Depth Buffer upside-down in some circumstances - help needed!

[DaveL99]

I have a camera that renders to an off-screen RenderTexture. I render this manually with the camera’s Render method. I also have a command-buffer that I’ve inserted into the camera “AfterSkybox”.

In this command-buffer, I draw objects again using CommandBuffer.DrawRenderer to a different colour render buffer, but I need to (re)use the original camera depth buffer.

This works fine. Except …

If the camera has any post-processing component active, or has HDR rendering enabled, then the depth buffer when executing my command-buffer is upside-down. (The original colour buffer is too - but I can cope with that!)

What can I do to resolve this?

I could copy ‘n’ flip the depth buffer to another RenderTexture’s depth buffer - but I can’t see any obvious (and lossless) way of copying depth. Can’t see any Graphics.Blit variants that would do this, for example.

I could draw all my objects v-flipped in the command-buffer, and then flip the whole render texture afterwards. I would need to try it and see if it still matches exactly (I’m relying on a z-equal depth test) due to rasterization rules etc.

Ideally I would avoid any additional blitting/flipping at all though. Is there any trick I’m missing that results in the camera drawing things a consistent way-up??

Any advice would be greatly appreciated.

[bgolus]

Meant to come back to this earlier. I don’t have a solution, but I can explain why.

Unity - Manual: Writing shaders for different graphics APIs

Vertical Texture coordinate conventions differ between two types of platforms: Direct3D-like and OpenGL-like.

• Direct3D-like: The coordinate is 0 at the top and increases downward. This applies to Direct3D, Metal and consoles.
• OpenGL-like: The coordinate is 0 at the bottom and increases upward. This applies to OpenGL and OpenGL ES.

This difference tends not to have any effect on your project, other than when rendering into a Render Texture
. When rendering into a Texture on a Direct3D-like platform, Unity internally flips rendering upside down. This makes the conventions match between platforms, with the OpenGL-like platform convention the standard.

Basically if the current render target is a render texture, and you’re rendering using Direct3D, the rendering is upside down, so Unity inverts it. When rendering using post processing or HDR, Unity internally switches the camera to render to a render texture instead of the frame buffer. Somewhere all that flipping isn’t happening, or is happening when it shouldn’t.