Smoke trail particle flipping FIX

[Taz1004]

I didn't know what category this is since this is not video corruption nor view system issue so I'm posting in General.

 

This I'm sure has bugged a lot of people especially the VR crowd. I believe I have found the solution to the problem but unfortunately touching anything to do with Smoke Trails breaks IC. So I'm posting my findings here hoping that ED can implement the fix.

 

Particle texture is turned off for better illustration

 

 

I first realized that the problem doesn't occur with vertical rising particles. Only with horizontal moving particles and if you're looking straight into it... such as smoke trail viewed from cockpit.

So I figured the problem has to be related to particle orientation... or axis.

 

So in smokeTrail_vs.hlsl line 15

 

Quote

o.params3.xyz = TANGENT/o.params3.w;

 

Changing the xyz to zxy will fix the flipping.

 

Quote

o.params3.zxy = TANGENT/o.params3.w;

 

Two issues that comes with this that I am aware of.

 

1. Smoke trail stretching will stretch wrong way. This needs to be disabled. Smoke trail stretching is not realistic. Missiles are leaving trail "behind". Trails are not moving with the missiles to create this motion blur effect. This should be disabled regardless. It can be quickly disabled in smokeTrail_sh.hlsl line 164 by multiplying with 0. Or if you really want to keep the stretching, change the stretch axis.
2. Second issue is the segment length needs to be about 4 times smaller to compensate for sine wave looking smoke turbulence movement. Or adjust the turbulent movement.

 

After looking at files closer, cloud rotation in VR seems to be different issue.

Edited October 25, 2021 by Taz1004

[dorianR666]

fixing ED's vertex shaders on your own, impressive

[Someone]

signal boost ...

@BIGNEWY/@Nineline, have you had a chance to discuss this with the team?

[rrohde]

+1

 

This should be on ED's list as well!

[Taz1004]

I've been running with this fix for couple weeks and yesterday, I turned it off to test my mod release. And I immediately noticed the rotating smoke trails and surprised at how much it annoyed me now. I included a version with this fix in the first post in case anyone wants to try it.

 

Warning.

• I do not have enough modules to test all missiles. It is possible this may break smoke trails on some missiles. I would like to know if it does.
  
• You may not want to go back once you try it and it will break IC.
  

 

Cloud rotating in VR seems to be different issue. Seems to be worldup vs camera up vector problem.

Edited September 21, 2020 by Taz1004

[Harker]

I've been running with this fix for couple weeks and yesterday, I turned it off to test my mod release. And I immediately noticed the rotating smoke trails and surprised at how much it annoyed me now. I included a version with this fix in the first post in case anyone wants to try it.

 

Warning.

• I do not have enough modules to test all missiles. It is possible this may break smoke trails on some missiles. I would like to know if it does.
  
• You may not want to go back once you try it and it will break IC.
  

 

Cloud rotating in VR seems to be different issue. Seems to be worldup vs camera up vector problem.

Did some tests. PM sent :thumbup:

[Sérvalpilot]

Hi!

This solution fixes the flipping, which is great, but missile smoke trails and contrails have a sine-wave look to them.

You mentioned something about reducing segment length to fix this effect, so where can I find that?

Cheers!

Edited January 26, 2022 by Sérvalpilot

[Munkwolf]

This is great. Is there a way to do the same fix for trees?