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Fixed some DDGI issues #176

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Merged
maxvdec merged 3 commits into from
Jul 20, 2026
Merged

Fixed some DDGI issues #176

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b06fd28
Reversed IBL lighting technique
maxvdec Jul 20, 2026
3db9854
Some improvements to DDGI
maxvdec Jul 20, 2026
2a5bff4
Finished fixing DDGI
maxvdec Jul 20, 2026
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17 changes: 9 additions & 8 deletions atlas/graphics/deferred.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -254,6 +254,7 @@ buildGPUAreaLights(const std::vector<AreaLight *> &lights, int maxCount) {
#ifdef METAL
void Window::enableGlobalIllumination() {
usesGlobalIllumination = true;
useSSR = true;
ddgiSystem = std::make_shared<photon::GlobalIllumination>();
ddgiSystem->sampleNormalMaps = false;
ddgiSystem->init();
Expand Down Expand Up @@ -627,7 +628,9 @@ void Window::deferredRendering(
if (usesGlobalIllumination && ddgiSystem != nullptr &&
ddgiSystem->probeSpace != nullptr &&
ddgiSystem->irradianceMap != nullptr &&
ddgiSystem->irradianceMap->texture != nullptr) {
ddgiSystem->irradianceMap->texture != nullptr &&
ddgiSystem->distanceMap != nullptr &&
ddgiSystem->distanceMap->texture != nullptr) {
lightPipeline->setUniform3f("ps.origin",
ddgiSystem->probeSpace->originWorldSpace.x,
ddgiSystem->probeSpace->originWorldSpace.y,
Expand All @@ -653,12 +656,10 @@ void Window::deferredRendering(

std::shared_ptr<opal::Texture> ddgiIrradianceTexture =
ddgiSystem->irradianceMap->texture;
if (ddgiSystem->irradianceMapPrev != nullptr &&
ddgiSystem->irradianceMapPrev->texture != nullptr &&
ddgiSystem->frameIndex <= 1) {
ddgiIrradianceTexture = ddgiSystem->irradianceMapPrev->texture;
}
std::shared_ptr<opal::Texture> ddgiDistanceTexture =
ddgiSystem->distanceMap->texture;
lightPipeline->bindTexture("irradianceMap", ddgiIrradianceTexture, 16);
lightPipeline->bindTexture("ddgiDistanceMap", ddgiDistanceTexture, 17);
} else {
lightPipeline->setUniform3f("ps.origin", 0.0f, 0.0f, 0.0f);
lightPipeline->setUniform3f("ps.spacing", 1.0f, 1.0f, 1.0f);
Expand All @@ -667,6 +668,8 @@ void Window::deferredRendering(
lightPipeline->setUniform4f("ps.atlasParams", 0.0f, 0.0f, 0.0f, 0.0f);
lightPipeline->bindTexture2D("irradianceMap",
fallbackIrradianceTexture->textureID, 16);
lightPipeline->bindTexture2D("ddgiDistanceMap",
fallbackIrradianceTexture->textureID, 17);
}
#endif

Expand Down Expand Up @@ -972,8 +975,6 @@ void Window::deferredRendering(
lightPipeline->bindTextureCubemap(
"skybox", fallbackSkyboxTexture->textureID, boundTextures);
}
lightPipeline->setUniformBool(
"useIBL", scene->skybox != nullptr && scene->skybox->cubemap.id != 0);
boundTextures++;

lightPipeline->setUniform1f(
Expand Down
524 changes: 391 additions & 133 deletions include/atlas/core/default_shaders.h
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8 changes: 8 additions & 0 deletions include/photon/illuminate.h
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Original file line number Diff line number Diff line change
Expand Up @@ -156,6 +156,8 @@ class GlobalIllumination {
std::shared_ptr<Texture> irradianceMap;
/** @brief Previous irradiance atlas for temporal blending. */
std::shared_ptr<Texture> irradianceMapPrev;
std::shared_ptr<Texture> distanceMap;
std::shared_ptr<Texture> distanceMapPrev;
/** @brief Compute program that writes probe irradiance tiles to the atlas.
*/
std::shared_ptr<ShaderProgram> giWriteShader;
Expand All @@ -171,6 +173,12 @@ class GlobalIllumination {
/** @brief Byte capacity currently allocated for probeRadianceBuffer. */
int probeRadianceCapacity = 0;

std::shared_ptr<opal::Buffer> triangleBuffer;
std::shared_ptr<opal::Buffer> materialBuffer;
std::shared_ptr<opal::PrimitiveAccelerationStructure> sceneBLAS;
std::shared_ptr<opal::InstanceAccelerationStructure> sceneTLAS;
bool accelerationStructureDirty = false;

/** @brief Active probe-space definition used for DDGI dispatch. */
std::shared_ptr<ProbeSpace> probeSpace;

Expand Down
208 changes: 179 additions & 29 deletions photon/gi.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -29,7 +29,44 @@
#ifdef METAL
namespace {
constexpr int kDdgiMaterialTextureUnitStart = 10;
constexpr int kDdgiMaxMaterialTextures = 24;
constexpr int kDdgiMaxMaterialTextures = 48;
constexpr int kDdgiSkyboxTextureUnit = 60;
constexpr int kDdgiPreviousIrradianceTextureUnit = 61;

std::shared_ptr<opal::Texture> createDdgiFallbackSkyboxTexture() {
constexpr unsigned char value[4] = {0, 0, 0, 255};
const unsigned char *faces[6] = {value, value, value, value, value, value};
auto texture = opal::Texture::create(
opal::TextureType::TextureCubeMap, opal::TextureFormat::Rgba8, 1, 1,
opal::TextureDataFormat::Rgba, nullptr, 1);
texture->setFilterMode(opal::TextureFilterMode::Linear,
opal::TextureFilterMode::Linear);
texture->setWrapMode(opal::TextureAxis::S,
opal::TextureWrapMode::ClampToEdge);
texture->setWrapMode(opal::TextureAxis::T,
opal::TextureWrapMode::ClampToEdge);
texture->setWrapMode(opal::TextureAxis::R,
opal::TextureWrapMode::ClampToEdge);
for (int face = 0; face < 6; ++face) {
texture->updateFace(face, faces[face], 1, 1,
opal::TextureDataFormat::Rgba);
}
return texture;
}

void clearDdgiTexture(const std::shared_ptr<Texture> &texture) {
if (texture == nullptr || texture->texture == nullptr ||
texture->creationData.width <= 0 || texture->creationData.height <= 0) {
return;
}
std::vector<float> zeros(
static_cast<size_t>(texture->creationData.width) *
static_cast<size_t>(texture->creationData.height) * 4,
0.0f);
texture->texture->updateData(zeros.data(), texture->creationData.width,
texture->creationData.height,
opal::TextureDataFormat::Rgba);
}

int registerMaterialTextureSlot(
const Texture &texture,
Expand Down Expand Up @@ -251,6 +288,19 @@ void photon::GlobalIllumination::init() {
Texture::create(512, 512, opal::TextureFormat::Rgba16F,
opal::TextureDataFormat::Rgba, TextureType::Color));

distanceMap = std::make_shared<Texture>(
Texture::create(512, 512, opal::TextureFormat::Rgba16F,
opal::TextureDataFormat::Rgba, TextureType::Color));

distanceMapPrev = std::make_shared<Texture>(
Texture::create(512, 512, opal::TextureFormat::Rgba16F,
opal::TextureDataFormat::Rgba, TextureType::Color));

clearDdgiTexture(irradianceMap);
clearDdgiTexture(irradianceMapPrev);
clearDdgiTexture(distanceMap);
clearDdgiTexture(distanceMapPrev);

giPipeline = opal::Pipeline::create();
giPipeline->setShaderProgram(giWriteShader->shader);
giPipeline->setComputeThreadgroupSize(8, 8, 1);
Expand Down Expand Up @@ -299,7 +349,9 @@ void photon::GlobalIllumination::updateProbeLayout() {
probeSpace->probeResolution, probeSpace->textureBorderSize);
if (hasCachedLayoutSignature && cachedLayoutSignature == layoutSignature &&
probeRadianceBuffer != nullptr && irradianceMap != nullptr &&
irradianceMapPrev != nullptr) {
irradianceMapPrev != nullptr && distanceMap != nullptr &&
distanceMapPrev != nullptr && triangleBuffer != nullptr &&
materialBuffer != nullptr && sceneBLAS != nullptr) {
return;
}
cachedLayoutSignature = layoutSignature;
Expand All @@ -311,6 +363,14 @@ void photon::GlobalIllumination::updateProbeLayout() {
materials.reserve(ddgiObjects.size());
std::unordered_map<uint64_t, int> textureSlots;

for (auto *object : ddgiObjects) {
if (object == nullptr || !object->canUseDeferredRendering()) {
continue;
}
findTextureSlotForType(object->textures, TextureType::Color,
materialTextures, textureSlots);
}

for (auto *object : ddgiObjects) {
if (object == nullptr || !object->canUseDeferredRendering()) {
continue;
Expand All @@ -323,11 +383,7 @@ void photon::GlobalIllumination::updateProbeLayout() {

const auto &indices = object->indices;
const bool useIndexBuffer = indices.size() >= 3;
glm::mat4 model(1.0f);
model = glm::translate(model, object->getPosition().toGlm());
model *=
glm::mat4_cast(glm::normalize(object->getRotation().toGlmQuat()));
model = glm::scale(model, object->getScale().toGlm());
glm::mat4 model = object->model;
glm::mat3 linearMatrix = glm::mat3(model);
glm::mat3 normalMatrix = glm::transpose(glm::inverse(glm::mat3(model)));

Expand Down Expand Up @@ -458,6 +514,48 @@ void photon::GlobalIllumination::updateProbeLayout() {
}
}

if (hasGeometry) {
glm::vec3 rawExtent = glm::max(boundsMax - boundsMin, glm::vec3(0.0f));
spacing = std::max(spacing, std::max(rawExtent.x, std::max(rawExtent.y,
rawExtent.z)) /
15.0f);
}

std::vector<opal::PrimitiveVertex> accelerationVertices;
std::vector<uint32_t> accelerationIndices;
accelerationVertices.reserve(triangles.size() * 3);
accelerationIndices.reserve(triangles.size() * 3);
for (const auto &triangle : triangles) {
const glm::vec4 positions[3] = {triangle.v0, triangle.v1, triangle.v2};
for (const auto &position : positions) {
opal::PrimitiveVertex vertex{};
vertex.position[0] = position.x;
vertex.position[1] = position.y;
vertex.position[2] = position.z;
accelerationIndices.push_back(
static_cast<uint32_t>(accelerationVertices.size()));
accelerationVertices.push_back(vertex);
}
}
if (!accelerationVertices.empty()) {
sceneBLAS = opal::PrimitiveAccelerationStructure::create(
accelerationVertices, accelerationIndices);
sceneTLAS.reset();
accelerationStructureDirty = true;
triangleBuffer = opal::Buffer::create(
opal::BufferUsage::ShaderRead,
triangles.size() * sizeof(DDGITriangle), triangles.data());
materialBuffer = opal::Buffer::create(
opal::BufferUsage::ShaderRead,
materials.size() * sizeof(DDGIMaterial), materials.data());
} else {
sceneBLAS.reset();
sceneTLAS.reset();
triangleBuffer.reset();
materialBuffer.reset();
accelerationStructureDirty = false;
}

float layoutPad = spacing * 0.25f;
Position3d minWs = hasGeometry ? Position3d(boundsMin.x - layoutPad,
boundsMin.y - layoutPad,
Expand Down Expand Up @@ -498,7 +596,10 @@ void photon::GlobalIllumination::updateProbeLayout() {
static_cast<int>(std::ceil(std::sqrt((float)totalProbeCount))), 1, 64);

probeSpace->originWorldSpace = minWs;
probeSpace->spacing = Position3d(spacing, spacing, spacing);
probeSpace->spacing = Position3d(
Nx > 1 ? extent.x / static_cast<float>(Nx - 1) : spacing,
Ny > 1 ? extent.y / static_cast<float>(Ny - 1) : spacing,
Nz > 1 ? extent.z / static_cast<float>(Nz - 1) : spacing);
probeSpace->probeCount = Vector3((float)Nx, (float)Ny, (float)Nz);
probeSpace->probesPerRow = probesPerRow;

Expand All @@ -522,7 +623,8 @@ void photon::GlobalIllumination::updateProbeLayout() {

const int atlasW = std::max(1, probeSpace->atlasWidth());
const int atlasH = std::max(1, probeSpace->atlasHeight());
bool needCreate = !irradianceMap || !irradianceMapPrev;
bool needCreate = !irradianceMap || !irradianceMapPrev || !distanceMap ||
!distanceMapPrev;
bool sizeChanged =
!needCreate && (irradianceMap->creationData.width != atlasW ||
irradianceMap->creationData.height != atlasH);
Expand All @@ -535,6 +637,16 @@ void photon::GlobalIllumination::updateProbeLayout() {
irradianceMapPrev = std::make_shared<Texture>(
Texture::create(atlasW, atlasH, opal::TextureFormat::Rgba16F,
opal::TextureDataFormat::Rgba, TextureType::Color));
distanceMap = std::make_shared<Texture>(
Texture::create(atlasW, atlasH, opal::TextureFormat::Rgba16F,
opal::TextureDataFormat::Rgba, TextureType::Color));
distanceMapPrev = std::make_shared<Texture>(
Texture::create(atlasW, atlasH, opal::TextureFormat::Rgba16F,
opal::TextureDataFormat::Rgba, TextureType::Color));
clearDdgiTexture(irradianceMap);
clearDdgiTexture(irradianceMapPrev);
clearDdgiTexture(distanceMap);
clearDdgiTexture(distanceMapPrev);
}

int effectiveRaysPerProbe = std::max(1, raysPerProbe);
Expand All @@ -560,19 +672,36 @@ void photon::GlobalIllumination::render(
probeRadianceBuffer == nullptr || irradianceMap == nullptr ||
irradianceMapPrev == nullptr || irradianceMap->texture == nullptr ||
irradianceMapPrev->texture == nullptr ||
distanceMap == nullptr || distanceMapPrev == nullptr ||
distanceMap->texture == nullptr || distanceMapPrev->texture == nullptr ||
triangleBuffer == nullptr || materialBuffer == nullptr ||
sceneBLAS == nullptr ||
copySrcFramebuffer == nullptr || copyDstFramebuffer == nullptr) {
return;
}

if (accelerationStructureDirty) {
commandBuffer->buildPrimitiveAccelerationStructure(sceneBLAS);
opal::AccelerationStructureInstance instance{};
instance.blas = sceneBLAS;
instance.transform = glm::mat4(1.0f);
instance.instanceId = 0;
instance.mask = 0xFF;
instance.cullDisable = true;
sceneTLAS = opal::InstanceAccelerationStructure::create({instance});
commandBuffer->buildInstanceAccelerationStructure(sceneTLAS);
accelerationStructureDirty = false;
}
if (sceneTLAS == nullptr || !sceneTLAS->isBuilt) {
return;
}

const uint totalProbes =
static_cast<uint>(std::max(1, this->probeSpace->totalProbes()));
const uint requestedRays =
static_cast<uint>(std::max(1, this->raysPerProbe));
const uint effectiveRays = std::max(1u, requestedRays);
uint updateStride = static_cast<uint>(std::max(1, this->probeUpdateStride));
if (frameIndex < static_cast<int>(updateStride) + 2) {
updateStride = 1u;
}
uint updateOffset =
(updateStride > 1u)
? static_cast<uint>(std::max(0, frameIndex)) % updateStride
Expand All @@ -597,6 +726,11 @@ void photon::GlobalIllumination::render(
auto copy = opal::ResolveAction::createForColorAttachment(
copySrcFramebuffer, copyDstFramebuffer, 0);
commandBuffer->performResolve(copy);
copySrcFramebuffer->attachTexture(distanceMap->texture, 0);
copyDstFramebuffer->attachTexture(distanceMapPrev->texture, 0);
copy = opal::ResolveAction::createForColorAttachment(
copySrcFramebuffer, copyDstFramebuffer, 0);
commandBuffer->performResolve(copy);

// Perform Ray Tracing
giRaytracingPipeline->bindShaderReadWriteBuffer("probeRadianceOut",
Expand Down Expand Up @@ -754,23 +888,8 @@ void photon::GlobalIllumination::render(
areaLights.empty() ? sizeof(GPUAreaLight)
: areaLights.size() * sizeof(GPUAreaLight));

DDGITriangle fallbackTriangle{};
DDGIMaterial fallbackMaterial{};
const void *triangleData =
triangles.empty() ? static_cast<const void *>(&fallbackTriangle)
: static_cast<const void *>(triangles.data());
const size_t triangleSize = triangles.empty()
? sizeof(DDGITriangle)
: triangles.size() * sizeof(DDGITriangle);
const void *materialData =
materials.empty() ? static_cast<const void *>(&fallbackMaterial)
: static_cast<const void *>(materials.data());
const size_t materialSize = materials.empty()
? sizeof(DDGIMaterial)
: materials.size() * sizeof(DDGIMaterial);
giRaytracingPipeline->bindBufferData("tris", triangleData, triangleSize);
giRaytracingPipeline->bindBufferData("materials", materialData,
materialSize);
giRaytracingPipeline->bindBuffer("tris", triangleBuffer, 1);
giRaytracingPipeline->bindBuffer("materials", materialBuffer, 2);

struct GPUSceneCounts {
uint32_t triCount;
Expand Down Expand Up @@ -805,6 +924,31 @@ void photon::GlobalIllumination::render(
kDdgiMaterialTextureUnitStart + i);
}

static std::shared_ptr<opal::Texture> fallbackSkybox = nullptr;
if (fallbackSkybox == nullptr) {
fallbackSkybox = createDdgiFallbackSkyboxTexture();
}
std::shared_ptr<opal::Texture> skyboxTexture = fallbackSkybox;
int useSkybox = 0;
glm::vec3 skyColor(0.12f, 0.14f, 0.18f);
if (scene != nullptr) {
auto skybox = scene->getSkybox();
if (skybox != nullptr && skybox->cubemap.texture != nullptr) {
skyboxTexture = skybox->cubemap.texture;
useSkybox = 1;
} else if (scene->atmosphere.isEnabled()) {
Color atmosphereColor = scene->atmosphere.getLightColor();
skyColor = glm::vec3(atmosphereColor.r, atmosphereColor.g,
atmosphereColor.b) *
std::max(scene->atmosphere.getLightIntensity(), 0.0f);
}
}
giRaytracingPipeline->bindTexture("skybox", skyboxTexture,
kDdgiSkyboxTextureUnit);
giRaytracingPipeline->bindTexture("previousIrradiance",
irradianceMapPrev->texture,
kDdgiPreviousIrradianceTextureUnit);

giRaytracingPipeline->setUniform3f(
"ps.origin", probeSpace->originWorldSpace.x,
probeSpace->originWorldSpace.y, probeSpace->originWorldSpace.z);
Expand Down Expand Up @@ -837,15 +981,21 @@ void photon::GlobalIllumination::render(
static_cast<int>(updateStride));
giRaytracingPipeline->setUniform1i("rt.probeUpdateCount",
static_cast<int>(activeProbeCount));
giRaytracingPipeline->setUniform3f("rt.skyColor", skyColor.x, skyColor.y,
skyColor.z);
giRaytracingPipeline->setUniform1i("rt.useSkybox", useSkybox);

commandBuffer->bindPipeline(giRaytracingPipeline);
commandBuffer->bindInstanceAccelerationStructure(sceneTLAS, 10);
commandBuffer->dispatch(totalRays, 1, 1);

commandBuffer->computeBarrier();

// Write to irradiance texture
giPipeline->bindTexture("outTexture", irradianceMap->texture, 0);
giPipeline->bindTexture("prevTexture", irradianceMapPrev->texture, 1);
giPipeline->bindTexture("outDistance", distanceMap->texture, 2);
giPipeline->bindTexture("prevDistance", distanceMapPrev->texture, 3);

giPipeline->bindBuffer("probeRadiance", this->probeRadianceBuffer);

Expand Down
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