D3D hlsl: Cosmic Chasm display problems

[ghost]

MAME version

0.180 to current 0.255

System information

Windows 10 Home, 64-bit, version 22H2, USA, US English Installed RAM 8.00 GB AMD A6-5200 APU with Radeon(TM) HD Graphics 2.00 GHz

INI configuration details

mame -cc

Emulated system/software

cchasm and clones

Incorrect behaviour

Cosmic Chasm displays black pixels during the explosion that occurs during the attract mode when the ship flies into the upper right corner of the screen. These should be white. Also, the lines on some of the letters onscreen (i.e. Y and H) are cut short (see images).

Expected behaviour

The explosion pixels should be white and the letters should look correct and not partially cut off in places.

Steps to reproduce

1. run cchasm with this command: mame cchasm -video d3d -hlsl
2. let attract mode play and observe the attract mode and game summary
3. now run cchasm with this command: mame cchasm -video bgfx and choose any -bgfx_backend option
4. watch the game again and see the differences

Additional details

Comparisons below with 0.253 hlsl vs bgfx, may have to open them in new tabs to get the full effect since github scales them down. explosion upper right corner:

Here the letters Y and H are compared:

Here we have mame 0.172 d3d hlsl and it looks fine here in both instances:

and finally a comparison of the spinning "pinwheel" in the service mode from 0.172 and 0.253: It looks like each of those black lines is tethered to the individual multi-colored octogons in the wheel. The letters X and K look a bit rough too.

[ghost]

Tested with latest 0.255 and still the same results as previous versions, so Ryan's recent updates had no effect on this game.

not okay mame cchasm -video d3d -hlsl

okay mame cchasm -video d3d -nohlsl mame cchasm -video bgfx -bgfx_backend d3d9 mame cchasm -video bgfx -bgfx_backend d3d11 mame cchasm -video bgfx -bgfx_backend d3d12 mame cchasm -video bgfx -bgfx_backend opengl mame cchasm -video bgfx -bgfx_backend vulkan mame cchasm -video opengl mame cchasm -video opengl -gl_glsl

I noticed that these white lines appear for about a frame or two just as the ship explodes, but I don't know if this is a BTANB because I can't find any real hardware footage, and it happens in all mame versions:

[ghost]

I identified mame version 0.180 from 30 Nov 2016 as the point where this started. Glanced at the whatsnew but nothing in it seemed to give any clues to me as to why this would have broken suddenly. Updating the description one more time. I'll leave this to the big brains around here to figure out sometime.