refactor how multiple overlays get grabbed at the same time

README.md

@@ -1,3 +1,5 @@
 # ovr-screen
 A SteamVR overlay for Linux+X11 that displays all your screens in VR.
 
+From my limited testing, this uses about half the CPU performance of Steam's built-in desktop overlay, if running at 60 FPS. Currently the default is 30 FPS which brings the factor to 3-4x. On my machine, the Steam desktop view increases cpu usage by about 100% of a CPU thread (looking only at the `steam` process), while this overlay uses around 25% at 30 FPS and 45% at 60 FPS.
+

src/app.cpp

@@ -46,6 +46,11 @@ App::App()
 		_panels[i].GetOverlay()->SetWidth(width);
 	}
 
+	for (auto &panel : _panels)
+	{
+		_root_overlay.AddChildOverlay(panel.GetOverlay());
+	}
+
 	{ // initialize SteamVR input
 		auto exe_path = std::filesystem::read_symlink("/proc/self/exe");
 		_actions_path = exe_path.parent_path().string() + "/bindings/action_manifest.json";
@@ -126,19 +131,6 @@ void App::InitRootOverlay()
 	// clang-format on
 	_root_overlay.SetTransformWorld(&root_start_pose);
 	_root_overlay.SetTextureToColor(110, 30, 190);
-
-	_root_overlay._GrabBeginCallback = [this](Controller *controller) {
-		for (auto &panel : _panels)
-		{
-			panel.GetOverlay()->ControllerGrab(controller);
-		}
-	};
-	_root_overlay._GrabEndCallback = [this]() {
-		for (auto &panel : _panels)
-		{
-			panel.GetOverlay()->ControllerRelease();
-		}
-	};
 }
 
 void App::Update()

src/controller.cpp

@@ -8,6 +8,7 @@ const float width = 0.004f;
 
 Controller::Controller(App *app, ControllerSide side)
 {
+	_grabbed_overlay = nullptr;
 	_app = app;
 	_input_handle = 0;
 	_is_connected = false;
@@ -51,29 +52,30 @@ void Controller::SetHidden(bool state)
 	_hidden = state;
 }
 
-void Controller::RegisterGrabbedOverlay(Overlay *overlay)
+void Controller::ReleaseOverlay()
 {
-	_grabbed_overlays.push_back(overlay);
-}
-
-void Controller::ReleaseOverlay(Overlay *overlay)
-{
-	for (auto i = _grabbed_overlays.begin(); i != _grabbed_overlays.end(); i++)
-	{
-		if (*i == overlay)
-		{
-			_grabbed_overlays.erase(i);
-			break;
-		}
-	}
+	_grabbed_overlay = nullptr;
 }
 
 void Controller::Update()
 {
 	UpdateStatus();
-	if (!_is_connected)
+	if (!_is_connected || _hidden)
 		return;
 
+	UpdateLaser();
+
+	float move = _app->GetInputAnalog(_app->_input_handles.distance, _input_handle).y * 0.1; // TODO use frame time
+	if (_grabbed_overlay && move != 0.0f)
+	{
+		auto transform = _grabbed_overlay->GetTarget()->transform;
+		transform.m[2][3] = glm::clamp(transform.m[2][3] - move, -5.0f, -0.1f); // moving along z axis
+		_grabbed_overlay->SetTransformTracker(_device_index, &transform);
+	}
+}
+
+void Controller::UpdateLaser()
+{
 	auto controller_pose = _app->GetTrackerPose(_device_index);
 	auto controller_pos = GetPos(controller_pose);
 	auto forward = -glm::vec3(controller_pose[2]);
@@ -92,25 +94,14 @@ void Controller::Update()
 	{
 		if (_app->IsInputJustPressed(_app->_input_handles.grab, _input_handle))
 		{
-			ray.overlay->ControllerGrab(this);
-		}
-	}
-
-	if (!_grabbed_overlays.empty())
-	{
-		float move = _app->GetInputAnalog(_app->_input_handles.distance, _input_handle).y * 0.1; // TODO use frame time
-		if (move != 0.0f)
-		{
-			// delta is calculated & clamped for first overlay so that child overlays don't move further than the root
-			float main_z = _grabbed_overlays[0]->GetTarget()->transform.m[2][3];
-			float new_main_z = glm::clamp(main_z - move, -5.0f, -0.1f);
-			float real_delta = new_main_z - main_z;
-
-			for (auto overlay : _grabbed_overlays)
+			if (ray.overlay->IsHeld())
 			{
-				auto transform = overlay->GetTarget()->transform;
-				transform.m[2][3] += real_delta;
-				overlay->SetTransformTracker(_device_index, &transform);
+				// TODO resize mode
+			}
+			else
+			{
+				_grabbed_overlay = ray.overlay;
+				ray.overlay->ControllerGrab(this);
 			}
 		}
 	}

src/controller.h

@@ -23,13 +23,14 @@ class Controller
 
 	void SetHidden(bool state);
 
-	void RegisterGrabbedOverlay(Overlay *overlay);
-	void ReleaseOverlay(Overlay *overlay);
+	void ReleaseOverlay();
 
 	void Update();
-	void UpdateStatus();
 
   private:
+	void UpdateStatus();
+	void UpdateLaser();
+
 	App *_app;
 	Overlay _laser;
 	ControllerSide _side;
@@ -37,5 +38,5 @@ class Controller
 	vr::VRInputValueHandle_t _input_handle;
 	bool _is_connected;
 	bool _hidden;
-	std::vector<Overlay *> _grabbed_overlays;
+	Overlay *_grabbed_overlay;
 };

src/overlay.cpp

@@ -109,10 +109,21 @@ void Overlay::SetTextureToColor(uint8_t r, uint8_t g, uint8_t b)
 
 void Overlay::SetTransformTracker(TrackerID tracker, const VRMat *transform)
 {
+	auto original_pose = _target.transform;
 	_app->vr_overlay->SetOverlayTransformTrackedDeviceRelative(_id, tracker, transform);
 	_target.type = TargetType::Tracker;
 	_target.id = tracker;
 	_target.transform = *transform;
+
+	auto relative_transform = ConvertMat(*transform) * glm::inverse(ConvertMat(original_pose));
+	for (auto child : _children)
+	{
+		if (!child->IsHeld() && child->_target.type == TargetType::Tracker)
+		{
+			VRMat local_transform = ConvertMat(relative_transform * ConvertMat(child->_target.transform));
+			child->SetTransformTracker(tracker, &local_transform);
+		}
+	}
 }
 
 void Overlay::SetTransformWorld(const VRMat *transform)
@@ -122,6 +133,14 @@ void Overlay::SetTransformWorld(const VRMat *transform)
 	_target.transform = *transform;
 }
 
+void Overlay::SetTargetTracker(TrackerID tracker)
+{
+	auto abs_mat = GetTransformAbsolute();
+	auto controller_mat = _app->GetTrackerPose(tracker);
+	VRMat relative_pose = ConvertMat(glm::inverse(controller_mat) * abs_mat);
+	SetTransformTracker(tracker, &relative_pose);
+}
+
 void Overlay::SetTargetWorld()
 {
 	auto abs_pose = ConvertMat(GetTransformAbsolute());
@@ -213,25 +232,16 @@ void Overlay::Update()
 
 void Overlay::ControllerGrab(Controller *controller)
 {
-	if (_holding_controller != nullptr)
-	{
-		_holding_controller->ReleaseOverlay(this);
-	}
-
 	_app->vr_overlay->SetOverlayColor(_id, 0.6f, 0.8f, 0.8f);
+	SetTargetTracker(controller->DeviceIndex());
 
-	auto abs_mat = GetTransformAbsolute();
-	auto controller_mat = _app->GetTrackerPose(controller->DeviceIndex());
-	VRMat relative_pose = ConvertMat(glm::inverse(controller_mat) * abs_mat);
-
-	SetTransformTracker(controller->DeviceIndex(), &relative_pose);
-
-	controller->RegisterGrabbedOverlay(this);
-	if (_GrabBeginCallback != nullptr)
+	for (auto child : _children)
 	{
-		_GrabBeginCallback(controller);
+		if (!child->IsHeld()) // overlay may have been picked up by other controller
+		{
+			child->SetTargetTracker(controller->DeviceIndex());
+		}
 	}
-
 	_holding_controller = controller;
 }
 
@@ -239,16 +249,34 @@ void Overlay::ControllerRelease()
 {
 	if (_holding_controller != nullptr)
 	{
-		_holding_controller->ReleaseOverlay(this);
+		_holding_controller->ReleaseOverlay();
 	}
 	_app->vr_overlay->SetOverlayColor(_id, 1.0f, 1.0f, 1.0f);
 
-	auto new_pose = ConvertMat(GetTransformAbsolute());
-	SetTransformWorld(&new_pose);
-
-	if (_GrabEndCallback != nullptr)
+	SetTargetWorld();
+	for (auto child : _children)
 	{
-		_GrabEndCallback();
+		if (!child->IsHeld()) // overlay may have been picked up by other controller
+		{
+			child->SetTargetWorld();
+		}
 	}
 	_holding_controller = nullptr;
 }
+
+void Overlay::AddChildOverlay(Overlay *overlay)
+{
+	_children.push_back(overlay);
+}
+
+void Overlay::RemoveChildOverlay(Overlay *overlay)
+{
+	for (auto i = _children.begin(); i != _children.end(); i++)
+	{
+		if (*i == overlay)
+		{
+			_children.erase(i);
+			break;
+		}
+	}
+}

src/overlay.h

@@ -3,6 +3,7 @@
 #include "util.h"
 #include <functional>
 #include <string>
+#include <vector>
 
 class App;
 struct Ray;
@@ -49,17 +50,17 @@ class Overlay
 	void SetTransformTracker(TrackerID tracker, const VRMat *transform);
 	void SetTransformWorld(const VRMat *transform);
 
-	// void SetTargetTracker(TrackerID tracker);
+	void SetTargetTracker(TrackerID tracker);
 	void SetTargetWorld();
 
 	Ray IntersectRay(glm::vec3 origin, glm::vec3 direction, float max_len);
 
-	std::function<void(Controller *)> _GrabBeginCallback;
-	std::function<void()> _GrabEndCallback;
-
 	void ControllerRelease();
 	void ControllerGrab(Controller *controller);
 
+	void AddChildOverlay(Overlay *child);
+	void RemoveChildOverlay(Overlay *child);
+
   private:
 	bool _initialized;
 
@@ -73,5 +74,7 @@ class Overlay
 	float _ratio;
 	Controller *_holding_controller;
 
+	std::vector<Overlay *> _children;
+
 	Target _target;
 };