use new Unity API in 2020.3.37 to create compatible external texture

Author: zhuxingwei

Samples/UIWidgetsSamples_2019_4/Assets/Script/ModelViewHelper.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using Unity.UIWidgets.engine;
 using Unity.UIWidgets.foundation;
 using UnityEngine;
 
@@ -81,7 +82,12 @@ public bool Load(int id, string path)
 
             var gameObj = (GameObject) Instantiate(modelViewPrefab, Vector3.zero, Quaternion.identity);
 
-            var renderTexture = new RenderTexture(100, 100, 32);
+            var renderTexture = UIWidgetsExternalTextureHelper.createCompatibleExternalTexture(new RenderTextureDescriptor(
+                width: 100, height: 100
+                )
+            {
+                depthBufferBits = 32
+            });
 
             gameObj.transform.Find("Camera").GetComponent<Camera>().targetTexture = renderTexture;
 

Samples/UIWidgetsSamples_2019_4/Assets/Script/Scene3DTest1.cs

@@ -8,6 +8,7 @@
 using UnityEngine;
 using Color = Unity.UIWidgets.ui.Color;
 using Image = Unity.UIWidgets.widgets.Image;
+using TextStyle = Unity.UIWidgets.painting.TextStyle;
 using Texture = Unity.UIWidgets.widgets.Texture;
 using ui_ = Unity.UIWidgets.widgets.ui_;
 
@@ -62,8 +63,8 @@ public override Widget build(BuildContext context)
                     child: new Column(
                         children: new List<Widget>
                         {
-                            new Lottie("wine.json", size: new Size(100, 100)),
-                            new Container(width: 200, height: 200, color: Colors.red, child: new Center(child: new Container(width: 100, height: 100, child:new Texture(texture: text)))),
+                            new Text("External Texture is Only Available on OpenGLCore (Mac), OpenGLes(iOS and android) and D3d11(Windows)", style: new TextStyle(fontSize: 16f, decoration: TextDecoration.none, color: Colors.red)),
+                            new Container(width: 120, height: 120, color: Colors.red, child: new Center(child: new Container(width: 100, height: 100, child:new Texture(texture: text)))),
                             /*new Container(
                                 width: 100,
                                 height: 100,

com.unity.uiwidgets/Runtime/engine/UIWidgetsExternalTextureRegistry.cs

@@ -1,8 +1,20 @@
 using System;
 using System.Collections.Generic;
 using Unity.UIWidgets.foundation;
+using UnityEngine;
 
 namespace Unity.UIWidgets.engine {
+    public static class UIWidgetsExternalTextureHelper {
+        public static RenderTexture createCompatibleExternalTexture(RenderTextureDescriptor descriptor) {
+#if UNITY_2020_3_OR_NEWER && !UNITY_2020_3_1 && !UNITY_2020_3_2 && !UNITY_2020_3_3 && !UNITY_2020_3_4&& !UNITY_2020_3_5 && !UNITY_2020_3_6 && !UNITY_2020_3_7 && !UNITY_2020_3_8 && !UNITY_2020_3_9 && !UNITY_2020_3_10&& !UNITY_2020_3_11&& !UNITY_2020_3_12 && !UNITY_2020_3_13 && !UNITY_2020_3_14 && !UNITY_2020_3_15 && !UNITY_2020_3_16 && !UNITY_2020_3_17 && !UNITY_2020_3_18 && !UNITY_2020_3_19 && !UNITY_2020_3_20 && !UNITY_2020_3_21 && !UNITY_2020_3_22 && !UNITY_2020_3_23 && !UNITY_2020_3_24 && !UNITY_2020_3_25 && !UNITY_2020_3_26 && !UNITY_2020_3_27 && !UNITY_2020_3_28 && !UNITY_2020_3_29 && !UNITY_2020_3_30 && !UNITY_2020_3_31 && !UNITY_2020_3_32 && !UNITY_2020_3_33 && !UNITY_2020_3_34 && !UNITY_2020_3_35 && !UNITY_2020_3_36
+            //this API is only available for 2020.3.37 and later Unity
+            return UIWidgetsInternal.CreateBindableRenderTexture(descriptor);
+#else
+            return new RenderTexture(descriptor);
+#endif
+        }
+    }
+    
     public partial class UIWidgetsPanelWrapper {
         readonly Dictionary<IntPtr, int> externalTextures = new Dictionary<IntPtr, int>();