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I'm experiencing the same problem as some other people have noticed in Blender 2.82 (win64) - when trying to assign material to a face, the surface suddenly becomes transparent.

Here, in the left mesh, I have the grey material as the default. When I assign either of the material.salmon or material.tuna (both made from default materials with only the base color changed), the faces become transparent.

In the block on the right, the primary material is material.tuna and the missing faces have been assigned material.salmon. I've created a small block to the side using only material.salmon to show that it's not the material itself. secondary material problem

In Vygintas' question Assigning faces to new materials, Martynas Žiemys recommends checking

  • blend mode (in my screenshot above, my blend mode is opaque)
  • eevee vs cycles (my renderer is set to eevee)
  • face orientation (all my faces are blue, facing outward) face orientation

In Mins' question How do we assign a second material to selected faces in 2.8? DarkSoul asks if alpha has been enabled. In my case it has not.

I have tried a brand new project, with a default cube, and as soon as I assign a new material to a face it becomes transparent as well. default cube

Any suggestions would be appreciated.

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Mladen
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  • Went back to previous versions - 2.81 has the same issue but it works in 2.80! screenshot – Mladen Mar 04 '20 at 23:16
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    Does your system fulfill the minimum requirements for running Blender 2.8x? – Robert Gützkow Mar 04 '20 at 23:21
  • Probably your blender is having a problem, because is working correctly in mineenter image description here Try to install it again as new – Emir Mar 04 '20 at 23:19
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    Sounds like you should report it as a bug. Then maybe either downgrade for now or even see if the latest experimental build has things fixed. – John Mar 05 '20 at 02:58
  • Thanks for posting your screenshot @Emir - that's exactly what it should look like. I took your advice and uninstalled and reinstalled Blender (v2.87.7) and also updated my graphics card drivers just in case, but nothing changed when I colored a default cube. Flipping the order of the materials around seemed to fix it until I looked at the back [front vs back](https://www.screencast.com/t/vxLfVWUf5veX} – Mladen Mar 05 '20 at 04:43
  • Thanks for checking @RobertGützkow - yes my system is above the minimum and exceeds the recommended level by a bit: 64-bit 8 core CPU, 20GB RAM and dual Nvidia GeForce cards with 4GB each. – Mladen Mar 05 '20 at 04:49
  • @John I'm going to finish the sushi tutorial series by Polygon Runway using Blender 2.80 for now. Thanks for the suggestion about reporting it - I've submitted it to developer.blender.org. – Mladen Mar 05 '20 at 05:42
  • @RobertGützkow you were correct. Although it seemed like my system met the minimum requirements, there is a specific issue in using certain older GPUs, specifically the age of the drivers. The Blender code even contains workarounds for GPU_legacy_nvidia_driver and GPU_crappy_amd_driver but in my case didn't work and thus ended up with the missing faces. – Mladen Mar 05 '20 at 21:16

1 Answers1

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I hope this helps others who run across this. This is a known issue when using multiple materials with a number of older GeForce and Quadro graphics cards.

Blender Known Issue: Drawing error with multi-material object. Faces disappear or showing artifacts with 2 or more material slots applied to same object. When trying to use a second material or more on an object, the faces where it is applied become transparent or in some cases they are distorted as black rectangles that stretch to the origin (this second occurs above all with more complex models than a cube). It happens in Blender 2.81 as well as in Blender 2.82, but in Blender 2.80 there is no such error.

While the bug report lists multiple cards such as the ones below, the list is not exhaustive (my card for instance, GeForce 9800 GTX+, is not listed), the core issue is that the GPU has to be able to run NVIDIA drivers greater than v400. The highest driver that I can install is the GeForce v342.01 driver.

  • GeForce 210
  • GeForce 410M
  • GeForce GT 220
  • GeForce GTX 275
  • Quadro FX 3700
  • Quadro FX 3800
  • Quadro FX 4800

I can also confirm that as listed in the bug report, Blender 2.80 does work for me.

Mladen
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  • Your list seems to be inaccurate, the Nvidia GTX 980 and Nvidia GTX 1080 are certainly not affected by this. The ones listed in the ticket do not meet the minimum requirements, which was also mentioned by Jeroen Bakker. Anything that is older than the GeForce 400 series or Quadro cards before the Tesla architecture aren't supported. – Robert Gützkow Mar 05 '20 at 21:03
  • Thanks @RobertGützkow - I corrected the list. – Mladen Mar 05 '20 at 21:19