Question 3 Cameras, change priority on button press?

StateDrivenCamera is overkill for this job.

All you have to do is to set the vcam's Priority field. Higher numbers will dominate. As an example, here is a simple script that lets you set up a list of vcams and it displays an on-screen GUI to select the vcam to switch to. The actual work is done in the Prioritize() method.

Code (CSharp):

1. using System.Collections.Generic;
2. using UnityEngine;
3. using Cinemachine;
4. using System;
5.  
6. #if UNITY_EDITOR
7. using UnityEditor;
8. using UnityEditorInternal;
9. #endif
10.  
11. public class VcamPrioritizerGUI : MonoBehaviour
12. {
13.     [Header("On-Screen GUI")]
14.     public Vector2 Position = new Vector3(30, 10);
15.     public float Width = 100;
16.  
17.     [Header("Priority Levels")]
18.     public int LowPriority = 1;
19.     public int HighPriority = 10;
20.  
21.     [Serializable]
22.     public struct Item
23.     {
24.         public CinemachineVirtualCameraBase Vcam;
25.     }
26.     [HideInInspector]
27.     public List<Item> Vcams;
28.  
29.     // Display a vcam selector on the Game view
30.     public void OnGUI()
31.     {
32.         var numNodes = Vcams?.Count;
33.         if (numNodes == 0)
34.             return;
35.         var style = GUI.skin.button;
36.         var pos = Position;
37.         var size = style.CalcSize(new GUIContent("Button")); size.x = Width;
38.         const float vSpace = 3.0f;
39.         var baseColor = GUI.color;
40.         var liveColor = CinemachineBrain.GetSoloGUIColor();
41.         for (int i = 0; i < numNodes; ++i)
42.         {
43.             var vcam = Vcams[i].Vcam;
44.             if (vcam != null)
45.             {
46.                 GUI.color = CinemachineCore.Instance.IsLive(vcam) ? liveColor : baseColor;
47.                 if (GUI.Button(new Rect(pos, size), vcam.Name))
48.                     Prioritize(vcam);
49.                 pos.y += size.y + vSpace;
50.             }
51.         }
52.         GUI.color = baseColor;
53.     }
54.  
55.     // Prioritize the selected vcam
56.     void Prioritize(CinemachineVirtualCameraBase vcam)
57.     {
58.         for (int i = 0; i < Vcams.Count; ++i)
59.             if (Vcams[i].Vcam != null)
60.                 Vcams[i].Vcam.Priority = Vcams[i].Vcam == vcam ? HighPriority : LowPriority;
61.     }
62. }
63.  
64. // What follows if for drawing the custom inspector
65.  
66. #if UNITY_EDITOR
67. [CustomEditor(typeof(VcamPrioritizerGUI))]
68. class CmNodePrioritizerGUIEditor : Editor
69. {
70.     private ReorderableList m_Nodes;
71.  
72.     public override void OnInspectorGUI()
73.     {
74.         base.OnInspectorGUI();
75.         EditorGUILayout.Space();
76.         if (m_Nodes == null)
77.             SetupNodeList();
78.         m_Nodes.DoLayoutList();
79.         serializedObject.ApplyModifiedProperties();
80.     }
81.  
82.     void SetupNodeList()
83.     {
84.         var propertyName = "Vcams";
85.         m_Nodes = new ReorderableList(serializedObject,
86.             serializedObject.FindProperty(propertyName), true, true, true, true);
87.  
88.         m_Nodes.drawHeaderCallback = (Rect r) =>
89.         {
90.             EditorGUI.LabelField(r, propertyName);
91.         };
92.  
93.         m_Nodes.elementHeightCallback = (int index) =>
94.         {
95.             SerializedProperty element = m_Nodes.serializedProperty.GetArrayElementAtIndex(index);
96.             var h = EditorGUI.GetPropertyHeight(element.FindPropertyRelative("Vcam"));
97.             return h + EditorGUIUtility.standardVerticalSpacing;
98.         };
99.  
100.         m_Nodes.drawElementCallback = (Rect rect, int index, bool isActive, bool isFocused) =>
101.         {
102.             var oldLabelWidth = EditorGUIUtility.labelWidth;
103.             EditorGUIUtility.labelWidth = 1;
104.             SerializedProperty element = m_Nodes.serializedProperty.GetArrayElementAtIndex(index);
105.             var p = element.FindPropertyRelative("Vcam");
106.             EditorGUI.PropertyField(rect, p, GUIContent.none);
107.             EditorGUIUtility.labelWidth = oldLabelWidth;
108.         };
109.     }
110. }
111. #endif
112.