/// <summary>
/// Transformを計算します。
/// </summary>
/// <param name="position">座標</param>
/// <param name="angle">角度（弧度法）</param>
/// <param name="scale">拡大率</param>
/// <returns></returns>
internal static Matrix44F CalcTransform(Vector2F position, float angle, Vector2F scale)
{
var matPosition = Matrix44F.GetTranslation2D(position);
var matRotate = Matrix44F.GetRotationZ(angle);
var matScale = Matrix44F.GetScale2D(scale);
return(matPosition * matRotate * matScale);
// NOTE: 一気に計算したほうがよさそう
}
/// <summary>
/// <see cref="Matrix44F"/>から2次元座標，拡大率，角度を算出します。
/// </summary>
/// <param name="transform">計算元となる4x4行列</param>
/// <param name="absolutePosition">出力される座標</param>
/// <param name="scale">出力される拡大率</param>
/// <param name="angle">出力される角度(度数法)</param>
public static void CalcFromTransform2D(Matrix44F transform, out Vector2F absolutePosition, out Vector2F scale, out float angle)
{
absolutePosition = new Vector2F(transform[0, 3], transform[1, 3]);
var sx = new Vector3F(transform[0, 0], transform[1, 0], transform[2, 0]).Length;
var sy = new Vector3F(transform[0, 1], transform[1, 1], transform[2, 1]).Length;
scale = new Vector2F(sx, sy);
transform *= Matrix44F.GetScale2D(new Vector2F(sx == 0 ? 1f : (1f / sx), sy == 0 ? 1f : (1f / sy)));
angle = new Vector2F(transform[0, 0], transform[1, 0]).Degree;
}
