May relate to MC-259614.
The bug
On blocks with coplanar, coinciding faces, the cracking animation is rendered once per plane, resulting in the cracks rendering much darker than they should.
How to reproduce
Place a wall (all four connections, plus post)
Get under it
Start breaking it
Observe the cracks
Expected results
Normal cracking animation.
Actual results
It looks much darker.
Further notes
Changing the model would get rid of this issue from walls specifically, but would not eliminate it from other custom models, so code changes of some sort will be required.
Related issues
is duplicated by
relates to
Attachments
Comments


Testing this in some older versions, in 1.14.4 this appears to cause z-fighting:
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1.4.2 does not appear to be affected:
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I'm not sure if the model was handled differently at this point. though.

For the specific case of walls, this appears to have been introduced in 15w31a (alongside multipart models). I have yet to test custom models in 1.8 snapshots and release versions.
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