69 lines
3.0 KiB
C#
69 lines
3.0 KiB
C#
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// snapshot for snapshot interpolation
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// https://gafferongames.com/post/snapshot_interpolation/
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// position, rotation, scale for compatibility for now.
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using UnityEngine;
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namespace Mirror
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{
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// NetworkTransform Snapshot
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public struct TransformSnapshot : Snapshot
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{
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// time or sequence are needed to throw away older snapshots.
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//
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// glenn fiedler starts with a 16 bit sequence number.
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// supposedly this is meant as a simplified example.
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// in the end we need the remote timestamp for accurate interpolation
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// and buffering over time.
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//
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// note: in theory, IF server sends exactly(!) at the same interval then
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// the 16 bit ushort timestamp would be enough to calculate the
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// remote time (sequence * sendInterval). but Unity's update is
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// not guaranteed to run on the exact intervals / do catchup.
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// => remote timestamp is better for now
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//
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// [REMOTE TIME, NOT LOCAL TIME]
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// => DOUBLE for long term accuracy & batching gives us double anyway
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public double remoteTime { get; set; }
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// the local timestamp (when we received it)
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// used to know if the first two snapshots are old enough to start.
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public double localTime { get; set; }
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public Vector3 position;
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public Quaternion rotation;
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public Vector3 scale;
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public TransformSnapshot(double remoteTime, double localTime, Vector3 position, Quaternion rotation, Vector3 scale)
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{
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this.remoteTime = remoteTime;
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this.localTime = localTime;
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this.position = position;
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this.rotation = rotation;
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this.scale = scale;
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}
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public static TransformSnapshot Interpolate(TransformSnapshot from, TransformSnapshot to, double t)
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{
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// NOTE:
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// Vector3 & Quaternion components are float anyway, so we can
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// keep using the functions with 't' as float instead of double.
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return new TransformSnapshot(
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// interpolated snapshot is applied directly. don't need timestamps.
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0, 0,
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// lerp position/rotation/scale unclamped in case we ever need
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// to extrapolate. atm SnapshotInterpolation never does.
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Vector3.LerpUnclamped(from.position, to.position, (float)t),
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// IMPORTANT: LerpUnclamped(0, 60, 1.5) extrapolates to ~86.
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// SlerpUnclamped(0, 60, 1.5) extrapolates to 90!
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// (0, 90, 1.5) is even worse. for Lerp.
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// => Slerp works way better for our euler angles.
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Quaternion.SlerpUnclamped(from.rotation, to.rotation, (float)t),
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Vector3.LerpUnclamped(from.scale, to.scale, (float)t)
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);
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}
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public override string ToString() =>
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$"TransformSnapshot(remoteTime={remoteTime:F2}, localTime={localTime:F2}, pos={position}, rot={rotation}, scale={scale})";
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}
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}
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