Created
March 30, 2016 00:35
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using UnityEngine; | |
using System.Collections; | |
public class NetworkRigidbody : MonoBehaviour | |
{ | |
public double m_InterpolationBackTime = 0.1; | |
public double m_ExtrapolationLimit = 0.5; | |
internal struct State | |
{ | |
internal double timestamp; | |
internal Vector3 pos; | |
internal Vector3 velocity; | |
internal Quaternion rot; | |
internal Vector3 angularVelocity; | |
} | |
// We store twenty states with "playback" information | |
State[] m_BufferedState = new State[20]; | |
// Keep track of what slots are used | |
int m_TimestampCount; | |
private void OnSerializeNetworkView(BitStream stream, NetworkMessageInfo info) | |
{ | |
// Send data to server | |
if (stream.isWriting) | |
{ | |
Vector3 pos, velocity, angularVelocity; | |
Quaternion rot; | |
if (rigidbody != null) | |
{ | |
pos = rigidbody.position; | |
rot = rigidbody.rotation; | |
velocity = rigidbody.velocity; | |
angularVelocity = rigidbody.angularVelocity; | |
} | |
else | |
{ | |
pos = transform.position; | |
rot = transform.rotation; | |
velocity = Vector3.zero; | |
angularVelocity = Vector3.zero; | |
} | |
stream.Serialize(ref pos); | |
stream.Serialize(ref velocity); | |
stream.Serialize(ref rot); | |
stream.Serialize(ref angularVelocity); | |
} | |
else // Read data from remote client | |
{ | |
Vector3 pos = Vector3.zero; | |
Vector3 velocity = Vector3.zero; | |
Quaternion rot = Quaternion.identity; | |
Vector3 angularVelocity = Vector3.zero; | |
stream.Serialize(ref pos); | |
stream.Serialize(ref velocity); | |
stream.Serialize(ref rot); | |
stream.Serialize(ref angularVelocity); | |
// Shift the buffer sideways, deleting state 20 | |
for (int i = m_BufferedState.Length - 1; i >= 1; i--) | |
{ | |
m_BufferedState[i] = m_BufferedState[i - 1]; | |
} | |
// Record current state in slot 0 | |
State state; | |
state.timestamp = info.timestamp; | |
state.pos = pos; | |
state.velocity = velocity; | |
state.rot = rot; | |
state.angularVelocity = angularVelocity; | |
m_BufferedState[0] = state; | |
// Update used slot count, however never exceed the buffer size | |
// Slots aren't actually freed so this just makes sure the buffer is | |
// filled up and that uninitalized slots aren't used. | |
m_TimestampCount = Mathf.Min(m_TimestampCount + 1, m_BufferedState.Length); | |
// Check if states are in order, if it is inconsistent you could reshuffel or | |
// drop the out-of-order state. Nothing is done here | |
for (int i = 0; i < m_TimestampCount - 1; i++) | |
{ | |
if (m_BufferedState[i].timestamp < m_BufferedState[i + 1].timestamp) | |
{ | |
Debug.Log("State inconsistent"); | |
} | |
} | |
} | |
} | |
// We have a window of interpolationBackTime where we basically play | |
// By having interpolationBackTime the average ping, you will usually use interpolation. | |
// And only if no more data arrives we will use extra polation | |
private void Update() | |
{ | |
// This is the target playback time of the rigid body | |
double interpolationTime = Network.time - m_InterpolationBackTime; | |
// Use interpolation if the target playback time is present in the buffer | |
if (m_BufferedState[0].timestamp > interpolationTime) | |
{ | |
// Go through buffer and find correct state to play back | |
for (int i = 0; i < m_TimestampCount; i++) | |
{ | |
if (m_BufferedState[i].timestamp <= interpolationTime || i == m_TimestampCount - 1) | |
{ | |
// The state one slot newer (<100ms) than the best playback state | |
State rhs = m_BufferedState[Mathf.Max(i - 1, 0)]; | |
// The best playback state (closest to 100 ms old (default time)) | |
State lhs = m_BufferedState[i]; | |
// Use the time between the two slots to determine if interpolation is necessary | |
double length = rhs.timestamp - lhs.timestamp; | |
float t = 0.0f; | |
// As the time difference gets closer to 100 ms t gets closer to 1 in | |
// which case rhs is only used | |
// Example: | |
// Time is 10.000, so sampleTime is 9.900 | |
// lhs.time is 9.910 rhs.time is 9.980 length is 0.070 | |
// t is 9.900 - 9.910 / 0.070 = 0.14. So it uses 14% of rhs, 86% of lhs | |
if (length > 0.0001) | |
{ | |
t = (float)((interpolationTime - lhs.timestamp) / length); | |
} | |
// if t=0 => lhs is used directly | |
transform.localPosition = Vector3.Lerp(lhs.pos, rhs.pos, t); | |
transform.localRotation = Quaternion.Slerp(lhs.rot, rhs.rot, t); | |
return; | |
} | |
} | |
} | |
else // Use extrapolation | |
{ | |
State latest = m_BufferedState[0]; | |
float extrapolationLength = (float)(interpolationTime - latest.timestamp); | |
// Don't extrapolation for more than 500 ms, you would need to do that carefully | |
if (extrapolationLength < m_ExtrapolationLimit) | |
{ | |
float axisLength = extrapolationLength * latest.angularVelocity.magnitude * Mathf.Rad2Deg; | |
Quaternion angularRotation = Quaternion.AngleAxis(axisLength, latest.angularVelocity); | |
if (rigidbody != null && !rigidbody.isKinematic) | |
{ | |
rigidbody.position = latest.pos + latest.velocity * extrapolationLength; | |
rigidbody.rotation = angularRotation * latest.rot; | |
rigidbody.velocity = latest.velocity; | |
rigidbody.angularVelocity = latest.angularVelocity; | |
} | |
} | |
} | |
} | |
} |
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