graphics: Strange rendering with Radeon RX 580

[hajimehoshi]

Version: OpenDiablo2/OpenDiablo2@dba17fc
This is not reproduced with Ebiten 1.10.

GPU: RX 580 sapphire

[hajimehoshi]

Confirmed that this happens with examples/flappy

[hajimehoshi]

by Troispoils

[hajimehoshi]

Note that this worked before introducing glMapBuffer.

[hajimehoshi]

We might need to avoid glMapBuffer due to portability, maybe? On the other hand, glTexSubImage2d should be called once for multiple rectangle regions, or the performance would be poor.

My current idea is:

• If the number of the region is 1, call glTexSubImage2d or glTexSubImage2d.
• If not:
  • Create one big byte slice that includes the rectangle regions
  • Create a temporary texture (if needed)
  • Call glTexSubImage2d on the temporary texture with the big byte slice
  • Render the temporary texture to the target in the regular glDrawElement way.

Instead of glTexSubImage2d, glBuffer(Sub)Data might be better. In this case, we still use PBO.

[hajimehoshi]

Radeon R4 Graphics (Bungbungame Photon2) didn't cause this issue.

[hajimehoshi]

https://www.reddit.com/r/blender/comments/e0iv5q/blender_suddenly_looks_like_this_looks_kinda_cool/ is similar to the previous report:

[auyer]

Does not occur with Go1.12.5 / Go1.13.4 windows/amd64 on an AMD Vega 64.

[hajimehoshi]

Thanks! I think this means that not all external AMD GPUs caused this issue.

[hajimehoshi]

@auyer What is the SHA1 hash of Ebiten?

[hajimehoshi]

Meh, I could not reproduce this with MacBook Pro 2018 and an eGPU (Radeon RX 580)

[auyer]

Thanks! I think this means that not all external AMD GPUs caused this issue.

The GPU I used is dedicated, but not external.

@auyer What is the SHA1 hash of Ebiten?

f6390ab

I can re-test with a different commit if you want.

[hajimehoshi]

Thanks!

I can re-test with a different commit if you want.

That commit is fine (this should include the reported problem). Thanks.

[hajimehoshi]

Now I replaced glMapBuffer / glUnmapBuffer with glBufferSubData, then this should not be problematic more.