Making a render texture composed of other render textures side by side

I want to create an a render texture which is made up from three or more render textures side by side. Specifically, I have three cameras, each of which is rendering to separate a render texture. I want these three render texture made into one.

Side by side, like so:

[camera1] [camera2] [camera3]

reason being that I want to syphon this single big texture out of unity to use with another application.

Firstly, is this possible? From the Unity script reference on RenderTextures I can’t see where I would start.

Secondly, if you have any ideas that that would be much appreciated. I have placed them all onto a GUI texture side by side, onto an orthogonal camera and then used the render texture of this camera, but there must be a better way to do it.

Thanks

Yes it is quite possible.

Render the three cameras to their own textures

Then copy all three textures to the fourth, combined texture, using Graphics.Blit.

Note that you need Pro to use RenderTextures at all.