axiosengine/axios/Common/Path.cs

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C#
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2012-03-19 23:57:59 +00:00
using System;
using System.Collections.Generic;
using System.Text;
using System.Xml.Serialization;
using Microsoft.Xna.Framework;
namespace FarseerPhysics.Common
{
//Contributed by Matthew Bettcher
/// <summary>
/// Path:
/// Very similar to Vertices, but this
/// class contains vectors describing
/// control points on a Catmull-Rom
/// curve.
/// </summary>
[XmlRoot("Path")]
public class Path
{
/// <summary>
/// All the points that makes up the curve
/// </summary>
[XmlElement("ControlPoints")]
public List<Vector2> ControlPoints;
private float _deltaT;
/// <summary>
/// Initializes a new instance of the <see cref="Path"/> class.
/// </summary>
public Path()
{
ControlPoints = new List<Vector2>();
}
/// <summary>
/// Initializes a new instance of the <see cref="Path"/> class.
/// </summary>
/// <param name="vertices">The vertices to created the path from.</param>
public Path(Vector2[] vertices)
{
ControlPoints = new List<Vector2>(vertices.Length);
for (int i = 0; i < vertices.Length; i++)
{
Add(vertices[i]);
}
}
/// <summary>
/// Initializes a new instance of the <see cref="Path"/> class.
/// </summary>
/// <param name="vertices">The vertices to created the path from.</param>
public Path(IList<Vector2> vertices)
{
ControlPoints = new List<Vector2>(vertices.Count);
for (int i = 0; i < vertices.Count; i++)
{
Add(vertices[i]);
}
}
/// <summary>
/// True if the curve is closed.
/// </summary>
/// <value><c>true</c> if closed; otherwise, <c>false</c>.</value>
[XmlElement("Closed")]
public bool Closed { get; set; }
/// <summary>
/// Gets the next index of a controlpoint
/// </summary>
/// <param name="index">The index.</param>
/// <returns></returns>
public int NextIndex(int index)
{
if (index == ControlPoints.Count - 1)
{
return 0;
}
return index + 1;
}
/// <summary>
/// Gets the previous index of a controlpoint
/// </summary>
/// <param name="index">The index.</param>
/// <returns></returns>
public int PreviousIndex(int index)
{
if (index == 0)
{
return ControlPoints.Count - 1;
}
return index - 1;
}
/// <summary>
/// Translates the control points by the specified vector.
/// </summary>
/// <param name="vector">The vector.</param>
public void Translate(ref Vector2 vector)
{
for (int i = 0; i < ControlPoints.Count; i++)
ControlPoints[i] = Vector2.Add(ControlPoints[i], vector);
}
/// <summary>
/// Scales the control points by the specified vector.
/// </summary>
/// <param name="value">The Value.</param>
public void Scale(ref Vector2 value)
{
for (int i = 0; i < ControlPoints.Count; i++)
ControlPoints[i] = Vector2.Multiply(ControlPoints[i], value);
}
/// <summary>
/// Rotate the control points by the defined value in radians.
/// </summary>
/// <param name="value">The amount to rotate by in radians.</param>
public void Rotate(float value)
{
Matrix rotationMatrix;
Matrix.CreateRotationZ(value, out rotationMatrix);
for (int i = 0; i < ControlPoints.Count; i++)
ControlPoints[i] = Vector2.Transform(ControlPoints[i], rotationMatrix);
}
public override string ToString()
{
StringBuilder builder = new StringBuilder();
for (int i = 0; i < ControlPoints.Count; i++)
{
builder.Append(ControlPoints[i].ToString());
if (i < ControlPoints.Count - 1)
{
builder.Append(" ");
}
}
return builder.ToString();
}
/// <summary>
/// Returns a set of points defining the
/// curve with the specifed number of divisions
/// between each control point.
/// </summary>
/// <param name="divisions">Number of divisions between each control point.</param>
/// <returns></returns>
public Vertices GetVertices(int divisions)
{
Vertices verts = new Vertices();
float timeStep = 1f / divisions;
for (float i = 0; i < 1f; i += timeStep)
{
verts.Add(GetPosition(i));
}
return verts;
}
public Vector2 GetPosition(float time)
{
Vector2 temp;
if (ControlPoints.Count < 2)
throw new Exception("You need at least 2 control points to calculate a position.");
if (Closed)
{
Add(ControlPoints[0]);
_deltaT = 1f / (ControlPoints.Count - 1);
int p = (int)(time / _deltaT);
// use a circular indexing system
int p0 = p - 1;
if (p0 < 0) p0 = p0 + (ControlPoints.Count - 1);
else if (p0 >= ControlPoints.Count - 1) p0 = p0 - (ControlPoints.Count - 1);
int p1 = p;
if (p1 < 0) p1 = p1 + (ControlPoints.Count - 1);
else if (p1 >= ControlPoints.Count - 1) p1 = p1 - (ControlPoints.Count - 1);
int p2 = p + 1;
if (p2 < 0) p2 = p2 + (ControlPoints.Count - 1);
else if (p2 >= ControlPoints.Count - 1) p2 = p2 - (ControlPoints.Count - 1);
int p3 = p + 2;
if (p3 < 0) p3 = p3 + (ControlPoints.Count - 1);
else if (p3 >= ControlPoints.Count - 1) p3 = p3 - (ControlPoints.Count - 1);
// relative time
float lt = (time - _deltaT * p) / _deltaT;
temp = Vector2.CatmullRom(ControlPoints[p0], ControlPoints[p1], ControlPoints[p2], ControlPoints[p3], lt);
RemoveAt(ControlPoints.Count - 1);
}
else
{
int p = (int)(time / _deltaT);
//
int p0 = p - 1;
if (p0 < 0) p0 = 0;
else if (p0 >= ControlPoints.Count - 1) p0 = ControlPoints.Count - 1;
int p1 = p;
if (p1 < 0) p1 = 0;
else if (p1 >= ControlPoints.Count - 1) p1 = ControlPoints.Count - 1;
int p2 = p + 1;
if (p2 < 0) p2 = 0;
else if (p2 >= ControlPoints.Count - 1) p2 = ControlPoints.Count - 1;
int p3 = p + 2;
if (p3 < 0) p3 = 0;
else if (p3 >= ControlPoints.Count - 1) p3 = ControlPoints.Count - 1;
// relative time
float lt = (time - _deltaT * p) / _deltaT;
temp = Vector2.CatmullRom(ControlPoints[p0], ControlPoints[p1], ControlPoints[p2], ControlPoints[p3], lt);
}
return temp;
}
/// <summary>
/// Gets the normal for the given time.
/// </summary>
/// <param name="time">The time</param>
/// <returns>The normal.</returns>
public Vector2 GetPositionNormal(float time)
{
float offsetTime = time + 0.0001f;
Vector2 a = GetPosition(time);
Vector2 b = GetPosition(offsetTime);
Vector2 output, temp;
Vector2.Subtract(ref a, ref b, out temp);
#if (XBOX360 || WINDOWS_PHONE)
output = new Vector2();
#endif
output.X = -temp.Y;
output.Y = temp.X;
Vector2.Normalize(ref output, out output);
return output;
}
public void Add(Vector2 point)
{
ControlPoints.Add(point);
_deltaT = 1f / (ControlPoints.Count - 1);
}
public void Remove(Vector2 point)
{
ControlPoints.Remove(point);
_deltaT = 1f / (ControlPoints.Count - 1);
}
public void RemoveAt(int index)
{
ControlPoints.RemoveAt(index);
_deltaT = 1f / (ControlPoints.Count - 1);
}
public float GetLength()
{
List<Vector2> verts = GetVertices(ControlPoints.Count * 25);
float length = 0;
for (int i = 1; i < verts.Count; i++)
{
length += Vector2.Distance(verts[i - 1], verts[i]);
}
if (Closed)
length += Vector2.Distance(verts[ControlPoints.Count - 1], verts[0]);
return length;
}
public List<Vector3> SubdivideEvenly(int divisions)
{
List<Vector3> verts = new List<Vector3>();
float length = GetLength();
float deltaLength = length / divisions + 0.001f;
float t = 0.000f;
// we always start at the first control point
Vector2 start = ControlPoints[0];
Vector2 end = GetPosition(t);
// increment t until we are at half the distance
while (deltaLength * 0.5f >= Vector2.Distance(start, end))
{
end = GetPosition(t);
t += 0.0001f;
if (t >= 1f)
break;
}
start = end;
// for each box
for (int i = 1; i < divisions; i++)
{
Vector2 normal = GetPositionNormal(t);
float angle = (float)Math.Atan2(normal.Y, normal.X);
verts.Add(new Vector3(end, angle));
// until we reach the correct distance down the curve
while (deltaLength >= Vector2.Distance(start, end))
{
end = GetPosition(t);
t += 0.00001f;
if (t >= 1f)
break;
}
if (t >= 1f)
break;
start = end;
}
return verts;
}
}
}