layers of 3D noises with a strong art direction, not unlike how we fake water waves with 2D noises (as normal maps or height offset).
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This covers how to use one layer of static volume data. Usually 8 bit per channel is good enough for volumetric FX. We can choose which texture format we want to save as Volume Texture. VolumeTexture->UpdateSourceFromFunction(QueryVoxel, End.X - Start.X, End.Y - Start.Y, End.Z - Start.Z, TextureFormat) Voxel = accessor.getValue(xyz) * ValueScale If (TextureFormat = ETextureSourceFormat::TSF_RGBA16F) Voxel = accessor.getValue(xyz) * 256 * ValueScale If (TextureFormat = ETextureSourceFormat::TSF_G8) Openvdb::Coord xyz(x + Start.X, y + Start.Y, z + Start.Z) auto QueryVoxel = (const int32 x, const int32 y, const int32 z, void* ret) Note: This is a very experimental test and it only supports older VDB files since I imported OpenVDB library from UE4 ProxyLODPlugins. Here is an example I did a while back that imports a single VDB file into a Volume Texture asset.
It’s also possible to feed a function into UVolumeTexture::UpdateSourceFromFunction() to read from VDB files directly. ( Optional part, read if you are interested in VDB) For learning’s purpose, you can maximize the quality as long as your machine runs it smoothly. Final fog is about 8 times as much consuming than regular volumetric fog at high quality (as in the video) 2 times as much consuming at default quality. And because we’ll do multiple texture sampling per voxel it costs even more. Half the value means there are 4x more voxels to render for the same screen resolution. Which costs ~4ms on a 2080Ti (1080p) for the final FX.ĭefault GridPixelSize value is 8. Volumetric fog is targeted for mainstream PCs/Consoles, but in order to express the detailed shapes of dense fog we need to crank up the parameters by quite a bit.įor the sake of demonstration I tuned up the quality by changing cvar:
Later we’ll learn some neat tricks to fake self-shadow as a workdaround.īefore starting I need to make clear that what we are going to create is a pretty demanding visual effects. The major downsides include lacking IES support, doesn’t work with Ray Tracing and most importantly, no self-shadow or light scattering for performance reasons. it’s well embedded into the engine with good performance. It also supports Volumetric Lightmaps and Particle Lights. Comparing to custom volumetric raymarcher, which usually only supports one directional light and skylight, UE4 Volumetric Fog supports one Directional Light, any number of Point and Spot Lights, Skylight, all with various shadowing method support like static shadow, CSM, distance field soft shadow and DFAO. Volumetric Fog has been in Unreal Engine since 4.16.
This is done purely within Volumetric Fog and Volume Material systems, thus requires no low-level coding and supports various lighting feature within UE4. Inspired by the Gears 5 tech talk and the good ol’ Guerrilla paper on cloudspaces, I decided to do my own take and created this fluffy dry ice fog using Volumetric Fog feature that comes with UE4. Making beautiful and feasible volumetric effects has been a trending topic for game development. Volumetric Fog small demos 体积雾小demo下载 Download
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