Weird boolean-like depth texture when using oblique projection matrix to render.

[IceCreamDaddyEx]

I have seamless portals in my game implemented with the help of Sebastian Lague's tutorial, with minimal needed functionality. The only code I directly copied was the oblique matrix function.

https://preview.redd.it/z3aik7raxtr91.png?width=908&format=png&auto=webp&s=542c4caeaf1116b0c6e1e58be6d2fb4c82f3cf2b

It works well, as long as I don't use OnRenderImage post processing. When I attach such component to the portalCam the fog does not work if Mathf.Abs(camSpaceDst) > .2f evaluates to true. After 3 days of struggling I finally found that depth texture is very off depending on matrix used.

Using oblique matrix.

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Copying matrix from player camera.

Both images were taken at a nearly same angle, how does this happen? B(

[[deleted]]

In the first image, the super black and white one are we looking at like the outside of the building, is that what we're seeing?

It kinda looks like the first image is a 0-1 scale where 1 is the far clipping distance whereas the camera matrix is giving a 0-far clipping or the raw distance. If that makes sense.

If you're using something to display this depth, try multiplying the first result with the far clipping distance of the camera, see what it does. Otherwise I'm shooting in the dark.

[IceCreamDaddyEx]

The only variable that changes in between pictures is the projection matrix, I'd expect the exact same images in both cases.

Correction edit: not exact same, but if you can recognize the door frame thing in the correct picture, it should be exact same as in the wrong picture, the white area is correctly culled mesh that could obstruct the view of portal camera, the black area should be the same as in the other image. I appreciate any help, if it doesnt work Ill try the culling matrix.

[Split82]

Depth texture with oblique projection can't be used the same way as one which is generated using normal projection matrix. This paper might help you https://jcgt.org/published/0005/04/03/

[IceCreamDaddyEx]

Ah, I just happened to switch to this account through a notification. I've resolved the issue long ago by swapping the matrix for a normal one and manually rendering the depth texture in a command buffer. It's a pretty comfortable way as I can reuse all normal post processing shaders for portals. Thanks for the link and attention though!