[hdEmbree] add light texture support

pxr/imaging/plugin/hdEmbree/CMakeLists.txt

@@ -46,6 +46,7 @@ pxr_plugin(hdEmbree
         renderParam.h
 
     PRIVATE_CLASSES
+        debugCodes
         implicitSurfaceSceneIndexPlugin
 
     RESOURCE_FILES

pxr/imaging/plugin/hdEmbree/debugCodes.cpp

@@ -0,0 +1,20 @@
+//
+// Copyright 2024 Pixar
+//
+// Licensed under the terms set forth in the LICENSE.txt file available at
+// https://openusd.org/license.
+//
+#include "pxr/pxr.h"
+#include "pxr/imaging/plugin/hdEmbree/debugCodes.h"
+
+#include "pxr/base/tf/debug.h"
+#include "pxr/base/tf/registryManager.h"
+
+PXR_NAMESPACE_OPEN_SCOPE
+
+TF_REGISTRY_FUNCTION(TfDebug)
+{
+    TF_DEBUG_ENVIRONMENT_SYMBOL(HDEMBREE_LIGHT_CREATE, "Creation of HdEmbree lights");
+}
+
+PXR_NAMESPACE_CLOSE_SCOPE

pxr/imaging/plugin/hdEmbree/debugCodes.h

@@ -0,0 +1,21 @@
+//
+// 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_DEBUG_CODES_H
+#define PXR_IMAGING_PLUGIN_HD_EMBREE_DEBUG_CODES_H
+
+#include "pxr/pxr.h"
+#include "pxr/base/tf/debug.h"
+
+PXR_NAMESPACE_OPEN_SCOPE
+
+TF_DEBUG_CODES(
+    HDEMBREE_LIGHT_CREATE
+);
+
+PXR_NAMESPACE_CLOSE_SCOPE
+
+#endif // PXR_IMAGING_PLUGIN_HD_EMBREE_DEBUG_CODES_H

pxr/imaging/plugin/hdEmbree/light.cpp

@@ -21,6 +21,61 @@
 #include <sstream>
 #include <vector>
 
+namespace {
+
+PXR_NAMESPACE_USING_DIRECTIVE
+
+HdEmbree_LightTexture
+_LoadLightTexture(std::string const& path)
+{
+    if (path.empty()) {
+        return HdEmbree_LightTexture();
+    }
+
+    HioImageSharedPtr img = HioImage::OpenForReading(path);
+    if (!img) {
+        return HdEmbree_LightTexture();
+    }
+
+    int width = img->GetWidth();
+    int height = img->GetHeight();
+
+    std::vector<GfVec3f> pixels(width * height * 3.0f);
+
+    HioImage::StorageSpec storage;
+    storage.width = width;
+    storage.height = height;
+    storage.depth = 1;
+    storage.format = HioFormatFloat32Vec3;
+    storage.data = &pixels.front();
+
+    if (img->Read(storage)) {
+        return {std::move(pixels), width, height};
+    }
+    TF_WARN("Could not read image %s", path.c_str());
+    return { std::vector<GfVec3f>(), 0, 0 };
+}
+
+
+void
+_SyncLightTexture(const SdfPath& id, HdEmbree_LightData& light, HdSceneDelegate *sceneDelegate)
+{
+    std::string path;
+    if (VtValue textureValue = sceneDelegate->GetLightParamValue(
+            id, HdLightTokens->textureFile);
+        textureValue.IsHolding<SdfAssetPath>()) {
+        SdfAssetPath texturePath =
+            textureValue.UncheckedGet<SdfAssetPath>();
+        path = texturePath.GetResolvedPath();
+        if (path.empty()) {
+            path = texturePath.GetAssetPath();
+        }
+    }
+    light.texture = _LoadLightTexture(path);
+}
+
+
+} // anonymous namespace
 PXR_NAMESPACE_OPEN_SCOPE
 
 HdEmbree_Light::HdEmbree_Light(SdfPath const& id, TfToken const& lightType)
@@ -29,6 +84,8 @@ HdEmbree_Light::HdEmbree_Light(SdfPath const& id, TfToken const& lightType)
         return;
     }
 
+    TF_DEBUG(HDEMBREE_LIGHT_CREATE).Msg("Creating light %s: %s\n", id.GetText(), lightType.GetText());
+
     // Set the variant to the right type - Sync will fill rest of data
     if (lightType == HdSprimTypeTokens->cylinderLight) {
         _lightData.lightVariant = HdEmbree_Cylinder();
@@ -73,6 +130,8 @@ HdEmbree_Light::Sync(HdSceneDelegate *sceneDelegate,
     // Store luminance parameters
     _lightData.intensity = sceneDelegate->GetLightParamValue(
         id, HdLightTokens->intensity).GetWithDefault(1.0f);
+    _lightData.diffuse = sceneDelegate->GetLightParamValue(
+        id, HdLightTokens->diffuse).GetWithDefault(1.0f);
     _lightData.exposure = sceneDelegate->GetLightParamValue(
         id, HdLightTokens->exposure).GetWithDefault(0.0f);
     _lightData.color = sceneDelegate->GetLightParamValue(
@@ -112,6 +171,7 @@ HdEmbree_Light::Sync(HdSceneDelegate *sceneDelegate,
                 sceneDelegate->GetLightParamValue(id, HdLightTokens->height)
                     .Get<float>(),
             };
+            _SyncLightTexture(id, _lightData, sceneDelegate);
         } else if constexpr (std::is_same_v<T, HdEmbree_Sphere>) {
             typedLight = HdEmbree_Sphere{
                 sceneDelegate->GetLightParamValue(id, HdLightTokens->radius)

pxr/imaging/plugin/hdEmbree/light.h

@@ -53,6 +53,13 @@ using HdEmbree_LightVariant = std::variant<
     HdEmbree_Rect,
     HdEmbree_Sphere>;
 
+struct HdEmbree_LightTexture
+{
+    std::vector<GfVec3f> pixels;
+    int width = 0;
+    int height = 0;
+};
+
 struct HdEmbree_Shaping
 {
     GfVec3f focusTint;
@@ -67,7 +74,9 @@ struct HdEmbree_LightData
     GfMatrix3f normalXformLightToWorld;
     GfMatrix4f xformWorldToLight;
     GfVec3f color;
+    HdEmbree_LightTexture texture;
     float intensity = 1.0f;
+    float diffuse = 1.0f;
     float exposure = 0.0f;
     float colorTemperature = 6500.0f;
     bool enableColorTemperature = false;

pxr/imaging/plugin/hdEmbree/mesh.h

@@ -99,6 +99,11 @@ class HdEmbreeMesh final : public HdMesh {
     ///                      embree state.
     virtual void Finalize(HdRenderParam *renderParam) override;
 
+    bool EmbreeMeshIsDoubleSided() const
+    {
+        return _doubleSided;
+    }
+
 protected:
     // Initialize the given representation of this Rprim.
     // This is called prior to syncing the prim, the first time the repr

pxr/imaging/plugin/hdEmbree/renderer.cpp

@@ -246,6 +246,19 @@ struct _LightSample {
     float invPdfW;
 };
 
+GfVec3f
+_SampleLightTexture(HdEmbree_LightTexture const& texture, float s, float t)
+{
+    if (texture.pixels.empty()) {
+        return GfVec3f(0.0f);
+    }
+
+    int x = float(texture.width) * s;
+    int y = float(texture.height) * t;
+
+    return texture.pixels.at(y*texture.width + x);
+}
+
 _ShapeSample
 _SampleRect(GfMatrix4f const& xf, GfMatrix3f const& normalXform, float width,
             float height, float u1, float u2)
@@ -364,7 +377,9 @@ _SampleCylinder(GfMatrix4f const& xf, GfMatrix3f const& normalXform,
 GfVec3f
 _EvalLightBasic(HdEmbree_LightData const& light)
 {
-    GfVec3f Le = light.color * light.intensity * powf(2.0f, light.exposure);
+    // Our current material model is always 100% diffuse, so diffuse parameter
+    // is a stright multiplier
+    GfVec3f Le = light.color * light.intensity * light.diffuse * powf(2.0f, light.exposure);
     if (light.enableColorTemperature) {
         Le = GfCompMult(Le,
             _BlackbodyTemperatureAsRgb(light.colorTemperature));
@@ -393,6 +408,12 @@ _EvalAreaLight(HdEmbree_LightData const& light, _ShapeSample const& ss,
         _EvalLightBasic(light)
         : GfVec3f(0.0f);
 
+    // Multiply by the texture, if there is one
+    if (!light.texture.pixels.empty()) {
+        Le = GfCompMult(Le, _SampleLightTexture(light.texture, ss.uv[0],
+                                                1.0f - ss.uv[1]));
+    }
+
     // If normalize is enabled, we need to divide the luminance by the surface
     // area of the light, which for an area light is equivalent to multiplying
     // by the area pdf, which is itself the reciprocal of the surface area
@@ -1617,8 +1638,23 @@ HdEmbreeRenderer::_ComputeLighting(
         float vis = _Visibility(position, ls.wI, ls.dist * 0.99f);
 
         // Add exitant luminance
+        float cosOffNormal = GfDot(ls.wI, normal);
+        if (cosOffNormal < 0.0f) {
+            bool doubleSided = false;
+            HdEmbreeMesh *mesh =
+                dynamic_cast<HdEmbreeMesh*>(prototypeContext->rprim);
+            if (mesh) {
+                doubleSided = mesh->EmbreeMeshIsDoubleSided();
+            }
+
+            if (doubleSided) {
+                cosOffNormal *= -1.0f;
+            } else {
+                cosOffNormal = 0.0f;
+            }
+        }
         finalColor += ls.Li
-            * _DotZeroClip(ls.wI, normal)
+            * cosOffNormal
             * brdf
             * vis
             * ls.invPdfW;