feat: Add gui_opacity configuration and apply opacity in GUI rendering

CMakeUserPresets.json

@@ -4,7 +4,6 @@
         "conan": {}
     },
     "include": [
-        "build/build/Release/generators/CMakePresets.json",
-        "build/Release/generators/CMakePresets.json"
+        "build/build/Release/generators/CMakePresets.json"
     ]
 }

config/gui_runtime.json

@@ -61,5 +61,6 @@
     },
     "gamepad_axis_action_threshold": 0.5
   },
+  "gui_opacity": 1.0,
   "config_file": "config/gui_runtime.json"
 }

config/seed_runtime.json

@@ -72,5 +72,6 @@
     "pbr_roughness": 0.3,
     "pbr_metallic": 0.1
   },
+  "gui_opacity": 0.75,
   "config_file": "config/seed_runtime.json"
 }

scripts/gui.lua

@@ -125,6 +125,10 @@ Context.__index = Context
 function Context:new(options)
     options = options or {}
     local style = options.style or DEFAULT_STYLE
+    local opacity = 1.0
+    if type(config) == "table" and type(config.gui_opacity) == "number" then
+        opacity = config.gui_opacity
+    end
     local instance = {
         commands = {},
         input = nil,
@@ -133,6 +137,7 @@ function Context:new(options)
         focusWidget = nil,
         nextFocus = nil,
         style = style,
+        opacity = opacity,
         mousePressed = false,
         mouseReleased = false,
     }
@@ -184,15 +189,27 @@ function Context:markHot(widgetId, hovered)
     end
 end
 
+function Context:applyOpacity(color)
+    if not color then
+        return color
+    end
+    local result = {color[1], color[2], color[3], color[4]}
+    if result[4] then
+        result[4] = result[4] * self.opacity
+    end
+    return result
+end
+
 function Context:pushRect(rect, params)
     params = params or {}
+    local color = params.color and self:applyOpacity(params.color) or params.color
     local command = {
         type = "rect",
         x = rect.x,
         y = rect.y,
         width = rect.width,
         height = rect.height,
-        color = params.color,
+        color = color,
         borderColor = params.borderColor,
         borderWidth = params.borderWidth or (params.borderColor and 1 or 0),
         radius = params.radius or self.style.radius,

src/services/impl/json_config_service.cpp

@@ -361,6 +361,14 @@ RuntimeConfig JsonConfigService::LoadFromJson(std::shared_ptr<ILogger> logger,
         readFloat("pbr_metallic", config.atmospherics.pbrMetallic);
     }
 
+    if (document.HasMember("gui_opacity")) {
+        const auto& value = document["gui_opacity"];
+        if (!value.IsNumber()) {
+            throw std::runtime_error("JSON member 'gui_opacity' must be a number");
+        }
+        config.guiOpacity = static_cast<float>(value.GetDouble());
+    }
+
     return config;
 }
 
@@ -462,6 +470,8 @@ std::string JsonConfigService::BuildConfigJson(const RuntimeConfig& config,
         addStringMember("shaders_directory", "shaders");
     }
 
+    document.AddMember("gui_opacity", config.guiOpacity, allocator);
+
     rapidjson::Value extensionArray(rapidjson::kArrayType);
     for (const char* extension : kDeviceExtensions) {
         rapidjson::Value extensionValue(extension, allocator);

src/services/impl/script_engine_service.cpp

@@ -311,6 +311,7 @@ void ScriptEngineService::RegisterBindings(lua_State* L) {
     bind("window_get_relative_mouse_mode", &ScriptEngineService::WindowGetRelativeMouseMode);
     bind("window_set_cursor_visible", &ScriptEngineService::WindowSetCursorVisible);
     bind("window_is_cursor_visible", &ScriptEngineService::WindowIsCursorVisible);
+    bind("print", &ScriptEngineService::LuaPrint);
 }
 
 int ScriptEngineService::LoadMeshFromFile(lua_State* L) {
@@ -794,4 +795,48 @@ int ScriptEngineService::GlmMatrixFromTransform(lua_State* L) {
     return lua::LuaGlmMatrixFromTransform(L);
 }
 
+int ScriptEngineService::LuaPrint(lua_State* L) {
+    auto* context = static_cast<LuaBindingContext*>(lua_touserdata(L, lua_upvalueindex(1)));
+    auto logger = context ? context->logger : nullptr;
+
+    int nargs = lua_gettop(L);
+    std::string message;
+
+    for (int i = 1; i <= nargs; ++i) {
+        if (i > 1) {
+            message += "\t";
+        }
+
+        const char* str = nullptr;
+        if (lua_isstring(L, i)) {
+            str = lua_tostring(L, i);
+        } else if (lua_isnil(L, i)) {
+            str = "nil";
+        } else if (lua_isboolean(L, i)) {
+            str = lua_toboolean(L, i) ? "true" : "false";
+        } else if (lua_isnumber(L, i)) {
+            lua_pushvalue(L, i);
+            str = lua_tostring(L, -1);
+            lua_pop(L, 1);
+        } else {
+            lua_pushvalue(L, i);
+            str = lua_tostring(L, -1);
+            if (!str) {
+                str = lua_typename(L, lua_type(L, i));
+            }
+            lua_pop(L, 1);
+        }
+
+        if (str) {
+            message += str;
+        }
+    }
+
+    if (logger) {
+        logger->Info("[Lua] " + message);
+    }
+
+    return 0;
+}
+
 }  // namespace sdl3cpp::services::impl

src/services/impl/script_engine_service.hpp

@@ -86,6 +86,7 @@ private:
     static int WindowGetRelativeMouseMode(lua_State* L);
     static int WindowSetCursorVisible(lua_State* L);
     static int WindowIsCursorVisible(lua_State* L);
+    static int LuaPrint(lua_State* L);
 
     std::shared_ptr<ILogger> logger_;
     std::shared_ptr<IMeshService> meshService_;

src/services/interfaces/config_types.hpp

@@ -91,6 +91,7 @@ struct RuntimeConfig {
     MouseGrabConfig mouseGrab{};
     InputBindings inputBindings{};
     AtmosphericsConfig atmospherics{};
+    float guiOpacity = 1.0f;
 };
 
 }  // namespace sdl3cpp::services