Shader channel setting and zDepth

[SonyBoy]

Is there a way to have a shader that has refractions and which is set to All Channels NOT pass transparency into certain render elements. In particular, when a refracting shader is set to All Channels and the zDepth render element is enabled, it results in transparency also being passed into the depth AOV. Under most circumstances this is undesirable and results in the pass being unusable. Seems a bit unintuitive that the zDepth render element doesn't have this hardwired into it, although perhaps this is an unavoidable side effect of render calculations. Vray's AOV system is amazing, but it would be nice to have this ability, rather than having to create render layers with overrides to get the right pass.

[wizzackr]

Under most circumstances this is undesirable and results in the pass being unusable. Seems a bit unintuitive that the zDepth render element doesn't have this hardwired into it, although perhaps this is an unavoidable side effect of render calculations.

Out of curiosity: Why would this ever be undesirable? For anything faking distance discolorations, DOF or similar that would give you the physically plausible result or what am I missing? We always thought it is a blessing how vray handles the zdepth pass in this regards (and still shudder at the hoops you had to jump through to make this work in mental ray...)

[yolov]

That's not currently possible, unless we implement an option for the shader to affect or not each channel, instead of color/alpha/all. Which is somewhere on the list, but is not a high-priority task at the moment.

[SonyBoy]

@ Wizzackr A simple grayscale depth pass can only represent one defocus value at any given pixel. So if you have a glass jar, for example, you would generally want the front of the jar to represent the object's depth in Z. If the depth pass renders the jar with transparency, you are not going to get the correct value.