[hdEmbree] Initial UsdLux reference implementation

This modifies the hdEmbree example plugin to do direct lighting so as to provide a reference implementation of the expected behaviour for UsdLux. If no lights are present in the stage, the old ambient occlusion path will be used.
PixarAnimationStudios · Aug 1, 2024 · a6a9136 · a6a9136
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Showing 8 changed files with 987 additions and 65 deletions.
diff --git a/pxr/imaging/plugin/hdEmbree/CMakeLists.txt b/pxr/imaging/plugin/hdEmbree/CMakeLists.txt
@@ -31,6 +31,7 @@ pxr_plugin(hdEmbree
     PUBLIC_CLASSES
         config
         instancer
+        light
         mesh
         meshSamplers
         renderBuffer

diff --git a/pxr/imaging/plugin/hdEmbree/light.cpp b/pxr/imaging/plugin/hdEmbree/light.cpp
@@ -0,0 +1,171 @@
+//
+// Copyright 2024 Pixar
+//
+// Licensed under the terms set forth in the LICENSE.txt file available at
+// https://openusd.org/license.
+//
+#include "pxr/imaging/plugin/hdEmbree/light.h"
+
+#include "light.h"
+#include "pxr/imaging/plugin/hdEmbree/debugCodes.h"
+#include "pxr/imaging/plugin/hdEmbree/renderParam.h"
+#include "pxr/imaging/plugin/hdEmbree/renderer.h"
+
+#include "pxr/imaging/hd/sceneDelegate.h"
+#include "pxr/imaging/hio/image.h"
+
+#include <embree3/rtcore_buffer.h>
+#include <embree3/rtcore_scene.h>
+
+#include <fstream>
+#include <sstream>
+#include <vector>
+
+PXR_NAMESPACE_OPEN_SCOPE
+
+HdEmbree_Light::HdEmbree_Light(SdfPath const& id, TfToken const& lightType)
+    : HdLight(id) {
+    if (id.IsEmpty()) {
+        return;
+    }
+
+    // Set the variant to the right type - Sync will fill rest of data
+    if (lightType == HdSprimTypeTokens->cylinderLight) {
+        _lightData.lightVariant = HdEmbree_Cylinder();
+    } else if (lightType == HdSprimTypeTokens->diskLight) {
+        _lightData.lightVariant = HdEmbree_Disk();
+    } else if (lightType == HdSprimTypeTokens->rectLight) {
+        // Get shape parameters
+        _lightData.lightVariant = HdEmbree_Rect();
+    } else if (lightType == HdSprimTypeTokens->sphereLight) {
+        _lightData.lightVariant = HdEmbree_Sphere();
+    } else {
+        TF_WARN("HdEmbree - Unrecognized light type: %s", lightType.GetText());
+        _lightData.lightVariant = HdEmbree_UnknownLight();
+    }
+}
+
+HdEmbree_Light::~HdEmbree_Light() = default;
+
+void
+HdEmbree_Light::Sync(HdSceneDelegate *sceneDelegate,
+                         HdRenderParam *renderParam, HdDirtyBits *dirtyBits)
+{
+    HD_TRACE_FUNCTION();
+    HF_MALLOC_TAG_FUNCTION();
+
+    HdEmbreeRenderParam *embreeRenderParam =
+        static_cast<HdEmbreeRenderParam*>(renderParam);
+
+    // calling this bumps the scene version and causes a re-render
+    embreeRenderParam->AcquireSceneForEdit();
+
+    SdfPath const& id = GetId();
+
+    // Get _lightData's transform. We'll only consider the first time sample for now
+    HdTimeSampleArray<GfMatrix4d, 1> xformSamples;
+    sceneDelegate->SampleTransform(id, &xformSamples);
+    _lightData.xformLightToWorld = GfMatrix4f(xformSamples.values[0]);
+    _lightData.xformWorldToLight = _lightData.xformLightToWorld.GetInverse();
+    _lightData.normalXformLightToWorld =
+        _lightData.xformWorldToLight.ExtractRotationMatrix().GetTranspose();
+
+    // Store luminance parameters
+    _lightData.intensity = sceneDelegate->GetLightParamValue(
+        id, HdLightTokens->intensity).GetWithDefault(1.0f);
+    _lightData.exposure = sceneDelegate->GetLightParamValue(
+        id, HdLightTokens->exposure).GetWithDefault(0.0f);
+    _lightData.color = sceneDelegate->GetLightParamValue(
+        id, HdLightTokens->color).GetWithDefault(GfVec3f{1.0f, 1.0f, 1.0f});
+    _lightData.normalize = sceneDelegate->GetLightParamValue(
+        id, HdLightTokens->normalize).GetWithDefault(false);
+    _lightData.colorTemperature = sceneDelegate->GetLightParamValue(
+        id, HdLightTokens->colorTemperature).GetWithDefault(6500.0f);
+    _lightData.enableColorTemperature = sceneDelegate->GetLightParamValue(
+        id, HdLightTokens->enableColorTemperature).GetWithDefault(false);
+
+    // Get visibility
+    _lightData.visible = sceneDelegate->GetVisible(id);
+
+    // Switch on the _lightData type and pull the relevant attributes from the scene
+    // delegate
+    std::visit([this, &id, &sceneDelegate](auto& typedLight) {
+        using T = std::decay_t<decltype(typedLight)>;
+        if constexpr (std::is_same_v<T, HdEmbree_UnknownLight>) {
+            // Do nothing
+        } else if constexpr (std::is_same_v<T, HdEmbree_Cylinder>) {
+            typedLight = HdEmbree_Cylinder{
+                sceneDelegate->GetLightParamValue(id, HdLightTokens->radius)
+                    .GetWithDefault(0.5f),
+                sceneDelegate->GetLightParamValue(id, HdLightTokens->length)
+                    .GetWithDefault(1.0f),
+            };
+        } else if constexpr (std::is_same_v<T, HdEmbree_Disk>) {
+            typedLight = HdEmbree_Disk{
+                sceneDelegate->GetLightParamValue(id, HdLightTokens->radius)
+                    .GetWithDefault(0.5f),
+            };
+        } else if constexpr (std::is_same_v<T, HdEmbree_Rect>) {
+            typedLight = HdEmbree_Rect{
+                sceneDelegate->GetLightParamValue(id, HdLightTokens->width)
+                    .Get<float>(),
+                sceneDelegate->GetLightParamValue(id, HdLightTokens->height)
+                    .Get<float>(),
+            };
+        } else if constexpr (std::is_same_v<T, HdEmbree_Sphere>) {
+            typedLight = HdEmbree_Sphere{
+                sceneDelegate->GetLightParamValue(id, HdLightTokens->radius)
+                    .GetWithDefault(0.5f),
+            };
+        } else {
+            static_assert(false, "non-exhaustive _LightVariant visitor");
+        }
+    }, _lightData.lightVariant);
+
+    if (const auto value = sceneDelegate->GetLightParamValue(
+            id, HdLightTokens->shapingFocus);
+        value.IsHolding<float>()) {
+        _lightData.shaping.focus = value.UncheckedGet<float>();
+    }
+
+    if (const auto value = sceneDelegate->GetLightParamValue(
+            id, HdLightTokens->shapingFocusTint);
+        value.IsHolding<GfVec3f>()) {
+        _lightData.shaping.focusTint = value.UncheckedGet<GfVec3f>();
+    }
+
+    if (const auto value = sceneDelegate->GetLightParamValue(
+            id, HdLightTokens->shapingConeAngle);
+        value.IsHolding<float>()) {
+        _lightData.shaping.coneAngle = value.UncheckedGet<float>();
+    }
+
+    if (const auto value = sceneDelegate->GetLightParamValue(
+            id, HdLightTokens->shapingConeSoftness);
+        value.IsHolding<float>()) {
+        _lightData.shaping.coneSoftness = value.UncheckedGet<float>();
+    }
+
+    HdEmbreeRenderer *renderer = embreeRenderParam->GetRenderer();
+    renderer->AddLight(id, this);
+
+    *dirtyBits &= ~HdLight::AllDirty;
+}
+
+HdDirtyBits
+HdEmbree_Light::GetInitialDirtyBitsMask() const
+{
+    return HdLight::AllDirty;
+}
+
+void
+HdEmbree_Light::Finalize(HdRenderParam *renderParam)
+{
+    auto* embreeParam = static_cast<HdEmbreeRenderParam*>(renderParam);
+
+    // Remove from renderer's light map
+    HdEmbreeRenderer *renderer = embreeParam->GetRenderer();
+    renderer->RemoveLight(GetId(), this);
+}
+
+PXR_NAMESPACE_CLOSE_SCOPE
diff --git a/pxr/imaging/plugin/hdEmbree/light.h b/pxr/imaging/plugin/hdEmbree/light.h
@@ -0,0 +1,109 @@
+//
+// Copyright 2024 Pixar
+//
+// Licensed under the terms set forth in the LICENSE.txt file available at
+// https://openusd.org/license.
+//
+#ifndef PXR_IMAGING_PLUGIN_HD_EMBREE_LIGHT_H
+#define PXR_IMAGING_PLUGIN_HD_EMBREE_LIGHT_H
+
+#include "pxr/base/gf/vec3f.h"
+#include "pxr/base/gf/matrix3f.h"
+#include "pxr/base/gf/matrix4f.h"
+#include "pxr/imaging/hd/light.h"
+
+#include <embree3/rtcore_common.h>
+#include <embree3/rtcore_geometry.h>
+
+#include <limits>
+#include <variant>
+
+PXR_NAMESPACE_OPEN_SCOPE
+
+class HdEmbreeRenderer;
+
+struct HdEmbree_UnknownLight
+{};
+struct HdEmbree_Cylinder
+{
+    float radius;
+    float length;
+};
+
+struct HdEmbree_Disk
+{
+    float radius;
+};
+
+struct HdEmbree_Rect
+{
+    float width;
+    float height;
+};
+
+struct HdEmbree_Sphere
+{
+    float radius;
+};
+
+using HdEmbree_LightVariant = std::variant<
+    HdEmbree_UnknownLight,
+    HdEmbree_Cylinder,
+    HdEmbree_Disk,
+    HdEmbree_Rect,
+    HdEmbree_Sphere>;
+
+struct HdEmbree_Shaping
+{
+    GfVec3f focusTint;
+    float focus = 0.0f;
+    float coneAngle = 180.0f;
+    float coneSoftness = 0.0f;
+};
+
+struct HdEmbree_LightData
+{
+    GfMatrix4f xformLightToWorld;
+    GfMatrix3f normalXformLightToWorld;
+    GfMatrix4f xformWorldToLight;
+    GfVec3f color;
+    float intensity = 1.0f;
+    float exposure = 0.0f;
+    float colorTemperature = 6500.0f;
+    bool enableColorTemperature = false;
+    HdEmbree_LightVariant lightVariant;
+    bool normalize = false;
+    bool visible = true;
+    HdEmbree_Shaping shaping;
+};
+
+class HdEmbree_Light final : public HdLight
+{
+public:
+    HdEmbree_Light(SdfPath const& id, TfToken const& lightType);
+    ~HdEmbree_Light();
+
+    /// Synchronizes state from the delegate to this object.
+    void Sync(HdSceneDelegate* sceneDelegate,
+              HdRenderParam* renderParam,
+              HdDirtyBits* dirtyBits) override;
+
+    /// Returns the minimal set of dirty bits to place in the
+    /// change tracker for use in the first sync of this prim.
+    /// Typically this would be all dirty bits.
+    HdDirtyBits GetInitialDirtyBitsMask() const override;
+
+    void Finalize(HdRenderParam *renderParam) override;
+
+    HdEmbree_LightData const& LightData() const {
+        return _lightData;
+    }
+
+private:
+    HdEmbree_LightData _lightData;
+};
+
+
+PXR_NAMESPACE_CLOSE_SCOPE
+
+#endif
diff --git a/pxr/imaging/plugin/hdEmbree/renderBuffer.h b/pxr/imaging/plugin/hdEmbree/renderBuffer.h
@@ -166,7 +166,7 @@ class HdEmbreeRenderBuffer : public HdRenderBuffer
     // For multisampled buffers: the input write buffer.
     std::vector<uint8_t> _sampleBuffer;
     // For multisampled buffers: the sample count buffer.
-    std::vector<uint8_t> _sampleCount;
+    std::vector<uint32_t> _sampleCount;
 
     // The number of callers mapping this buffer.
     std::atomic<int> _mappers;

diff --git a/pxr/imaging/plugin/hdEmbree/renderDelegate.cpp b/pxr/imaging/plugin/hdEmbree/renderDelegate.cpp
@@ -8,6 +8,7 @@
 
 #include "pxr/imaging/plugin/hdEmbree/config.h"
 #include "pxr/imaging/plugin/hdEmbree/instancer.h"
+#include "pxr/imaging/plugin/hdEmbree/light.h"
 #include "pxr/imaging/plugin/hdEmbree/renderParam.h"
 #include "pxr/imaging/plugin/hdEmbree/renderPass.h"
 
@@ -35,6 +36,10 @@ const TfTokenVector HdEmbreeRenderDelegate::SUPPORTED_SPRIM_TYPES =
 {
     HdPrimTypeTokens->camera,
     HdPrimTypeTokens->extComputation,
+    HdPrimTypeTokens->cylinderLight,
+    HdPrimTypeTokens->diskLight,
+    HdPrimTypeTokens->rectLight,
+    HdPrimTypeTokens->sphereLight,
 };
 
 const TfTokenVector HdEmbreeRenderDelegate::SUPPORTED_BPRIM_TYPES =
@@ -147,7 +152,7 @@ HdEmbreeRenderDelegate::_Initialize()
     // Store top-level embree objects inside a render param that can be
     // passed to prims during Sync(). Also pass a handle to the render thread.
     _renderParam = std::make_shared<HdEmbreeRenderParam>(
-        _rtcDevice, _rtcScene, &_renderThread, &_sceneVersion);
+        _rtcDevice, _rtcScene, &_renderThread, &_renderer, &_sceneVersion);
 
     // Pass the scene handle to the renderer.
     _renderer.SetScene(_rtcScene);
@@ -230,7 +235,7 @@ HdAovDescriptor
 HdEmbreeRenderDelegate::GetDefaultAovDescriptor(TfToken const& name) const
 {
     if (name == HdAovTokens->color) {
-        return HdAovDescriptor(HdFormatUNorm8Vec4, true,
+        return HdAovDescriptor(HdFormatFloat32Vec4, true,
                                VtValue(GfVec4f(0.0f)));
     } else if (name == HdAovTokens->normal || name == HdAovTokens->Neye) {
         return HdAovDescriptor(HdFormatFloat32Vec3, false,
@@ -331,6 +336,12 @@ HdEmbreeRenderDelegate::CreateSprim(TfToken const& typeId,
         return new HdCamera(sprimId);
     } else if (typeId == HdPrimTypeTokens->extComputation) {
         return new HdExtComputation(sprimId);
+    } else if (typeId == HdPrimTypeTokens->light ||
+               typeId == HdPrimTypeTokens->diskLight ||
+               typeId == HdPrimTypeTokens->rectLight ||
+               typeId == HdPrimTypeTokens->sphereLight ||
+               typeId == HdPrimTypeTokens->cylinderLight) {
+        return new HdEmbree_Light(sprimId, typeId);
     } else {
         TF_CODING_ERROR("Unknown Sprim Type %s", typeId.GetText());
     }
@@ -347,6 +358,12 @@ HdEmbreeRenderDelegate::CreateFallbackSprim(TfToken const& typeId)
         return new HdCamera(SdfPath::EmptyPath());
     } else if (typeId == HdPrimTypeTokens->extComputation) {
         return new HdExtComputation(SdfPath::EmptyPath());
+    } else if (typeId == HdPrimTypeTokens->light ||
+               typeId == HdPrimTypeTokens->diskLight ||
+               typeId == HdPrimTypeTokens->rectLight ||
+               typeId == HdPrimTypeTokens->sphereLight ||
+               typeId == HdPrimTypeTokens->cylinderLight) {
+        return new HdEmbree_Light(SdfPath::EmptyPath(), typeId);
     } else {
         TF_CODING_ERROR("Unknown Sprim Type %s", typeId.GetText());
     }