Using Manipulators to Transform Objects

#region Math Variables
#if UNIGINE_DOUBLE
using Scalar = System.Double;
using Vec2 = Unigine.dvec2;
using Vec3 = Unigine.dvec3;
using Vec4 = Unigine.dvec4;
using Mat4 = Unigine.dmat4;
#else
using Scalar = System.Single;
using Vec2 = Unigine.vec2;
using Vec3 = Unigine.vec3;
using Vec4 = Unigine.vec4;
using Mat4 = Unigine.mat4;
using WorldBoundBox = Unigine.BoundBox;
using WorldBoundSphere = Unigine.BoundSphere;
using WorldBoundFrustum = Unigine.BoundFrustum;
#endif
#endregion

using System;
using System.Collections;
using System.Collections.Generic;
using Unigine;

[Component(PropertyGuid = "AUTOGENERATED_GUID")] // <-- this line is generated automatically for a new component
public class Manipulator : Component
{
	// WorldIntersection object to store the information about the intersection 
	WorldIntersection intersection = new WorldIntersection();
 
	// Unigine.Object object to gain access to a selected object's transform in Unigine 
	Unigine.Node obj;
 
	// create manipulators for each type of transform(Translating, Scaling, Rotating) 
	WidgetManipulator ObjManTranslator;
	WidgetManipulator ObjManScaler;
	WidgetManipulator ObjManRotator;
	
	// create widget manipulator used to store transformation matrix of an active widget
	WidgetManipulator CurrentObjectManipulator;
	Gui gui;

	[Method(Order=2)] private void Init()
	{
		// write here code to be called on component initialization 
		gui = Gui.GetCurrent();

		// create widget for each transformation type
		ObjManTranslator = new WidgetManipulatorTranslator(gui);
		ObjManScaler = new WidgetManipulatorScaler(gui);
		ObjManRotator = new WidgetManipulatorRotator(gui);
		
		// set projection for the widgets
		ObjManTranslator.Projection= Game.Player.Camera.Projection;
		ObjManScaler.Projection = Game.Player.Camera.Projection;
		ObjManRotator.Projection = Game.Player.Camera.Projection;

		// add widgets to UI
		gui.AddChild(ObjManTranslator);
		gui.AddChild(ObjManScaler);
		gui.AddChild(ObjManRotator);

		// add a callback for each widget   
		ObjManTranslator.AddCallback(Gui.CALLBACK_INDEX.CHANGED, ApplyTransform);
		ObjManRotator.AddCallback(Gui.CALLBACK_INDEX.CHANGED, ApplyTransform);
		ObjManScaler.AddCallback(Gui.CALLBACK_INDEX.CHANGED, ApplyTransform);

		// hide created widgets
		ObjManScaler.Hidden = true;
		ObjManRotator.Hidden = true;
		ObjManTranslator.Hidden = true;
	}
 
	private void Update()
	{
		// write here code to be called before updating each render frame
		 if (!Game.Player)
			return;
	
		// set modelview for each widget manipulator every frame
		ObjManTranslator.Modelview = Game.Player.Camera.Modelview;
		ObjManScaler.Modelview = Game.Player.Camera.Modelview;
		ObjManRotator.Modelview = Game.Player.Camera.Modelview;

		// select an object with right-click
		if (Input.IsMouseButtonDown(Input.MOUSE_BUTTON.RIGHT))
		{
			obj = GetNodeUnderCursor();
			CurrentObjectManipulator.Transform = obj.WorldTransform;
		}

		// choose manipulator with Z,X,C keys
		if(obj)
		{
			if(Input.IsKeyDown(Input.KEY.Z))
				SwitchManipulator(ObjManTranslator);
			if(Input.IsKeyDown(Input.KEY.X))
				SwitchManipulator(ObjManRotator);
			if(Input.IsKeyDown(Input.KEY.C))
				SwitchManipulator(ObjManScaler);
			if (!Input.IsMouseButtonPressed(Input.MOUSE_BUTTON.LEFT))
				CurrentObjectManipulator.Transform = obj.WorldTransform;
		}
	}
 
	// transform an object
	private void ApplyTransform()
	{
		if(obj != null && Input.IsMouseButtonPressed(Input.MOUSE_BUTTON.LEFT))
			obj.WorldTransform = CurrentObjectManipulator.Transform;
	}
 
	// find an object under the cursor
	private Unigine.Node GetNodeUnderCursor()
	{
		ivec2 mouse = Input.MousePosition;

		// find a point 100 units away in front of the camera
		Vec3 p0 = Game.Player.WorldPosition;
		
		EngineWindow main_window = WindowManager.MainWindow;
		if (main_window)
		{
			ivec2 main_pos = main_window.Position;
			mouse.x += main_pos.x;
			mouse.y += main_pos.y;
		}
		Vec3 p1 = p0 + new vec3(Game.Player.GetDirectionFromMainWindow(mouse.x, mouse.y)) * 100;
		
		// cast a ray, that will detect an object within 100 units in front of the camera
		return World.GetIntersection(p0, p1, 1, intersection);
	}

	// relocate chosen manipulator to the position of selected object and make it visible
	void SwitchManipulator(WidgetManipulator CurrentManipulator)
	{
		// relocate a widget and making it visible
		CurrentManipulator.Transform = obj.WorldTransform;
		CurrentManipulator.Hidden = false;
		
		// make other widgets hidden
		CurrentObjectManipulator = CurrentManipulator;
		if(ObjManTranslator != CurrentManipulator)
			ObjManTranslator.Hidden = true;
		if(ObjManRotator != CurrentManipulator)
			ObjManRotator.Hidden = true;
		if(ObjManScaler != CurrentManipulator)
			ObjManScaler.Hidden = true;
	}
}