Direct3D custom z testing.

You can set the depth bias renderstate (D3DRS_DEPTHBIAS) in Dx 9 or use the DepthBias member of the D3D11_RASTERIZER_DESC1 in Dx 11


Alternatively, in the vertex shader you can add a vector pointing towards the camera to offset the location:


biasedPos = pos + (vectorToCamera.normalize() * biasValue)


Or you can slightly push out your near and far clip planes, which will cause everything rendered after to be slightly closer (z-wise) than everything rendered before.

Edit: brain fart.

You can't have differen values for testing and writing. The easiest thing to do would be to have a z-only pass, then render your geometry again with depth biasing and depth writes disabled.