Debugging (Feature request?) - Step through game frame-by-frame (for inspection)

Hi, I watched a video the other day about ’ Nier: Automata ’ and in that game there is a debug mode which allows the developers to step through the game frame-by-frame. Meaning that the game is ‘paused’ and every time you press a particular button, the game proceeds by a single frame. I think this is very useful for inspecting cinematics and other types of transitions/animations. Does this feature exist in UE4 already?

As far as I can tell, it doesn’t exist, but it should be relatively easy to implement. Just do something like this:

Pause game
Press advance one frame button
Unpause the game and set a bool
In the tick, check that bool and if it’s true, pause the game

Include a LINK to the video…:wink:

I would have but it was actually a long time ago and I can’t remember what the video was called… :frowning:

No worries. Did you try the suggestion from @ddbrown30?

If so how far away was that from what you saw in the video?

I haven’t tried it yet as this feature isn’t a super high priority. However, I can’t see why it wouldn’t work.

What you have seen there is actually the animation system that can be paused in playtest runtime and stepped through, frame by frame, to test collisions and damage triggers. So designers can adjust “defective frames” in engine, that was built there because some fight animations are too fast and if collisions were not adjusted for each frame there would be a lot of physics bugs even with substepping.

Unreal has anim notifies per frame as well, but you cannot set collision capsule’s location offset per frame in animations unless you do some serious C++ hackery.
So in Unreal people do a lot of raycast hit tests, trying to detect if an animation of a melee attack did hit something or not.

wow, thanks for the insight. I mainly wanted a feature like that because I make a lot of scene transitions and I need to verify how seamless the transitions are on a frame by frame basis.

Well, of course it exists. Just run the game in PIE, then pause the game and an “Advance Single Frame” button should appear in the toolbar where you have the PIE controls.

I already know about that. I was wondering if there was a version of that for non PIE modes. I prefer to test my games in the standalone mode rather than the PIE mode.