From 060820248368d1d15a74005d64288f1753abdfb7 Mon Sep 17 00:00:00 2001
From: zvon <tom.zvon@gmail.com>
Date: Sat, 7 Aug 2021 21:58:53 +0200
Subject: [PATCH] SDLPP: add option to specify background objects in scene and
 move Z index of objects just above those background objects

---
 sdlpp/sdlpp_scene.cpp | 16 ++++++++++++++++
 sdlpp/sdlpp_scene.hpp |  5 +++++
 2 files changed, 21 insertions(+)

diff --git a/sdlpp/sdlpp_scene.cpp b/sdlpp/sdlpp_scene.cpp
index 96d97a4..cb737c6 100644
--- a/sdlpp/sdlpp_scene.cpp
+++ b/sdlpp/sdlpp_scene.cpp
@@ -69,6 +69,9 @@ void Scene::moveZTop( const std::shared_ptr< RenderObject > &obj ) {
 void Scene::moveZBottom( const std::shared_ptr< RenderObject > &obj ) {
     setZIndex( obj, 0 );
 }
+void Scene::moveZJustAboveBackground( const std::shared_ptr< RenderObject > &obj ) {
+    setZIndex( obj, first_non_background_index );
+}
 std::shared_ptr< RenderObject > Scene::getObject( int index ) {
     return render_objects[index];
 }
@@ -231,6 +234,19 @@ void Scene::resetScene() {
     }
 }
 
+void Scene::setBackgroundObjectIDs(const std::unordered_set<uint64_t> &ids) {
+    background_ids = ids;
+}
+void Scene::updateBackgroundObjectZIndex() {
+    first_non_background_index = 1;
+    for(uint64_t i = 1; i < render_objects.size(); i++) {
+        if(background_ids.find(render_objects[i]->getId()) != background_ids.end()) {
+            setZIndex(render_objects[i], 1);
+            first_non_background_index++;
+        }
+    }
+}
+
 void Scene::checkKilled() {
     std::lock_guard< std::mutex > lock( render_mutex );
     std::vector< int > killed;
diff --git a/sdlpp/sdlpp_scene.hpp b/sdlpp/sdlpp_scene.hpp
index 7161351..de80e7a 100644
--- a/sdlpp/sdlpp_scene.hpp
+++ b/sdlpp/sdlpp_scene.hpp
@@ -22,6 +22,7 @@ public:
     void moveZ( const std::shared_ptr< RenderObject > &obj, int addition );
     void moveZTop( const std::shared_ptr< RenderObject > &obj );
     void moveZBottom( const std::shared_ptr< RenderObject > &obj );
+    void moveZJustAboveBackground( const std::shared_ptr< RenderObject > &obj );
     std::shared_ptr< RenderObject > getObject( int index );
     std::vector< std::shared_ptr< RenderObject > > getObjects();
     std::vector< std::shared_ptr< RenderObject > >
@@ -49,6 +50,8 @@ public:
     void setPrevTicks( int ticks );
     void saveScene();
     void resetScene();
+    void setBackgroundObjectIDs(const std::unordered_set<uint64_t> &ids);
+    void updateBackgroundObjectZIndex();
 
 private:
     void checkKilled();
@@ -64,6 +67,8 @@ private:
     std::shared_ptr< RenderObject > rightmost_obj;
     uint64_t max_object_id = 0;
     std::mutex render_mutex;
+    std::unordered_set<uint64_t> background_ids;
+    uint64_t first_non_background_index = 1;
 };
 } // end of namespace SDLPP
 #endif