Added background scripts

Background scripts are scripts that are launched when a map is loaded. They differ in use from a map's init script in that they are expected to contain an infinite loop. These scripts are linked to a sprite and will be killed when that sprite is destroyed (usually when the map is unloaded, but if the sprite is made persistent then it may last longer). The thread running the script is given no warning that it is being killed; the coroutine is simply never called again, and the thread is disposed of. Because of this, background scripts MUST ensure the game is in a consistent state before coroutine yielding, because it is not guaranteed that the coroutine will ever be called again.

5 files changed, 24 insertions, 2 deletions

@@ -52,6 +52,7 @@ void Game::loadMap(std::string filename) {
   // Load the new map.
   map_ = std::make_unique<Map>(filename);
 
+  std::vector<std::tuple<int, std::string>> backgroundScripts;
   for (const Prototype& p : map_->getPrototypes()) {
     if (spritesByAlias_.count(p.name)) continue;
 
@@ -84,6 +85,9 @@ void Game::loadMap(std::string filename) {
       getSprite(spriteId).mirrorAxis = p.mirrorAxis;
       getSprite(spriteId).mirroredSpriteId = getSpriteByAlias(p.spriteToMirror);
     }
+    if (!p.backgroundScript.empty()) {
+      backgroundScripts.push_back({spriteId, p.backgroundScript});
+    }
   }
 
   for (const Trigger& t : map_->getTriggers()) {
@@ -99,4 +103,9 @@ void Game::loadMap(std::string filename) {
   if (getSystem<ScriptSystem>().mapHasScript(map_->getName(), "init")) {
     getSystem<ScriptSystem>().runScript(map_->getName(), "init");
   }
+
+  // Run any background scripts associated with new sprites.
+  for (auto& [spriteId, scriptName] : backgroundScripts) {
+    getSystem<ScriptSystem>().runScript(map_->getName(), scriptName, spriteId);
+  }
 }
@@ -121,6 +121,8 @@ Map::Map(std::string_view name) : name_(name) {
               p.spriteToMirror = property.getStringValue();
             } else if (property.getName() == "bumpPlayerScript") {
               p.bumpPlayerScript = property.getStringValue();
+            } else if (property.getName() == "backgroundScript") {
+              p.backgroundScript = property.getStringValue();
             }
           }
 
@@ -28,6 +28,7 @@ struct Prototype {
   Direction dir = Direction::down;
   std::string interactionScript;
   std::string bumpPlayerScript;
+  std::string backgroundScript;
   bool shadow = false;
   bool wander = false;
   int movementSpeed = -1;
@@ -269,6 +269,12 @@ void ScriptSystem::tick(double dt) {
   });
 }
 
+void ScriptSystem::destroySprite(int spriteId) {
+  scripts_.remove_if([spriteId] (const Script& script) {
+    return (script.linkedSprite == spriteId);
+  });
+}
+
 void ScriptSystem::loadMapScripts(std::string mapName) {
   if (!loadedScripts_.count(mapName)) {
     engine_.script_file("../res/scripts/" + mapName + ".lua");
@@ -282,7 +288,7 @@ bool ScriptSystem::mapHasScript(std::string mapName, std::string scriptName) {
   return !!engine_.traverse_get<sol::function>(mapName, scriptName);
 }
 
-void ScriptSystem::runScript(std::string mapName, std::string scriptName) {
+void ScriptSystem::runScript(std::string mapName, std::string scriptName, int linkedSprite) {
   loadMapScripts(mapName);
 
   Script newScript;
@@ -291,6 +297,7 @@ void ScriptSystem::runScript(std::string mapName, std::string scriptName) {
 #ifdef TANETANE_DEBUG
   newScript.debugInfo = mapName + "." + scriptName;
 #endif
+  newScript.linkedSprite = linkedSprite;
 
   if (!*newScript.callable) {
     throw std::runtime_error("Error running script: " + mapName + "." + scriptName);
@@ -19,9 +19,11 @@ public:
 
   void tick(double dt) override;
 
+  void destroySprite(int spriteId) override;
+
   bool mapHasScript(std::string mapName, std::string scriptName);
 
-  void runScript(std::string mapName, std::string scriptName);
+  void runScript(std::string mapName, std::string scriptName, int linkedSprite = -1);
 
   void runDebugScript(std::string script);
 
@@ -33,6 +35,7 @@ private:
     std::unique_ptr<sol::thread> runner;
     std::unique_ptr<sol::coroutine> callable;
     std::string debugInfo;
+    int linkedSprite = -1;
   };
 
   Game& game_;