Feedback Volumetric Clouds

Hello,i've tried the new Cloud Layer in 2022.2.0a13.
it's sooooooo beautiful,i love it !
thank you for your hard work !

just a small bug or something i haven't figured out.
the default tint color of the Cloud Layer seems a bit yellow...?
i have to use a blue tint color for it to blend with the volumetric clouds.

 

Hey, I tried reproducing in a new project, didn't work. Though I found out it's related to the "Lighting Override Mask" (Edit-> Project Settings ->HDRP ->Sky->Lighting Override Mask) so I will check if it's a bug or if I just didn't configure that correctly.

 

Hello! I have been trying to create a weather system using volumetric clouds + physically based sky. The main challenge for me was to create smooth transitions - i.e. in-between presets or single properties. One method I tried was to use Animator and to transition over time in between profiles. It has the downside, that it "resets" the clouds if I transition in between i.e. overcast and cloudy instead of smooth transitioning from one to another.

Then I went and tried to transition 2 values of a single preset (cloud thickness and altitude) by code over time.deltatime . It does the trick (at least for single properties). However, it also produces artifacts of your screen edges in the clouds when you rotate the camera (they disappear after a few seconds) and it forces you to disable Realtime Global Illumination, since it gives the error "UpdateEnvironment readback buffer overflow, please schedule fewer updates." if you don't.

I then went ahead and tried to gradually increase aerosol density over time. This produces sudden light changes once the increase stops and completely kills the performance.

Is there a "right" or better way to transition between profiles, presets and/or individual properties over time? And will there be the option in the future to adjust individual properties over time using the animator?

Thanks for any answer in advance!

P.s. and if you would have a hint for me how to adjust Shadows, Midtones, Highlights from code.. i tried:

Skyvolume.TryGet<ShadowsMidtonesHighlights>(out ShadowsMidtonesHighlights shadows);

shadows.shadows.value.Set(-1, 1, 1, 100);

gives me no errors but doesn't work and also returns wrong values in debug

 

Thanks a lot - at last my mind can rest and I know it's not just me ! I'll just sit back tight then and wait for the next public release or try the alpha. Thanks again!

P.s. Are there plans to allow adjustment of individual HDRP Postprocessing and VS parameters through Animator/Animations in the future?

 

is there a way to exclude volumetric clouds from being rendered into the cubemap in:
UpdateSkyEnvironment -> RenderSkyToCubemap?
VolumetricCloudsTrace takes 0.8ms on my rtx2060 rendering to a 128px cubemap and i really do not need clouds here.

 

thanks a lot! the temporal accumulation fix is a great tip. As for the volumes and blending their weights - that was my first attempt, but it seemed that it does not do what I expected, which is actually blending the properties so i.e. transitioning the size from small clouds in the original volume to bigger clouds in the target volume. Instead, it looks like in the first frame of the weight transition, a set of new clouds of the second volume appear which then gradually blend in. That creates a very hard transition. But maybe I did something wrong.. I'll try again since you say it's possible!

 

how do you control the directional light that effects the clouds? It seems to choose it itself, which makes things unpredictable / unmanageable.

What if we want to use a light to light the clouds that does not cast shadows? Is this possible?
It worked in an earlier version of unity, but after going to the new LTS version, the light I used for cloud effects (lightening) stopped working. Now the lighting only works when I turn the shadow light off, which can't happen. Is there a better way to give the impression of thunder / lightening?

I feel like if you has made the scattering tint color hdr, this wouldn't be an issue, an we as artists and developers would have a lot more freedom. Is there a way to change that, or is there some deeper reason it wasn't made HDR?

 

We finally need some kind of point light support, that would perfectly fit to simulate lightning.

 

Couple of questions - haven't tested origin shifting with these clouds (local ones) but I expect there's some scheme or other to do.

Also point lights seem interesting in both local and non local scenarios.

 

How do you get these light beams aka god rays from the volumetric clouds? I have my directional light with volumetric intensity of max 16 and I don't see anything ...

 

I use crest, which uses shader graph together with raytraced reflections. Am I missing something or is the reflection wrong?

I would expect this result from screen space reflection (KWS Water):


It seems to be the difference between raytracing and raymarching.

Thank you in advance,
Andre

 

Maybe tweaking this parameter will fix pixelization in ray tracing mode (with the cost of performance):

 

I increased the resulution and it looks better. But what I found out is that the reflection stays while the clouds are moving.


When I change the Reflection cubemap size it is synced again. This should be a realtime sky reflection probe I guess?
It is indeed updated, when I change the Directional Light and thus the physically based sky.

Found out there is an option in the physically based sky to update the sky reflection probe frequently.

 

I also need point light support. One does not simply simulate lightning without it.
Is there any time frame for it?
HDRP Volumetric Clouds tick all the boxes for us, except for this one thing.

 

Point lights to affect the volumetric clouds?

 

Oh hell yeah, it should be enough to just put a strong point light inside the clouds and enable Volumetrics on that light.
Surrounding clouds should then be lit by that light. This is necessary for a good looking lightnings.

 

Dayum
Any ideas on some workarounds? I could use a local volumetric fog that supports volumetric lights. And put it high in the sky while using cloudy preset. That way, it should not look out of place, but not sure about blending of these two etc.

Also is there a way to find out where clouds are located on XZ plane?
This would be useful to make it rain only below the clouds.

 

Render your effects before the cloud, in the skybox for example, or even opaque with suitable bloom, and the cloud will render after it with suitable extinction, so it might be close enough.

 

I was wondering if you could add custom Erosion Noise Type in a texture format. I think it would help a lot. Is this something you would consider?

 

Can you give me an example? Right now you can set any 3d texture as the detail noise...

 

Any news on PlanetCenterPosition setting?

 

@jjxtra You can't control this one in any type of Cloud Control. I think it would help me customize the shape of moving clouds.

 

I'm noticing these artifacts. The artifacts only appear in the mac standalone build and not in unity editor.
Any ideas what might be causing this or how I can go about fixing it?
Unity 2021.3.1f1

 

Strangely, I get similar issues in 2023.1 on PC, in Editor, when I iterate and switch often between raytracing override volumes, and pathtracing. IE switching on/off pathtracing and off again, 30% of the time I get these artefacts also and only way to get rid of it is to restart the editor....

 

I saw the blitz day post and thought to myself that Anis and Pierre are having a high 5 moment on this.

Really really nice results

 

Thanks, but I am still unable to get shadows from volumetric clouds in 2021.3 LTS, I just given up and proceeding without it.

 

What can we expect from performance standpoint? I really like "Quality" preset

 

I thought it might have just been an issue with the water-vs-clouds, like this post from the Water thread

But I think it's clouds vs everything else.

In these pics, I've got the HDRP/Lit shader, but the one not sorting is set to Surface Type: Transparent. I've got support for depth pre-and post-pass enabled, even got Depth Write enabled.

Are clouds always going to be behind anything and everything transparent, or is there some queue for them? The Sorting Priority slider doesn't seem to do anything to help.

 

Hello. 2022 is out and I don't see planet center position setting anywhere. So it is still hardcoded? And as I understood we can't expect it to appear any time soon?

 

will that also include volumetric fog shadowing? at the moment we don't have self shadowing if we use volumetric shaders. Sorry if this a bit out of topic

 

Thanks for info. I waited for this for two years, can wait one more.

 

So I gave the manual cloud authoring mode another shot and quickly realised that the cloud density can still only be changed in the cloud map but not in the cloud LUT, which makes it impossible to define different densities per cloud type and/or per altitude.

I provided a solution for this back then https://forum.unity.com/threads/volumetric-clouds.1078811/page-2#post-7025461 and adopted it to the latest source code, in case someone is interested.
Changes are made in VolumetricCloudsUtilities.hlsl starting around line 440 and are marked with "//MOD swap";

Code (CSharp):

1. // Function that evaluates the coverage data for a given point in planet space
2. void GetCloudCoverageData(float3 positionPS, out CloudCoverageData data)
3. {
4.     // Convert the position into dome space and center the texture is centered above (0, 0, 0)
5.     float2 normalizedPosition = AnimateCloudMapPosition(positionPS).xz / _NormalizationFactor * _CloudMapTiling.xy + _CloudMapTiling.zw - 0.5;
6.     // Read the data from the texture
7.     float4 cloudMapData =  SAMPLE_TEXTURE2D_LOD(_CloudMapTexture, s_linear_repeat_sampler, float2(normalizedPosition), 0);
8.  
9. //MOD swap //data.coverage = float2(cloudMapData.x, cloudMapData.x * cloudMapData.x);
10.     data.coverage = float2(cloudMapData.x, 0);
11.  
12.     data.rainClouds = cloudMapData.y;
13.     data.cloudType = cloudMapData.z;
14.     data.maxCloudHeight = cloudMapData.w;
15. }
16.  
17. // Function that evaluates the cloud properties at a given absolute world space position
18. void EvaluateCloudProperties(float3 positionWS, float noiseMipOffset, float erosionMipOffset, bool cheapVersion, bool lightSampling,
19.                             out CloudProperties properties)
20. {
21.     // Convert to planet space
22.     float3 positionPS = positionWS + float3(0, _EarthRadius, 0);
23.  
24.     // Initliaze all the values to 0 in case
25.     ZERO_INITIALIZE(CloudProperties, properties);
26.  
27.     // By default the ambient occlusion is 1.0
28.     properties.ambientOcclusion = 1.0;
29.  
30.     // If the next sampling point is not inside the coud volume the density
31.     if (!PointInsideCloudVolume(positionPS) || positionPS.y < 0.0f)
32.         return;
33.  
34.     // Compute the normalized position for the three channels
35.     float3 normalizedPos = positionPS / _NormalizationFactor;
36.  
37.     // Evaluate the normalized height of the position within the cloud volume
38.     properties.height = EvaluateNormalizedCloudHeight(positionPS);
39.  
40.     // Evaluate the generic sampling coordinates
41.     float3 baseNoiseSamplingCoordinates = float3(AnimateBaseNoisePosition(positionPS).xzy / NOISE_TEXTURE_NORMALIZATION_FACTOR) * _ShapeScale - float3(_ShapeNoiseOffset.x, _ShapeNoiseOffset.y, _VerticalShapeNoiseOffset);
42.  
43.     // Evaluate the coordinates at which the noise will be sampled and apply wind displacement
44.     baseNoiseSamplingCoordinates += properties.height * float3(_WindDirection.x, _WindDirection.y, 0.0f) * _AltitudeDistortion;
45.  
46.     // Read the low frequency Perlin-Worley and Worley noises
47.     float lowFrequencyNoise = SAMPLE_TEXTURE3D_LOD(_Worley128RGBA, s_trilinear_repeat_sampler, baseNoiseSamplingCoordinates.xyz, noiseMipOffset);
48.  
49.     // Initiliaze the erosion and shape factors (that will be overriden)
50.     float shapeFactor = lerp(0.1, 1.0, _ShapeFactor);
51.     float erosionFactor = _ErosionFactor;
52.  
53.     // Evaluate the cloud coverage data for this position
54.     CloudCoverageData cloudCoverageData;
55.     GetCloudCoverageData(positionPS, cloudCoverageData);
56.  
57.     // If this region of space has no cloud coverage, exit right away
58.     if (cloudCoverageData.coverage.x <= CLOUD_DENSITY_TRESHOLD || cloudCoverageData.maxCloudHeight < properties.height)
59.         return;
60.  
61.     // Read from the LUT
62.  
63.     float3 densityErosionAO = SAMPLE_TEXTURE2D_LOD(_CloudLutTexture, s_linear_clamp_sampler, float2(cloudCoverageData.cloudType, properties.height), CLOUD_LUT_MIP_OFFSET);
64.  
65.     // Adjust the shape and erosion factor based on the LUT and the coverage
66.     shapeFactor = shapeFactor * densityErosionAO.y;
67.     erosionFactor = erosionFactor * densityErosionAO.y;
68.  
69.     // Combine with the low frequency noise, we want less shaping for large clouds
70.     lowFrequencyNoise = lerp(1.0, lowFrequencyNoise, shapeFactor);
71.     float base_cloud = 1.0 - densityErosionAO.x * cloudCoverageData.coverage.x * (1.0 - shapeFactor);
72.  
73. //MOD swap //base_cloud = saturate(DensityRemap(lowFrequencyNoise, base_cloud, 1.0, 0.0, 1.0)) * cloudCoverageData.coverage.y;
74.     base_cloud = saturate(DensityRemap(lowFrequencyNoise, base_cloud, 1.0, 0.0, 1.0)) * densityErosionAO.y * densityErosionAO.y;
75.  
76.     // Weight the ambient occlusion's contribution
77.     properties.ambientOcclusion = densityErosionAO.z;
78.  
79.     // Change the sigma based on the rain cloud data
80.     properties.sigmaT = lerp(0.04, 0.12, cloudCoverageData.rainClouds);
81.  
82.     // The ambient occlusion value that is baked is less relevant if there is shaping or erosion, small hack to compensate that
83.     float ambientOcclusionBlend = saturate(1.0 - max(erosionFactor, shapeFactor) * 0.5);
84.     properties.ambientOcclusion = lerp(1.0, properties.ambientOcclusion, ambientOcclusionBlend);
85.  
86.     // Apply the erosion for nifer details
87.     if (!cheapVersion)
88.     {
89.         float3 fineNoiseSamplingCoordinates = AnimateFineNoisePosition(positionPS) / NOISE_TEXTURE_NORMALIZATION_FACTOR * _ErosionScale;
90.         float highFrequencyNoise = 1.0 - SAMPLE_TEXTURE3D_LOD(_ErosionNoise, s_linear_repeat_sampler, fineNoiseSamplingCoordinates, CLOUD_DETAIL_MIP_OFFSET + erosionMipOffset).x;
91.         // Compute the weight of the low frequency noise
92.    
93. //MOD swap //highFrequencyNoise = lerp(0.0, highFrequencyNoise, erosionFactor * 0.75f * cloudCoverageData.coverage.x * _ErosionFactorCompensation);
94.         highFrequencyNoise = lerp(0.0, highFrequencyNoise, erosionFactor * 0.75f * densityErosionAO.y * _ErosionFactorCompensation);
95.  
96.         base_cloud = DensityRemap(base_cloud, highFrequencyNoise, 1.0, 0.0, 1.0);
97.         properties.ambientOcclusion = saturate(properties.ambientOcclusion - sqrt(highFrequencyNoise * _ErosionOcclusion));
98.     }
99.  
100.     // Given that we are not sampling the erosion texture, we compensate by substracting an erosion value
101.     if (lightSampling)
102.         base_cloud -= erosionFactor * 0.1;
103.  
104.     // Make sure we do not send any negative values
105.     base_cloud = max(0, base_cloud);
106.  
107.     // Attenuate everything by the density multiplier
108.     properties.density = base_cloud * _DensityMultiplier;
109. }

It now reuses the erosion channel in the LUT for the density too (I used the free alpha channel before, but it turned out that erosion and density using the same value looks the best anyway). The coverage cannel in the cloud map now only controls the coverage (like it is supposed to do), but not the density.

So finally I was able to have any cloud type / density at any given position, which is essential to create realistic cloudscapes.


EDIT
Btw, the alpha channel in the cloud map defines the maximum height of the cloud layer at the given pixel position, this isn't noted in the documentation.

I hope Unity considers to implement the change how density is handled, so I don't have to change it manually each time a new version of HDRP releases.

 

There's an issue with the ambient lighting of the clouds.
It simply samples the ambient probe from two directions (up and down) and lerps between the results depending on cloud height.
This leads to pitch black (lower)clouds when the sun is below the horizon and the planet in shadow.

I changed the ambient contribution to be more average, which greatly improves the visuals.


It's a simple change in VolumetricCloudsUtilities.hlsl at "EvaluateEnvironmentLighting";

Code (CSharp):

1. // Functions that evaluates all the lighting data that will be needed by the cloud ray
2. EnvironmentLighting EvaluateEnvironmentLighting(CloudRay ray, float3 entryEvaluationPointWS, float3 exitEvaluationPointWS)
3. {
4.     // Sun parameters
5.     EnvironmentLighting lighting;
6.     lighting.sunDirection = _SunDirection.xyz;
7.     lighting.sunColor0 = _SunLightColor.xyz * GetCurrentExposureMultiplier();
8.     lighting.sunColor1 = lighting.sunColor0;
9.  
10. //MOD swap... more average ambient contribution
11.     //lighting.ambientTermTop = SampleSH9(_VolumetricCloudsAmbientProbeBuffer, float3(0, 1, 0)) * GetCurrentExposureMultiplier();
12.     //lighting.ambientTermBottom = SampleSH9(_VolumetricCloudsAmbientProbeBuffer, float3(0, -1, 0)) * GetCurrentExposureMultiplier();
13.     lighting.ambientTermTop = SampleSH9(_VolumetricCloudsAmbientProbeBuffer, float3(0, 0.5, 0)) * GetCurrentExposureMultiplier();
14.     lighting.ambientTermBottom = SampleSH9(_VolumetricCloudsAmbientProbeBuffer, float3(0, -0.5, 0)) * GetCurrentExposureMultiplier();
15. ...
16. ...

 

I've been searching like mad, but can't seem to find something which I feel like should be very simple. I love the quality of these clouds, they're perfect for my needs, except I need to be able to move them without the clouds changing. I'd like to be able to just use the Simple Cloudy preset, but I need to use a floating origin (or origin re-basing) to allow for larger worlds. Literally all I need to do is just take the clouds exactly as they are, and offset them in a given direction. "Shape Offset" gets me close, but per the docs (and my testing) it effects "larger noise passing through the cloud coverage", not the clouds themselves. So when I try to shift using that, erosion details on a given cloud would change, which would be pretty jarring if someone were staring at or moving through a cloud.
Notice how the shape of the cloud changes as I adjust the shape offset? I don't want to change the shape, just to move it somewhere else.

Is there any way to accomplish what I want? I'll take whatever advice you can give, even if I have to dive down the rabbit hole of the advanced features (which I've tried, but I'll try again). And if not, will such a feature possibly exist in the future?

 

There are horizontal and vertical wind erosion controls that could be worth adjusting depending on the situation. A note to remember is that erosion textures ( high ad low frequency) continuously pass through the clouds, however, the speed and frequency at which this occurs both vertically and horizontally is up to you.

Spoiler: Inspector and Properties

`shapeSpeedMultiplier.m_Value`
`erosionSpeedMultiplier.m_Value`

`verticalShapeWindSpeed.m_Value`
`verticalErosionWindSpeed.m_Value`

Experiment: Speed Ramping:

1. Erosion Speed Multiplier and Vertical Erosion Wind Speed:
   • These parameters control the erosion scrolling of the small frequency in the vertical (V) and horizontal (H) directions.
2. Shape Speed Multiplier and Vertical Shape Wind Speed:
   • These parameters control the scrolling appearance of the clouds.
     
     
   • If the shape values are set to 0, the cloud will not scroll up or down in the scene (only the smaller erosions will scroll if their values are above 0).

How to Implement Ramping:

1. Gradually decrease the Shape values or both the Shape and Erosion values leading up to the origin shift.
2. Perform the origin shift.
3. Gradually increase the values back to their original settings.

Using this ramping technique, you should be able to smooth out any abrupt curves or changes resulting from the shifting space.

 

I appreciate the response, and while the info you gave me is very helpful in terms of understanding how those parameters work, I don't see how they help me with this problem. I think I might either be misunderstanding your advice, or you may be misunderstanding my question.

When I execute the origin shift, everything in my world will move by a few thousand meters in a single frame. I'm effectively offsetting everything by a single Vector3. I need to offset my clouds by that same Vector3.

I've set up my volumetric clouds so that there is no wind:


When the origin move happens, I try using shapeOffset to move the clouds.

clouds.shapeOffset.value += Shift * shapeOffsetPerMeter;

(Through testing and research, I've found that shapeOffsetPerMeter = ~0.00005f)

This is what it looks like from a camera that is moving along with the clouds:


The finer shapes of the clouds change suddenly and very noticeably, even though their general shape stays the same.