From 138a13fc86c89a9d6710ee72027848898bc393f1 Mon Sep 17 00:00:00 2001 From: mischa Date: Fri, 26 Apr 2024 19:43:55 +0800 Subject: [PATCH] GuessForecastingStartPosition encapsulated --- .../ForecastRigidbody/ForecastRigidbody.cs | 160 ++++++++++-------- 1 file changed, 92 insertions(+), 68 deletions(-) diff --git a/Assets/Mirror/Components/ForecastRigidbody/ForecastRigidbody.cs b/Assets/Mirror/Components/ForecastRigidbody/ForecastRigidbody.cs index f58517721..29cc91888 100644 --- a/Assets/Mirror/Components/ForecastRigidbody/ForecastRigidbody.cs +++ b/Assets/Mirror/Components/ForecastRigidbody/ForecastRigidbody.cs @@ -302,6 +302,97 @@ protected override void ApplySnapshot(NTSnapshot interpolated) } } + // guess FORECASTING.startPosition + bool GuessForecastingStartPosition(out Vector3 position, out Quaternion rotation) + { + // first principles: + // + // BLENDING needs to interpolate between PREDICTING & FOLLOWING. + // the only way to do this without jitter and jumps is by + // interpolating from PREDICTION.endPosition to FOLLOWING.startPosition. + // anything else, no matter how smooth, will always cause jumps. + // + // PREDICTION.endPosition is easy: just remember before transition. + // + // FOLLOWING.startPosition is a bit harder. + // => we can sample snapshots @ blendingEndTime (if any). + // => if we haven't received it yet, we need to extrpolate based + // on current velocity to guess where we'll be at blendingEndTime. + + position = Vector3.zero; + rotation = Quaternion.identity; + + // first, see if there's a snapshot at blendingEndTime already. + // this would be super precise. + // returns false if there isn't any yet. + if (SnapshotInterpolation.TrySample( + clientSnapshots, + clientTimeline + blendingTime, + out int from, + out int to, + out double t)) + { + // interpolate between from & to + NTSnapshot fromSnapshot = clientSnapshots[from]; + NTSnapshot toSnapshot = clientSnapshots[to]; + NTSnapshot interpolated = NTSnapshot.Interpolate(fromSnapshot, toSnapshot, t); + position = interpolated.position; + rotation = interpolated.rotation; + + // debug colors + if (debugColors) + { + rend.material.color = blendingExactColor; + } + + return true; + } + // if not, then we need to guess. + // calculate the velocity of the latest known state. + // because that's the most accurate velocity we have. + // then extrapolate forward to blendingEndTime. + // TODO UNIT TEST THIS + else if (clientSnapshots.Count >= 2) + { + NTSnapshot latest = clientSnapshots.Values[clientSnapshots.Count - 1]; + NTSnapshot previous = clientSnapshots.Values[clientSnapshots.Count - 2]; + float timeDelta = (float)(latest.remoteTime - previous.remoteTime); // remote time gives us exact remote velocity + Vector3 positionDelta = latest.position - previous.position; + Quaternion rotationDelta = (latest.rotation * Quaternion.Inverse(previous.rotation)).normalized; // always need to normalize after mult + + // avoid division by zero + if (timeDelta > 0) + { + // now we have the remote velocity + Vector3 velocity = positionDelta / timeDelta; + + // extrapolate this from latest time to blendingEndTime + // TODO validate rotation formula? + float timeToBlendingEnd = (float)(blendingEndTime - clientTimeline); + position = latest.position + velocity * timeToBlendingEnd; + rotation = latest.rotation * Quaternion.Slerp(Quaternion.identity, rotationDelta, timeToBlendingEnd / timeDelta); + + // debug colors + if (debugColors) + { + rend.material.color = blendingGuessColor; + } + + return true; + } + // this shouldn't really happen. if timedelta is zero: do nothing. + else + { + return false; + } + } + // if we don't have enough snapshots: do nothing. wait for more. + else + { + return false; + } + } + // store the latest FOLLOWING.startPosition guess for visual debugging Vector3 followingStartPositionEstimate = Vector3.zero; @@ -352,75 +443,8 @@ void UpdateClient() // => we can sample snapshots @ blendingEndTime (if any). // => if we haven't received it yet, we need to extrpolate based // on current velocity to guess where we'll be at blendingEndTime. - - Vector3 followStartPosition = Vector3.zero; - Quaternion followStartRotation = Quaternion.identity; - - // first, see if there's a snapshot at blendingEndTime already. - // this would be super precise. - // returns false if there isn't any yet. - if (SnapshotInterpolation.TrySample( - clientSnapshots, - clientTimeline + blendingTime, - out int from, - out int to, - out double t)) - { - // interpolate between from & to - NTSnapshot fromSnapshot = clientSnapshots[from]; - NTSnapshot toSnapshot = clientSnapshots[to]; - NTSnapshot interpolated = NTSnapshot.Interpolate(fromSnapshot, toSnapshot, t); - followStartPosition = interpolated.position; - followStartRotation = interpolated.rotation; - - // debug colors - if (debugColors) - { - rend.material.color = blendingExactColor; - } - } - // if not, then we need to guess. - // calculate the velocity of the latest known state. - // because that's the most accurate velocity we have. - // then extrapolate forward to blendingEndTime. - // TODO UNIT TEST THIS - else if (clientSnapshots.Count >= 2) - { - NTSnapshot latest = clientSnapshots.Values[clientSnapshots.Count - 1]; - NTSnapshot previous = clientSnapshots.Values[clientSnapshots.Count - 2]; - float timeDelta = (float)(latest.remoteTime - previous.remoteTime); // remote time gives us exact remote velocity - Vector3 positionDelta = latest.position - previous.position; - Quaternion rotationDelta = (latest.rotation * Quaternion.Inverse(previous.rotation)).normalized; // always need to normalize after mult - - // avoid division by zero - if (timeDelta > 0) - { - // now we have the remote velocity - Vector3 velocity = positionDelta / timeDelta; - - // extrapolate this from latest time to blendingEndTime - // TODO validate rotation formula? - float timeToBlendingEnd = (float)(blendingEndTime - clientTimeline); - followStartPosition = latest.position + velocity * timeToBlendingEnd; - followStartRotation = latest.rotation * Quaternion.Slerp(Quaternion.identity, rotationDelta, timeToBlendingEnd / timeDelta); - - // debug colors - if (debugColors) - { - rend.material.color = blendingGuessColor; - } - } - // this shouldn't really happen. if timedelta is zero: do nothing. - else - { - return; - } - } - // if we don't have enough snapshots: do nothing. wait for more. - else - { + if (!GuessForecastingStartPosition(out Vector3 followStartPosition, out Quaternion followStartRotation)) return; - } // store the latest FOLLOWING.startPosition guess for visual debugging followingStartPositionEstimate = followStartPosition;