Spawn location editor

UOP1_Project/Assets/Prefabs/GameplayEssentials/SpawnSystem.prefab

@@ -59,6 +59,7 @@ GameObject:
   serializedVersion: 6
   m_Component:
   - component: {fileID: 2125786286893897154}
+  - component: {fileID: 4671891876261113940}
   m_Layer: 0
   m_Name: Location 01
   m_TagString: Untagged
@@ -80,3 +81,16 @@ Transform:
   m_Father: {fileID: 2125786285293829335}
   m_RootOrder: 0
   m_LocalEulerAnglesHint: {x: 0, y: 0, z: 0}
+--- !u!114 &4671891876261113940
+MonoBehaviour:
+  m_ObjectHideFlags: 0
+  m_CorrespondingSourceObject: {fileID: 0}
+  m_PrefabInstance: {fileID: 0}
+  m_PrefabAsset: {fileID: 0}
+  m_GameObject: {fileID: 2125786286893897213}
+  m_Enabled: 1
+  m_EditorHideFlags: 0
+  m_Script: {fileID: 11500000, guid: 14441bd075da9464e9c254e66e1849e3, type: 3}
+  m_Name: 
+  m_EditorClassIdentifier: 
+  _verticalOffset: 0.1

UOP1_Project/Assets/Scripts/ClickToPlaceHelper.cs

@@ -0,0 +1,69 @@
+using UnityEditor;
+using UnityEngine;
+
+[ExecuteInEditMode]
+[AddComponentMenu("UOP1/Tools/Click to Place")]
+public class ClickToPlaceHelper : MonoBehaviour
+{
+	[Tooltip("Vertical offset above the clicked point. Useful to avoid spawn points to be directly ON the geometry which might cause issues.")]
+	[SerializeField] float _verticalOffset = 0.1f;
+
+	private Vector3 _spawnPosition;
+	private bool _displaySpawnPosition = false;
+
+	private delegate void ButtonAction();
+	private ButtonAction myButtonAction;
+
+	private void OnDrawGizmos()
+	{
+		if (_displaySpawnPosition)
+		{
+			Gizmos.color = Color.green;
+			Gizmos.DrawCube(_spawnPosition, Vector3.one * 0.3f);
+		}
+	}
+
+	void OnMouseClick(SceneView scene)
+	{
+		Event currentGUIEvent = Event.current;
+
+		Vector3 mousePos = currentGUIEvent.mousePosition;
+		float pixelsPerPoint = EditorGUIUtility.pixelsPerPoint;
+		mousePos.y = scene.camera.pixelHeight - mousePos.y * pixelsPerPoint;
+		mousePos.x *= pixelsPerPoint;
+
+		Ray ray = scene.camera.ScreenPointToRay(mousePos);
+
+		if (Physics.Raycast(ray, out RaycastHit hit))
+		{
+			_spawnPosition = hit.point + Vector3.up * _verticalOffset;
+
+			if (currentGUIEvent.type == EventType.MouseDown
+				&& currentGUIEvent.button == 0) // Wait for Left mouse button down
+			{
+				myButtonAction();
+				SceneView.duringSceneGui -= OnMouseClick;
+				_displaySpawnPosition = false;
+
+				currentGUIEvent.Use(); // This consumes the event, so that other controls/buttons won't be able to use it
+			}
+		}
+	}
+
+	public void SetSpawnLocationAtCursor()
+	{
+		Debug.Log("Use the LMB to position this object");
+		myButtonAction = SetTransform;
+		_displaySpawnPosition = true;
+		SceneView.duringSceneGui += OnMouseClick;
+	}
+
+	/// <summary>
+	/// The delegate called when the mouse is clicked in the viewport
+	/// </summary>
+	private void SetTransform()
+	{
+		transform.position = _spawnPosition;
+		Debug.Log("Object moved to " + _spawnPosition);
+	}
+}

UOP1_Project/Assets/Scripts/Editor/SpawnLocationEditor.cs

@@ -0,0 +1,18 @@
+using UnityEditor;
+using UnityEngine;
+
+[CustomEditor(typeof(ClickToPlaceHelper))]
+public class ClickToPlaceHelperEditor : Editor
+{
+	public override void OnInspectorGUI()
+	{
+		base.OnInspectorGUI();
+
+		ClickToPlaceHelper myTarget = target as ClickToPlaceHelper;
+
+		if (GUILayout.Button("Place at Mouse cursor"))
+		{
+			myTarget.SetSpawnLocationAtCursor();
+		}
+	}
+}