fixed timestep + render interpolation: the moving platform problem nobody warns you about

camera interpolation on platforms is genuinely one of those problems that sounds simple and then eats your whole afternoon. what worked for me: interpolate the camera in platform-local space, same way ApexFlare is doing for nested platforms above. so the camera has a "mount point" that's a child of the platform transform, you interpolate that, then compose with the platform's own interpolated world position at render time. keeps the camera glued to the platform visually without needing any special-case logic. still had to debug it for like 3 days though lol

The blend-out transition is genuinely the hardest part of this whole system. What ended up working for me: when the player leaves the platform, I don't snap back to world space at all — I take the current platform-local camera position, convert it to world space at that exact moment, and continue interpolating from there. The blend-out becomes a gradual shift from 'tracking platform velocity' to 'standard world-space damping', with no position discontinuity at the handoff point.

I also scale the blend-out duration based on how much residual velocity the platform was contributing when the player left. Stepping off a slow elevator is nearly instant. Jumping off a fast-moving ship takes a full second or two to fully decouple. That scaling alone made it feel intentional rather than janky.

the nested platform floating point thing is brutal. my janky solution was to store all child platform transforms relative to their parent in the physics tick and only compose them at render time. means the accumulated error only happens during the short composition step instead of snowballing tick-over-tick. still not perfect on 5+ levels of nesting but honestly if your game has 5 nested moving platforms that's a different problem lol

The "sample the interpolated world-space velocity at departure and use it as your new anchor" approach is exactly what I landed on too. The edge case that gets me is when the platform was mid-acceleration at the moment the player leaves. The instantaneous velocity at that frame isn't representative of what the camera was "feeling", so the blend-out has a subtle pop. I ended up doing a short weighted average over the last 4-5 frames of platform velocity before departure, which smooths it considerably. Small thing but it matters on fast-moving platforms.

the nested platform case is where this whole system starts showing its seams. even if you handle the chain correctly, floating point accumulates fast when you're composing multiple interpolated transforms. outer platform interpolates, inner platform interpolates relative to that, and by the time you get to the player standing on top you've got enough drift to cause visible jitter at high relative speeds.

I ended up computing the full world-space interpolated transform for each platform in the chain rather than compositing local→parent, which at least keeps the error bounded to one interpolation step instead of N.

Camera interpolation in platform-local space works really well until you need to blend out of it, like when the player jumps off the platform and the camera needs to stop following it. The transition back to world space is abrupt if you don't handle it explicitly. I track a "camera attachment weight" that lerps from 1 to 0 over a short window when the player leaves the platform, then compose the final camera position from both spaces weighted together. Adds some complexity but the blend out feels natural instead of snapping.