From c331f1029c6e64b693882562fb1c66fca37483fc Mon Sep 17 00:00:00 2001
From: Adam Mitchell <41760870+AdamMitchell-ms@users.noreply.github.com>
Date: Fri, 3 May 2019 16:57:27 -0700
Subject: [PATCH] OrbitCamera now supports right mouse buttons to change
 position (#422)

* right mouse camera controls

* More accurate right click mouse motion
---
 Examples/OrbitCameraController.cs | 76 ++++++++++++++++++++-----------
 1 file changed, 49 insertions(+), 27 deletions(-)

diff --git a/Examples/OrbitCameraController.cs b/Examples/OrbitCameraController.cs
index 071071fe7..a3d678389 100644
--- a/Examples/OrbitCameraController.cs
+++ b/Examples/OrbitCameraController.cs
@@ -3,10 +3,11 @@
 // Taken from http://wiki.unity3d.com/index.php?title=MouseOrbitImproved
 namespace UnityGLTF.Examples
 {
+	[RequireComponent(typeof(Camera))]
 	[AddComponentMenu("Camera-Control/Mouse Orbit with zoom")]
 	public class OrbitCameraController : MonoBehaviour
 	{
-		public Transform target;
+		public Vector3 targetPosition = Vector3.zero;
 		public float distance = 5.0f;
 		public float xSpeed = 120.0f;
 		public float ySpeed = 120.0f;
@@ -18,21 +19,28 @@ public class OrbitCameraController : MonoBehaviour
 		public float distanceMin = .5f;
 		public float distanceMax = 150f;
 
+		private Camera camera;
+
 		private Rigidbody cameraRigidBody;
 
-		float x = 0.0f;
-		float y = 0.0f;
+		private float x = 0.0f;
+		private float y = 0.0f;
+		private Vector3 prevMousePosition;
 
 		Quaternion rotation;
 
 		// Use this for initialization
 		void Start()
 		{
+			camera = GetComponent<Camera>();
+
 			Vector3 angles = transform.eulerAngles;
 			x = angles.y;
 			y = angles.x;
 			rotation = Quaternion.Euler(y, x, 0);
 
+			prevMousePosition = Input.mousePosition;
+
 			cameraRigidBody = GetComponent<Rigidbody>();
 
 			// Make the rigid body not change rotation
@@ -44,38 +52,52 @@ void Start()
 
 		void LateUpdate()
 		{
-			if (target)
+			var height = Display.main.renderingHeight;
+			var width = Display.main.renderingWidth;
+
+			if (Input.GetMouseButton(0))
 			{
-				if (Input.GetMouseButton(0))
-				{
-					x += Input.GetAxis("Mouse X") * xSpeed * 0.06f;
-					y -= Input.GetAxis("Mouse Y") * ySpeed * 0.06f;
+				x += Input.GetAxis("Mouse X") * xSpeed * 0.06f;
+				y -= Input.GetAxis("Mouse Y") * ySpeed * 0.06f;
 
-					y = ClampAngle(y, yMinLimit, yMaxLimit);
+				y = ClampAngle(y, yMinLimit, yMaxLimit);
 
-					rotation = Quaternion.Euler(y, x, 0);
-				}
+				rotation = Quaternion.Euler(y, x, 0);
+			}
+			else if (Input.GetMouseButton(1))
+			{
+				var prevMouseWorldPosition = ProjectScreenPointToTargetPlane(prevMousePosition);
+				var mouseWorldPosition = ProjectScreenPointToTargetPlane(Input.mousePosition);
 
-				var height = Display.main.renderingHeight;
-				var width = Display.main.renderingWidth;
+				targetPosition += prevMouseWorldPosition - mouseWorldPosition;
+			}
 
-				var mouseOverRenderArea =
-					Input.mousePosition.x >= 0 &&
-					Input.mousePosition.x <= width &&
-					Input.mousePosition.y >= 0 &&
-					Input.mousePosition.y <= height;
+			var mouseOverRenderArea =
+				Input.mousePosition.x >= 0 &&
+				Input.mousePosition.x <= width &&
+				Input.mousePosition.y >= 0 &&
+				Input.mousePosition.y <= height;
 
-				if (Input.GetMouseButton(0) || mouseOverRenderArea)
-				{
-					distance = Mathf.Clamp(distance * Mathf.Exp(-Input.GetAxis("Mouse ScrollWheel") * zoomSpeed), distanceMin, distanceMax);
-				}
+			if (Input.GetMouseButton(0) || mouseOverRenderArea)
+			{
+				distance = Mathf.Clamp(distance * Mathf.Exp(-Input.GetAxis("Mouse ScrollWheel") * zoomSpeed), distanceMin, distanceMax);
+			}
 
-				Vector3 negDistance = new Vector3(0.0f, 0.0f, -distance);
-				Vector3 position = rotation * negDistance + target.position;
+			Vector3 negDistance = new Vector3(0.0f, 0.0f, -distance);
+			Vector3 position = rotation * negDistance + targetPosition;
 
-				transform.rotation = rotation;
-				transform.position = position;
-			}
+			transform.rotation = rotation;
+			transform.position = position;
+
+			prevMousePosition = Input.mousePosition;
+		}
+
+		private Vector3 ProjectScreenPointToTargetPlane(Vector3 screenPosition)
+		{
+			var ray = camera.ScreenPointToRay(screenPosition);
+			var planeDistance = distance / Mathf.Cos(Mathf.Deg2Rad * Vector3.Angle(camera.transform.forward, ray.direction));
+
+			return camera.transform.position + (ray.direction * planeDistance);
 		}
 
 		public static float ClampAngle(float angle, float min, float max)