EffectPass.setDepthTexture from DepthSavePass

[swingingtom]

Hi postprocessing community,

Im trying to reproduce the codesandbox postprocessing-god-rays but using DepthSavePass instead of DepthPass

Here is a sandbox showing where Im stuck : https://codesandbox.io/s/setdepthtexture-from-depthsavepass-39zp6?file=/src/App.js

It can show/hide the saved depth texture as TextureEffect from the gui. Where it seems that SaveDepthPass is correctly saved.

But

  effectPass.setDepthTexture(
    savedDepthPass.renderTarget.texture,
    RGBADepthPacking
  );

Seems to do absolutely nothing when feeded with DepthSavePass instead of DepthPass.
I can omit or comment out that statement, and its still working.

Working until ... another pass ( RenderPass or ClearPass ) comes after the DepthSavePass.
A render pass can also be enable/disabled from the gui.

Any advices are welcome. Thanks

[vanruesc]

It's possible to use the DepthSavePass in combination with a RenderPass to save a custom depth texture before rendering the main scene. Here's an example: https://codesandbox.io/s/postprocessing-god-rays-forked-tsq18?file=/src/App.js

This setup unearthed a problem though. The DepthSavePass uses RGBADepthPacking by default, but this produces fully white black pixels for fragments that read 0 1 in the input depth texture. I think this might be a quirk of the RGBA packing function, but I'm not sure if and how that could be fixed. Here's a comparison of the discrepancy:

DepthSavePass	DepthPass

BasicDepthPacking can be used instead, but this will store depth in a FloatType texture which may not be supported on some devices.

Seems to do absolutely nothing when feeded with DepthSavePass instead of DepthPass.
I can omit or comment out that statement, and its still working.

Setting a custom depth texture must be done after the pass was added to the composer. Otherwise the depth texture will be reset.

From #330:

But is there any other differences? On the internal structure or something else? I tried to replace DepthPass with DepthSavePass in godrays example as explained here #331 but something works different, and I struggle to find what.

The DepthSavePass copies the contents of a depth texture into another render target. It doesn't produce depth by itself and requires a depth texture as input which can be produced by a DepthPass or as a by-product of a RenderPass with a DepthTexture on the output render target.

[swingingtom]

Thanks you for the provided informations and the sandbox.
I was able to notice the behaviours you described in your post by messing with the sandbox. Much more clear now !