Implement metaroom background changing

TODO: supposed to be per-camera? wonder if that's actually true

src/MetaRoom.cpp

@@ -51,6 +51,7 @@ void MetaRoom::addBackground(std::string back) {
 		firstback = back;
 		fullwid = totalwidth;
 		fullhei = totalheight;
+		current_background = back;
 	} else {
 		// make sure other backgrounds are the same size
 		if (engine.gametype == "sm")
@@ -69,18 +70,23 @@ std::vector<std::string> MetaRoom::backgroundList() {
 	return b;
 }
 
-std::shared_ptr<creaturesImage> MetaRoom::getBackground(std::string back) {
-	// return the first background by default
-	if (back.empty()) {
-		return backgrounds[firstback];
-	}
+std::shared_ptr<creaturesImage> MetaRoom::getCurrentBackground() {
+	return backgrounds[current_background];
+}
 
-	// if this background name isn't found, return null
-	if (backgrounds.find(back) != backgrounds.end())
-		return std::shared_ptr<creaturesImage>();
+std::string MetaRoom::getCurrentBackgroundName() const {
+	return current_background;
+}
+
+bool MetaRoom::hasBackground(std::string back) const {
+	return backgrounds.find(back) != backgrounds.end();
+}
 
-	// otherwise, return the relevant background
-	return backgrounds[back];
+void MetaRoom::setBackground(std::string back) {
+	// TODO: supposedly the current background is per-camera
+	// TODO: camera transition effects??
+	assert(hasBackground(back));
+	current_background = back;
 }
 
 MetaRoom::~MetaRoom() {

src/MetaRoom.h

@@ -37,6 +37,7 @@ class MetaRoom {
 	unsigned int xloc, yloc, wid, hei, fullwid, fullhei;
 	std::map<std::string, std::shared_ptr<creaturesImage> > backgrounds;
 	std::string firstback;
+	std::string current_background;
 	bool wraps;
 
 	MetaRoom() {}
@@ -54,8 +55,12 @@ class MetaRoom {
 	void setWraparound(bool w) { wraps = !!w; }
 
 	unsigned int addRoom(std::shared_ptr<class Room>);
+
 	void addBackground(std::string);
-	std::shared_ptr<creaturesImage> getBackground(std::string);
+	bool hasBackground(std::string) const;
+	void setBackground(std::string);
+	std::shared_ptr<creaturesImage> getCurrentBackground();
+	std::string getCurrentBackgroundName() const;
 	std::vector<std::string> backgroundList();
 
 	std::shared_ptr<Room> nextFloorFromPoint(float x, float y);

src/World.cpp

@@ -404,7 +404,8 @@ void World::drawWorld(Camera* cam, RenderTarget* surface) {
 	}
 	int adjustx = cam->getX();
 	int adjusty = cam->getY();
-	std::shared_ptr<creaturesImage> bkgd = m->getBackground(""); // TODO
+	// TODO: current backgrounds is per camera (supposedly?)
+	std::shared_ptr<creaturesImage> bkgd = m->getCurrentBackground();
 
 	// TODO: work out what c2e does when it doesn't have a background..
 	if (!bkgd)

src/caos/caosVM_camera.cpp

@@ -465,7 +465,13 @@ void v_LOFT(caosVM* vm) {
 
 /**
  BKGD (command) metaroom_id (integer) background (string) transition (integer)
- %status stub
+ %status maybe
+
+ Changes the current background displayed for the selected camera (with SCAM).
+ Transition is as for META. The background must have been specified with the ADDM
+ or ADDB command first.
+
+ TODO: track different backgrounds per metaroom per camera
 */
 void c_BKGD(caosVM* vm) {
 	VM_PARAM_INTEGER(transition)
@@ -474,8 +480,10 @@ void c_BKGD(caosVM* vm) {
 
 	MetaRoom* metaroom = world.map->getMetaRoom(metaroomid);
 	caos_assert(metaroom);
-
-	// TODO
+	caos_assert(background.size());
+	caos_assert(metaroom->hasBackground(background));
+	caos_assert(transition == 0);
+	metaroom->setBackground(background);
 }
 
 /**
@@ -487,8 +495,7 @@ void v_BKGD(caosVM* vm) {
 
 	MetaRoom* metaroom = world.map->getMetaRoom(metaroomid);
 	caos_assert(metaroom);
-
-	vm->result.setString(""); // TODO
+	vm->result.setString(metaroom->getCurrentBackgroundName());
 }
 
 /**