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using System;
using UnityEngine.Rendering;
using System.Collections.Generic;
namespace UnityEngine.Experimental.Rendering.HDPipeline
{
[GenerateHLSL]
public struct VolumeProperties
{
public Vector3 scattering; // [0, 1], prefer sRGB
public float extinction; // [0, 1], prefer sRGB
public static VolumeProperties GetNeutralVolumeProperties()
{
VolumeProperties properties = new VolumeProperties();
properties.scattering = Vector3.zero;
properties.extinction = 0;
return properties;
}
} // struct VolumeProperties
[Serializable]
public class VolumeParameters
{
public bool isLocal; // Enables voxelization
public Color albedo; // Single scattering albedo [0, 1]
public float meanFreePath; // In meters [1, inf]. Should be chromatic - this is an optimization!
public float asymmetry; // Single global parameter for all volumes. TODO: UX
public VolumeParameters()
{
isLocal = true;
albedo = new Color(0.5f, 0.5f, 0.5f);
meanFreePath = 10.0f;
asymmetry = 0.0f;
}
public bool IsLocalVolume()
{
return isLocal;
}
public Vector3 GetAbsorptionCoefficient()
{
float extinction = GetExtinctionCoefficient();
Vector3 scattering = GetScatteringCoefficient();
return Vector3.Max(new Vector3(extinction, extinction, extinction) - scattering, Vector3.zero);
}
public Vector3 GetScatteringCoefficient()
{
float extinction = GetExtinctionCoefficient();
return new Vector3(albedo.r * extinction, albedo.g * extinction, albedo.b * extinction);
}
public float GetExtinctionCoefficient()
{
return 1.0f / meanFreePath;
}
public void Constrain()
{
albedo.r = Mathf.Clamp01(albedo.r);
albedo.g = Mathf.Clamp01(albedo.g);
albedo.b = Mathf.Clamp01(albedo.b);
meanFreePath = Mathf.Max(meanFreePath, 1.0f);
asymmetry = Mathf.Clamp(asymmetry, -1.0f, 1.0f);
}
public VolumeProperties GetProperties()
{
VolumeProperties properties = new VolumeProperties();
properties.scattering = GetScatteringCoefficient();
properties.extinction = GetExtinctionCoefficient();
return properties;
}
} // class VolumeParameters
public class VolumetricLightingModule
{
public enum VolumetricLightingPreset
{
Off,
Normal,
Ultra,
Count
}
class VBuffer
{
public long viewID = -1; // -1 is invalid; positive for Game Views, 0 otherwise
public RenderTexture[] lightingRTEX = null;
public RenderTargetIdentifier[] lightingRTID = null;
public RenderTexture densityRTEX = null;
public RenderTargetIdentifier densityRTID = -1; // RenderTargetIdentifier cannot be NULL
public RenderTargetIdentifier GetLightingIntegralBuffer() // Of the current frame
{
Debug.Assert(viewID >= 0);
return lightingRTID[0];
}
public RenderTargetIdentifier GetLightingHistoryBuffer() // From the previous frame
{
Debug.Assert(viewID > 0); // Game View only
return lightingRTID[1 + ((Time.renderedFrameCount + 0) & 1)];
}
public RenderTargetIdentifier GetLightingFeedbackBuffer() // For the next frame
{
Debug.Assert(viewID > 0); // Game View only
return lightingRTID[1 + ((Time.renderedFrameCount + 1) & 1)];
}
public RenderTargetIdentifier GetDensityBuffer()
{
Debug.Assert(viewID >= 0);
return densityRTID;
}
public void Create(long viewID, int w, int h, int d)
{
Debug.Assert(viewID >= 0);
Debug.Assert(w > 0 && h > 0 && d > 0);
// Clean up first.
Destroy();
// The required number of buffers depends on the view type.
bool isGameView = viewID > 0;
int n = isGameView ? 3 : 1;
this.viewID = viewID;
this.lightingRTEX = new RenderTexture[n];
this.lightingRTID = new RenderTargetIdentifier[n];
for (int i = 0; i < n; i++)
{
this.lightingRTEX[i] = new RenderTexture(w, h, 0, RenderTextureFormat.ARGBHalf, RenderTextureReadWrite.Linear);
this.lightingRTEX[i].hideFlags = HideFlags.HideAndDontSave;
this.lightingRTEX[i].filterMode = FilterMode.Trilinear; // Custom
this.lightingRTEX[i].dimension = TextureDimension.Tex3D; // TODO: request the thick 3D tiling layout
this.lightingRTEX[i].volumeDepth = d;
this.lightingRTEX[i].enableRandomWrite = true;
this.lightingRTEX[i].name = CoreUtils.GetRenderTargetAutoName(w, h, RenderTextureFormat.ARGBHalf, String.Format("Volumetric{0}", i));
this.lightingRTEX[i].Create();
this.lightingRTID[i] = new RenderTargetIdentifier(this.lightingRTEX[i]);
}
}
public void Destroy()
{
if (this.lightingRTEX != null)
{
for (int i = 0, n = this.lightingRTEX.Length; i < n; i++)
{
if (this.lightingRTEX[i] != null)
{
this.lightingRTEX[i].Release();
}
}
}
this.viewID = -1;
this.lightingRTEX = null;
this.lightingRTID = null;
}
} // class VBuffer
public VolumetricLightingPreset preset { get { return (VolumetricLightingPreset)Math.Min(ShaderConfig.s_VolumetricLightingPreset, (int)VolumetricLightingPreset.Count); } }
ComputeShader m_VolumetricLightingCS = null;
List<VBuffer> m_VBuffers = null;
List<OrientedBBox> m_VisibleVolumes = null;
List<VolumeProperties> m_VisibleVolumeProperties = null;
public const int k_MaxVisibleVolumeCount = 512;
// Static keyword is required here else we get a "DestroyBuffer can only be called from the main thread"
static ComputeBuffer s_VisibleVolumesBuffer = null;
static ComputeBuffer s_VisibleVolumePropertiesBuffer = null;
float m_VBufferNearPlane = 0.5f; // Distance in meters; dynamic modifications not handled by reprojection
float m_VBufferFarPlane = 64.0f; // Distance in meters; dynamic modifications not handled by reprojection
const float k_LogScale = 0.5f;
public void Build(HDRenderPipelineAsset asset)
{
if (preset == VolumetricLightingPreset.Off) return;
m_VolumetricLightingCS = asset.renderPipelineResources.volumetricLightingCS;
m_VBuffers = new List<VBuffer>();
m_VisibleVolumes = new List<OrientedBBox>();
m_VisibleVolumeProperties = new List<VolumeProperties>();
s_VisibleVolumesBuffer = new ComputeBuffer(k_MaxVisibleVolumeCount, System.Runtime.InteropServices.Marshal.SizeOf(typeof(OrientedBBox)));
s_VisibleVolumePropertiesBuffer = new ComputeBuffer(k_MaxVisibleVolumeCount, System.Runtime.InteropServices.Marshal.SizeOf(typeof(VolumeProperties)));
}
public void Cleanup()
{
if (preset == VolumetricLightingPreset.Off) return;
m_VolumetricLightingCS = null;
for (int i = 0, n = m_VBuffers.Count; i < n; i++)
{
m_VBuffers[i].Destroy();
}
m_VBuffers = null;
m_VisibleVolumes = null;
m_VisibleVolumeProperties = null;
CoreUtils.SafeRelease(s_VisibleVolumesBuffer);
CoreUtils.SafeRelease(s_VisibleVolumePropertiesBuffer);
}
public void ResizeVBuffer(HDCamera camera, int screenWidth, int screenHeight)
{
if (preset == VolumetricLightingPreset.Off) return;
long viewID = camera.GetViewID();
Debug.Assert(viewID >= 0);
int w = 0, h = 0, d = 0;
ComputeVBufferResolutionAndScale(preset, screenWidth, screenHeight, ref w, ref h, ref d);
VBuffer vBuffer = FindVBuffer(viewID);
if (vBuffer != null)
{
Debug.Assert(vBuffer.lightingRTEX != null);
Debug.Assert(vBuffer.lightingRTEX[0] != null);
Debug.Assert(vBuffer.lightingRTID != null);
// Found, check resolution.
if (w == vBuffer.lightingRTEX[0].width &&
h == vBuffer.lightingRTEX[0].height &&
d == vBuffer.lightingRTEX[0].volumeDepth)
{
// Everything matches, nothing to do here.
return;
}
}
else
{
// Not found - grow the array.
vBuffer = new VBuffer();
m_VBuffers.Add(vBuffer);
}
vBuffer.Create(viewID, w, h, d);
}
VBuffer FindVBuffer(long viewID)
{
Debug.Assert(viewID >= 0);
VBuffer vBuffer = null;
if (m_VBuffers != null)
{
int n = m_VBuffers.Count;
for (int i = 0; i < n; i++)
{
// Check whether domain reload killed it...
if (viewID == m_VBuffers[i].viewID && m_VBuffers[i].lightingRTEX != null && m_VBuffers[i].lightingRTEX[0] != null)
{
vBuffer = m_VBuffers[i];
}
}
}
return vBuffer;
}
static int ComputeVBufferTileSize(VolumetricLightingPreset preset)
{
switch (preset)
{
case VolumetricLightingPreset.Normal:
return 8;
case VolumetricLightingPreset.Ultra:
return 4;
case VolumetricLightingPreset.Off:
return 0;
default:
Debug.Assert(false, "Encountered an unexpected VolumetricLightingPreset.");
return 0;
}
}
static int ComputeVBufferSliceCount(VolumetricLightingPreset preset)
{
switch (preset)
{
case VolumetricLightingPreset.Normal:
return 64;
case VolumetricLightingPreset.Ultra:
return 128;
case VolumetricLightingPreset.Off:
return 0;
default:
Debug.Assert(false, "Encountered an unexpected VolumetricLightingPreset.");
return 0;
}
}
// Since a single voxel corresponds to a tile (e.g. 8x8) of pixels,
// the VBuffer can potentially extend past the boundaries of the viewport.
// The function returns the fraction of the {width, height} of the VBuffer visible on screen.
// Note: for performance reasons, scale is unused (implicitly 1). The error is typically under 1%.
static Vector2 ComputeVBufferResolutionAndScale(VolumetricLightingPreset preset,
int screenWidth, int screenHeight,
ref int w, ref int h, ref int d)
{
int t = ComputeVBufferTileSize(preset);
// Ceil(ScreenSize / TileSize).
w = (screenWidth + t - 1) / t;
h = (screenHeight + t - 1) / t;
d = ComputeVBufferSliceCount(preset);
return new Vector2((float)screenWidth / (float)(w * t), (float)screenHeight / (float)(h * t));
}
// See EncodeLogarithmicDepthGeneralized().
static Vector4 ComputeLogarithmicDepthEncodingParams(float nearPlane, float farPlane, float c)
{
Vector4 depthParams = new Vector4();
float n = nearPlane;
float f = farPlane;
depthParams.x = Mathf.Log(c, 2) * (1.0f / Mathf.Log(c * (f - n) + 1, 2));
depthParams.y = 1.0f / Mathf.Log(c * (f - n) + 1, 2);
depthParams.z = n - 1.0f / c; // Same
depthParams.w = 0.0f;
return depthParams;
}
// See DecodeLogarithmicDepthGeneralized().
static Vector4 ComputeLogarithmicDepthDecodingParams(float nearPlane, float farPlane, float c)
{
Vector4 depthParams = new Vector4();
float n = nearPlane;
float f = farPlane;
depthParams.x = 1.0f / c;
depthParams.y = c * (f - n) + 1;
depthParams.z = n - 1.0f / c; // Same
depthParams.w = 0.0f;
return depthParams;
}
void SetPreconvolvedAmbientLightProbe(CommandBuffer cmd, float asymmetry)
{
SphericalHarmonicsL2 probeSH = SphericalHarmonicMath.UndoCosineRescaling(RenderSettings.ambientProbe);
ZonalHarmonicsL2 phaseZH = ZonalHarmonicsL2.GetCornetteShanksPhaseFunction(asymmetry);
SphericalHarmonicsL2 finalSH = SphericalHarmonicMath.PremultiplyCoefficients(SphericalHarmonicMath.Convolve(probeSH, phaseZH));
cmd.SetGlobalVectorArray(HDShaderIDs._AmbientProbeCoeffs, SphericalHarmonicMath.PackCoefficients(finalSH));
}
float CornetteShanksPhasePartConstant(float asymmetry)
{
float g = asymmetry;
return (1.0f / (4.0f * Mathf.PI)) * 1.5f * (1.0f - g * g) / (2.0f + g * g);
}
public void PushGlobalParams(HDCamera camera, CommandBuffer cmd)
{
if (preset == VolumetricLightingPreset.Off) return;
HomogeneousDensityVolume globalVolume = HomogeneousDensityVolume.GetGlobalHomogeneousDensityVolume();
// TODO: may want to cache these results somewhere.
VolumeProperties globalVolumeProperties = (globalVolume != null) ? globalVolume.volumeParameters.GetProperties()
: VolumeProperties.GetNeutralVolumeProperties();
float asymmetry = globalVolume != null ? globalVolume.volumeParameters.asymmetry : 0;
cmd.SetGlobalVector(HDShaderIDs._GlobalScattering, globalVolumeProperties.scattering);
cmd.SetGlobalFloat( HDShaderIDs._GlobalExtinction, globalVolumeProperties.extinction);
cmd.SetGlobalFloat( HDShaderIDs._GlobalAsymmetry, asymmetry);
int w = 0, h = 0, d = 0;
ComputeVBufferResolutionAndScale(preset, (int)camera.screenSize.x, (int)camera.screenSize.y, ref w, ref h, ref d);
VBuffer vBuffer = FindVBuffer(camera.GetViewID());
Debug.Assert(vBuffer != null);
SetPreconvolvedAmbientLightProbe(cmd, asymmetry);
cmd.SetGlobalVector( HDShaderIDs._VBufferResolution, new Vector4(w, h, 1.0f / w, 1.0f / h));
cmd.SetGlobalVector( HDShaderIDs._VBufferSliceCount, new Vector4(d, 1.0f / d));
cmd.SetGlobalVector( HDShaderIDs._VBufferDepthEncodingParams, ComputeLogarithmicDepthEncodingParams(m_VBufferNearPlane, m_VBufferFarPlane, k_LogScale));
cmd.SetGlobalVector( HDShaderIDs._VBufferDepthDecodingParams, ComputeLogarithmicDepthDecodingParams(m_VBufferNearPlane, m_VBufferFarPlane, k_LogScale));
cmd.SetGlobalTexture(HDShaderIDs._VBufferLighting, vBuffer.GetLightingIntegralBuffer());
}
public void VoxelizeDensityVolumes(HDCamera camera, CommandBuffer cmd)
{
if (preset == VolumetricLightingPreset.Off) return;
Vector3 camPosition = camera.camera.transform.position;
Vector3 camOffset = Vector3.zero; // World-origin-relative
if (ShaderConfig.s_CameraRelativeRendering != 0)
{
camOffset = -camPosition; // Camera-relative
}
m_VisibleVolumes.Clear();
m_VisibleVolumeProperties.Clear();
// Collect all the visible volume data, and upload it to the GPU.
HomogeneousDensityVolume[] volumes = Object.FindObjectsOfType(typeof(HomogeneousDensityVolume)) as HomogeneousDensityVolume[];
foreach (HomogeneousDensityVolume volume in volumes)
{
// Only test active finite volumes.
if (volume.enabled && volume.volumeParameters.IsLocalVolume())
{
// TODO: cache these?
var obb = OrientedBBox.Create(volume.transform);
// Frustum cull on the CPU for now. TODO: do it on the GPU.
if (GeometryUtils.Overlap(obb, camOffset, camera.frustum, 6, 8))
{
// TODO: cache these?
var properties = volume.volumeParameters.GetProperties();
m_VisibleVolumes.Add(obb);
m_VisibleVolumeProperties.Add(properties);
}
}
}
s_VisibleVolumesBuffer.SetData(m_VisibleVolumes);
s_VisibleVolumePropertiesBuffer.SetData(m_VisibleVolumeProperties);
}
// Ref: https://en.wikipedia.org/wiki/Close-packing_of_equal_spheres
// The returned {x, y} coordinates (and all spheres) are all within the (-0.5, 0.5)^2 range.
// The pattern has been rotated by 15 degrees to maximize the resolution along X and Y:
// https://www.desmos.com/calculator/kcpfvltz7c
static Vector2[] GetHexagonalClosePackedSpheres7()
{
Vector2[] coords = new Vector2[7];
float r = 0.17054068870105443882f;
float d = 2 * r;
float s = r * Mathf.Sqrt(3);
// Try to keep the weighted average as close to the center (0.5) as possible.
// (7)(5) ( )( ) ( )( ) ( )( ) ( )( ) ( )(o) ( )(x) (o)(x) (x)(x)
// (2)(1)(3) ( )(o)( ) (o)(x)( ) (x)(x)(o) (x)(x)(x) (x)(x)(x) (x)(x)(x) (x)(x)(x) (x)(x)(x)
// (4)(6) ( )( ) ( )( ) ( )( ) (o)( ) (x)( ) (x)(o) (x)(x) (x)(x)
coords[0] = new Vector2( 0, 0);
coords[1] = new Vector2(-d, 0);
coords[2] = new Vector2( d, 0);
coords[3] = new Vector2(-r, -s);
coords[4] = new Vector2( r, s);
coords[5] = new Vector2( r, -s);
coords[6] = new Vector2(-r, s);
// Rotate the sampling pattern by 15 degrees.
const float cos15 = 0.96592582628906828675f;
const float sin15 = 0.25881904510252076235f;
for (int i = 0; i < 7; i++)
{
Vector2 coord = coords[i];
coords[i].x = coord.x * cos15 - coord.y * sin15;
coords[i].y = coord.x * sin15 + coord.y * cos15;
}
return coords;
}
public void VolumetricLightingPass(HDCamera camera, CommandBuffer cmd, FrameSettings frameSettings)
{
if (preset == VolumetricLightingPreset.Off) return;
using (new ProfilingSample(cmd, "Volumetric Lighting"))
{
VBuffer vBuffer = FindVBuffer(camera.GetViewID());
Debug.Assert(vBuffer != null);
HomogeneousDensityVolume globalVolume = HomogeneousDensityVolume.GetGlobalHomogeneousDensityVolume();
float asymmetry = globalVolume != null ? globalVolume.volumeParameters.asymmetry : 0;
if (globalVolume == null)
{
// Clear the render target instead of running the shader.
// CoreUtils.SetRenderTarget(cmd, GetVBufferLightingIntegral(viewOffset), ClearFlag.Color, CoreUtils.clearColorAllBlack);
// return;
// Clearing 3D textures does not seem to work!
// Use the workaround by running the full shader with no volume.
}
bool enableClustered = frameSettings.lightLoopSettings.enableTileAndCluster;
bool enableReprojection = Application.isPlaying && camera.camera.cameraType == CameraType.Game;
int kernel;
if (enableReprojection)
{
// Only available in the Play Mode because all the frame counters in the Edit Mode are broken.
kernel = m_VolumetricLightingCS.FindKernel(enableClustered ? "VolumetricLightingClusteredReproj"
: "VolumetricLightingAllLightsReproj");
}
else
{
kernel = m_VolumetricLightingCS.FindKernel(enableClustered ? "VolumetricLightingClustered"
: "VolumetricLightingAllLights");
}
int w = 0, h = 0, d = 0;
ComputeVBufferResolutionAndScale(preset, (int)camera.screenSize.x, (int)camera.screenSize.y, ref w, ref h, ref d);
// Compose the matrix which allows us to compute the world space view direction.
float vFoV = camera.camera.fieldOfView * Mathf.Deg2Rad;
Vector4 resolution = new Vector4(w, h, 1.0f / w, 1.0f / h);
Matrix4x4 transform = HDUtils.ComputePixelCoordToWorldSpaceViewDirectionMatrix(vFoV, resolution, camera.viewMatrix, false);
camera.SetupComputeShader(m_VolumetricLightingCS, cmd);
Vector2[] xySeq = GetHexagonalClosePackedSpheres7();
// This is a sequence of 7 equidistant numbers from 1/14 to 13/14.
// Each of them is the centroid of the interval of length 2/14.
// They've been rearranged in a sequence of pairs {small, large}, s.t. (small + large) = 1.
// That way, the running average position is close to 0.5.
// | 6 | 2 | 4 | 1 | 5 | 3 | 7 |
// | | | | o | | | |
// | | o | | x | | | |
// | | x | | x | | o | |
// | | x | o | x | | x | |
// | | x | x | x | o | x | |
// | o | x | x | x | x | x | |
// | x | x | x | x | x | x | o |
// | x | x | x | x | x | x | x |
float[] zSeq = {7.0f/14.0f, 3.0f/14.0f, 11.0f/14.0f, 5.0f/14.0f, 9.0f/14.0f, 1.0f/14.0f, 13.0f/14.0f};
int rfc = Time.renderedFrameCount;
int sampleIndex = rfc % 7;
Vector4 offset = new Vector4(xySeq[sampleIndex].x, xySeq[sampleIndex].y, zSeq[sampleIndex], rfc);
// TODO: set 'm_VolumetricLightingPreset'.
cmd.SetComputeFloatParam( m_VolumetricLightingCS, HDShaderIDs._CornetteShanksConstant, CornetteShanksPhasePartConstant(asymmetry));
cmd.SetComputeVectorParam( m_VolumetricLightingCS, HDShaderIDs._VBufferSampleOffset, offset);
cmd.SetComputeMatrixParam( m_VolumetricLightingCS, HDShaderIDs._VBufferCoordToViewDirWS, transform);
cmd.SetComputeTextureParam(m_VolumetricLightingCS, kernel, HDShaderIDs._VBufferLightingIntegral, vBuffer.GetLightingIntegralBuffer()); // Write
if (enableReprojection)
{
cmd.SetComputeTextureParam(m_VolumetricLightingCS, kernel, HDShaderIDs._VBufferLightingFeedback, vBuffer.GetLightingFeedbackBuffer()); // Write
cmd.SetComputeTextureParam(m_VolumetricLightingCS, kernel, HDShaderIDs._VBufferLightingHistory, vBuffer.GetLightingHistoryBuffer()); // Read
}
// The shader defines GROUP_SIZE_1D = 16.
cmd.DispatchCompute(m_VolumetricLightingCS, kernel, (w + 15) / 16, (h + 15) / 16, 1);
}
}
} // class VolumetricLightingModule
} // namespace UnityEngine.Experimental.Rendering.HDPipeline