p3d_pbrt-scenes/html/mtl.patch.txt

diff --git a/src/core/api.cpp b/src/core/api.cpp
index e0c4b4a..b275b85 100644
--- a/src/core/api.cpp
+++ b/src/core/api.cpp
@@ -234,6 +234,9 @@ static std::vector<uint32_t> pushedActiveTransformBits;
 static TransformCache transformCache;
 int catIndentCount = 0;
 
+static bool renderEachMaterial = getenv("PBRT_MTL_HACK");
+static std::map<std::string, std::shared_ptr<Material>>::iterator namedMaterialsIter;
+
 // API Forward Declarations
 std::vector<std::shared_ptr<Shape>> MakeShapes(const std::string &name,
                                                const Transform *ObjectToWorld,
@@ -1346,6 +1349,14 @@ void pbrtWorldEnd() {
     // Create scene and render
     if (PbrtOptions.cat || PbrtOptions.toPly) {
         printf("%*sWorldEnd\n", catIndentCount, "");
+    } else if (renderEachMaterial) {
+      for (namedMaterialsIter = graphicsState.namedMaterials.begin();
+           namedMaterialsIter != graphicsState.namedMaterials.end(); ++namedMaterialsIter) {
+        std::unique_ptr<Integrator> integrator(renderOptions->MakeIntegrator());
+        std::unique_ptr<Scene> scene(renderOptions->MakeScene());
+        if (scene && integrator) integrator->Render(*scene);
+      }
+      // TODO? render stuff with no material bound?
     } else {
         std::unique_ptr<Integrator> integrator(renderOptions->MakeIntegrator());
         std::unique_ptr<Scene> scene(renderOptions->MakeScene());
@@ -1371,13 +1382,24 @@ void pbrtWorldEnd() {
 }
 
 Scene *RenderOptions::MakeScene() {
-    std::shared_ptr<Primitive> accelerator =
-        MakeAccelerator(AcceleratorName, primitives, AcceleratorParams);
+    std::shared_ptr<Primitive> accelerator;
+    if (renderEachMaterial) {
+        std::vector<std::shared_ptr<Primitive>> filteredPrims;
+        std::copy_if(primitives.begin(), primitives.end(), std::back_inserter(filteredPrims),
+                     [](const std::shared_ptr<Primitive> &p) -> bool {
+                       return p->GetMaterial() == namedMaterialsIter->second.get();
+                     });
+        accelerator = MakeAccelerator(AcceleratorName, filteredPrims, AcceleratorParams);
+    } else {
+        accelerator = MakeAccelerator(AcceleratorName, primitives, AcceleratorParams);
+    }
     if (!accelerator) accelerator = std::make_shared<BVHAccel>(primitives);
     Scene *scene = new Scene(accelerator, lights);
-    // Erase primitives and lights from _RenderOptions_
-    primitives.erase(primitives.begin(), primitives.end());
-    lights.erase(lights.begin(), lights.end());
+    if (!renderEachMaterial) {
+      // Erase primitives and lights from _RenderOptions_
+      primitives.erase(primitives.begin(), primitives.end());
+      lights.erase(lights.begin(), lights.end());
+    }
     return scene;
 }
 
@@ -1427,7 +1449,17 @@ Integrator *RenderOptions::MakeIntegrator() const {
 
 Camera *RenderOptions::MakeCamera() const {
     std::unique_ptr<Filter> filter = MakeFilter(FilterName, FilterParams);
-    Film *film = MakeFilm(FilmName, FilmParams, std::move(filter));
+    Film *film = nullptr;
+    if (renderEachMaterial) {
+      ParamSet fp = FilmParams;
+      std::unique_ptr<std::string[]> fns(new std::string[1]);
+      fns[0] = namedMaterialsIter->first + ".exr";
+      fp.AddString("filename", std::move(fns), 1);
+      std::unique_ptr<Filter> box(new BoxFilter({0.5f, 0.5f}));
+      film = MakeFilm(FilmName, fp, std::move(box));
+    } else
+      film = MakeFilm(FilmName, FilmParams, std::move(filter));
+
     if (!film) {
         Error("Unable to create film.");
         return nullptr;