fix: material serialization

destrum/CMakeLists.txt

@@ -119,6 +119,7 @@ set(SRC_FILES
         "src/Serialization/SceneSerializer.cpp"
         "src/Serialization/ObjectSerialization.cpp"
         "src/Serialization/PrefabSerializer.cpp"
+        "src/Serialization/MaterialSerialization.cpp"
         "src/Serialization/PrefabCache.cpp"
         "src/Serialization/ComponentRegistry.cpp"
 

destrum/include/destrum/FS/AssetFS.h

@@ -32,6 +32,8 @@ public:
 
     [[nodiscard]] std::filesystem::path GetCookedPathForFile(std::string_view vpath) const;
 
+    [[nodiscard]] std::optional<std::string> ToVirtualPath(const std::filesystem::path& fullPath) const;
+
 private:
     static std::vector<uint8_t> ReadFile(const std::filesystem::path& fullPath);
 

destrum/include/destrum/Graphics/Caches/ImageCache.h

@@ -19,6 +19,13 @@ class ImageCache {
     friend class ResourcesInspector;
 
 public:
+    struct LoadedImageInfo {
+        std::filesystem::path path;
+        TextureIntent intent;
+        VkImageUsageFlags usage;
+        bool mipMap;
+    };
+
     explicit ImageCache(GfxDevice& gfxDevice);
 
     ImageID loadImageFromFile(
@@ -29,6 +36,7 @@ public:
     ImageID addImage(GPUImage image);
     ImageID addImage(ImageID id, GPUImage image);
     [[nodiscard]] const GPUImage& getImage(ImageID id) const;
+    [[nodiscard]] const LoadedImageInfo* findLoadedImageInfo(ImageID id) const;
     void removeImage(ImageID id);
 
     [[nodiscard]] ImageID getFreeImageId() const;
@@ -57,12 +65,6 @@ private:
     std::shared_ptr<std::vector<ImageID>> freeIds = std::make_shared<std::vector<ImageID>>();
     GfxDevice& gfxDevice;
 
-    struct LoadedImageInfo {
-        std::filesystem::path path;
-        TextureIntent intent;
-        VkImageUsageFlags usage;
-        bool mipMap;
-    };
     std::unordered_map<ImageID, LoadedImageInfo> loadedImagesInfo;
     ImageID errorImageId{NULL_IMAGE_ID};
 };

destrum/include/destrum/Graphics/Caches/MaterialCache.h

@@ -27,7 +27,7 @@ public:
 
     void cleanup(GfxDevice& gfxDevice);
 
-    MaterialID addMaterial(Material material);
+    MaterialID addMaterial(Material material, std::string key = {});
     MaterialID addSimpleColorMaterial(
         glm::vec3 color,
         std::string name = {});

destrum/include/destrum/Serialization/MaterialSerialization.h

@@ -0,0 +1,27 @@
+#ifndef DESTRUM_MATERIALSERIALIZATION_H
+#define DESTRUM_MATERIALSERIALIZATION_H
+
+#include <functional>
+#include <optional>
+#include <string>
+
+#include <nlohmann/json.hpp>
+
+#include <destrum/Graphics/Material.h>
+
+namespace MaterialSerialization {
+    using TextureWriter = std::function<nlohmann::json(ImageID)>;
+    using TextureReader = std::function<ImageID(const nlohmann::json&)>;
+
+    [[nodiscard]] nlohmann::json ToJson(const Material& material, const TextureWriter& writeTexture);
+    [[nodiscard]] Material FromJson(const nlohmann::json& data, const TextureReader& readTexture);
+
+    [[nodiscard]] std::optional<std::string> Validate(const nlohmann::json& materials);
+
+    // Materials that only exist at runtime (no source file) are stored in the scene or prefab
+    // file under their cache key, so the materialKeys in its objects resolve after a restart
+    [[nodiscard]] nlohmann::json CollectEmbedded(const nlohmann::json& objects);
+    void RegisterEmbedded(const nlohmann::json& materials);
+}
+
+#endif //DESTRUM_MATERIALSERIALIZATION_H

destrum/src/FS/AssetFS.cpp

@@ -201,6 +201,19 @@ std::filesystem::path AssetFS::GetCookedPathForFile(std::string_view vpath) cons
     return rawPath;
 }
 
+std::optional<std::string> AssetFS::ToVirtualPath(const std::filesystem::path& fullPath) const {
+    const std::filesystem::path normalized = fullPath.lexically_normal();
+    for (const FSMount& mount : mounts) {
+        const std::filesystem::path relative = normalized.lexically_relative(mount.root);
+        if (relative.empty() || relative.is_absolute() || relative == "." ||
+            relative == ".." || relative.generic_string().starts_with("../")) {
+            continue;
+        }
+        return mount.scheme + "://" + relative.generic_string();
+    }
+    return std::nullopt;
+}
+
 std::vector<uint8_t> AssetFS::ReadFile(const std::filesystem::path& fullPath) {
     std::ifstream file(fullPath, std::ios::binary);
     if (!file) {

destrum/src/Graphics/Caches/ImageCache.cpp

@@ -107,6 +107,11 @@ ImageID ImageCache::addImage(ImageID id, GPUImage image) {
     }
 }
 
+const ImageCache::LoadedImageInfo* ImageCache::findLoadedImageInfo(ImageID id) const {
+    const auto it = loadedImagesInfo.find(id);
+    return it != loadedImagesInfo.end() ? &it->second : nullptr;
+}
+
 void ImageCache::removeImage(ImageID id) {
     if (id >= images.size() || images[id].image == VK_NULL_HANDLE) {
         return;

destrum/src/Graphics/Caches/MaterialCache.cpp

@@ -50,7 +50,7 @@ void MaterialCache::cleanup(GfxDevice& gfxDevice)
     device = nullptr;
 }
 
-MaterialID MaterialCache::addMaterial(Material material)
+MaterialID MaterialCache::addMaterial(Material material, std::string key)
 {
     MaterialData* data = static_cast<MaterialData*>(materialDataBuffer.info.pMappedData);
 
@@ -71,10 +71,9 @@ MaterialID MaterialCache::addMaterial(Material material)
         sizeof(MaterialData));
 
     const auto materialId = static_cast<MaterialID>(materials.size());
-    std::string key;
+    if (key.empty() && !material.assetReference.empty()) {
-    if (!material.assetReference.empty()) {
         key = material.assetReference.cacheKey();
-    } else {
+    } else if (key.empty()) {
         key = material.name.empty()
             ? "material:" + std::to_string(materialId)
             : material.name;

destrum/src/Serialization/MaterialSerialization.cpp

@@ -0,0 +1,208 @@
+#include <destrum/Serialization/MaterialSerialization.h>
+
+#include <array>
+#include <filesystem>
+#include <utility>
+
+#include <spdlog/spdlog.h>
+
+#include <destrum/FS/AssetFS.h>
+#include <destrum/Graphics/GfxDevice.h>
+#include <destrum/Graphics/Renderer.h>
+#include <destrum/Serialization/GlmJson.h>
+#include <destrum/Util/GameState.h>
+
+using json = nlohmann::json;
+
+namespace {
+    using TextureSlot = std::pair<const char*, ImageID Material::*>;
+
+    constexpr std::array<TextureSlot, 6> TextureSlots{{
+        {"diffuse", &Material::diffuseTexture},
+        {"normal", &Material::normalTexture},
+        {"metallic", &Material::metallicTexture},
+        {"roughness", &Material::roughnessTexture},
+        {"occlusion", &Material::occlusionTexture},
+        {"emissive", &Material::emissiveTexture},
+    }};
+
+    [[nodiscard]] const char* FilteringName(TextureFilteringMode mode) {
+        switch (mode) {
+            case TextureFilteringMode::Nearest: return "nearest";
+            case TextureFilteringMode::Anisotropic: return "anisotropic";
+            case TextureFilteringMode::Linear: break;
+        }
+        return "linear";
+    }
+
+    [[nodiscard]] TextureFilteringMode ParseFiltering(const std::string& name) {
+        if (name == "nearest") return TextureFilteringMode::Nearest;
+        if (name == "anisotropic") return TextureFilteringMode::Anisotropic;
+        return TextureFilteringMode::Linear;
+    }
+
+    [[nodiscard]] RenderResources* GetResources() {
+        if (!GameState::GetInstance().HasRenderer() || !GameState::GetInstance().HasGfxDevice()) {
+            return nullptr;
+        }
+        return GameState::GetInstance().Renderer().getResources();
+    }
+}
+
+namespace MaterialSerialization {
+    json ToJson(const Material& material, const TextureWriter& writeTexture) {
+        json data = {
+            {"name", material.name},
+            {"baseColor", material.baseColor},
+            {"metallic", material.metallicFactor},
+            {"roughness", material.roughnessFactor},
+            {"emissiveColor", material.emissiveColor},
+            {"normalScale", material.normalScale},
+            {"occlusionStrength", material.occlusionStrength},
+            {"filtering", FilteringName(material.textureFilteringMode)},
+        };
+
+        json textures = json::object();
+        for (const auto& [slot, member] : TextureSlots) {
+            if (material.*member == NULL_IMAGE_ID) {
+                continue;
+            }
+            json texture = writeTexture(material.*member);
+            if (!texture.is_null()) {
+                textures[slot] = std::move(texture);
+            }
+        }
+        if (!textures.empty()) {
+            data["textures"] = std::move(textures);
+        }
+        return data;
+    }
+
+    Material FromJson(const json& data, const TextureReader& readTexture) {
+        Material material{};
+        material.name = data.value("name", std::string{});
+        material.baseColor = data.value("baseColor", material.baseColor);
+        material.metallicFactor = data.value("metallic", material.metallicFactor);
+        material.roughnessFactor = data.value("roughness", material.roughnessFactor);
+        material.emissiveColor = data.value("emissiveColor", material.emissiveColor);
+        material.normalScale = data.value("normalScale", material.normalScale);
+        material.occlusionStrength = data.value("occlusionStrength", material.occlusionStrength);
+        material.textureFilteringMode = ParseFiltering(data.value("filtering", std::string{"linear"}));
+
+        if (data.contains("textures")) {
+            const json& textures = data.at("textures");
+            for (const auto& [slot, member] : TextureSlots) {
+                if (textures.contains(slot)) {
+                    material.*member = readTexture(textures.at(slot));
+                }
+            }
+        }
+        return material;
+    }
+
+    std::optional<std::string> Validate(const json& materials) {
+        if (!materials.is_object()) {
+            return "\"materials\" must be an object";
+        }
+        for (auto it = materials.begin(); it != materials.end(); ++it) {
+            const std::string context = "materials[\"" + it.key() + "\"]";
+            if (!it.value().is_object()) {
+                return context + " must be an object";
+            }
+            if (!it.value().contains("textures")) {
+                continue;
+            }
+            const json& textures = it.value().at("textures");
+            if (!textures.is_object()) {
+                return context + ".textures must be an object";
+            }
+            for (auto texture = textures.begin(); texture != textures.end(); ++texture) {
+                if (!texture.value().is_object() || !texture.value().contains("path") ||
+                    !texture.value().at("path").is_string()) {
+                    return context + ".textures." + texture.key() + " must have a \"path\" string";
+                }
+            }
+        }
+        return std::nullopt;
+    }
+
+    json CollectEmbedded(const json& objects) {
+        json materials = json::object();
+        const RenderResources* resources = GetResources();
+        if (resources == nullptr) {
+            return materials;
+        }
+        const MaterialCache& cache = resources->materials();
+
+        const auto writeTexture = [&](ImageID id) -> json {
+            const ImageCache::LoadedImageInfo* info = resources->images().findLoadedImageInfo(id);
+            if (info == nullptr) {
+                spdlog::warn("Texture {} was not loaded from a file, it is not saved", id);
+                return nullptr;
+            }
+            const auto virtualPath = AssetFS::GetInstance().ToVirtualPath(info->path);
+            return {
+                {"path", virtualPath ? *virtualPath : info->path.generic_string()},
+                {"srgb", info->intent == TextureIntent::ColorSrgb},
+                {"mipMap", info->mipMap},
+            };
+        };
+
+        for (const json& objectJson : objects) {
+            if (!objectJson.contains("components")) {
+                continue;
+            }
+            for (const json& componentJson : objectJson.at("components")) {
+                if (!componentJson.contains("data") || !componentJson.at("data").contains("materialKey")) {
+                    continue;
+                }
+                const json& keyJson = componentJson.at("data").at("materialKey");
+                if (!keyJson.is_string() || materials.contains(keyJson.get<std::string>())) {
+                    continue;
+                }
+
+                const std::string key = keyJson.get<std::string>();
+                const auto id = cache.findMaterialByKey(key);
+                if (!id || *id == cache.getPlaceholderMaterialId() ||
+                    !cache.getMaterial(*id).assetReference.empty()) {
+                    continue;
+                }
+                materials[key] = ToJson(cache.getMaterial(*id), writeTexture);
+            }
+        }
+        return materials;
+    }
+
+    void RegisterEmbedded(const json& materials) {
+        RenderResources* resources = GetResources();
+        if (resources == nullptr || !materials.is_object()) {
+            return;
+        }
+        GfxDevice& gfxDevice = GameState::GetInstance().Gfx();
+
+        const auto readTexture = [&](const json& texture) -> ImageID {
+            const std::string path = texture.at("path").get<std::string>();
+            const TextureIntent intent = texture.value("srgb", true)
+                ? TextureIntent::ColorSrgb
+                : TextureIntent::DataLinear;
+            try {
+                const std::filesystem::path fullPath = path.find("://") != std::string::npos
+                    ? AssetFS::GetInstance().GetFullPath(path)
+                    : std::filesystem::path{path};
+                return resources->loadImageFromFile(
+                    gfxDevice, fullPath, VK_IMAGE_USAGE_SAMPLED_BIT, texture.value("mipMap", true), intent);
+            } catch (const std::exception& exception) {
+                spdlog::warn("Material texture \"{}\" could not be loaded: {}", path, exception.what());
+                return resources->getErrorTextureID();
+            }
+        };
+
+        // A key that is already cached wins, so duplicating objects keeps sharing their material
+        for (auto it = materials.begin(); it != materials.end(); ++it) {
+            if (resources->materials().findMaterialByKey(it.key())) {
+                continue;
+            }
+            resources->materials().addMaterial(FromJson(it.value(), readTexture), it.key());
+        }
+    }
+}

destrum/src/Serialization/PrefabSerializer.cpp

@@ -8,6 +8,7 @@
 #include <destrum/ObjectModel/Transform.h>
 #include <destrum/Scene/Scene.h>
 #include <destrum/Serialization/ComponentRegistry.h>
+#include <destrum/Serialization/MaterialSerialization.h>
 #include <destrum/Serialization/ObjectSerialization.h>
 #include <destrum/Serialization/PrefabCache.h>
 
@@ -33,6 +34,9 @@ namespace {
         }
 
         try {
+            if (prefab.contains("materials")) {
+                MaterialSerialization::RegisterEmbedded(prefab.at("materials"));
+            }
             auto built = ObjectSerialization::BuildObjects(scene, prefab.at("objects"), externalObjects);
             GameObject* root = built.objects.front();
             if (parent != nullptr) {
@@ -58,6 +62,9 @@ std::optional<json> PrefabSerializer::Capture(const GameObject& root) {
     prefab["name"] = root.GetName();
     try {
         prefab["objects"] = ObjectSerialization::SerializeObjects(ObjectSerialization::CollectHierarchy(root));
+        if (json materials = MaterialSerialization::CollectEmbedded(prefab["objects"]); !materials.empty()) {
+            prefab["materials"] = std::move(materials);
+        }
     } catch (const std::exception& exception) {
         spdlog::error("Cannot capture prefab \"{}\": {}", root.GetName(), exception.what());
         return std::nullopt;
@@ -135,6 +142,12 @@ std::optional<std::string> PrefabSerializer::Validate(const json& prefab) {
         return "prefab must contain a non-empty \"objects\" array";
     }
 
+    if (prefab.contains("materials")) {
+        if (auto error = MaterialSerialization::Validate(prefab.at("materials"))) {
+            return error;
+        }
+    }
+
     const auto& objects = prefab.at("objects");
     if (auto error = ObjectSerialization::ValidateObjects(objects, ObjectSerialization::CurrentObjectVersion)) {
         return error;

destrum/src/Serialization/SceneSerializer.cpp

@@ -13,6 +13,7 @@
 #include <destrum/Components/Physics/Rigidbody.h>
 #include <destrum/Serialization/ComponentRegistry.h>
 #include <destrum/Serialization/GlmJson.h>
+#include <destrum/Serialization/MaterialSerialization.h>
 #include <destrum/Serialization/ObjectSerialization.h>
 
 using json = nlohmann::json;
@@ -49,6 +50,12 @@ namespace {
             return "\"currentCamera\" must be an object id";
         }
 
+        if (root.contains("materials")) {
+            if (auto error = MaterialSerialization::Validate(root.at("materials"))) {
+                return error;
+            }
+        }
+
         return ObjectSerialization::ValidateObjects(root.at("objects"), version);
     }
 }
@@ -94,6 +101,9 @@ bool SceneSerializer::Save(Scene& scene, const std::filesystem::path& path) {
 
     try {
         root["objects"] = ObjectSerialization::SerializeObjects(objects);
+        if (json materials = MaterialSerialization::CollectEmbedded(root["objects"]); !materials.empty()) {
+            root["materials"] = std::move(materials);
+        }
     } catch (const std::exception& exception) {
         spdlog::error("Cannot save scene \"{}\": {}", scene.GetName(), exception.what());
         return false;
@@ -183,6 +193,11 @@ bool SceneSerializer::ConstructScene(Scene& scene, LoadResult& result,
     std::string context = "scene";
 
     try {
+        if (root.contains("materials")) {
+            context = "materials";
+            MaterialSerialization::RegisterEmbedded(root.at("materials"));
+            context = "scene";
+        }
         idMap = ObjectSerialization::BuildObjects(stagingScene, root.at("objects")).idMap;
 
         // Move objects from pending to objects list without physics registration

hotpink.html

@@ -0,0 +1,16 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+    <meta charset="UTF-8">
+    <title>Title</title>
+</head>
+<body>
+
+<style>
+    * {
+        background-color: hotpink;
+    }
+</style>
+
+</body>
+</html>

tests/serialization_tests.cpp

@@ -9,6 +9,7 @@
 #include <destrum/Scene/Scene.h>
 #include <destrum/Scene/SceneManager.h>
 #include <destrum/Serialization/GlmJson.h>
+#include <destrum/Serialization/MaterialSerialization.h>
 #include <destrum/Serialization/SceneSerializer.h>
 #include <destrum/Components/CameraComponent.h>
 #include <destrum/Components/LightComponent.h>
@@ -281,6 +282,58 @@ namespace {
 
         SceneManager::GetInstance().Destroy();
     }
+
+    void testMaterialJsonRoundTrip()
+    {
+        Material material = Material::SimpleColor(glm::vec3{0.2f, 0.4f, 0.6f}, "Crate");
+        material.metallicFactor = 0.3f;
+        material.roughnessFactor = 0.55f;
+        material.emissiveColor = {1.0f, 0.5f, 0.0f};
+        material.textureFilteringMode = TextureFilteringMode::Anisotropic;
+        material.diffuseTexture = 3;
+        material.emissiveTexture = 7;
+        material.normalTexture = 9;
+
+        // Texture 9 has no source file, it must be left out instead of saved as a dangling id
+        const nlohmann::json data = MaterialSerialization::ToJson(material, [](ImageID id) -> nlohmann::json {
+            if (id == 9) {
+                return nullptr;
+            }
+            return {{"path", "game://tex" + std::to_string(id) + ".png"}, {"srgb", id == 3}};
+        });
+        check(!MaterialSerialization::Validate(nlohmann::json{{"Crate", data}}).has_value(),
+              "a serialized material must pass validation");
+        check(!data.at("textures").contains("normal"), "textures without a source must not be saved");
+
+        const Material loaded = MaterialSerialization::FromJson(data, [](const nlohmann::json& texture) {
+            const std::string path = texture.at("path").get<std::string>();
+            return path == "game://tex3.png" ? ImageID{30} : ImageID{70};
+        });
+        check(loaded.name == "Crate" && loaded.baseColor == material.baseColor &&
+              close(loaded.metallicFactor, 0.3f) && close(loaded.roughnessFactor, 0.55f) &&
+              loaded.emissiveColor == material.emissiveColor &&
+              loaded.textureFilteringMode == TextureFilteringMode::Anisotropic,
+              "material factors must round-trip through json");
+        check(loaded.diffuseTexture == 30 && loaded.emissiveTexture == 70 &&
+              loaded.normalTexture == NULL_IMAGE_ID && loaded.metallicTexture == NULL_IMAGE_ID,
+              "material textures must round-trip through their slots");
+    }
+
+    void testSceneValidatesEmbeddedMaterials()
+    {
+        const auto path = std::filesystem::temp_directory_path() / "destrum_materials_scene.json";
+        Scene& scene = SceneManager::GetInstance().CreateScene("materials");
+
+        std::ofstream{path} << R"({"version":2,"objects":[],"materials":{"Bad":{"textures":{"diffuse":5}}}})";
+        check(!SceneSerializer::Load(scene, path), "a material texture without a path must be rejected");
+
+        std::ofstream{path} << R"({"version":2,"objects":[{"id":1,"name":"box"}],)"
+                              R"("materials":{"Good":{"baseColor":[1,0,0],"textures":{"diffuse":{"path":"game://a.png"}}}}})";
+        check(SceneSerializer::Load(scene, path), "a scene with embedded materials must load");
+        std::filesystem::remove(path);
+
+        SceneManager::GetInstance().Destroy();
+    }
 }
 
 void RunSerializationTests()
@@ -295,4 +348,6 @@ void RunSerializationTests()
     testSceneLoadDropsMissingCamera();
     testGlmJson();
     testSceneFileIdsAreLocal();
+    testMaterialJsonRoundTrip();
+    testSceneValidatesEmbeddedMaterials();
 }