/// <summary>
/// Gets the previous point in the path. If this is the first point and
/// and the path is closed, this method will return the last point.
/// </summary>
/// <returns>The previous point.</returns>
/// <param name="point">Point.</param>
public BezierPointAttribute GetPreviousPoint(BezierPointAttribute point)
{
int index = m_Points.IndexOf(point);
return GetPreviousPoint(index);
}
/// <summary>
/// Creates a bezier circle path.
/// </summary>
/// <param name="radius">Radius.</param>
public static BezierPath Circle(float radius)
{
BezierPath path = CreateInstance<BezierPath>(null);
path.closed = true;
float controlDistance = radius * 4.0f * (s_Root2 - 1.0f) / 3.0f;
Quaternion offset = Quaternion.identity;
Quaternion increment = Quaternion.Euler(0.0f, 0.0f, 90.0f);
BezierPointAttribute[] points = new BezierPointAttribute[4];
for (int index = 0; index < 4; index++)
{
Vector3 position = Vector3.up * radius;
Vector3 inTangent = Vector3.right * controlDistance;
Vector3 outTangent = Vector3.left * controlDistance;
BezierPointAttribute point = BezierPointAttribute.CreateInstance<BezierPointAttribute>();
point.tangentMode = TangentMode.Smooth;
point.position = offset * position;
point.inTangent = offset * inTangent;
point.outTangent = offset * outTangent;
points[index] = point;
offset *= increment;
}
path.points = points;
return path;
}
/// <summary>
/// Provides the patch and patch delta for the given path delta.
/// </summary>
/// <param name="pointA">Point a.</param>
/// <param name="pointB">Point b.</param>
/// <param name="patchDelta">Patch delta.</param>
/// <param name="delta">Delta.</param>
private void PatchForDelta(out BezierPointAttribute pointA, out BezierPointAttribute pointB, out float patchDelta,
float delta)
{
int patches = m_Points.Length - 1;
if (m_Closed)
patches++;
if (patches < 1)
throw new Exception("No patches in the path!");
delta = Mathf.Repeat(delta, 1.0f);
int patchIndex = HydraMathUtils.FloorToInt(delta * patches);
pointA = m_Points[patchIndex];
pointB = GetNextPoint(patchIndex);
float singlePatchDelta = 1.0f / patches;
patchDelta = delta - (patchIndex * singlePatchDelta);
patchDelta *= patches;
}
/// <summary>
/// Returns the normal at the given non-linear delta.
/// </summary>
/// <returns>The normal vector.</returns>
/// <param name="pointA">Point a.</param>
/// <param name="pointB">Point b.</param>
/// <param name="delta">Delta.</param>
public Vector3 Normal(BezierPointAttribute pointA, BezierPointAttribute pointB, float delta)
{
Vector3 position = Interpolate(pointA, pointB, delta);
Vector3 tangent = Tangent(pointA, pointB, delta).normalized;
// Cheat to get the next point along the curve
float nextDelta = delta + NORMAL_INTERVAL;
Vector3 position2 = Interpolate(pointA, pointB, nextDelta);
Vector3 tangent2 = Tangent(pointA, pointB, nextDelta);
tangent2 -= (position2 - position);
tangent2 = tangent2.normalized;
Vector3 c =
new Vector3(tangent2.y * tangent.z - tangent2.z * tangent.y, tangent2.z * tangent.x - tangent2.x * tangent.z,
tangent2.x * tangent.y - tangent2.y * tangent.x).normalized;
Matrix4x4 r = Matrix4x4.identity;
r.SetRow(0, new Vector4(c.x * c.x, c.x * c.y - c.z, c.x * c.z + c.y));
r.SetRow(1, new Vector4(c.x * c.y + c.z, c.y * c.y, c.y * c.z - c.x));
r.SetRow(2, new Vector4(c.x * c.z - c.y, c.y * c.z + c.x, c.z * c.z));
return r.MultiplyVector(tangent);
}
/// <summary>
/// Returns the tangent at the given non-linear delta.
/// </summary>
/// <returns>The tangent vector.</returns>
/// <param name="pointA">Point a.</param>
/// <param name="pointB">Point b.</param>
/// <param name="delta">Delta.</param>
public Vector3 Tangent(BezierPointAttribute pointA, BezierPointAttribute pointB, float delta)
{
BezierPointAttribute previousPoint = GetPreviousPoint(pointA);
BezierPointAttribute nextPoint = GetNextPoint(pointB);
Vector3 outTangent = GetOutTangent(previousPoint, pointA, pointB);
Vector3 inTangent = GetInTangent(pointA, pointB, nextPoint);
float x = ComputeBezierDerivative(pointA.position.x, outTangent.x, inTangent.x, pointB.position.x, delta);
float y = ComputeBezierDerivative(pointA.position.y, outTangent.y, inTangent.y, pointB.position.y, delta);
float z = ComputeBezierDerivative(pointA.position.z, outTangent.z, inTangent.z, pointB.position.z, delta);
return new Vector3(x, y, z);
}
/// <summary>
/// Returns the positions on the curve between the two points at the given deltas.
///
/// This method is faster than calling Interpolate multiple times for the same patch.
/// </summary>
/// <returns>The interpolated positions.</returns>
/// <param name="output">Output.</param>
/// <param name="pointA">Point a.</param>
/// <param name="pointB">Point b.</param>
/// <param name="deltas">Deltas.</param>
public void Interpolate(ref Vector3[] output, BezierPointAttribute pointA, BezierPointAttribute pointB, float[] deltas)
{
BezierPointAttribute previousPoint = GetPreviousPoint(pointA);
BezierPointAttribute nextPoint = GetNextPoint(pointB);
Interpolate(ref output, previousPoint, pointA, pointB, nextPoint, deltas);
}
