Add new Lua functions to get a list of all scene graph nodes, scene graph nodes by renderable type (closes #2558), and all screenspace renderables

src/scene/scene.cpp

@@ -860,6 +860,9 @@ scripting::LuaLibrary Scene::luaLibrary() {
             codegen::lua::RemoveSceneGraphNode,
             codegen::lua::RemoveSceneGraphNodesFromRegex,
             codegen::lua::HasSceneGraphNode,
+            codegen::lua::SceneGraphNodes,
+            codegen::lua::NodeByRenderableType,
+            codegen::lua::ScreenSpaceRenderables,
             codegen::lua::AddInterestingTime,
             codegen::lua::WorldPosition,
             codegen::lua::WorldRotation,

src/scene/scene_lua.inl

@@ -52,6 +52,8 @@
 #include <openspace/properties/vector/vec2property.h>
 #include <openspace/properties/vector/vec3property.h>
 #include <openspace/properties/vector/vec4property.h>
+#include <openspace/rendering/renderable.h>
+#include <openspace/rendering/screenspacerenderable.h>
 #include <algorithm>
 #include <cctype>
 
@@ -877,6 +879,51 @@ namespace {
     return node != nullptr;
 }
 
+// Returns a list of all scene graph nodes in the scene
+[[codegen::luawrap]] std::vector<std::string> sceneGraphNodes() {
+    using namespace openspace;
+    
+    const std::vector<SceneGraphNode*>& nodes =
+        global::renderEngine->scene()->allSceneGraphNodes();
+    std::vector<std::string> res;
+    res.reserve(nodes.size());
+    for (SceneGraphNode* node : nodes) {
+        res.push_back(node->identifier());
+    }
+    return res;
+}
+
+// Returns a list of all scene graph nodes in the scene that have a renderable of the
+// specific type
+[[codegen::luawrap]] std::vector<std::string> nodeByRenderableType(std::string type) {
+    using namespace openspace;
+
+    const std::vector<SceneGraphNode*>& nodes =
+        global::renderEngine->scene()->allSceneGraphNodes();
+    std::vector<std::string> res;
+    for (SceneGraphNode* node : nodes) {
+        Renderable* renderable = node->renderable();
+        if (renderable && renderable->typeAsString() == type) {
+            res.push_back(node->identifier());
+        }
+    }
+    return res;
+}
+
+// Returns a list of all screen-space renderables
+[[codegen::luawrap]] std::vector<std::string> screenSpaceRenderables() {
+    using namespace openspace;
+
+    const std::vector<ScreenSpaceRenderable*>& ssrs = 
+        global::renderEngine->screenSpaceRenderables();
+    std::vector<std::string> res;
+    res.reserve(ssrs.size());
+    for (ScreenSpaceRenderable* ssr : ssrs) {
+        res.push_back(ssr->identifier());
+    }
+    return res;
+}
+
 /**
  * Adds an interesting time to the current scene. The first argument is the name of the
  * time and the second argument is the time itself in the format YYYY-MM-DDThh:mm:ss.uuu