RenderTexture 3D to Texture3D

Is it possible to Convert a Rendertexture with depth to a Texture3D? or Store the Rendertexture as a Texture3D.

 

It should be possible, but it'll take a bit of extra work.

Right now there's no way to read back a specific layer of a 3D render texture to the CPU. I've not tried, but I suspect if you tried to use

ReadPixels

on a render texture with volume depth, you'll always get the top slice. So instead you'll need to create a 2D render texture with the same width, height and format as the 3D one and use

Graphics.CopyTexture()

to copy a single layer at a time out. You can then use

tex.ReadPixels()

to read that 2D render texture into a

Texture2D

. You can then use

GetPixels

/

SetPixels 

or

CopyTexture

again to copy each slice from a

Texture2D

into a

Texture3D

.


Also as an aside, you said "a render texture with depth". A render texture with depth isn't a 3D render texture, it's a render texture with a separate 2D depth buffer. To make a 3D render texture you need to create a render texture using a RenderTextureDescriptor with a

TextureDimension.tex3D

dimension

and

volumeDepth

.

 

This worked for me.

 

Fastest way for even large (multiple GB) textures:

Code (CSharp):

1. void SaveRT3DToTexture3DAsset(RenderTexture rt3D, string pathWithoutAssetsAndExtension)
2. {
3.     int width = rt3D.width, height = rt3D.height, depth = rt3D.volumeDepth;
4.     var a = new NativeArray<byte>(width * height * depth, Allocator.Persistent, NativeArrayOptions.UninitializedMemory); //change if format is not 8 bits (i was using R8_UNorm) (create a struct with 4 bytes etc)
5.     AsyncGPUReadback.RequestIntoNativeArray(ref a, rt3D, 0, (_) =>
6.     {
7.         Texture3D output = new Texture3D(width, height, depth, rt3D.graphicsFormat, TextureCreationFlags.None);
8.         output.SetPixelData(a, 0);
9.         output.Apply(updateMipmaps: false, makeNoLongerReadable: true);
10.         AssetDatabase.CreateAsset(output, $"Assets/{pathWithoutAssetsAndExtension}.asset");
11.         AssetDatabase.SaveAssetIfDirty(output);
12.         a.Dispose();
13.         rt3D.Release();
14.     });
15. }