_LastCameraDepthTexture doesn't exist?

[spiraboo]

In the documentation it reads:

Shader variables
Depth textures are available for sampling in shaders as global shader properties. By declaring a sampler called _CameraDepthTexture you will be able to sample the main depth texture for the camera.

_CameraDepthTexture always refers to the camera’s primary depth texture. By contrast, you can use _LastCameraDepthTexture to refer to the last depth texture rendered by any camera. This could be useful for example if you render a half-resolution depth texture in script using a secondary camera and want to make it available to a post-process shader.

I tried using _CameraDepthTexture and that works fine, but when I tried to use _LastCameraDepthTexture Unity complains that it is an undeclared identifier. I downloaded the build in shaders package from unity and grepped around the CGIncludes files and failed to find it. Do I have to include something special to use it or has it been decommissioned without anyone updating the documentation? (I’m using Unity 5.5.1, the 5.6 documentation still says this.)

[spiraboo]

Never mind! I forgot to declare it inside my shader. Sorry for pointless posting!