Modding, Mission Design, and Coding > FS2 Open Coding - The Source Code Project (SCP)

Thrusterglow flickering seems to depend on model orientation


Col. Fishguts:
While testing a mod-mission I noticed that the thruster glows on one of my capship was completely static (as in: none of the usual flickering of the normal and tertiary glow sprites).
At first I thought I had broken something in the tables, but rotating my fighter around at full speed while in external view, I noticed the flickering animation comes and goes as you rotate the ship.

I turns out that ships oriented along the x-axis (both in + or - direction) show completely static thrusterglows when moving.
As the ship rotates away from the x-axis towards the z-axis, the flickering gradually starts. Ships pointing along the y-axis (straight up/down) also have static glows.

You can also see this in the F3 lab, enable thrusters in the rendering options and rotate any ship 90° clockwise/counterclockwise form the default position.

I checked in FS2 retail, and thrusterglows do the flickering animation consistently, independent of model orientation.
Retail FS2 even does the flickering at all times (i.e. when the ship is stopped), while fs2_open seems to scale the flickering intensity related with ship speed? So some part of the code that controls the flickering was changed at one point.

I also checked older builds in my folder, from fs2_open_19 to fs2_open_23, and all behave the same way. So if this is a bug, it's an old one.

See attached mission to test yourself ingame. Download

Huh, that's interesting.

Good eye, a small oversight from some changes 8 years ago. Inspecting the retail code, however, it seems to be doing the same fundamental thing and it would also seem that there should be no flicker at 0 throttle, but it's hard to say without running and stepping through it myself which is difficult.

Col. Fishguts:
I just checked retail-behavior again, it's actually more subtle than I remember (or ever noticed).
The flickering animation depends on the current throttle setting and whether or not "reverse thrust" (default z) is pressed.

- If the throttle is set to any value >0
    - The flickering animation plays at any ship speed (even at 0)
    - The overall radius of the thrusterglow scales with throttle setting (higher throttle = bigger radius)
    - I "z" is pressed and held until the ship stops -> the flickering animation plays at a slower rate if throttle is less than full (I think the animation speed is scaled with the throttle setting (as in 0.0 to 1.0)

- If the throttle is set to 0 (backspace)
      - If "z"is pressed -> the flickering animation stops (I assume scaling with 0.0 throttle results in animation speed 0)
      - If "z" is released  -> the flickering animation resumes as normal

I guess at one point someone tried to change this code, so that the animation speed just scales with throttle setting independently of "z" state.
Also to me that would make more sense than the retail behavior.

That ship orientation got involved here seems like an accident.

Col. Fishguts:
I checked the latest nightly and the issue is fixed :yes:


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