Writing to Depth Buffer with Structured Buffer

vvvv beta question
#1

I have a pixel shader that is writing to both color & depth (SV_TARGET & SV_DEPTH).

If use any value derived from a structured buffer it’s fine with the color, but not with the depth. Any clues? Simplified patch & shader attached.

// load a vaule from SB
	float myValue = valueDefault;
	uint vCount, dummy;	
	valueBuffer.GetDimensions(vCount, dummy);
	if (vCount > 0)  myValue = valueBuffer[0](0);
	
	Out.Color = float4(In.TexCd.xy,0,1);
	Out.Depth = In.PosWVP.z/In.PosWVP.w;
	
	//error here, writing to color is fine, but depth is not happy
	Out.Color += myValue; //ok
	//Out.Depth += myValue; // not ok
	
    return Out;

DepthWrite.zip (3.5 kB)

#2

https://msdn.microsoft.com/en-us/library/windows/desktop/bb509647(v=vs.85).aspx

I guess this is related? Still don’t understand though tbh. If it’s not possible can use an extra render target for the depth instead of the SV (boo!).

#3

hey man i checked your line of code… all fine here

anyways few stuff i wanted to mention
valueBuffer.GetDimensions(vCount, dummy); <-- Bad idea for a pixelshader (too expensive)

second one, what MS statements means on my taste, that depth get written only in the area ur object covers on the screen

#4

Hey man! Thanks for having a look.

If you uncomment this line you should see the error:
//Out.Depth += myValue; // not ok

#5

that what i did, no errors, i can offset depth whatever i like…

#6

oh! interesting… Here’s what I get if I try to enable that line:

Card / driver difference perhaps?

#7

you’re quite right about asking every pixel to check the buffersize! Don’t think that’s the problem, good point though.

#8

u can also try to change SV_TARGET with SV_Target0 and SV_DEPTH with SV_Depth don’t think there is difference thought, are u on latest DX Build?

#9

No joy changing the naming, also tried driver updates. Not sure about latest DX build- I’m on Windows 8.1 and thought it was already included (correct me here, that’s just from googling).

hmmm how annoying.

#10

I guess he means vux’s dx latest build

#11

i’m on GTX 960, w10
just double checked…
i’m using dx11 build from contributions btw

#12

Ok thanks I’m using that one too. Can anyone else on windows 8 say if this works for them?

#13

cannot reproduce error

win 10, 770 gtx, beta34.2

#14

Seems it is indeed a compiler error.

Was in in fact reported to MS a couple of years ago, and they seem to have kindly fixed it with the newer compiler shipping with windows10.