[Can't fix] Thing position interpolation inconsistent between FP/TP

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Thing position interpolation inconsistent between FP/TP

Postby Nash » Sat Dec 23, 2017 5:51 am

Run attached example. Observe the floating model in front of you while moving the player's view angle and pitch.

- In first person, the model appears jittery and is "lagging behind" the actual player view.
- In third person chase camera, the model is firmly planted in front of the player relative to the player view.

Expected behavior: in first person, the model is firmly planted in front of the player view.
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sticky.pk3
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Nash
Nash Muhandes
 
 
 
Joined: 27 Oct 2003
Location: Kuala Lumpur, Malaysia

Re: Thing position interpolation inconsistent between FP/TP

Postby Graf Zahl » Wed Feb 28, 2018 7:52 am

Looks correct to me with today's build. What version did this problem occur in?
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Re: Thing position interpolation inconsistent between FP/TP

Postby Nash » Wed Feb 28, 2018 9:21 am

It still looks wrong with GZDoom g3.3pre-437-ge702504. Are you sure you don't have capped framerate turned on? I'm playing with uncapped framerate and it's very obvious. Try swiping your mouse very fast to the left or right while in first person view. Notice how jittery the model is. But if you do the same action while in third person view, it's not jittery.
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Nash
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Re: Thing position interpolation inconsistent between FP/TP

Postby Graf Zahl » Wed Feb 28, 2018 9:25 am

Capped frame rate is definitely off for me. The thing doesn't even move one pixel, regardless of what I do.

EDIT: I found the cause.
GZDoom allows to read mouse input per render frame if the update rate is high enough.

In that case I cannot help you because the player's camera position is no longer being interpolated between playsim frames but adjusted to the current mouse info in real time. But your model still only gets repositioned every 1/35 seconds per play tick.

This can be disabled by setting 'smooth_mouse' to true, and that's really the ONLY way your setup can possibly work ever. I have this variable enabled because my mouse got such a shitty update rate that otherwise the experience wouldn't be smooth anymore if mouse position was not interpolated between playsim frames.
Last edited by Graf Zahl on Wed Feb 28, 2018 9:36 am, edited 2 times in total.
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Graf Zahl
Lead GZDoom Developer
 
Joined: 19 Jul 2003
Location: Germany

Re: Thing position interpolation inconsistent between FP/TP

Postby Nash » Wed Feb 28, 2018 9:27 am

How odd! What else can I do to help you debug this? The model is definitely jittery for me only in first person.
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Joined: 27 Oct 2003
Location: Kuala Lumpur, Malaysia


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