color copy with mips works, but fetching from BiRP SG not yet

UnityGLTF/Assets/UnityGLTF/Runtime/Scripts/RenderPipelines/CopyColorBuiltin.cs

@@ -1,29 +1,73 @@
+using System;
+using System.Collections.Generic;
 using UnityEngine;
 
 [ExecuteAlways, ImageEffectAllowedInSceneView]
 public class CopyColorBuiltin : MonoBehaviour
 {
+	public Renderer tempOutput;
+	private MaterialPropertyBlock tempBlock;
+
 	private RenderTexture opaqueTexture;
-	private RenderTexture temp;
+	private Dictionary<Camera, RenderTexture> temp = new Dictionary<Camera, RenderTexture>();
+
 	private void OnDisable()
 	{
-		if(temp != null)
-			RenderTexture.ReleaseTemporary(temp);
+		if (temp != null) {
+			foreach(var kvp in temp)
+				RenderTexture.ReleaseTemporary(kvp.Value);
+		}
+		temp.Clear();
+	}
+
+	private void OnPreRender()
+	{
+		SetTexture();
+	}
+
+	private void SetTexture()
+	{
+		var current = Camera.current;
+		if (!temp.ContainsKey(current))
+		{
+			Shader.SetGlobalTexture("_CameraOpaqueTexture", Texture2D.blackTexture);
+			return;
+		}
+
+		Shader.SetGlobalTexture("_CameraOpaqueTexture", temp[current]);
+
+		if (tempOutput)
+		{
+			if (tempBlock == null) tempBlock = new MaterialPropertyBlock();
+			tempBlock.SetTexture("_MainTex", temp[current]);
+			tempOutput.SetPropertyBlock(tempBlock);
+		}
 	}
 
 	[ImageEffectOpaque]
 	private void OnRenderImage(RenderTexture src, RenderTexture dest)
 	{
 		var dsc = src.descriptor;
 		dsc.useMipMap = true;
-		dsc.autoGenerateMips = true;
+		dsc.autoGenerateMips = false;
+		dsc.msaaSamples = 1;
+		dsc.width = Mathf.ClosestPowerOfTwo(dsc.width);
+		dsc.height = Mathf.ClosestPowerOfTwo(dsc.height);
+
+		var current = Camera.current;
+		if (!temp.ContainsKey(current))
+			temp.Add(current, null);
+		if(temp[current])
+			RenderTexture.ReleaseTemporary(temp[current]);
 
-		RenderTexture.ReleaseTemporary(temp);
-		temp = RenderTexture.GetTemporary(dsc);
+		temp[current] = RenderTexture.GetTemporary(dsc);
+		temp[current].filterMode = FilterMode.Trilinear;
+		// temp[current].useMipMap = true;
 
-		Graphics.Blit(src, temp);
+		Graphics.Blit(src, temp[current]);
+		temp[current].GenerateMips();
 		Graphics.Blit(src, dest);
 
-		Shader.SetGlobalTexture("_CameraOpaqueTexture", temp);
+		SetTexture();
 	}
 }