/// <summary>
/// Builds a rotation 4 * 4 matrix created from an axis vector and an angle.
/// </summary>
/// <param name="m">The m.</param>
/// <param name="angle">The angle.</param>
/// <param name="v">The v.</param>
/// <returns></returns>
public static Matrix4f rotate(Matrix4f m, float angle, Vector3f v)
{
float c = Trigonometric.Cos(angle);
float s = Trigonometric.Sin(angle);
Vector3f axis = Geometric.Normalize(v);
Vector3f temp = (1.0f - c) * axis;
Matrix4f rotate = Matrix4f.identity();
rotate[0, 0] = c + temp[0] * axis[0];
rotate[0, 1] = 0 + temp[0] * axis[1] + s * axis[2];
rotate[0, 2] = 0 + temp[0] * axis[2] - s * axis[1];
rotate[1, 0] = 0 + temp[1] * axis[0] - s * axis[2];
rotate[1, 1] = c + temp[1] * axis[1];
rotate[1, 2] = 0 + temp[1] * axis[2] + s * axis[0];
rotate[2, 0] = 0 + temp[2] * axis[0] + s * axis[1];
rotate[2, 1] = 0 + temp[2] * axis[1] - s * axis[0];
rotate[2, 2] = c + temp[2] * axis[2];
Matrix4f result = Matrix4f.identity();
result[0] = m[0] * rotate[0][0] + m[1] * rotate[0][1] + m[2] * rotate[0][2];
result[1] = m[0] * rotate[1][0] + m[1] * rotate[1][1] + m[2] * rotate[1][2];
result[2] = m[0] * rotate[2][0] + m[1] * rotate[2][1] + m[2] * rotate[2][2];
result[3] = m[3];
return(result);
}
/// <summary>
/// Builds a perspective projection matrix based on a field of view.
/// </summary>
/// <param name="fov">The fov (in radians).</param>
/// <param name="width">The width.</param>
/// <param name="height">The height.</param>
/// <param name="zNear">The z near.</param>
/// <param name="zFar">The z far.</param>
/// <returns></returns>
/// <exception cref="System.ArgumentOutOfRangeException"></exception>
public static Matrix4f perspectiveFov(float fov, float width, float height, float zNear, float zFar)
{
if (width <= 0 || height <= 0 || fov <= 0)
{
throw new ArgumentOutOfRangeException();
}
var rad = fov;
var h = Trigonometric.Cos((0.5f) * rad) / Trigonometric.Sin((0.5f) * rad);
var w = h * height / width;
var result = new Matrix4f(0);
result[0, 0] = w;
result[1, 1] = h;
result[2, 2] = -(zFar + zNear) / (zFar - zNear);
result[2, 3] = -(1f);
result[3, 2] = -((2f) * zFar * zNear) / (zFar - zNear);
return(result);
}
