/// <summary>
/// Sets the value of this quaternion to one that represents rotation by given angle around Z-axis.
/// </summary>
/// <param name="r">Angle of rotation in radians.</param>
public void SetRotationAroundZ(float r)
{
float s, c;
MathHelpers.SinCos(r * 0.5f, out s, out c);
this.W = c;
this.V.X = 0;
this.V.Y = 0;
this.V.Z = s;
}
/// <summary>
/// Sets value of this quaternion to value that represents rotation to given vector from
/// <see cref="Vector3.Up" />(?) vector.
/// </summary>
/// <param name="vdir">
/// <see cref="Vector3" /> that represents direction to which we need to find a rotation.
/// </param>
/// <param name="r">Angle of rotation around forward axis to apply to new quaternion.</param>
/// <seealso cref="Quaternion.SetRotationToViewDirection(Vector3)"/>
public void SetRotationToViewDirection(Vector3 vdir, float r)
{
this.SetRotationToViewDirection(vdir);
float sy, cy; MathHelpers.SinCos(r * 0.5f, out sy, out cy);
float vx = this.V.X, vy = this.V.Y;
this.V.X = vx * cy - this.V.Z * sy;
this.V.Y = this.W * sy + vy * cy;
this.V.Z = this.V.Z * cy + vx * sy;
this.W = this.W * cy - vy * sy;
}
/// <summary>
/// Sets this matrix to represent rotation around fixed Axes.
/// </summary>
/// <param name="rad"><see cref="EulerAngles"/> that defines rotations around XYZ.</param>
public void SetRotationFromAngles(EulerAngles rad)
{
double sx, cx; MathHelpers.SinCos(rad.Pitch, out sx, out cx);
double sy, cy; MathHelpers.SinCos(rad.Roll, out sy, out cy);
double sz, cz; MathHelpers.SinCos(rad.Yaw, out sz, out cz);
double sycz = (sy * cz), sysz = (sy * sz);
this.M00 = (float)(cy * cz); this.M01 = (float)(sycz * sx - cx * sz); this.M02 = (float)(sycz * cx + sx * sz);
this.M10 = (float)(cy * sz); this.M11 = (float)(sysz * sx + cx * cz); this.M12 = (float)(sysz * cx - sx * cz);
this.M20 = (float)(-sy); this.M21 = (float)(cy * sx); this.M22 = (float)(cy * cx);
}
/// <summary>
/// Sets the value of this quaternion to one that represents rotation defined by Euler angles.
/// </summary>
/// <param name="angle"><see cref="Vector3" /> that defines Euler angles.</param>
public void SetRotationAroundXYZAxes(Vector3 angle)
{
float sx;
float cx;
MathHelpers.SinCos(angle.X * 0.5f, out sx, out cx);
float sy;
float cy;
MathHelpers.SinCos(angle.Y * 0.5f, out sy, out cy);
float sz;
float cz;
MathHelpers.SinCos(angle.Z * 0.5f, out sz, out cz);
this.W = cx * cy * cz + sx * sy * sz;
this.V.X = cz * cy * sx - sz * sy * cx;
this.V.Y = cz * sy * cx + sz * cy * sx;
this.V.Z = sz * cy * cx - cz * sy * sx;
}
