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#region License
/*
MIT License
Copyright © 2006 The Mono.Xna Team
All rights reserved.
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
*/
#endregion License
using System;
using System.ComponentModel;
namespace Microsoft.Xna.Framework
{
// TODO [TypeConverter(ExpandableObjectConverter)]
[Serializable]
public class Curve
{
#region Private Fields
private CurveKeyCollection keys;
private CurveLoopType postLoop;
private CurveLoopType preLoop;
#endregion Private Fields
#region Public Properties
public bool IsConstant
{
get { return this.keys.Count <= 1; }
}
public CurveKeyCollection Keys
{
get { return this.keys; }
}
public CurveLoopType PostLoop
{
get { return this.postLoop; }
set { this.postLoop = value; }
}
public CurveLoopType PreLoop
{
get { return this.preLoop; }
set { this.preLoop = value; }
}
#endregion Public Properties
#region Public Constructors
public Curve()
{
this.keys = new CurveKeyCollection();
}
#endregion Public Constructors
#region Public Methods
public Curve Clone()
{
Curve curve = new Curve();
curve.keys = this.keys.Clone();
curve.preLoop = this.preLoop;
curve.postLoop = this.postLoop;
return curve;
}
public float Evaluate(float position)
{
CurveKey first = keys[0];
CurveKey last = keys[keys.Count - 1];
if (position < first.Position)
{
switch (this.PreLoop)
{
case CurveLoopType.Constant:
//constant
return first.Value;
case CurveLoopType.Linear:
// linear y = a*x +b with a tangeant of last point
return first.Value - first.TangentIn * (first.Position - position);
case CurveLoopType.Cycle:
//start -> end / start -> end
int cycle = GetNumberOfCycle(position);
float virtualPos = position - (cycle * (last.Position - first.Position));
return GetCurvePosition(virtualPos);
case CurveLoopType.CycleOffset:
//make the curve continue (with no step) so must up the curve each cycle of delta(value)
cycle = GetNumberOfCycle(position);
virtualPos = position - (cycle * (last.Position - first.Position));
return (GetCurvePosition(virtualPos) + cycle * (last.Value - first.Value));
case CurveLoopType.Oscillate:
//go back on curve from end and target start
// start-> end / end -> start
cycle = GetNumberOfCycle(position);
if (0 == cycle % 2f)//if pair
virtualPos = position - (cycle * (last.Position - first.Position));
else
virtualPos = last.Position - position + first.Position + (cycle * (last.Position - first.Position));
return GetCurvePosition(virtualPos);
}
}
else if (position > last.Position)
{
int cycle;
switch (this.PostLoop)
{
case CurveLoopType.Constant:
//constant
return last.Value;
case CurveLoopType.Linear:
// linear y = a*x +b with a tangeant of last point
return last.Value + first.TangentOut * (position - last.Position);
case CurveLoopType.Cycle:
//start -> end / start -> end
cycle = GetNumberOfCycle(position);
float virtualPos = position - (cycle * (last.Position - first.Position));
return GetCurvePosition(virtualPos);
case CurveLoopType.CycleOffset:
//make the curve continue (with no step) so must up the curve each cycle of delta(value)
cycle = GetNumberOfCycle(position);
virtualPos = position - (cycle * (last.Position - first.Position));
return (GetCurvePosition(virtualPos) + cycle * (last.Value - first.Value));
case CurveLoopType.Oscillate:
//go back on curve from end and target start
// start-> end / end -> start
cycle = GetNumberOfCycle(position);
virtualPos = position - (cycle * (last.Position - first.Position));
if (0 == cycle % 2f)//if pair
virtualPos = position - (cycle * (last.Position - first.Position));
else
virtualPos = last.Position - position + first.Position + (cycle * (last.Position - first.Position));
return GetCurvePosition(virtualPos);
}
}
//in curve
return GetCurvePosition(position);
}
public void ComputeTangents (CurveTangent tangentType )
{
throw new NotImplementedException();
}
public void ComputeTangents( CurveTangent tangentInType, CurveTangent tangentOutType )
{
throw new NotImplementedException();
}
#endregion Public Methods
#region Private Methods
private int GetNumberOfCycle(float position)
{
float cycle = (position - keys[0].Position) / (keys[keys.Count - 1].Position - keys[0].Position);
if (cycle < 0f)
cycle--;
return (int)cycle;
}
private float GetCurvePosition(float position)
{
//only for position in curve
CurveKey prev = this.keys[0];
CurveKey next;
for (int i = 1; i < this.keys.Count; i++)
{
next = this.Keys[i];
if (next.Position >= position)
{
if (prev.Continuity == CurveContinuity.Step)
{
if (position >= 1f)
{
return next.Value;
}
return prev.Value;
}
float t = (position - prev.Position) / (next.Position - prev.Position);//to have t in [0,1]
float ts = t * t;
float tss = ts * t;
//After a lot of search on internet I have found all about spline function
// and bezier (phi'sss ancien) but finaly use hermite curve
//http://en.wikipedia.org/wiki/Cubic_Hermite_spline
//P(t) = (2*t^3 - 3t^2 + 1)*P0 + (t^3 - 2t^2 + t)m0 + (-2t^3 + 3t^2)P1 + (t^3-t^2)m1
//with P0.value = prev.value , m0 = prev.tangentOut, P1= next.value, m1 = next.TangentIn
return (2 * tss - 3 * ts + 1f) * prev.Value + (tss - 2 * ts + t) * prev.TangentOut + (3 * ts - 2 * tss) * next.Value + (tss - ts) * next.TangentIn;
}
prev = next;
}
return 0f;
}
#endregion
}
}
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