/// lhsIndex and rhsIndex are the indices in the keys array. The lhsIndex/rhsIndex may be -1, in which it creates a synthetic first key
/// at startTime, or beyond the length of the array, in which case it creates a synthetic key at endTime.
static private Keyframe EvalKeyAtTime([DisallowNull] NativeArray <Keyframe> keys, int lhsIndex, int rhsIndex, float startTime, float endTime, float currTime)
{
var lhsKey = KeyframeUtility.FetchKeyFromIndexClampEdge(keys, lhsIndex, startTime, endTime);
var rhsKey = KeyframeUtility.FetchKeyFromIndexClampEdge(keys, rhsIndex, startTime, endTime);
float currValue;
float currDeriv;
KeyframeUtility.EvalCurveSegmentAndDeriv(out currValue, out currDeriv, lhsKey, rhsKey, currTime);
return(new Keyframe(currTime, currValue, currDeriv, currDeriv));
}
/// <summary>
/// Interpolates two AnimationCurves. Since both curves likely have control points at different places
/// in the curve, this method will create a new curve from the union of times between both curves. However, to avoid creating
/// garbage, this function will always replace the keys of lhsAndResultCurve with the final result, and return lhsAndResultCurve.
/// </summary>
/// <param name="lhsAndResultCurve">The start value. Additionaly, this instance will be reused and returned as the result.</param>
/// <param name="rhsCurve">The end value.</param>
/// <param name="t">The interpolation factor in range [0,1].</param>
static public void InterpAnimationCurve(ref AnimationCurve lhsAndResultCurve, [DisallowNull] AnimationCurve rhsCurve, float t)
{
if (t <= 0.0f || rhsCurve.length == 0)
{
// no op. lhsAndResultCurve is already the result
}
else if (t >= 1.0f || lhsAndResultCurve.length == 0)
{
// In this case the obvous solution would be to return the rhsCurve. BUT (!) the lhsCurve and rhsCurve are different. This function is
// called by:
// stateParam.Interp(stateParam, toParam, interpFactor);
//
// stateParam (lhsCurve) is a temporary in/out parameter, but toParam (rhsCurve) might point to the original component, so it's unsafe to
// change that data. Thus, we need to copy the keys from the rhsCurve to the lhsCurve instead of returning rhsCurve.
KeyframeUtility.ResetAnimationCurve(lhsAndResultCurve);
for (int i = 0; i < rhsCurve.length; i++)
{
lhsAndResultCurve.AddKey(rhsCurve[i]);
}
lhsAndResultCurve.postWrapMode = rhsCurve.postWrapMode;
lhsAndResultCurve.preWrapMode = rhsCurve.preWrapMode;
}
else
{
// Note: If we reached this code, we are guaranteed that both lhsCurve and rhsCurve are valid with at least 1 key
// create a native array for the temp keys to avoid GC
var lhsCurveKeys = new NativeArray <Keyframe>(lhsAndResultCurve.length, Allocator.Temp);
var rhsCurveKeys = new NativeArray <Keyframe>(rhsCurve.length, Allocator.Temp);
for (int i = 0; i < lhsAndResultCurve.length; i++)
{
lhsCurveKeys[i] = lhsAndResultCurve[i];
}
for (int i = 0; i < rhsCurve.length; i++)
{
rhsCurveKeys[i] = rhsCurve[i];
}
float startTime = Mathf.Min(lhsCurveKeys[0].time, rhsCurveKeys[0].time);
float endTime = Mathf.Max(lhsCurveKeys[lhsAndResultCurve.length - 1].time, rhsCurveKeys[rhsCurve.length - 1].time);
// we don't know how many keys the resulting curve will have (because we will compact keys that are at the exact
// same time), but in most cases we will need the worst case number of keys. So allocate the worst case.
int maxNumKeys = lhsAndResultCurve.length + rhsCurve.length;
int currNumKeys = 0;
var dstKeys = new NativeArray <Keyframe>(maxNumKeys, Allocator.Temp);
int lhsKeyCurr = 0;
int rhsKeyCurr = 0;
while (lhsKeyCurr < lhsCurveKeys.Length || rhsKeyCurr < rhsCurveKeys.Length)
{
// the index is considered invalid once it goes off the end of the array
bool lhsValid = lhsKeyCurr < lhsCurveKeys.Length;
bool rhsValid = rhsKeyCurr < rhsCurveKeys.Length;
// it's actually impossible for lhsKey/rhsKey to be uninitialized, but have to
// add initialize here to prevent compiler erros
var lhsKey = new Keyframe();
var rhsKey = new Keyframe();
if (lhsValid && rhsValid)
{
lhsKey = GetKeyframeAndClampEdge(lhsCurveKeys, lhsKeyCurr);
rhsKey = GetKeyframeAndClampEdge(rhsCurveKeys, rhsKeyCurr);
if (lhsKey.time == rhsKey.time)
{
lhsKeyCurr++;
rhsKeyCurr++;
}
else if (lhsKey.time < rhsKey.time)
{
// in this case:
// rhsKey[curr-1].time <= lhsKey.time <= rhsKey[curr].time
// so interpolate rhsKey at the lhsKey.time.
rhsKey = KeyframeUtility.EvalKeyAtTime(rhsCurveKeys, rhsKeyCurr - 1, rhsKeyCurr, startTime, endTime, lhsKey.time);
lhsKeyCurr++;
}
else
{
// only case left is (lhsKey.time > rhsKey.time)
Assert.IsTrue(lhsKey.time > rhsKey.time);
// this is the reverse of the lhs key case
// lhsKey[curr-1].time <= rhsKey.time <= lhsKey[curr].time
// so interpolate lhsKey at the rhsKey.time.
lhsKey = KeyframeUtility.EvalKeyAtTime(lhsCurveKeys, lhsKeyCurr - 1, lhsKeyCurr, startTime, endTime, rhsKey.time);
rhsKeyCurr++;
}
}
else if (lhsValid)
{
// we are still processing lhsKeys, but we are out of rhsKeys, so increment lhs and evaluate rhs
lhsKey = GetKeyframeAndClampEdge(lhsCurveKeys, lhsKeyCurr);
// rhs will be evaluated between the last rhs key and the extrapolated rhs key at the end time
rhsKey = KeyframeUtility.EvalKeyAtTime(rhsCurveKeys, rhsKeyCurr - 1, rhsKeyCurr, startTime, endTime, lhsKey.time);
lhsKeyCurr++;
}
else
{
// either lhsValid is True, rhsValid is True, or they are both True. So to miss the first two cases,
// right here rhsValid must be true.
Assert.IsTrue(rhsValid);
// we still have rhsKeys to lerp, but we are out of lhsKeys, to increment rhs and evaluate lhs
rhsKey = GetKeyframeAndClampEdge(rhsCurveKeys, rhsKeyCurr);
// lhs will be evaluated between the last lhs key and the extrapolated lhs key at the end time
lhsKey = KeyframeUtility.EvalKeyAtTime(lhsCurveKeys, lhsKeyCurr - 1, lhsKeyCurr, startTime, endTime, rhsKey.time);
rhsKeyCurr++;
}
var dstKey = KeyframeUtility.LerpSingleKeyframe(lhsKey, rhsKey, t);
dstKeys[currNumKeys] = dstKey;
currNumKeys++;
}
// Replace the keys in lhsAndResultCurve with our interpolated curve.
KeyframeUtility.ResetAnimationCurve(lhsAndResultCurve);
for (int i = 0; i < currNumKeys; i++)
{
lhsAndResultCurve.AddKey(dstKeys[i]);
}
dstKeys.Dispose();
}
}