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FlaxEngine/Source/Engine/Renderer/GI/DynamicDiffuseGlobalIllumination.cpp
Wojtek Figat c5a28a5734 Refactor DDGI irradiance sampling when nearby probe is missing to use precomputed fallback probes 
Also, insert fallback/dummy probes when there is no SDF nearby to have lighting in all cases.
This both improves sampling performance and fixes issues when sampling in areas far away from valid GI.
2026-01-05 12:04:02 +01:00

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// Copyright (c) Wojciech Figat. All rights reserved.
#include "DynamicDiffuseGlobalIllumination.h"
#include "GlobalSurfaceAtlasPass.h"
#include "../GlobalSignDistanceFieldPass.h"
#include "../RenderList.h"
#include "Engine/Core/Random.h"
#include "Engine/Core/Types/Variant.h"
#include "Engine/Core/Math/Int3.h"
#include "Engine/Core/Math/Matrix3x3.h"
#include "Engine/Core/Math/Quaternion.h"
#include "Engine/Core/Config/GraphicsSettings.h"
#include "Engine/Engine/Engine.h"
#include "Engine/Engine/Units.h"
#include "Engine/Content/Content.h"
#include "Engine/Debug/DebugDraw.h"
#include "Engine/Graphics/GPUContext.h"
#include "Engine/Graphics/GPUDevice.h"
#include "Engine/Graphics/GPUPass.h"
#include "Engine/Graphics/Graphics.h"
#include "Engine/Graphics/RenderTask.h"
#include "Engine/Graphics/RenderBuffers.h"
#include "Engine/Graphics/RenderTargetPool.h"
#include "Engine/Graphics/RenderTools.h"
#include "Engine/Graphics/Shaders/GPUShader.h"
#include "Engine/Level/Actors/BrushMode.h"
#include "Engine/Renderer/GBufferPass.h"
// Implementation based on:
// "Dynamic Diffuse Global Illumination with Ray-Traced Irradiance Probes", Journal of Computer Graphics Tools, April 2019
// Zander Majercik, Jean-Philippe Guertin, Derek Nowrouzezahrai, and Morgan McGuire
// https://morgan3d.github.io/articles/2019-04-01-ddgi/index.html and https://gdcvault.com/play/1026182/
//
// Additional references:
// "Scaling Probe-Based Real-Time Dynamic Global Illumination for Production", https://jcgt.org/published/0010/02/01/
// "Dynamic Diffuse Global Illumination with Ray-Traced Irradiance Fields", https://jcgt.org/published/0008/02/01/
// This must match HLSL
#define DDGI_TRACE_RAYS_PROBES_COUNT_LIMIT 4096 // Maximum amount of probes to update at once during rays tracing and blending
#define DDGI_TRACE_RAYS_LIMIT 256 // Limit of rays per-probe (runtime value can be smaller)
#define DDGI_PROBE_RESOLUTION_IRRADIANCE 6 // Resolution (in texels) for probe irradiance data (excluding 1px padding on each side)
#define DDGI_PROBE_RESOLUTION_DISTANCE 14 // Resolution (in texels) for probe distance data (excluding 1px padding on each side)
#define DDGI_PROBE_UPDATE_BORDERS_GROUP_SIZE 8
#define DDGI_PROBE_CLASSIFY_GROUP_SIZE 32
#define DDGI_PROBE_EMPTY_AREA_DENSITY 10 // Spacing (in probe grid) between fallback probes placed into empty areas to provide valid GI for nearby dynamic objects or transparency
#define DDGI_DEBUG_STATS 0 // Enables additional GPU-driven stats for probe/rays count
#define DDGI_DEBUG_INSTABILITY 0 // Enables additional probe irradiance instability debugging
#if DDGI_DEBUG_STATS
#include "Engine/Core/Collections/SamplesBuffer.h"
#define DDGI_DEBUG_STATS_FRAMES 60
struct StatsData
{
uint32 RaysCount;
uint32 ProbesCount;
};
#endif
GPU_CB_STRUCT(Data0 {
DynamicDiffuseGlobalIlluminationPass::ConstantsData DDGI;
GlobalSignDistanceFieldPass::ConstantsData GlobalSDF;
GlobalSurfaceAtlasPass::ConstantsData GlobalSurfaceAtlas;
ShaderGBufferData GBuffer;
Float4 RaysRotation;
float SkyboxIntensity;
uint32 ProbesCount;
float ResetBlend;
float TemporalTime;
Int4 ProbeScrollClears[4];
Float3 ViewDir;
float Padding1;
Float3 QuantizationError;
int32 FrameIndexMod8;
});
GPU_CB_STRUCT(Data1 {
// TODO: use push constants on Vulkan or root signature data on DX12 to reduce overhead of changing single DWORD
Float2 Padding2;
uint32 CascadeIndex;
uint32 ProbeIndexOffset;
});
class DDGICustomBuffer : public RenderBuffers::CustomBuffer
{
public:
struct
{
Float3 ProbesOrigin;
float ProbesSpacing = 0.0f;
Int3 ProbeScrollOffsets;
Int3 ProbeScrollClears;
void Clear()
{
ProbesOrigin = Float3::Zero;
ProbeScrollOffsets = Int3::Zero;
ProbeScrollClears = Int3::Zero;
}
} Cascades[4];
int32 CascadesCount = 0;
int32 ProbeRaysCount = 0;
int32 ProbesCountTotal = 0;
Int3 ProbeCounts = Int3::Zero;
GPUTexture* ProbesTrace = nullptr; // Probes ray tracing: (RGB: hit radiance, A: hit distance)
GPUTexture* ProbesData = nullptr; // Probes data: (RGB: probe-space offset, A: state/data)
GPUTexture* ProbesIrradiance = nullptr; // Probes irradiance (RGB: sRGB color)
GPUTexture* ProbesDistance = nullptr; // Probes distance (R: mean distance, G: mean distance^2)
GPUBuffer* ActiveProbes = nullptr; // List with indices of the active probes (built during probes classification to use indirect dispatches for probes updating), counter at 0
GPUBuffer* UpdateProbesInitArgs = nullptr; // Indirect dispatch buffer for active-only probes updating (trace+blend)
#if DDGI_DEBUG_STATS
GPUBuffer* StatsWrite = nullptr;
GPUBuffer* StatsRead = nullptr;
SamplesBuffer<uint32, DDGI_DEBUG_STATS_FRAMES> StatsProbes;
SamplesBuffer<uint32, DDGI_DEBUG_STATS_FRAMES> StatsRays;
uint32 StatsFrames = 0;
#endif
#if DDGI_DEBUG_INSTABILITY
GPUTexture* ProbesInstability = nullptr;
#endif
DynamicDiffuseGlobalIlluminationPass::BindingData Result;
FORCE_INLINE void Release()
{
RenderTargetPool::Release(ProbesTrace);
RenderTargetPool::Release(ProbesData);
RenderTargetPool::Release(ProbesIrradiance);
RenderTargetPool::Release(ProbesDistance);
SAFE_DELETE_GPU_RESOURCE(ActiveProbes);
SAFE_DELETE_GPU_RESOURCE(UpdateProbesInitArgs);
#if DDGI_DEBUG_STATS
SAFE_DELETE_GPU_RESOURCE(StatsWrite);
SAFE_DELETE_GPU_RESOURCE(StatsRead);
StatsProbes.Clear();
StatsRays.Clear();
StatsFrames = 0;
#endif
#if DDGI_DEBUG_INSTABILITY
RenderTargetPool::Release(ProbesInstability);
#endif
}
~DDGICustomBuffer()
{
Release();
}
};
void CalculateVolumeRandomRotation(Matrix3x3& matrix)
{
// Reference: James Arvo's algorithm Graphics Gems 3 (pages 117-120)
// http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.53.1357&rep=rep1&type=pdf
float u1 = TWO_PI * Random::Rand();
float cos1 = Math::Cos(u1);
float sin1 = Math::Sin(u1);
float u2 = TWO_PI * Random::Rand();
float cos2 = Math::Cos(u2);
float sin2 = Math::Sin(u2);
float u3 = Random::Rand();
float sq3 = 2.0f * sqrtf(u3 * (1.0f - u3));
float s2 = 2.0f * u3 * sin2 * sin2 - 1.0f;
float c2 = 2.0f * u3 * cos2 * cos2 - 1.0f;
float sc = 2.0f * u3 * sin2 * cos2;
matrix.M11 = cos1 * c2 - sin1 * sc;
matrix.M12 = sin1 * c2 + cos1 * sc;
matrix.M13 = sq3 * cos2;
matrix.M21 = cos1 * sc - sin1 * s2;
matrix.M22 = sin1 * sc + cos1 * s2;
matrix.M23 = sq3 * sin2;
matrix.M31 = cos1 * (sq3 * cos2) - sin1 * (sq3 * sin2);
matrix.M32 = sin1 * (sq3 * cos2) + cos1 * (sq3 * sin2);
matrix.M33 = 1.0f - 2.0f * u3;
}
String DynamicDiffuseGlobalIlluminationPass::ToString() const
{
return TEXT("DynamicDiffuseGlobalIlluminationPass");
}
bool DynamicDiffuseGlobalIlluminationPass::Init()
{
// Check platform support
const auto device = GPUDevice::Instance;
_supported = device->GetFeatureLevel() >= FeatureLevel::SM5 && device->Limits.HasCompute && device->Limits.HasTypedUAVLoad;
return false;
}
bool DynamicDiffuseGlobalIlluminationPass::setupResources()
{
if (!_supported)
return true;
// Load shader
if (!_shader)
{
_shader = Content::LoadAsyncInternal<Shader>(TEXT("Shaders/GI/DDGI"));
if (_shader == nullptr)
return true;
#if COMPILE_WITH_DEV_ENV
_shader.Get()->OnReloading.Bind<DynamicDiffuseGlobalIlluminationPass, &DynamicDiffuseGlobalIlluminationPass::OnShaderReloading>(this);
#endif
}
if (!_shader->IsLoaded())
return true;
// Initialize resources
const auto shader = _shader->GetShader();
_cb0 = shader->GetCB(0);
_cb1 = shader->GetCB(1);
if (!_cb0 || !_cb1)
return true;
_csClassify = shader->GetCS("CS_Classify");
_csUpdateProbesInitArgs = shader->GetCS("CS_UpdateProbesInitArgs");
_csUpdateInactiveProbes = shader->GetCS("CS_UpdateInactiveProbes");
_csTraceRays[0] = shader->GetCS("CS_TraceRays", 0);
_csTraceRays[1] = shader->GetCS("CS_TraceRays", 1);
_csTraceRays[2] = shader->GetCS("CS_TraceRays", 2);
_csTraceRays[3] = shader->GetCS("CS_TraceRays", 3);
_csUpdateProbesIrradiance = shader->GetCS("CS_UpdateProbes", 0);
_csUpdateProbesDistance = shader->GetCS("CS_UpdateProbes", 1);
auto device = GPUDevice::Instance;
auto psDesc = GPUPipelineState::Description::DefaultFullscreenTriangle;
if (!_psIndirectLighting[0])
{
_psIndirectLighting[0] = device->CreatePipelineState();
_psIndirectLighting[1] = device->CreatePipelineState();
psDesc.PS = shader->GetPS("PS_IndirectLighting");
psDesc.BlendMode = BlendingMode::Add;
if (_psIndirectLighting[0]->Init(psDesc))
return true;
psDesc.PS = shader->GetPS("PS_IndirectLighting", 1);
if (_psIndirectLighting[1]->Init(psDesc))
return true;
}
return false;
}
#if COMPILE_WITH_DEV_ENV
void DynamicDiffuseGlobalIlluminationPass::OnShaderReloading(Asset* obj)
{
LastFrameShaderReload = Engine::FrameCount;
_csClassify = nullptr;
_csUpdateProbesInitArgs = nullptr;
_csUpdateInactiveProbes = nullptr;
_csTraceRays[0] = nullptr;
_csTraceRays[1] = nullptr;
_csTraceRays[2] = nullptr;
_csTraceRays[3] = nullptr;
_csUpdateProbesIrradiance = nullptr;
_csUpdateProbesDistance = nullptr;
SAFE_DELETE_GPU_RESOURCE(_psIndirectLighting[0]);
SAFE_DELETE_GPU_RESOURCE(_psIndirectLighting[1]);
invalidateResources();
}
#endif
void DynamicDiffuseGlobalIlluminationPass::Dispose()
{
RendererPass::Dispose();
// Cleanup
_cb0 = nullptr;
_cb1 = nullptr;
_shader = nullptr;
SAFE_DELETE_GPU_RESOURCE(_psIndirectLighting[0]);
SAFE_DELETE_GPU_RESOURCE(_psIndirectLighting[1]);
#if USE_EDITOR
_debugModel = nullptr;
_debugMaterial = nullptr;
#endif
}
bool DynamicDiffuseGlobalIlluminationPass::Get(const RenderBuffers* buffers, BindingData& result)
{
auto* ddgiData = buffers ? buffers->FindCustomBuffer<DDGICustomBuffer>(TEXT("DDGI")) : nullptr;
if (ddgiData && ddgiData->LastFrameUsed + 1 >= Engine::FrameCount) // Allow to use data from the previous frame (eg. particles in Editor using the Editor viewport in Game viewport - Game render task runs first)
{
result = ddgiData->Result;
return false;
}
return true;
}
bool DynamicDiffuseGlobalIlluminationPass::RenderInner(RenderContext& renderContext, GPUContext* context, DDGICustomBuffer& ddgiData)
{
// Render Global SDF and Global Surface Atlas for software raytracing
GlobalSignDistanceFieldPass::BindingData bindingDataSDF;
if (GlobalSignDistanceFieldPass::Instance()->Render(renderContext, context, bindingDataSDF))
return true;
GlobalSurfaceAtlasPass::BindingData bindingDataSurfaceAtlas;
if (GlobalSurfaceAtlasPass::Instance()->Render(renderContext, context, bindingDataSurfaceAtlas))
return true;
GPUTextureView* skybox = GBufferPass::Instance()->RenderSkybox(renderContext, context);
// Setup options
auto& settings = renderContext.List->Settings.GlobalIllumination;
auto* graphicsSettings = GraphicsSettings::Get();
const float probesSpacing = Math::Clamp(graphicsSettings->GIProbesSpacing, 10.0f, 1000.0f); // GI probes placement spacing nearby camera (for closest cascade; gets automatically reduced for further cascades)
int32 probeRaysCount; // Amount of rays to trace randomly around each probe
switch (Graphics::GIQuality) // Ensure to match CS_TraceRays permutations
{
case Quality::Low:
probeRaysCount = 96;
break;
case Quality::Medium:
probeRaysCount = 128;
break;
case Quality::High:
probeRaysCount = 192;
break;
case Quality::Ultra:
probeRaysCount = 256;
break;
default:
return true;
}
ASSERT_LOW_LAYER(probeRaysCount <= DDGI_TRACE_RAYS_LIMIT);
const float indirectLightingIntensity = settings.Intensity;
const float probeHistoryWeight = Math::Clamp(settings.TemporalResponse, 0.0f, 0.98f);
const float distance = settings.Distance;
const Color fallbackIrradiance = settings.FallbackIrradiance;
// Automatically calculate amount of cascades to cover the GI distance at the current probes spacing
const int32 idealProbesCount = 20; // Ideal amount of probes per-cascade to try to fit in order to cover whole distance
int32 cascadesCount = 1;
float idealDistance = idealProbesCount * probesSpacing;
while (cascadesCount < 4 && idealDistance < distance)
{
idealDistance *= 2;
cascadesCount++;
}
// Calculate the probes count based on the amount of cascades and the distance to cover
const float cascadesDistanceScales[] = { 1.0f, 3.0f, 5.0f, 10.0f }; // Scales each cascade further away from the camera origin
const float distanceExtent = distance / cascadesDistanceScales[cascadesCount - 1];
const float verticalRangeScale = 0.8f; // Scales the probes volume size at Y axis (horizontal aspect ratio makes the DDGI use less probes vertically to cover whole screen)
Int3 probesCounts(Float3::Ceil(Float3(distanceExtent, distanceExtent * verticalRangeScale, distanceExtent) / probesSpacing));
const int32 maxProbeSize = Math::Max(DDGI_PROBE_RESOLUTION_IRRADIANCE, DDGI_PROBE_RESOLUTION_DISTANCE) + 2;
const int32 maxTextureSize = Math::Min(GPUDevice::Instance->Limits.MaximumTexture2DSize, GPU_MAX_TEXTURE_SIZE);
while (probesCounts.X * probesCounts.Y * maxProbeSize > maxTextureSize
|| probesCounts.Z * cascadesCount * maxProbeSize > maxTextureSize)
{
// Decrease quality to ensure the probes texture won't overflow
probesCounts -= 1;
}
// Initialize cascades
float probesSpacings[4];
Float3 viewOrigins[4];
Float3 blendOrigins[4];
for (int32 cascadeIndex = 0; cascadeIndex < cascadesCount; cascadeIndex++)
{
// Each cascade has higher spacing between probes
float cascadeDistanceScale = cascadesDistanceScales[cascadeIndex];
float cascadeProbesSpacing = probesSpacing * cascadeDistanceScale;
probesSpacings[cascadeIndex] = cascadeProbesSpacing;
// Calculate view origin for cascade by shifting it towards the view direction to account for better view frustum coverage
Float3 viewOrigin = renderContext.View.Position;
Float3 viewDirection = renderContext.View.Direction;
const Float3 probesDistance = Float3(probesCounts - 1) * cascadeProbesSpacing;
const float probesDistanceMax = probesDistance.MaxValue();
const Float3 viewRayHit = CollisionsHelper::LineHitsBox(viewOrigin, viewOrigin + viewDirection * (probesDistanceMax * 2.0f), viewOrigin - probesDistance, viewOrigin + probesDistance);
const float viewOriginOffset = viewRayHit.Y * probesDistanceMax * 0.6f;
viewOrigin += viewDirection * viewOriginOffset;
//viewOrigin = Float3::Zero;
blendOrigins[cascadeIndex] = viewOrigin;
const float viewOriginSnapping = cascadeProbesSpacing;
viewOrigin = Float3::Floor(viewOrigin / viewOriginSnapping) * viewOriginSnapping;
viewOrigin -= UNITS_TO_METERS(0.5f); // Bias to avoid precision issues (eg. if floor mesh is exactly at Y=0)
viewOrigins[cascadeIndex] = viewOrigin;
}
// Init buffers
const int32 probesCountCascade = probesCounts.X * probesCounts.Y * probesCounts.Z;
const int32 probesCountTotal = probesCountCascade * cascadesCount;
if (probesCountTotal == 0 || indirectLightingIntensity <= ZeroTolerance)
return true;
int32 probesCountCascadeX = probesCounts.X * probesCounts.Y;
int32 probesCountCascadeY = probesCounts.Z;
int32 probesCountTotalX = probesCountCascadeX;
int32 probesCountTotalY = probesCountCascadeY * cascadesCount;
bool clear = false;
if (ddgiData.CascadesCount != cascadesCount || Math::NotNearEqual(ddgiData.Cascades[0].ProbesSpacing, probesSpacing) || ddgiData.ProbeCounts != probesCounts || ddgiData.ProbeRaysCount != probeRaysCount)
{
PROFILE_CPU_NAMED("Init");
ddgiData.Release();
ddgiData.CascadesCount = cascadesCount;
ddgiData.ProbeRaysCount = probeRaysCount;
ddgiData.ProbesCountTotal = probesCountTotal;
ddgiData.ProbeCounts = probesCounts;
for (int32 cascadeIndex = 0; cascadeIndex < cascadesCount; cascadeIndex++)
{
auto& cascade = ddgiData.Cascades[cascadeIndex];
cascade.Clear();
cascade.ProbesSpacing = probesSpacings[cascadeIndex];
cascade.ProbesOrigin = viewOrigins[cascadeIndex];
}
// Allocate probes textures
uint64 memUsage = 0;
auto desc = GPUTextureDescription::New2D(probesCountTotalX, probesCountTotalY, PixelFormat::Unknown);
#define INIT_TEXTURE(texture, format, width, height) desc.Format = format; desc.Width = width; desc.Height = height; ddgiData.texture = RenderTargetPool::Get(desc); if (!ddgiData.texture) return true; memUsage += ddgiData.texture->GetMemoryUsage(); RENDER_TARGET_POOL_SET_NAME(ddgiData.texture, "DDGI." #texture)
desc.Flags = GPUTextureFlags::ShaderResource | GPUTextureFlags::UnorderedAccess;
INIT_TEXTURE(ProbesTrace, PixelFormat::R16G16B16A16_Float, probeRaysCount, Math::Min(probesCountCascade, DDGI_TRACE_RAYS_PROBES_COUNT_LIMIT));
INIT_TEXTURE(ProbesData, PixelFormat::R8G8B8A8_SNorm, probesCountTotalX, probesCountTotalY);
// TODO: add BC6H compression to probes data (https://github.com/knarkowicz/GPURealTimeBC6H)
INIT_TEXTURE(ProbesIrradiance, PixelFormat::R11G11B10_Float, probesCountTotalX * (DDGI_PROBE_RESOLUTION_IRRADIANCE + 2), probesCountTotalY * (DDGI_PROBE_RESOLUTION_IRRADIANCE + 2));
INIT_TEXTURE(ProbesDistance, PixelFormat::R16G16_Float, probesCountTotalX * (DDGI_PROBE_RESOLUTION_DISTANCE + 2), probesCountTotalY * (DDGI_PROBE_RESOLUTION_DISTANCE + 2));
#if DDGI_DEBUG_INSTABILITY
INIT_TEXTURE(ProbesInstability, PixelFormat::R16_Float, probesCountTotalX * (DDGI_PROBE_RESOLUTION_IRRADIANCE + 2), probesCountTotalY * (DDGI_PROBE_RESOLUTION_IRRADIANCE + 2));
#endif
#undef INIT_TEXTURE
#define INIT_BUFFER(buffer, name) ddgiData.buffer = GPUDevice::Instance->CreateBuffer(TEXT(name)); if (!ddgiData.buffer || ddgiData.buffer->Init(desc2)) return true; memUsage += ddgiData.buffer->GetMemoryUsage();
GPUBufferDescription desc2 = GPUBufferDescription::Raw((probesCountCascade + 1) * sizeof(uint32), GPUBufferFlags::ShaderResource | GPUBufferFlags::UnorderedAccess);
INIT_BUFFER(ActiveProbes, "DDGI.ActiveProbes");
desc2 = GPUBufferDescription::Buffer(sizeof(GPUDispatchIndirectArgs) * Math::DivideAndRoundUp(probesCountCascade, DDGI_TRACE_RAYS_PROBES_COUNT_LIMIT), GPUBufferFlags::Argument | GPUBufferFlags::UnorderedAccess, PixelFormat::R32_UInt, nullptr, sizeof(uint32));
INIT_BUFFER(UpdateProbesInitArgs, "DDGI.UpdateProbesInitArgs");
#if DDGI_DEBUG_STATS
desc2 = GPUBufferDescription::Raw(sizeof(StatsData), GPUBufferFlags::UnorderedAccess);
INIT_BUFFER(StatsWrite, "DDGI.StatsWrite");
desc2 = desc2.ToStagingReadback();
INIT_BUFFER(StatsRead, "DDGI.StatsRead");
#endif
#undef INIT_BUFFER
LOG(Info, "Dynamic Diffuse Global Illumination probes: {0}, memory usage: {1} MB", probesCountTotal, memUsage / (1024 * 1024));
clear = true;
}
#if COMPILE_WITH_DEV_ENV
clear |= ddgiData.LastFrameUsed <= LastFrameShaderReload;
#endif
if (clear)
{
// Clear probes
PROFILE_GPU("Clear");
context->ClearUA(ddgiData.ProbesData, Float4::Zero);
context->ClearUA(ddgiData.ProbesIrradiance, Float4::Zero);
context->ClearUA(ddgiData.ProbesDistance, Float4::Zero);
#if DDGI_DEBUG_INSTABILITY
context->ClearUA(ddgiData.ProbesInstability, Float4::Zero);
#endif
}
ddgiData.LastFrameUsed = Engine::FrameCount;
// Calculate which cascades should be updated this frame
const uint64 cascadeFrequencies[] = { 2, 3, 5, 7 };
//const uint64 cascadeFrequencies[] = { 1, 2, 3, 5 };
//const uint64 cascadeFrequencies[] = { 1, 1, 1, 1 };
//const uint64 cascadeFrequencies[] = { 10, 10, 10, 10 };
bool cascadeSkipUpdate[4];
for (int32 cascadeIndex = 0; cascadeIndex < cascadesCount; cascadeIndex++)
{
cascadeSkipUpdate[cascadeIndex] = !clear && (ddgiData.LastFrameUsed % cascadeFrequencies[cascadeIndex]) != 0 && GPU_SPREAD_WORKLOAD;
}
// Compute scrolling (probes are placed around camera but are scrolling to increase stability during movement)
for (int32 cascadeIndex = 0; cascadeIndex < cascadesCount; cascadeIndex++)
{
if (cascadeSkipUpdate[cascadeIndex])
continue;
auto& cascade = ddgiData.Cascades[cascadeIndex];
// Calculate the count of grid cells between the view origin and the scroll anchor
const Float3 volumeOrigin = cascade.ProbesOrigin + Float3(cascade.ProbeScrollOffsets) * cascade.ProbesSpacing;
const Float3 translation = viewOrigins[cascadeIndex] - volumeOrigin;
for (int32 axis = 0; axis < 3; axis++)
{
const float value = translation.Raw[axis] / cascade.ProbesSpacing;
const int32 scroll = value >= 0.0f ? (int32)Math::Floor(value) : (int32)Math::Ceil(value);
cascade.ProbeScrollOffsets.Raw[axis] += scroll;
cascade.ProbeScrollClears.Raw[axis] = scroll;
}
// Shift the volume origin based on scroll offsets for each axis once it overflows
for (int32 axis = 0; axis < 3; axis++)
{
const int32 probeCount = ddgiData.ProbeCounts.Raw[axis];
int32& scrollOffset = cascade.ProbeScrollOffsets.Raw[axis];
while (scrollOffset >= probeCount)
{
cascade.ProbesOrigin.Raw[axis] += cascade.ProbesSpacing * probeCount;
scrollOffset -= probeCount;
}
while (scrollOffset <= -probeCount)
{
cascade.ProbesOrigin.Raw[axis] -= cascade.ProbesSpacing * probeCount;
scrollOffset += probeCount;
}
}
}
// Upload constants
{
ddgiData.Result.Constants.CascadesCount = cascadesCount;
ddgiData.Result.Constants.ProbesCounts[0] = probesCounts.X;
ddgiData.Result.Constants.ProbesCounts[1] = probesCounts.Y;
ddgiData.Result.Constants.ProbesCounts[2] = probesCounts.Z;
for (int32 cascadeIndex = 0; cascadeIndex < cascadesCount; cascadeIndex++)
{
auto& cascade = ddgiData.Cascades[cascadeIndex];
ddgiData.Result.Constants.ProbesOriginAndSpacing[cascadeIndex] = Float4(cascade.ProbesOrigin, cascade.ProbesSpacing);
ddgiData.Result.Constants.BlendOrigin[cascadeIndex] = Float4(blendOrigins[cascadeIndex], 0.0f);
ddgiData.Result.Constants.ProbesScrollOffsets[cascadeIndex] = Int4(cascade.ProbeScrollOffsets, 0);
}
ddgiData.Result.Constants.RayMaxDistance = distance;
ddgiData.Result.Constants.ViewPos = renderContext.View.Position;
ddgiData.Result.Constants.RaysCount = probeRaysCount;
ddgiData.Result.Constants.ProbeHistoryWeight = probeHistoryWeight;
ddgiData.Result.Constants.IrradianceGamma = 1.5f;
ddgiData.Result.Constants.IndirectLightingIntensity = indirectLightingIntensity;
ddgiData.Result.Constants.FallbackIrradiance = fallbackIrradiance.ToFloat3() * fallbackIrradiance.A;
ddgiData.Result.ProbesData = ddgiData.ProbesData->View();
ddgiData.Result.ProbesDistance = ddgiData.ProbesDistance->View();
ddgiData.Result.ProbesIrradiance = ddgiData.ProbesIrradiance->View();
Data0 data;
// Compute random rotation matrix for probe rays orientation (randomized every frame)
Matrix3x3 raysRotationMatrix;
CalculateVolumeRandomRotation(raysRotationMatrix);
Quaternion& raysRotation = *(Quaternion*)&data.RaysRotation;
Quaternion::RotationMatrix(raysRotationMatrix, raysRotation);
raysRotation.Conjugate();
data.DDGI = ddgiData.Result.Constants;
data.GlobalSDF = bindingDataSDF.Constants;
data.GlobalSurfaceAtlas = bindingDataSurfaceAtlas.Constants;
data.ProbesCount = data.DDGI.ProbesCounts[0] * data.DDGI.ProbesCounts[1] * data.DDGI.ProbesCounts[2];
data.ResetBlend = clear ? 1.0f : 0.0f;
for (int32 cascadeIndex = 0; cascadeIndex < cascadesCount; cascadeIndex++)
{
auto& cascade = ddgiData.Cascades[cascadeIndex];
data.ProbeScrollClears[cascadeIndex] = Int4(cascade.ProbeScrollClears, 0);
}
data.TemporalTime = renderContext.List->Setup.UseTemporalAAJitter ? RenderTools::ComputeTemporalTime() : 0.0f;
data.ViewDir = renderContext.View.Direction;
data.SkyboxIntensity = renderContext.List->Sky ? renderContext.List->Sky->GetIndirectLightingIntensity() : 1.0f;
data.QuantizationError = RenderTools::GetColorQuantizationError(ddgiData.ProbesIrradiance->Format());
data.FrameIndexMod8 = (int32)(Engine::FrameCount % 8);
GBufferPass::SetInputs(renderContext.View, data.GBuffer);
context->UpdateCB(_cb0, &data);
context->BindCB(0, _cb0);
}
// Update probes
{
PROFILE_GPU_CPU_NAMED("Probes Update");
uint32 threadGroupsX;
#if DDGI_DEBUG_STATS
uint32 zero[4] = {};
context->ClearUA(ddgiData.StatsWrite, zero);
#endif
for (int32 cascadeIndex = 0; cascadeIndex < cascadesCount; cascadeIndex++)
{
if (cascadeSkipUpdate[cascadeIndex])
continue;
// Classify probes (activation/deactivation and relocation)
{
PROFILE_GPU_CPU_NAMED("Classify Probes");
uint32 activeProbesCount = 0;
context->UpdateBuffer(ddgiData.ActiveProbes, &activeProbesCount, sizeof(uint32), 0);
threadGroupsX = Math::DivideAndRoundUp(probesCountCascade, DDGI_PROBE_CLASSIFY_GROUP_SIZE);
context->BindSR(0, bindingDataSDF.Texture ? bindingDataSDF.Texture->ViewVolume() : nullptr);
context->BindSR(1, bindingDataSDF.TextureMip ? bindingDataSDF.TextureMip->ViewVolume() : nullptr);
context->BindUA(0, ddgiData.Result.ProbesData);
context->BindUA(1, ddgiData.ActiveProbes->View());
Data1 data;
data.CascadeIndex = cascadeIndex;
context->UpdateCB(_cb1, &data);
context->BindCB(1, _cb1);
context->Dispatch(_csClassify, threadGroupsX, 1, 1);
context->ResetUA();
context->ResetSR();
}
// Build indirect args for probes updating (loop over active-only probes)
{
PROFILE_GPU_CPU_NAMED("Init Args");
context->BindSR(0, ddgiData.ActiveProbes->View());
context->BindUA(0, ddgiData.UpdateProbesInitArgs->View());
context->Dispatch(_csUpdateProbesInitArgs, 1, 1, 1);
context->ResetUA();
}
// For inactive probes, search nearby ones to find the closest valid for quick fallback when sampling irradiance
{
PROFILE_GPU_CPU_NAMED("Update Inactive Probes");
context->BindUA(0, ddgiData.Result.ProbesData);
int32 iterations = Math::Min(probesCounts.MaxValue() - 1, DDGI_PROBE_EMPTY_AREA_DENSITY) * 10;
for (int32 i = 0; i < iterations; i++)
context->Dispatch(_csUpdateInactiveProbes, threadGroupsX, 1, 1);
context->ResetUA();
}
// Update probes in batches so ProbesTrace texture can be smaller
uint32 arg = 0;
// TODO: use rays allocator to dispatch raytracing in packets (eg. 8 threads in a group instead of hardcoded limit)
for (int32 probesOffset = 0; probesOffset < probesCountCascade; probesOffset += DDGI_TRACE_RAYS_PROBES_COUNT_LIMIT)
{
Data1 data;
data.CascadeIndex = cascadeIndex;
data.ProbeIndexOffset = probesOffset;
context->UpdateCB(_cb1, &data);
context->BindCB(1, _cb1);
// Trace rays from probes
{
PROFILE_GPU_CPU_NAMED("Trace Rays");
// Global SDF with Global Surface Atlas software raytracing (thread X - per probe ray, thread Y - per probe)
context->BindSR(0, bindingDataSDF.Texture ? bindingDataSDF.Texture->ViewVolume() : nullptr);
context->BindSR(1, bindingDataSDF.TextureMip ? bindingDataSDF.TextureMip->ViewVolume() : nullptr);
context->BindSR(2, bindingDataSurfaceAtlas.Chunks ? bindingDataSurfaceAtlas.Chunks->View() : nullptr);
context->BindSR(3, bindingDataSurfaceAtlas.CulledObjects ? bindingDataSurfaceAtlas.CulledObjects->View() : nullptr);
context->BindSR(4, bindingDataSurfaceAtlas.Objects ? bindingDataSurfaceAtlas.Objects->View() : nullptr);
context->BindSR(5, bindingDataSurfaceAtlas.AtlasDepth->View());
context->BindSR(6, bindingDataSurfaceAtlas.AtlasLighting->View());
context->BindSR(7, ddgiData.Result.ProbesData);
context->BindSR(8, skybox);
context->BindSR(9, ddgiData.ActiveProbes->View());
context->BindUA(0, ddgiData.ProbesTrace->View());
#if DDGI_DEBUG_STATS
context->BindUA(1, ddgiData.StatsWrite->View());
#endif
context->DispatchIndirect(_csTraceRays[(int32)Graphics::GIQuality], ddgiData.UpdateProbesInitArgs, arg);
context->ResetUA();
context->ResetSR();
}
// Update probes irradiance and distance textures (one thread-group per probe)
{
PROFILE_GPU_CPU_NAMED("Update Probes");
GPUComputePass pass(context);
// Distance
context->BindSR(0, ddgiData.Result.ProbesData);
context->BindSR(1, ddgiData.ProbesTrace->View());
context->BindSR(2, ddgiData.ActiveProbes->View());
context->BindUA(0, ddgiData.Result.ProbesDistance);
context->DispatchIndirect(_csUpdateProbesDistance, ddgiData.UpdateProbesInitArgs, arg);
context->ResetUA();
context->ResetSR();
// Irradiance
context->BindSR(1, ddgiData.ProbesTrace->View());
context->BindSR(2, ddgiData.ActiveProbes->View());
context->BindUA(0, ddgiData.Result.ProbesIrradiance);
context->BindUA(1, ddgiData.Result.ProbesData);
#if DDGI_DEBUG_INSTABILITY
context->BindUA(2, ddgiData.ProbesInstability->View());
#endif
context->DispatchIndirect(_csUpdateProbesIrradiance, ddgiData.UpdateProbesInitArgs, arg);
context->ResetUA();
context->ResetSR();
}
arg += sizeof(GPUDispatchIndirectArgs);
}
}
#if DDGI_DEBUG_STATS
// Update stats
{
StatsData stats;
if (void* mapped = ddgiData.StatsRead->Map(GPUResourceMapMode::Read | GPUResourceMapMode::NoWait))
{
Platform::MemoryCopy(&stats, mapped, sizeof(stats));
ddgiData.StatsRead->Unmap();
ddgiData.StatsProbes.Add(stats.ProbesCount);
ddgiData.StatsRays.Add(stats.RaysCount);
}
context->CopyBuffer(ddgiData.StatsRead, ddgiData.StatsWrite, sizeof(stats));
if (++ddgiData.StatsFrames >= DDGI_DEBUG_STATS_FRAMES)
{
ddgiData.StatsFrames = 0;
stats.ProbesCount = ddgiData.StatsProbes.Average();
stats.RaysCount = ddgiData.StatsRays.Average();
LOG(Info, "DDGI active probes: {}, traced rays: {} per frame, rays per probe: {}", stats.ProbesCount, stats.RaysCount, stats.ProbesCount > 0 ? stats.RaysCount / stats.ProbesCount : 0);
}
}
#endif
}
return false;
}
bool DynamicDiffuseGlobalIlluminationPass::Render(RenderContext& renderContext, GPUContext* context, GPUTextureView* lightBuffer)
{
if (checkIfSkipPass())
return true;
if (renderContext.List->Scenes.Count() == 0)
return true;
RenderBuffers* renderBuffers = renderContext.Buffers;
bool render = true;
if (renderContext.View.IsOfflinePass)
{
// During offline pass (eg. probes rendering) we can try reuse main game viewport or editor viewport DDGI probes
// TODO: apply it for transparency too (in DynamicDiffuseGlobalIlluminationPass::Get)
for (auto* task : RenderTask::Tasks)
{
if (auto* sceneTask = ScriptingObject::Cast<SceneRenderTask>(task))
{
auto* sceneTaskDDGI = sceneTask->Buffers ? sceneTask->Buffers->FindCustomBuffer<DDGICustomBuffer>(TEXT("DDGI")) : nullptr;
if (sceneTaskDDGI && sceneTaskDDGI->LastFrameUsed + 1 >= Engine::FrameCount)
{
// Reuse DDGI from this task
renderBuffers = sceneTask->Buffers;
render = false;
break;
}
}
}
}
auto& ddgiData = *renderBuffers->GetCustomBuffer<DDGICustomBuffer>(TEXT("DDGI"));
if (render && ddgiData.LastFrameUsed == Engine::FrameCount)
render = false;
PROFILE_GPU_CPU("Dynamic Diffuse Global Illumination");
if (render)
{
if (RenderInner(renderContext, context, ddgiData))
{
context->ResetRenderTarget();
context->ResetSR();
context->ResetUA();
context->SetViewportAndScissors(renderContext.View.ScreenSize.X, renderContext.View.ScreenSize.Y);
return true;
}
}
// Render indirect lighting
if (lightBuffer)
{
PROFILE_GPU_CPU_NAMED("Indirect Lighting");
#if 0
// DDGI indirect lighting debug preview
context->Clear(lightBuffer, Color::Transparent);
#endif
if (!render)
{
Data0 data;
data.DDGI = ddgiData.Result.Constants;
data.TemporalTime = 0.0f;
GBufferPass::SetInputs(renderContext.View, data.GBuffer);
context->UpdateCB(_cb0, &data);
context->BindCB(0, _cb0);
}
context->BindSR(0, renderContext.Buffers->GBuffer0->View());
context->BindSR(1, renderContext.Buffers->GBuffer1->View());
context->BindSR(2, renderContext.Buffers->GBuffer2->View());
context->BindSR(3, renderContext.Buffers->DepthBuffer->View());
context->BindSR(4, ddgiData.Result.ProbesData);
context->BindSR(5, ddgiData.Result.ProbesDistance);
context->BindSR(6, ddgiData.Result.ProbesIrradiance);
context->SetViewportAndScissors(renderContext.View.ScreenSize.X, renderContext.View.ScreenSize.Y);
context->SetRenderTarget(lightBuffer);
context->SetState(_psIndirectLighting[Graphics::GICascadesBlending ? 1 : 0]);
context->DrawFullscreenTriangle();
}
#if USE_EDITOR
// Probes debug drawing
if (renderContext.View.Mode == ViewMode::GlobalIllumination && lightBuffer)
{
PROFILE_GPU_CPU_NAMED("Debug Probes");
if (!_debugModel)
_debugModel = Content::LoadAsyncInternal<Model>(TEXT("Editor/Primitives/Sphere"));
if (!_debugMaterial)
_debugMaterial = Content::LoadAsyncInternal<MaterialBase>(TEXT("Editor/DebugMaterials/DDGIDebugProbes"));
if (_debugModel && _debugModel->IsLoaded() && _debugModel->CanBeRendered() && _debugMaterial && _debugMaterial->IsLoaded())
{
RenderContext debugRenderContext(renderContext);
Matrix world;
Matrix::Scaling(Float3(0.2f), world);
const Mesh& debugMesh = _debugModel->LODs[0].Meshes[0];
constexpr int32 maxProbesPerDrawing = 32 * 1024;
int32 probesDrawingStart = 0;
while (probesDrawingStart < ddgiData.ProbesCountTotal)
{
debugRenderContext.List = RenderList::GetFromPool();
debugRenderContext.View.Pass = DrawPass::GBuffer;
debugRenderContext.View.Prepare(debugRenderContext);
// TODO: refactor this into BatchedDrawCalls for faster draw calls processing
const int32 probesDrawingEnd = Math::Min(probesDrawingStart + maxProbesPerDrawing, ddgiData.ProbesCountTotal);
for (int32 probeIndex = probesDrawingStart; probeIndex < probesDrawingEnd; probeIndex++)
debugMesh.Draw(debugRenderContext, _debugMaterial, world, StaticFlags::None, true, DrawPass::GBuffer, (float)probeIndex);
debugRenderContext.List->SortDrawCalls(debugRenderContext, false, DrawCallsListType::GBuffer);
context->SetViewportAndScissors(debugRenderContext.View.ScreenSize.X, debugRenderContext.View.ScreenSize.Y);
GPUTextureView* targetBuffers[5] =
{
lightBuffer,
renderContext.Buffers->GBuffer0->View(),
renderContext.Buffers->GBuffer1->View(),
renderContext.Buffers->GBuffer2->View(),
renderContext.Buffers->GBuffer3->View(),
};
context->SetRenderTarget(*renderContext.Buffers->DepthBuffer, ToSpan(targetBuffers, ARRAY_COUNT(targetBuffers)));
{
// Pass DDGI data to the material
_debugMaterial->SetParameterValue(TEXT("ProbesData"), Variant(ddgiData.ProbesData));
#if DDGI_DEBUG_INSTABILITY
_debugMaterial->SetParameterValue(TEXT("ProbesIrradiance"), Variant(ddgiData.ProbesInstability));
#else
_debugMaterial->SetParameterValue(TEXT("ProbesIrradiance"), Variant(ddgiData.ProbesIrradiance));
#endif
_debugMaterial->SetParameterValue(TEXT("ProbesDistance"), Variant(ddgiData.ProbesDistance));
auto cb = _debugMaterial->GetShader()->GetCB(3);
if (cb)
{
context->UpdateCB(cb, &ddgiData.Result.Constants);
context->BindCB(3, cb);
}
}
debugRenderContext.List->ExecuteDrawCalls(debugRenderContext, DrawCallsListType::GBuffer);
RenderList::ReturnToPool(debugRenderContext.List);
probesDrawingStart = probesDrawingEnd;
}
}
}
#endif
context->ResetRenderTarget();
context->ResetSR();
context->ResetUA();
context->SetViewportAndScissors(renderContext.View.ScreenSize.X, renderContext.View.ScreenSize.Y);
return false;
}
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