When I enable OIT through scene.useOrderIndependentTransparency = true;, the edges of translucent triangles are visible. They are not visible if OIT is disabled. Any idea? PG here (sorry, the file is ~100MB, so it takes a few seconds to load): https://playground.babylonjs.com/#YIU90M#717 [image…

Safeguarding derivates in bump shader by CraigFeldspar · Pull Request #12242 · BabylonJS/Babylon.js · GitHub Here you go :slight_smile:

w000t never seen this before and I have even no idea how it is possible, let me add @CraigFeldspar to the thread

hello @Michael Looked at your PG, and found that you have lots of opaque and alpha meshes in your model. [Capture d’écran 2022-02-27 à 19.29.25] Can you check that you don’t have 2 meshes layered on top of each other that share the exact same depth ? This usually doesn’t play well with OIT Le…

Hi, thanks for the answer and sorry for the delay. Indeed, at the exact location of the edges bug, there are two meshes at the exact same depth. But in the playground and in my Babylon.js v5.0.0 locally, I do not reproduce the issue (even without moving the meshes to have different depth…) So I don…

Here is the playground Sorry for ugly code, but the issue is here. If you disable oit it works, but if you enable it, you notice that the transparent textures stay at the same location on the screen. It looks like we are not flushing the dual-depth peeling framebuffers or something like that !

Thanks, @CraigFeldspar for your feedback. My previous PG is not working anymore, please try this new one: https://playground.babylonjs.com/#YIU90M#757 I managed to run Spectorjs on this one, showing that even the first draw call is showing these black edge artifacts, so I don’t think it’s related …

@CraigFeldspar My guess on the issue: my glTF doesn’t have tangents attribute, so the TBN matrix is computed using dFdx and dFdy. However, the derivatives must be called unconditionally, and it seems that the shader can return before cotangent_frame which uses the derivatives.

That s a pretty good catch, @CraigFeldspar should be able to look into it soon :slight_smile:

@sebavan @CraigFeldspar any update? I was able to confirm that the bug isn’t visible when my glTF file includes tangents, so it’s definitely related to cotangent_frame being called after the potential return resulting in undefined derivatives.

Hi Michael, Sorry I’m really swamp these days, I may be able to look into it over the weekend. I’ll keep you posted

Issue with OIT feature

Bugs

sebavan March 2, 2022, 4:18pm 5

@CraigFeldspar will fix it in no time with a playground sounds like a dispose issue

OIT bug on dispose

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Issue with OIT feature

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