渲染网格以将renderTexture转换为Texture2D

Question

I am trying to dynamically create a billboard from a given mesh. I am trying to do this with Graphics.DrawMeshNow to the active rendertexture, then convert the renderTexture to a texture 2d. This is my understanding of how RenderTexture through code works, that the next draw call is rendered to the active rt. for ReadPixel, it reads the pixels of the active rt. I have also tried to attach the renderTexture to the billboard, skipping the texture2d but with no luck.

var renderTexture = RenderTexture.GetTemporary(width,height,24);
var billboardTexture = new Texture2D(256, 256,TextureFormat.RGB24,false);
Graphics.SetRenderTarget(renderTexture);
Graphics.DrawMeshNow(quad, CurrentActiveGameObject.transform.localPosition,Quaternion.identity);
billboardTexture.ReadPixels(new Rect(0,0,width,height), 0,0);
billboardTexture.Apply();
billboardTexture.name = name + "_billboardTexture";
primMeshRenderer.material.mainTexture = billboardTexture;

When it gets to the last line of this code block, the billboardTexture is null. 1) What have I missed, how can I draw a mesh to a renderTexture? 2) can I only use renderTexture with a camera? 3) how can I test this? How can I test the DrawMeshNow is drawing to the renderTexture? I've step through the code but that gave me no clues as I wasn't too sure on what the objects should have contained. In my scene the mesh appears, which is suggesting its rendering to the camera still and not the RenderTexture.

Thanks.

Forgot to mention this is a editor script and is executed by a menu/shortcut.

Edit Question, Do I need to wait for endofFrame after DrawMeshNow for the ReadPixels to work?

Answer 1

The documents to me suggest that you should have been able to readPixel from a Temporary renderTexture, ReadPixel . But maybe a temp renderTexture is never 'active'? Since I was never able to readPixel from the Temporary rendertexture, in the end I created a 2nd camera, assigned the camera with a renderTexture object and made it active, I then readPixel from that renderTexture.