Differences between RenderPass.depth and DepthPass

[swingingtom]

Hi, Im not sure this is a bug, but as I didn't find any information in documentation or in existing issues, I create one.

Description of the bug

DepthPass doesn't produce the same results as RenderPass+DepthSavePass.
DepthPass seems to ignore : material.depthWrite=false , material.side , material.alpha|material.alphaTest

To Reproduce

Compare the results of both https://codesandbox.io/s/depthpass-vs-renderpass-depthsavepass-5bos0
Toggle DepthPass>>Show/Hide from the gui to compare both depth

Expected behavior

Should'nt both ways produce the same results ?

Screenshots

RenderPass

Depth( from RenderPass )

Depth( from DepthPass )

Library versions used

• Three: 0.132.2
• Post Processing: 6.23.3

[vanruesc]

DepthPass seems to ignore : material.depthWrite=false , material.side , material.alpha|material.alphaTest

That is correct; it's a limitation of three's override material system. The DepthPass uses a MeshDepthMaterial to render the depth of objects into a render target. It ignores individual settings of the original materials for performance reasons.

The RenderPass + DepthSavePass combo works because the DepthSavePass enables an internal depth texture attachment for the RenderPass. The resulting depth is correct because all objects use their original materials, including custom depth materials. The DepthPass ignores those too.

You can enable the override material workaround which was primarily created to support skinned and instanced meshes. It supports the side parameter, but not alphaTest, depthWrite, and probably many other settings.

Trying to handle all possible values of built-in materials, not to mention custom shaders, is not feasible. The best solution is to use MRT instead, but it's a change that needs to happen in postprocessing, not in user code, and I'm working on it.

[swingingtom]

Hey ! Sorry for the super long delay.
Thank you for the answer. I was expecting such performance reasons.

I could indeed adjust granularity of depth using available options DepthPass and OverrideMaterial workaround or simply rely on DepthSavePass.

I will therefore close this issue.

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.

[iuriiiurevich]

Trying to handle all possible values of built-in materials, not to mention custom shaders, is not feasible. The best solution is to use MRT instead, but it's a change that needs to happen in postprocessing, not in user code, and I'm working on it.

@vanruesc Are there any updates on this?

I ran into an issue when using SelectiveBloomEffect (which internally uses DepthPass) on meshes with ShaderMaterial, so the vertex shader is not being applied to the depth texture, resulting in a difference in vertex positions between objects on the screen and the bloom result (which is expected)

[vanruesc]

Are there any updates on this?

@iuriiiurevich Progress has been made but #419 skipped over a lot of details that I need to figure out as I go. There will be a big commit in the next few days to establish the baseline for v7.