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using System;
using System.Runtime.InteropServices;
namespace Godot
{
[StructLayout(LayoutKind.Sequential)]
public struct Quat : IEquatable<Quat>
{
private static readonly Quat identity = new Quat(0f, 0f, 0f, 1f);
public float x;
public float y;
public float z;
public float w;
public static Quat Identity
{
get { return identity; }
}
public float this[int index]
{
get
{
switch (index)
{
case 0:
return x;
case 1:
return y;
case 2:
return z;
case 3:
return w;
default:
throw new IndexOutOfRangeException();
}
}
set
{
switch (index)
{
case 0:
x = value;
break;
case 1:
y = value;
break;
case 2:
z = value;
break;
case 3:
w = value;
break;
default:
throw new IndexOutOfRangeException();
}
}
}
public Quat cubic_slerp(Quat b, Quat preA, Quat postB, float t)
{
float t2 = (1.0f - t) * t * 2f;
Quat sp = slerp(b, t);
Quat sq = preA.slerpni(postB, t);
return sp.slerpni(sq, t2);
}
public float dot(Quat b)
{
return x * b.x + y * b.y + z * b.z + w * b.w;
}
public Quat inverse()
{
return new Quat(-x, -y, -z, w);
}
public float length()
{
return Mathf.sqrt(length_squared());
}
public float length_squared()
{
return dot(this);
}
public Quat normalized()
{
return this / length();
}
public void set(float x, float y, float z, float w)
{
this.x = x;
this.y = y;
this.z = z;
this.w = w;
}
public Quat slerp(Quat b, float t)
{
// Calculate cosine
float cosom = x * b.x + y * b.y + z * b.z + w * b.w;
float[] to1 = new float[4];
// Adjust signs if necessary
if (cosom < 0.0)
{
cosom = -cosom; to1[0] = -b.x;
to1[1] = -b.y;
to1[2] = -b.z;
to1[3] = -b.w;
}
else
{
to1[0] = b.x;
to1[1] = b.y;
to1[2] = b.z;
to1[3] = b.w;
}
float sinom, scale0, scale1;
// Calculate coefficients
if ((1.0 - cosom) > Mathf.Epsilon)
{
// Standard case (Slerp)
float omega = Mathf.acos(cosom);
sinom = Mathf.sin(omega);
scale0 = Mathf.sin((1.0f - t) * omega) / sinom;
scale1 = Mathf.sin(t * omega) / sinom;
}
else
{
// Quaternions are very close so we can do a linear interpolation
scale0 = 1.0f - t;
scale1 = t;
}
// Calculate final values
return new Quat
(
scale0 * x + scale1 * to1[0],
scale0 * y + scale1 * to1[1],
scale0 * z + scale1 * to1[2],
scale0 * w + scale1 * to1[3]
);
}
public Quat slerpni(Quat b, float t)
{
float dot = this.dot(b);
if (Mathf.abs(dot) > 0.9999f)
{
return this;
}
float theta = Mathf.acos(dot);
float sinT = 1.0f / Mathf.sin(theta);
float newFactor = Mathf.sin(t * theta) * sinT;
float invFactor = Mathf.sin((1.0f - t) * theta) * sinT;
return new Quat
(
invFactor * this.x + newFactor * b.x,
invFactor * this.y + newFactor * b.y,
invFactor * this.z + newFactor * b.z,
invFactor * this.w + newFactor * b.w
);
}
public Vector3 xform(Vector3 v)
{
Quat q = this * v;
q *= this.inverse();
return new Vector3(q.x, q.y, q.z);
}
public Quat(float x, float y, float z, float w)
{
this.x = x;
this.y = y;
this.z = z;
this.w = w;
}
public Quat(Vector3 axis, float angle)
{
float d = axis.length();
if (d == 0f)
{
x = 0f;
y = 0f;
z = 0f;
w = 0f;
}
else
{
float s = Mathf.sin(angle * 0.5f) / d;
x = axis.x * s;
y = axis.y * s;
z = axis.z * s;
w = Mathf.cos(angle * 0.5f);
}
}
public static Quat operator *(Quat left, Quat right)
{
return new Quat
(
left.w * right.x + left.x * right.w + left.y * right.z - left.z * right.y,
left.w * right.y + left.y * right.w + left.z * right.x - left.x * right.z,
left.w * right.z + left.z * right.w + left.x * right.y - left.y * right.x,
left.w * right.w - left.x * right.x - left.y * right.y - left.z * right.z
);
}
public static Quat operator +(Quat left, Quat right)
{
return new Quat(left.x + right.x, left.y + right.y, left.z + right.z, left.w + right.w);
}
public static Quat operator -(Quat left, Quat right)
{
return new Quat(left.x - right.x, left.y - right.y, left.z - right.z, left.w - right.w);
}
public static Quat operator -(Quat left)
{
return new Quat(-left.x, -left.y, -left.z, -left.w);
}
public static Quat operator *(Quat left, Vector3 right)
{
return new Quat
(
left.w * right.x + left.y * right.z - left.z * right.y,
left.w * right.y + left.z * right.x - left.x * right.z,
left.w * right.z + left.x * right.y - left.y * right.x,
-left.x * right.x - left.y * right.y - left.z * right.z
);
}
public static Quat operator *(Vector3 left, Quat right)
{
return new Quat
(
right.w * left.x + right.y * left.z - right.z * left.y,
right.w * left.y + right.z * left.x - right.x * left.z,
right.w * left.z + right.x * left.y - right.y * left.x,
-right.x * left.x - right.y * left.y - right.z * left.z
);
}
public static Quat operator *(Quat left, float right)
{
return new Quat(left.x * right, left.y * right, left.z * right, left.w * right);
}
public static Quat operator *(float left, Quat right)
{
return new Quat(right.x * left, right.y * left, right.z * left, right.w * left);
}
public static Quat operator /(Quat left, float right)
{
return left * (1.0f / right);
}
public static bool operator ==(Quat left, Quat right)
{
return left.Equals(right);
}
public static bool operator !=(Quat left, Quat right)
{
return !left.Equals(right);
}
public override bool Equals(object obj)
{
if (obj is Vector2)
{
return Equals((Vector2)obj);
}
return false;
}
public bool Equals(Quat other)
{
return x == other.x && y == other.y && z == other.z && w == other.w;
}
public override int GetHashCode()
{
return y.GetHashCode() ^ x.GetHashCode() ^ z.GetHashCode() ^ w.GetHashCode();
}
public override string ToString()
{
return String.Format("({0}, {1}, {2}, {3})", new object[]
{
this.x.ToString(),
this.y.ToString(),
this.z.ToString(),
this.w.ToString()
});
}
public string ToString(string format)
{
return String.Format("({0}, {1}, {2}, {3})", new object[]
{
this.x.ToString(format),
this.y.ToString(format),
this.z.ToString(format),
this.w.ToString(format)
});
}
}
}
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