Resolved Optional fragment stage in Unity?

[EDIT] This was totally the wrong question. See below aleksandrk's reply for something hopefully more on track

Before using Unity I had previously done some experiements with gpu occlusion culling and one optimization used for one pass was to disable the rasterizer whilst keeping depth write enable in order to only render to the depth texture. In GL this was done using

glEnable(GL_RASTERIZER_DISCARD)

. I've seen that something similar exists in DirectX.

Is it possible to do this in Unity without using SRP? Its not the end of the world if I cant but it is a good optimization.

 

Thanks @aleksandrk, I completely misremembered, what I should have been asking about is if unity has an equivalent to GL in how it allows you not to specify a fragment stage, in which case it only writes to depth and stencil.
Disabling color writes might be what I'm after then, I'm not sure whether is this equivalent.

I must have transform feedback on the brain. Sorry for the confusion

 

I'm guessing disabling color writes is done using

ColorMask

. Any info you can provide on what that does behind the scenes would be very welcome

 

I often use this function:

Code (csharp):

1. void frag() {}

On Nvidia GPUs and some mobile GPUs this works just like having no fragment shader stage!

But on AMD GPUs you get black, and some mobile GPUs you get random noise.

TLDR: use

ColorMask 0

.

 

@bgolus @aleksandrk awesome, thanks a lot!

 

Sorry for the necro post. Unless I'm missing something, a fast way to completely skip running the fragment shader is to emit a constant like `float4(0, 0, 0, -1)` from the vertex shader as SV_POSITION.

(EDIT: avoid 0, 0, 0, 1 and return anything with w < 0, which should cleanly clip out)

 

Please don't necro posts like this. If you have questions about the behavior of the vertex shader please start a new thread.
To partially answer your question, no your suggestion is not equivalent to the answer above and wouldn't solve the original questions.